Subsonic .308 reloading process?

[B3dlam]

Well the form 4 on my 30P-1 was approved on the 3rd so I should be picking up my can any day now. I have been reading up on subsonic reloading for a while now and I wanted to run through the processes and see if you guys have any tips or tricks or things I may be looking at doing completely wrong.
The rifle I will be developing subsonics for is a R700 AAC-SD .308 with the 20" barrel and 1-10 twist. (the can will also be used on my 6.5 creedmoors but I dont want to loose the advantage of speed on thoose guns)

I will be using IMR trailboss powder and 208 AMax bullets to start out with as I have a bunch of them laying around. I figure I will start with 10~grains of trailboss and then work up or down as necessary to get the rounds leaving the gun right at around 1000fps. I will then shoot the rounds through paper at 25 yards looking for any signs of instability that could result in a baffel strike (looking for perfect round holes no tumble.) and then again at 100 yards looking at the same thing.

My questions are when using trailboss powder is it still necessary to drill out the flash holes. Also should I be using regular large rifle or magnum primers (not a big deal either way I have a decent supply of Large Rifle and the local store has enough magnum primers if I need to go that route).

Ideally I would like to avoid drilling the flash holes out to 9/64ths if I can but I dont want to compromise my gun or can.

I appreciate any info you guys that are loading subsonic pills can give me as what I have found thus far has been all over the place.

 

[Hogshooter]

Your process looks to be good. I load 10.4 gr. Trailboss behind a 170 or 180 gr. .30-30 bullet for 1040 - 1050 fps. Rifle has a 20" barrel with 1-12 twist so I cannot run the heavier bullets. I do not drill flash holes and use a standard primer. Never had any issues. I believe you have a typo in your post. If you were to drill your flash holes out to 9/16" you may have a slight issue with the case head...lol

 

[waste_knot]

Ideally I would like to avoid drilling the flash holes out to 9/16ths if I can but I dont want to compromise my gun or can.

Isn't 9/16 larger than a 1/2". I guess the stock size is 0.080 and 3/32" would be 0.093. I have no idea what size is required for trailboss but I need to load the same ammo.

 

[B3dlam]

Your process looks to be good. I load 10.4 gr. Trailboss behind a 170 or 180 gr. .30-30 bullet for 1040 - 1050 fps. Rifle has a 20" barrel with 1-12 twist so I cannot run the heavier bullets. I do not drill flash holes and use a standard primer. Never had any issues. I believe you have a typo in your post. If you were to drill your flash holes out to 9/16" you may have a slight issue with the case head...lol

Isn't 9/16 larger than a 1/2". I guess the stock size is 0.080 and 3/32" would be 0.093. I have no idea what size is required for trailboss but I need to load the same ammo.

Thanks guys I corrected it should have been 9/64ths I beleive? I see some guys mentioning that others just say they enlarge the hole slightly I guess I will give it a go without touching the flash hole and sticking to standard LR primers instead of mag primers unless I hear otherwise here.

 

[sic65stang]

I too do not drill flash holes. I treat the brass the same as if it were for supersonic ammo. The standard LR primer works fine for me. One of my 308's run 9.5 of trailboss and it seems to ignite just fine.

 

[lead ƒarmer]

Interested in what others have to say. I will be getting my 30p-1 in a few months and also have a bunch of 208s around that I would like to try some sub loads with

 

[B3dlam]

Interested in what others have to say. I will be getting my 30p-1 in a few months and also have a bunch of 208s around that I would like to try some sub loads with

I reloaded 4 rounds each with 9.8, 10, 10.2 of trailboss I plan to test them this weekend and see how they are doing velocity wise and I will try and report back with what I find.

 

[Huckleberry75]

What I found in developing the 220RN/208Amax subs for my AAC Rifle was that A) do not enlarge the flash holes, it is not necessary B) standard rifle primers were doing fine C) somewhere between 12.2 and 12.5gns of Trailboss would run them at 1030-1075 here in Oklahoma's atmosphere, when seated to the cannelure on the 220's and I did not adjust the die when seating the 208's. I am getting about 1 MOA at 100yds with that load. What you have already loaded are a little light, so be sure to confirm that the bullet exited the chamber after each and every shot of those test loads. I would go so far as to pull the bolt and look down the bore after every shot. I found that the 180 RN liked 10.5gns of TB and the 170 FN liked about 9.5-10.0gns of TB. All of these shot quite well, but YMMV.

 

[Huckleberry75]

Also, look here:

http://www.snipershide.com/shooting...ng-depot/603-loads-fo-subsonics-all-cals.html

 

[B3dlam]

What I found in developing the 220RN/208Amax subs for my AAC Rifle was that A) do not enlarge the flash holes, it is not necessary B) standard rifle primers were doing fine C) somewhere between 12.2 and 12.5gns of Trailboss would run them at 1030-1075 here in Oklahoma's atmosphere, when seated to the cannelure on the 220's and I did not adjust the die when seating the 208's. I am getting about 1 MOA at 100yds with that load. What you have already loaded are a little light, so be sure to confirm that the bullet exited the chamber after each and every shot of those test loads. I would go so far as to pull the bolt and look down the bore after every shot. I found that the 180 RN liked 10.5gns of TB and the 170 FN liked about 9.5-10.0gns of TB. All of these shot quite well, but YMMV.

Thanks for the info I started around 10 grains as that seemed to be what I had read people were using thus far. The first loads will be shot at around 25 yards to check stability and I will likely start with the largest charge then work down. As I will be firing at 25 yards I will be able to confirm the bullet leaves the barrel with impact on target, chorno, and likely a visual inspection as this subsonic reloading has gotten me a little paranoid even though I consider myself relatively competent with reloading lol.

 

[awonder]

Im shooting an AAC -SD with Winchester cases regular winchester primers, 10.0 grains of trailboss and a 178 Amax. Its VERY close to supersonic and is extremely effective on deer (headshots). Im running a YHM thread on Phanton suppressor.