Went to the range today to try out some subsonic loads. I loaded 10 of each different powder weight to find the best shooting one. I was using Sierra .30cal 220gr. RN bullets, new Winchester brass, Federal 210M primers, and TrailBoss powder, using my Savage 10FLP .308 w/ 24" barrel. I loaded them in 0.5gr increments from 9.5-11.5gr as per suggestions from the subsonic load page in the reloading section. The result were rather disappointing. With 11.5gr. I was only getting ~780fps and 10.5gr resulted in a stuck bullet which was thankfully easily tapped out with a rod. In addition to that my average velocities were all over the place with 50-80fps spread at times, even though I double checked all my charges with a beam scale and electronic scale. Not sure what's all going on here but it looks like I need to go back to the drawing board.
Range Report Subsonic load development
- Thread starter Luke
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Re: Subsonic load development
Similar to my experience. The lack of case fill leads to wildly different velocities, depending on how the powder is laying in the case when the trigger is pulled. I've stopped trying.
Similar to my experience. The lack of case fill leads to wildly different velocities, depending on how the powder is laying in the case when the trigger is pulled. I've stopped trying.
Re: Subsonic load development
guys you have to use a filler on top to keep it more consistant on the ignition... WP
guys you have to use a filler on top to keep it more consistant on the ignition... WP
Re: Subsonic load development
I did some testing a while back with Unique, and 220 RN in my 308. Velocities were consistent but my 1/12 twist was not quite stabilizing them. Holes were oval at 100 yards, about 2.0 moa accuracy.
Let me see if I can dredge up the thread.
I did some testing a while back with Unique, and 220 RN in my 308. Velocities were consistent but my 1/12 twist was not quite stabilizing them. Holes were oval at 100 yards, about 2.0 moa accuracy.
Let me see if I can dredge up the thread.
Re: Subsonic load development
10.8gr Unique was getting me 1050 fps in milsurp brass.
http://www.snipershide.com/forum/ubbthre...true#Post507912
10.8gr Unique was getting me 1050 fps in milsurp brass.
http://www.snipershide.com/forum/ubbthre...true#Post507912
Re: Subsonic load development
Unique is an ideal powder for 'microloads'.
There are several ways to deal with the free case volume issue. One is to use a filler. I don't. If I did, it would be grits/cream farina.
One is to tip the rifle muzzle up just prior to each shot, to establish some consistency in powder distribution within the case shot-to-shot.
The last, and I think best, is to use a case with less free capacity. I think the 7.62x39 case is a lot more ideal for .30cal subsonics than a .308. Lapua makes brass for 7.62x39, mine has the K-P headstamp for their USA affiliate Kaltron-Pettibone.
When I'm loading 'loopers', as I call them, a heavy boat tailed bullet is loaded backwards, to achieve two goals. First, the teardrop shape approximation is more aerodynamically efficient and stable in the purely subsonic regime, and secondly, the pointy end fills some of the free volume, without putting the full diameter of the ogive below the neck/shoulder junction.
I have used the 'wet bore' method with heavy BT's backward in a 7.62x39 Mauser bolt gun with no silencer, and the damned things are surprisingly 'quiet'. Since there is a calculated risk in using this method, I will direct you elsewhere for further particulars.
Greg
Unique is an ideal powder for 'microloads'.
There are several ways to deal with the free case volume issue. One is to use a filler. I don't. If I did, it would be grits/cream farina.
One is to tip the rifle muzzle up just prior to each shot, to establish some consistency in powder distribution within the case shot-to-shot.
The last, and I think best, is to use a case with less free capacity. I think the 7.62x39 case is a lot more ideal for .30cal subsonics than a .308. Lapua makes brass for 7.62x39, mine has the K-P headstamp for their USA affiliate Kaltron-Pettibone.
When I'm loading 'loopers', as I call them, a heavy boat tailed bullet is loaded backwards, to achieve two goals. First, the teardrop shape approximation is more aerodynamically efficient and stable in the purely subsonic regime, and secondly, the pointy end fills some of the free volume, without putting the full diameter of the ogive below the neck/shoulder junction.
I have used the 'wet bore' method with heavy BT's backward in a 7.62x39 Mauser bolt gun with no silencer, and the damned things are surprisingly 'quiet'. Since there is a calculated risk in using this method, I will direct you elsewhere for further particulars.
