Even Ackley found only certain cases really help to Ackley improve. One of the best cases were the 30-06 family and 280. I've Ackley 6.5-06 30-06 6mm rem 7mm stw (horrible idea) 6.5-280.
Gunsmithing What is the difference between a freebore reamer and bore ryder throated reamer
- Thread starter Emmaandhaley
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I'm not after anything just trying to help the op. I've had alot of ackelys over the years and been around them since I was a young kid. They are great I just got tires of blowing caees out
Little to none.
Nothing new or hit or miss about longer freebore, it’s a fundamental detail in lowering pressure or allowing more speed: 5.56 vs 223, Weatherby chambers, etc, and most of the big manufacturers use it to reduce pressures in their rifles for liability.
All of this stuff provides the same kind of gains as an AI chamber or going to a slightly bigger cartridge- you use more powder to get a little more speed and burn out the barrel a little faster.
Of course the common thread with AI chambers and I’m sure this “+P” throat too is that guys tend to push the pressure higher, which does burn out the throat disproportionately faster. That higher pressure has a lot more effect than maintaining the same pressure and accepting the modest gains of longer freebore or more case capacity.
Yes I understand all that. I get longer free bore to a specific bullet usually and get great results.
That’s a little different though; if you’re having a throat lengthened to match a specific bullet, you’re not usually cutting longer freebore in front of the bullet. That’s still a relatively short throat for that particular bullet. Obviously if you use a different shorter bullet then you’ll have longer freebore.
But what we’re talking about here is more like .100”-.200” or more between the bullet and the lands to either reduce pressure or allow more powder and velocity.
Right like a weatherby but I'm not saying anything besides what I did. I was never a part of convo besides trying to help op out. When I stayed some of the stuff that gets extra speed can be hit or miss like the p+ throat from the other guy said it didn't work
I had bad luck with the sherman case not getting speed only time was ackleys. To help op out
That’s just it though- saying it’s hit or miss, or didn’t work, is misleading to the OP. It’s really just a matter of you not finding the right powder and load to take advantage of it. More capacity always allows more velocity, same for a longer throat. The amount you gain may or may not be worth the time and effort, and there are definitely diminishing returns in capacity of larger cartridges, but it always “works”.
That's false some times it doesnt work. There are several guys saying the p+ throat doesn't work they didn't get the 100 fps. That is what the op was wondering about a few guys said didn't work.
That’s a lot like being surprised that factory ammo doesn’t match the speed on the box. Marketing claims are one thing; fundamentals of internal ballistics are something else entirely.
Obviously velocity gains will vary, even if everyone is using the same powder, which they aren’t. If you expect the same 100 fps gain for every rifle, and use that as your definition of what “works”, then yeah by that definition it won’t “work”. But any longer throat, or gentler transition like this +P thing, will allow gains on some level; by that definition it does work.
I am not defending this +P throat (and especially not any marketing behind it), and we started off talking about a bore rider throat anyway, just explaining the relationships with pressure and velocity.
I will add this - your earlier comments in this thread indicated you were thinking of this stuff as sort of a mysterious and poorly understood black art, but now that I’ve explained it you seem to be defensive. Am I wasting my time explaining this stuff?
I understand all that. But the company is stating get a p+ throat and get 100 fps or more. That is what they are selling. I get what you are saying 100%
No I understand all this and don't need a explanation on it. Not sure how you thought educating me was helping the op. Listen I get what you are saying but this is something a company is selling and saying 100 extra.
I think he used to be on LRH back before I got banned. That username sounds really familiar...@Huskydriver - was way back, before the scout days.
I searched the site, but couldnt find his stuff.
Sumbitch had a pile of Robert Gradous rifles and would post some amazing groups.
didnt live in a shitty trailer in AR, so I never really trusted him.
I had another look at the Defensive Edge web site, and they list multiple calibers that they have modified, and their results vary from 60 fps to around 200 fps. Don’t really see overly aggressive Marketing from their side. They basically say that the speed gain varies A LOT, that lighter weight bullets benefit less, and that if your spare case capacity (driven by powder choice) is not enough to accomodate another 3-4 gn of powder, you will have to switch powders and redo your load development, or live with a fairly small gain. There is also mention of drop tubes to get that much powder into very full cases and avoid inconsistent seating depth.
I don’t really know, but it looks like full disclosure to me. All/most of the caveats are listed.
defensiveedge.net
Just an aside: I have a very old Savage 12 with a factory barrel that shot 0.2” groups in its youth. After 2,500 rounds it lost 100 fps is speed and ES went way up (>90 fps!). Bought a new custom barrel that never shot that well (0.5-0.7” groups).
Once i got hold of a Teslong bore scope, i had another look: Found a really bad carbon ring in the chamber and a lot of hard baked on carbon in the first 10” of the barrel. Spent half a Saturday cleaning it out and mounted the barrel. Speed was still low, as the jump for a 140 gn ELDM was massive (probably 150 thou plus), due to extensive throat erosion. But ES came down to 23-32 fps, and SD went back to the prior 7-9 range. Switched to 147 ELDM bullets, loaded loaded as long as i could go (single feed only), and the gun is now shooting tiny groups again, even with a badly eroded throat, and pretty bad fire cracking for the first 10”. The barrel is now approaching 3,500 rounds and still shooting. Got the speed up to over 2850 fps for 147 projectiles using RL-17 and Superformance, and can go higher if i like. Jump is relatively small, but it takes 2.5 gn more powder than before, but no pressure signs.