Greg
Re: Subsonic load development
how was your group with this method
how was your group with this method
Re: Subsonic load development
Also forgot to say the last post, use malt o meal for the filler. works great just sub the differance. I also noted you only need to use maybe 70% of what you are short WP
Also forgot to say the last post, use malt o meal for the filler. works great just sub the differance. I also noted you only need to use maybe 70% of what you are short WP
Re: Subsonic load development
I think those 220's are gonna need more powder, along the lines of 12.5-13.5 grains or possibly better, especially with a 24" tube. Have you tried any lighter weight bullets? I use 170 Hornady flat points with 10.0 gr of Trailboss (& no filler) and have had very good accuracy. I know of a couple of guys using the 180 Hornady RN and 10.0-10.2 gr Trailboss (also with no fller) with good results (sub MOA) too. We all run 16" or shorter barrels though, so YMMV. Also try using large pistol primers, not rifle primers. The bullet seating depth will play havoc with subsonic loads as well, just have to play around with that. Good luck and don't get discouraged with it just yet!
I think those 220's are gonna need more powder, along the lines of 12.5-13.5 grains or possibly better, especially with a 24" tube. Have you tried any lighter weight bullets? I use 170 Hornady flat points with 10.0 gr of Trailboss (& no filler) and have had very good accuracy. I know of a couple of guys using the 180 Hornady RN and 10.0-10.2 gr Trailboss (also with no fller) with good results (sub MOA) too. We all run 16" or shorter barrels though, so YMMV. Also try using large pistol primers, not rifle primers. The bullet seating depth will play havoc with subsonic loads as well, just have to play around with that. Good luck and don't get discouraged with it just yet!
Re: Subsonic load development
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ggarrett1911</div><div class="ubbcode-body">I think those 220's are gonna need more powder, along the lines of 12.5-13.5 grains or possibly better, especially with a 24" tube. Have you tried any lighter weight bullets? I use 170 Hornady flat points with 10.0 gr of Trailboss (& no filler) and have had very good accuracy. I know of a couple of guys using the 180 Hornady RN and 10.0-10.2 gr Trailboss (also with no fller) with good results (sub MOA) too. We all run 16" or shorter barrels though, so YMMV. <span style="font-weight: bold">Also try using large pistol primers, not rifle primers. </span>The bullet seating depth will play havoc with subsonic loads as well, just have to play around with that. Good luck and don't get discouraged with it just yet! </div></div>
What is the advantage with the pistol primers? I use 210m's but am always looking for something better.
I am one of the 180gr RN/10.2grs of Trail Boss users.
thanks,
Keith
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ggarrett1911</div><div class="ubbcode-body">I think those 220's are gonna need more powder, along the lines of 12.5-13.5 grains or possibly better, especially with a 24" tube. Have you tried any lighter weight bullets? I use 170 Hornady flat points with 10.0 gr of Trailboss (& no filler) and have had very good accuracy. I know of a couple of guys using the 180 Hornady RN and 10.0-10.2 gr Trailboss (also with no fller) with good results (sub MOA) too. We all run 16" or shorter barrels though, so YMMV. <span style="font-weight: bold">Also try using large pistol primers, not rifle primers. </span>The bullet seating depth will play havoc with subsonic loads as well, just have to play around with that. Good luck and don't get discouraged with it just yet! </div></div>
What is the advantage with the pistol primers? I use 210m's but am always looking for something better.
I am one of the 180gr RN/10.2grs of Trail Boss users.
thanks,
Keith
Re: Subsonic load development
I have used, and prefer a magnum rifle primer for sub loads.
My logic is a more intense/uniform ignition will reduce the possibility of what I've heard referred to a "flashover" where the powder ignites with less uniformity and quirky pressures may occur.
I have used, and prefer a magnum rifle primer for sub loads.
My logic is a more intense/uniform ignition will reduce the possibility of what I've heard referred to a "flashover" where the powder ignites with less uniformity and quirky pressures may occur.
Re: Subsonic load development
I managed to reduce my velocity deviation by applying an oil patch to the bore before the first round and then rubbing a bit of oil on each bullet before firing. The first round is usually fast if I use too much oil, but thereafter, my spread is 30-40 fps max over a box of 50 rds. I'm just tossing charges with my Chargemaster. Groups are typically just over 1". Without the oil, they're 1.5-2.5" and the first round is always 5" low.
I managed to reduce my velocity deviation by applying an oil patch to the bore before the first round and then rubbing a bit of oil on each bullet before firing. The first round is usually fast if I use too much oil, but thereafter, my spread is 30-40 fps max over a box of 50 rds. I'm just tossing charges with my Chargemaster. Groups are typically just over 1". Without the oil, they're 1.5-2.5" and the first round is always 5" low.
Re: Subsonic load development
I use pistol primers to reduce velocity spread. This has been tested (not personally) back to back with rifle primers and shown spreads considerably smaller then rifle primers (5-12 fps spread vs 20's & up for LR primers). Luke, try 10 or 20 rounds with pistol primers and the same amount with rifle primers and just see if makes a difference for your setup. Also are you crimping your loads? If not that could explain a lot of your large velocity variation. Work your seating depth just like a normal round, load up a dummy cartridge, find max OAL to the lands and start backing them off .005" or .010" from there until you find a sweet spot (every rifle will be different but mine end up with the crimp just shy of the cannelure on the 170's, 2.560" IIRC). You're putting a lot of bullet down in the case with the 220's so with 13+ grains of Trailboss be mindful you aren't compressing the hell out of the load. Hope this helps you out, but you might just want to try some 170 or 180gr bullets next time, they seem to be a LOT more forgiving. Good luck!
As always: IMHO, YMMV, etc, etc, etc....
I use pistol primers to reduce velocity spread. This has been tested (not personally) back to back with rifle primers and shown spreads considerably smaller then rifle primers (5-12 fps spread vs 20's & up for LR primers). Luke, try 10 or 20 rounds with pistol primers and the same amount with rifle primers and just see if makes a difference for your setup. Also are you crimping your loads? If not that could explain a lot of your large velocity variation. Work your seating depth just like a normal round, load up a dummy cartridge, find max OAL to the lands and start backing them off .005" or .010" from there until you find a sweet spot (every rifle will be different but mine end up with the crimp just shy of the cannelure on the 170's, 2.560" IIRC). You're putting a lot of bullet down in the case with the 220's so with 13+ grains of Trailboss be mindful you aren't compressing the hell out of the load. Hope this helps you out, but you might just want to try some 170 or 180gr bullets next time, they seem to be a LOT more forgiving. Good luck!
As always: IMHO, YMMV, etc, etc, etc....
Re: Subsonic load development
Subsonic BT bullets grouped virtually the same backward as forward, which wasn't super in either case. I did the testing on a very superficial basis well over ten years ago, and never followed it up as I never had any sort of practical application for the data. I don't even own the 7.62x39 Century Arms low quality Mauser anymore. You really need to get your info from somebody with more current experience.
Greg
Subsonic BT bullets grouped virtually the same backward as forward, which wasn't super in either case. I did the testing on a very superficial basis well over ten years ago, and never followed it up as I never had any sort of practical application for the data. I don't even own the 7.62x39 Century Arms low quality Mauser anymore. You really need to get your info from somebody with more current experience.
Greg
Re: Subsonic load development
Just a quick update. I loaded up some more with 12.5gr-14gr. Trailboss and had much better success. 13gr. of Trailboss gave me ~970fps with about 20fps spread, and the groups were roughly 1-1.5MOA. They're still not shooting quite as pretty as I would like but it's a start anyway. Thanks for all your help.
Just a quick update. I loaded up some more with 12.5gr-14gr. Trailboss and had much better success. 13gr. of Trailboss gave me ~970fps with about 20fps spread, and the groups were roughly 1-1.5MOA. They're still not shooting quite as pretty as I would like but it's a start anyway. Thanks for all your help.
Re: Subsonic load development
How consistent is your velocity?
How consistent is your velocity?
Re: Subsonic load development
I'd try to get velocity up to 1040-1050 fps. It will add bit more rpm, and that may tighten up accuracy a bit.
I'd try to get velocity up to 1040-1050 fps. It will add bit more rpm, and that may tighten up accuracy a bit.
Re: Subsonic load development
Did you do anything other than bump up the charge weight to get the velocity that consistent? Pistol primers, oil, etc... ? Are you seeing a lower velocity on the first round?
Did you do anything other than bump up the charge weight to get the velocity that consistent? Pistol primers, oil, etc... ? Are you seeing a lower velocity on the first round?
Re: Subsonic load development
Been doing some thinking about the 'wet bore' method.
I think it's generally accepted that bore friction retards the bullet, allowing pressure to build. Lube reduces friction, retardation, and pressure. This keeps velocity (as well as report and possibly even flash) down.
Water is just another form of lube. I suspect that treating the bore with <span style="font-style: italic">anything</span> that reduces friction is going to produce the above effects.
I wonder what pretreating the bore with an application of oil and graphite would achieve. Subsequent rounds would strip this, but if a significant amount of graphite were added to the propellent, it might be possible to maintain a relatively steady state of lubrication, shot to shot.
I prefer oil and graphite because they are non-(or less)-corrosive, and largely common to bores anyway.
Just a thought.
Greg
Been doing some thinking about the 'wet bore' method.
I think it's generally accepted that bore friction retards the bullet, allowing pressure to build. Lube reduces friction, retardation, and pressure. This keeps velocity (as well as report and possibly even flash) down.
Water is just another form of lube. I suspect that treating the bore with <span style="font-style: italic">anything</span> that reduces friction is going to produce the above effects.
I wonder what pretreating the bore with an application of oil and graphite would achieve. Subsequent rounds would strip this, but if a significant amount of graphite were added to the propellent, it might be possible to maintain a relatively steady state of lubrication, shot to shot.
I prefer oil and graphite because they are non-(or less)-corrosive, and largely common to bores anyway.
Just a thought.
Greg
Re: Subsonic load development
The velocty became more consistant simply by increasing the charge. I tried lightly oiling a few of the bullets but didn't see any difference between the oiled/dry bullets. I didn't see any drop in velocity on the first round either. It was actually more on the high end of the spread.
The velocty became more consistant simply by increasing the charge. I tried lightly oiling a few of the bullets but didn't see any difference between the oiled/dry bullets. I didn't see any drop in velocity on the first round either. It was actually more on the high end of the spread.
Re: Subsonic load development
OK, good to know. Any other viewpoints?
OK, good to know. Any other viewpoints?
Re: Subsonic load development
I'm guessing that the longer bullet and bigger charger has something to do with it.
Luke, if you shake a loaded case, can you hear powder moving around?
I get smaller groups with Titegroup than with Trailboss (180 RN bullets), but both suffer from the first round velocity drop if I don't lube the bore and oil the bullets. Heard the same thing happens with 150 RN bullets.
I'm guessing that the longer bullet and bigger charger has something to do with it.
Luke, if you shake a loaded case, can you hear powder moving around?
I get smaller groups with Titegroup than with Trailboss (180 RN bullets), but both suffer from the first round velocity drop if I don't lube the bore and oil the bullets. Heard the same thing happens with 150 RN bullets.
Re: Subsonic load development
I can still hear the powder when I shake it and could load a little heavier charge before they would begin to compress.
After looking over my notes the results aren't as clear as I had originally thought. I loaded and shot 5 rounds of each charge:
12.5gr Trailboss = Avg: 923fps Max: 939fps Min: 909fps.
13.0gr Trailboss = Avg: 959fps Max: 977fps Min: 932fps.
13.5gr Trailboss = Avg: 1008fps Max: 1053fps Min: 963fps.
14.0gr Trailboss = Avg: 977fps Max: 1020fps Min: 890fps.
I can still hear the powder when I shake it and could load a little heavier charge before they would begin to compress.
After looking over my notes the results aren't as clear as I had originally thought. I loaded and shot 5 rounds of each charge:
12.5gr Trailboss = Avg: 923fps Max: 939fps Min: 909fps.
13.0gr Trailboss = Avg: 959fps Max: 977fps Min: 932fps.
13.5gr Trailboss = Avg: 1008fps Max: 1053fps Min: 963fps.
14.0gr Trailboss = Avg: 977fps Max: 1020fps Min: 890fps.
Re: Subsonic load development
I suspect that bullet bearing surface is at issue here, IMHO, the RN's have more than the HPBT's, whichever direction you run them. IMHO, the bullet with the lesser bearing surface could be the winner.
Greg
I suspect that bullet bearing surface is at issue here, IMHO, the RN's have more than the HPBT's, whichever direction you run them. IMHO, the bullet with the lesser bearing surface could be the winner.
Greg
Re: Subsonic load development
I have about 250lbs of 175's, and a box of 190gr, and 200gr SMK's I could still play with. I was hoping I could get those round nose Sierra's to work for their low velocity BC and lead point for terminal effects. I could also give those 180gr. RN's a try but I don't have any on hand.
I have about 250lbs of 175's, and a box of 190gr, and 200gr SMK's I could still play with. I was hoping I could get those round nose Sierra's to work for their low velocity BC and lead point for terminal effects. I could also give those 180gr. RN's a try but I don't have any on hand.
Re: Subsonic load development
I'm tempted to try the 168 SMK with Titegroups simply because its listed as a subsonic load on the Hodgdon site.
I'm tempted to try the 168 SMK with Titegroups simply because its listed as a subsonic load on the Hodgdon site.
Re: Subsonic load development
Think of a reversed lockbase bullet as a huge hollowpoint.
Greg
Think of a reversed lockbase bullet as a huge hollowpoint.
Greg
Re: Subsonic load development
For what it's worth, When you guys are hand loading for .308 and using the Trailboss. I have done a shitload of those. I could do several loaded rounds and all with the same powder charge but would only change the seating depth. Seating would change the Vel. bigtime because the trailboss is very case-volume sensitive. I don't do the trailboss-308 anymore as I have a dedicated bolt for 30-221. but I had pretty good results with trailboss-.308 cal.
Also what others have said in earlier post too. I always tap the loaded case on the bottom before single loading as to (try) and get all the powder in the same spot when shooting. For good consistent ignition.
I am sitting down latter today and try to do up a (Winter only) 30-221 load and do shooting. I think It is now going to be a must for my subsonic .30 cal. to have a Summer & Winter weather load worked-up as I like to have several hundred loaded rounds made-up @ a time.
Was out yesterday with the subs in 240 grn and 30-221, suppressed out a bolt gun. I had a bunch pop over the speed limit and crack even though several months earlier they were not popping over and cracking using the same box of loads.
Yesterday was cold, dark, damp and foggy. so I would say that you need to take in consideration of the outside weather in consistency of the Vel. with subsonic.
I also see inconsistency of Vel. and POI with my suppressed .22 rimfires with lubes lead on match ammo. Lubes are finicky for Temp. and that's why manufactures offer cold weather, match-ammo .22 with special lubes to accommodate.
For what it's worth, When you guys are hand loading for .308 and using the Trailboss. I have done a shitload of those. I could do several loaded rounds and all with the same powder charge but would only change the seating depth. Seating would change the Vel. bigtime because the trailboss is very case-volume sensitive. I don't do the trailboss-308 anymore as I have a dedicated bolt for 30-221. but I had pretty good results with trailboss-.308 cal.
Also what others have said in earlier post too. I always tap the loaded case on the bottom before single loading as to (try) and get all the powder in the same spot when shooting. For good consistent ignition.
I am sitting down latter today and try to do up a (Winter only) 30-221 load and do shooting. I think It is now going to be a must for my subsonic .30 cal. to have a Summer & Winter weather load worked-up as I like to have several hundred loaded rounds made-up @ a time.
Was out yesterday with the subs in 240 grn and 30-221, suppressed out a bolt gun. I had a bunch pop over the speed limit and crack even though several months earlier they were not popping over and cracking using the same box of loads.
Yesterday was cold, dark, damp and foggy. so I would say that you need to take in consideration of the outside weather in consistency of the Vel. with subsonic.
I also see inconsistency of Vel. and POI with my suppressed .22 rimfires with lubes lead on match ammo. Lubes are finicky for Temp. and that's why manufactures offer cold weather, match-ammo .22 with special lubes to accommodate.
Re: Subsonic load development
you asking about trailboss use or 30-221 powder choices ?
I think that trailboss is the best choice out there for filling case volume in doing .308 case in subsonic Vel. . The stuff is fluffy doughnuts in shape.
In 30-221 subsonic I have only worked with, A-# 9 (mag. pistol powder) as it seems to do pretty well for me. The 240 grain sierra is taller than the 30-221 case and takes a good bite out the case volume on that one.
.
you asking about trailboss use or 30-221 powder choices ?
I think that trailboss is the best choice out there for filling case volume in doing .308 case in subsonic Vel. . The stuff is fluffy doughnuts in shape.
In 30-221 subsonic I have only worked with, A-# 9 (mag. pistol powder) as it seems to do pretty well for me. The 240 grain sierra is taller than the 30-221 case and takes a good bite out the case volume on that one.
.
Re: Subsonic load development
(I may be wrong) ?. but I think that slow burn rate like that in not recommended and maybe unsafe. You need a fast burn rate + volume. As the most ideal situation, but I could not be remembering right so don't quote me on that.
.
(I may be wrong) ?. but I think that slow burn rate like that in not recommended and maybe unsafe. You need a fast burn rate + volume. As the most ideal situation, but I could not be remembering right so don't quote me on that.
.
Re: Subsonic load development
i have a yhm can i have used 10gr trailboss with 220 gr round nose and 180 gr with great results
i have a yhm can i have used 10gr trailboss with 220 gr round nose and 180 gr with great results
Re: Subsonic load development
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: kombayotch</div><div class="ubbcode-body">Did you do anything other than bump up the charge weight to get the velocity that consistent? Pistol primers, oil, etc... ? Are you seeing a lower velocity on the first round? </div></div>
I have found that my first round actually drops about 2" <span style="font-weight: bold">LESS </span>than the following shots.
Keith
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: kombayotch</div><div class="ubbcode-body">Did you do anything other than bump up the charge weight to get the velocity that consistent? Pistol primers, oil, etc... ? Are you seeing a lower velocity on the first round? </div></div>
I have found that my first round actually drops about 2" <span style="font-weight: bold">LESS </span>than the following shots.
Keith
Re: Subsonic load development
Treat the cartridge load development as if you were working up a pistol load.
Some weights and pressures, same empty case volume issues, the extra barrel length is not really an issue. For sound and flash reasons, you really want the charge to do its burn in the first, pistol length, portion of the barrel, anyway.
IMHO, perhaps what you really want to be doing is working with a large bore pistol cartridge to begin with, like a .44 Mag, or a .45ACP. The .45ACP is already subsonic, and the .44Mag can be downloaded to subsonic. Whole lot less finagling involved.
Greg
Treat the cartridge load development as if you were working up a pistol load.
Some weights and pressures, same empty case volume issues, the extra barrel length is not really an issue. For sound and flash reasons, you really want the charge to do its burn in the first, pistol length, portion of the barrel, anyway.
IMHO, perhaps what you really want to be doing is working with a large bore pistol cartridge to begin with, like a .44 Mag, or a .45ACP. The .45ACP is already subsonic, and the .44Mag can be downloaded to subsonic. Whole lot less finagling involved.
Greg
Re: Subsonic load development
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: KS</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: kombayotch</div><div class="ubbcode-body">Did you do anything other than bump up the charge weight to get the velocity that consistent? Pistol primers, oil, etc... ? Are you seeing a lower velocity on the first round? </div></div>
I have found that my first round actually drops about 2" <span style="font-weight: bold">LESS </span>than the following shots.
Keith </div></div>
Interesting... what are the specifics of your load? COAL, distance from the lands, etc...
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: KS</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: kombayotch</div><div class="ubbcode-body">Did you do anything other than bump up the charge weight to get the velocity that consistent? Pistol primers, oil, etc... ? Are you seeing a lower velocity on the first round? </div></div>
I have found that my first round actually drops about 2" <span style="font-weight: bold">LESS </span>than the following shots.
Keith </div></div>
Interesting... what are the specifics of your load? COAL, distance from the lands, etc...
Re: Subsonic load development
It may have to do with how much time there was between shooting the groups. Without lube, I notice the velocity drops when the barrel is cool. Did you fire the 13.5 gr. right after the previous group and then wait or clean prior to firing the 14.0 gr. group?
It may have to do with how much time there was between shooting the groups. Without lube, I notice the velocity drops when the barrel is cool. Did you fire the 13.5 gr. right after the previous group and then wait or clean prior to firing the 14.0 gr. group?
Re: Subsonic load development
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Greg Langelius *</div><div class="ubbcode-body">Think of a reversed lockbase bullet as a huge hollowpoint.
Greg </div></div>
I'm going to try this with 147 gr. Winchesters when I run out of 180 RN bullets. It takes less powder going from a boat tail to a flat base, so I imagine the opposite is true when turning the bullet upside down. How much more powder do you have to add to maintain the velocity? Anyone doing this with SMKs?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Greg Langelius *</div><div class="ubbcode-body">Think of a reversed lockbase bullet as a huge hollowpoint.
Greg </div></div>
I'm going to try this with 147 gr. Winchesters when I run out of 180 RN bullets. It takes less powder going from a boat tail to a flat base, so I imagine the opposite is true when turning the bullet upside down. How much more powder do you have to add to maintain the velocity? Anyone doing this with SMKs?
Re: Subsonic load development
As with any new load, start low, work up. Since you're already low, at least don't start by going up.
Greg
As with any new load, start low, work up. Since you're already low, at least don't start by going up.
Greg
Re: Subsonic load development
I thought the general wisdom on subsonic load development was to start higher and work down in order to avoid getting a bullet stuck in the barrel.
I thought the general wisdom on subsonic load development was to start higher and work down in order to avoid getting a bullet stuck in the barrel.
Re: Subsonic load development
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: kombayotch</div><div class="ubbcode-body">I thought the general wisdom on subsonic load development was to start higher and work down in order to avoid getting a bullet stuck in the barrel. </div></div>
It is........
Keith
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: kombayotch</div><div class="ubbcode-body">I thought the general wisdom on subsonic load development was to start higher and work down in order to avoid getting a bullet stuck in the barrel. </div></div>
It is........
Keith
Re: Subsonic load development
I run the Hornady 180 gr.RN bullet in front of 10.8 TB, Fed. case, CCI LR primer. No fill and no problems. Vel. runs 1040- 1050 out of my .308 LTR. (20")
I run the Hornady 180 gr.RN bullet in front of 10.8 TB, Fed. case, CCI LR primer. No fill and no problems. Vel. runs 1040- 1050 out of my .308 LTR. (20")
Re: Subsonic load development
Luke,
Are you using new brass in your search for a subsonic load? It would seem logical that a low pressure load using energy to fireform the brass to the chamber might cause pressure/velocity variances. I haven't tried any new brass for subsonic loads, however, my .308 hunting load impacts 3" lower at 500 yds. than the same load in fireformed brass!
My subsonic cold bore shots are at POA and are in the group. My load is similar to Hogshooters.
Lapua brass drilled 9/64"
F215M primers
180 gr. Hornady RN / stability factor of 3.42
9.8 gr. Trail Boss = 950 fps
1/2 MOA or better accuracy at 100 yds.
11.0 gr. = 1075 fps. down to 9.6 gr. = 920 fps.
I didn't go below 9.6 gr. My most consistent accuracy was at 9.8.
This is from an 18" 1 in 11 twist Broughton barrel with a SWR Omega.
I'm certainly no expert on this or any other subject. Just my observations.
Hope this helps.
Luke,
Are you using new brass in your search for a subsonic load? It would seem logical that a low pressure load using energy to fireform the brass to the chamber might cause pressure/velocity variances. I haven't tried any new brass for subsonic loads, however, my .308 hunting load impacts 3" lower at 500 yds. than the same load in fireformed brass!
My subsonic cold bore shots are at POA and are in the group. My load is similar to Hogshooters.
Lapua brass drilled 9/64"
F215M primers
180 gr. Hornady RN / stability factor of 3.42
9.8 gr. Trail Boss = 950 fps
1/2 MOA or better accuracy at 100 yds.
11.0 gr. = 1075 fps. down to 9.6 gr. = 920 fps.
I didn't go below 9.6 gr. My most consistent accuracy was at 9.8.
This is from an 18" 1 in 11 twist Broughton barrel with a SWR Omega.
I'm certainly no expert on this or any other subject. Just my observations.
Hope this helps.
Re: Subsonic load development
TO beat the first round velocity drop, push a wet patch with CLP through followed by 1 dry patch. That solved the problem in all 4 of the rifles and 1 pistol I shoot 308 sub loads in.
Trail boss has a hard time getting the 220+ pills to 1050. Several of you have mentioned this issue. It gave me fits for a month with my 308 pistol. I finally went to IMR SR 4759 and solved the problem. It's not quite as bulky as TB, but it's significantly bulkier than the commonly used shotgun and pistol powders. I've since started using it in the rifles and have had good, consistent results.
Another problem mentioned above is vertical stringing and a wide range of velocities. Sub loads with all powders I've tried over the past 11 years will increase speed significantly as the barrel heats up. I didn't see where anyone was waiting 5-10 min between shots to get an ambient temp bore, give it a try. It won't shrink the spread to +- 5fps, but it won't be +-100fps anymore. You're just eliminating one of the major causes for variation in these loads, the rest is primarily due to case capacity and position sensitivity.
Trail Boss is great for hunting loads where you don't want to dump the occasional round, but grouping results typically hover around 1.5-2.5 MOA depending on barrel length (longer barrels commonly are less accurate with these loads due to increased time in the bore). The best grouping results seem to come from the faster pistol powders (red dot, blue dot, green dot) but you'll have to tap the powder against the primer before each shot. For example, in my 16" tube on a windless day, TB will put 10 rounds within about 1 1/2 inches with the can on; same setup with Green Dot will stack 10 rounds into 1/4" at 100 and 10 into 1.5" at 200. HOWEVER, I've completely dumped rounds off the target with GreenDot when I forgot to slap the side of the reciever and ease the rifle back on the bipod.
TO beat the first round velocity drop, push a wet patch with CLP through followed by 1 dry patch. That solved the problem in all 4 of the rifles and 1 pistol I shoot 308 sub loads in.
Trail boss has a hard time getting the 220+ pills to 1050. Several of you have mentioned this issue. It gave me fits for a month with my 308 pistol. I finally went to IMR SR 4759 and solved the problem. It's not quite as bulky as TB, but it's significantly bulkier than the commonly used shotgun and pistol powders. I've since started using it in the rifles and have had good, consistent results.
Another problem mentioned above is vertical stringing and a wide range of velocities. Sub loads with all powders I've tried over the past 11 years will increase speed significantly as the barrel heats up. I didn't see where anyone was waiting 5-10 min between shots to get an ambient temp bore, give it a try. It won't shrink the spread to +- 5fps, but it won't be +-100fps anymore. You're just eliminating one of the major causes for variation in these loads, the rest is primarily due to case capacity and position sensitivity.
Trail Boss is great for hunting loads where you don't want to dump the occasional round, but grouping results typically hover around 1.5-2.5 MOA depending on barrel length (longer barrels commonly are less accurate with these loads due to increased time in the bore). The best grouping results seem to come from the faster pistol powders (red dot, blue dot, green dot) but you'll have to tap the powder against the primer before each shot. For example, in my 16" tube on a windless day, TB will put 10 rounds within about 1 1/2 inches with the can on; same setup with Green Dot will stack 10 rounds into 1/4" at 100 and 10 into 1.5" at 200. HOWEVER, I've completely dumped rounds off the target with GreenDot when I forgot to slap the side of the reciever and ease the rifle back on the bipod.
Re: Subsonic load development
tagged
tagged
Re: Subsonic load development
In my notes I have 8.5gr Unique for 150gr projo .308. You can call Sierra for subsonic load info. 800-223-8799, Duane was my contact.
For .223 subs, the Sierra recommended powder is Solo 1250. I have the data for 55gr to 75 gr. if it isn't posted elsewhere.
I'm sure you know, there is/are/was makers of reduced capacity cases for subsonic applications. A year or so ago, John at Whidden Gunworks mentioned to me that he was going to do a limited run of .308 cases. HTH
In my notes I have 8.5gr Unique for 150gr projo .308. You can call Sierra for subsonic load info. 800-223-8799, Duane was my contact.
For .223 subs, the Sierra recommended powder is Solo 1250. I have the data for 55gr to 75 gr. if it isn't posted elsewhere.
I'm sure you know, there is/are/was makers of reduced capacity cases for subsonic applications. A year or so ago, John at Whidden Gunworks mentioned to me that he was going to do a limited run of .308 cases. HTH
Re: Subsonic load development
good info here in this thread for sure. well, i finially got around to loading up some 308 subsonic loads with Trail Boss powder. thanks to many here for the previous tips and suggestions. the results were outstandingly quiet and since it was my first attempt at loading some up, i think there's potential.
180gr Speer SP hunting bullets (because i had some) and accuracy was around 1/4-inch at 30 yards out of my bolt gun (5-shot groups) this morning. Rifle is a Rem 700 with a 16-inch 1x10 twist Schneider barrel with a triple-x suppressor. very quiet, and mv's were around 1025fps with 10.5gr's TB and stepped up to 1050fps at 10.7 grains. i started out at 9gr's and was getting around 860fps and accuracy was about an inch+ so the slightly higher velocities produced better accuracy. yeah, i know its only 30 yards, so i hope to get out to a 100 yard range soon and see how she groups...
good info here in this thread for sure. well, i finially got around to loading up some 308 subsonic loads with Trail Boss powder. thanks to many here for the previous tips and suggestions. the results were outstandingly quiet and since it was my first attempt at loading some up, i think there's potential.
180gr Speer SP hunting bullets (because i had some) and accuracy was around 1/4-inch at 30 yards out of my bolt gun (5-shot groups) this morning. Rifle is a Rem 700 with a 16-inch 1x10 twist Schneider barrel with a triple-x suppressor. very quiet, and mv's were around 1025fps with 10.5gr's TB and stepped up to 1050fps at 10.7 grains. i started out at 9gr's and was getting around 860fps and accuracy was about an inch+ so the slightly higher velocities produced better accuracy. yeah, i know its only 30 yards, so i hope to get out to a 100 yard range soon and see how she groups...
Re: Subsonic load development
The Triple X cans are quiet.... and beefy. I swear you could always beat the target to death with the can if the rifle failed. Welded stainless goodness.
The Triple X cans are quiet.... and beefy. I swear you could always beat the target to death with the can if the rifle failed. Welded stainless goodness.
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