Point of the story: A long throat with more powder can certainly gain you “some” extra speed. No way to know ahead of time how much you will gain. Special double base powders can gain you 100-180 fps, and they are worth a try.
Yes, the combo of more powder and the use of a double base powder will wear out the barrel much faster, probably 2x faster. For a target rifle, that is probably not a good idea, but for a trusted hunting rifle that will fire maybe 50 rounds a year, it could be just the ticket.
As i understand it, the +P chamber mod will reduce the height of the grooves for the first 0.1 or 0.2” of the lands, so the bullet is still supported by the lands, and freebore is technically the same as before. The remaining portion of the grooves will center the bullet, but there is less engraving force, so under primer gas pressure the bullet will go deeper into the lands (creating more effective chamber volume) before it comes to a stop waiting for the pressure (from burning powder) to build up high enough to unstick the bullet. This is better than simply adding massive freebore like a Weatherby Mark IV, or shooting a barrel that is badly eroded (like my old Savage), as the lands still support the bullet keeping it concentric with the bore. [Rifles where the freebore is so long that the bullet has left the neck before it engraves the lands often suffers from accuracy problems, because the soft lead core bullet enters the barrel at an angle and that distorts (bends) the bullet. A mangled bullet that is not symmetrical / concentric anymore when it leaves the muzzle will be rather inaccurate. [Weatherby Mark 5 rifles in 300 Weatherby Magnum caliber are not known for shooting 0.1 or 0.2” groups (1” is more typical), but that is ok for a flat shooting magnum caliber hunting rifle meant for shoulder shots at large game animals at 300-400 yards.]
I intend to try the +P mod for my current 300 WSM build. If the lands wear out quickly (and i expect it will), then the plan is to cut off 0.2” from the threads and rechamber again. Will also QPQ melonite the new barrel to make it harder, which should slow down the throat erosion by some amount.
To the OP: I think the +P mod is worth a try, and it is not expensive to do. If it does not work out, cut the barrel back and rechamber in a Sherman Short or some such wildcat, and the speed will be there.
I don’t really know, but it looks like full disclosure to me. All/most of the caveats are listed.
+P Throating Applications
+P Throating Applications After fielding like a hundred questions about +P throating I decided to sit down and collect up all of our research and prior +P modified rounds. In short the +P modification is a benefit if there is sufficient capacity left in the case at the current load. For example...
defensiveedge.net Just an aside: I have a very old Savage 12 with a factory barrel that shot 0.2” groups in its youth. After 2,500 rounds it lost 100 fps is speed and ES went way up (>90 fps!). Bought a new custom barrel that never shot that well (0.5-0.7” groups).
Once i got hold of a Teslong bore scope, i had another look: Found a really bad carbon ring in the chamber and a lot of hard baked on carbon in the first 10” of the barrel. Spent half a Saturday cleaning it out and mounted the barrel. Speed was still low, as the jump for a 140 gn ELDM was massive (probably 150 thou plus), due to extensive throat erosion. But ES came down to 23-32 fps, and SD went back to the prior 7-9 range. Switched to 147 ELDM bullets, loaded loaded as long as i could go (single feed only), and the gun is now shooting tiny groups again, even with a badly eroded throat, and pretty bad fire cracking for the first 10”. The barrel is now approaching 3,500 rounds and still shooting. Got the speed up to over 2850 fps for 147 projectiles using RL-17 and Superformance, and can go higher if i like. Jump is relatively small, but it takes 2.5 gn more powder than before, but no pressure signs.
Point of the story: A long throat with more powder can certainly gain you “some” extra speed. No way to know ahead of time how much you will gain. Special double base powders can gain you 100-180 fps, and they are worth a try.
Yes, the combo of more powder and the use of a double base powder will wear out the barrel much faster, probably 2x faster. For a target rifle, that is probably not a good idea, but for a trusted hunting rifle that will fire maybe 50 rounds a year, it could be just the ticket.
As i understand it, the +P chamber mod will reduce the height of the grooves for the first 0.1 or 0.2” of the lands, so the bullet is still supported by the lands, and freebore is technically the same as before. The remaining portion of the grooves will center the bullet, but there is less engraving force, so under primer gas pressure the bullet will go deeper into the lands (creating more effective chamber volume) before it comes to a stop waiting for the pressure (from burning powder) to build up high enough to unstick the bullet. This is better than simply adding massive freebore like a Weatherby Mark IV, or shooting a barrel that is badly eroded (like my old Savage), as the lands still support the bullet keeping it concentric with the bore. [Rifles where the freebore is so long that the bullet has left the neck before it engraves the lands often suffers from accuracy problems, because the soft lead core bullet enters the barrel at an angle and that distorts (bends) the bullet. A mangled bullet that is not symmetrical / concentric anymore when it leaves the muzzle will be rather inaccurate. [Weatherby Mark 5 rifles in 300 Weatherby Magnum caliber are not known for shooting 0.1 or 0.2” groups (1” is more typical), but that is ok for a flat shooting magnum caliber hunting rifle meant for shoulder shots at large game animals at 300-400 yards.]
I intend to try the +P mod for my current 300 WSM build. If the lands wear out quickly (and i expect it will), then the plan is to cut off 0.2” from the threads and rechamber again. Will also QPQ melonite the new barrel to make it harder, which should slow down the throat erosion by some amount.
To the OP: I think the +P mod is worth a try, and it is not expensive to do. If it does not work out, cut the barrel back and rechamber in a Sherman Short or some such wildcat, and the speed will be there.
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Yeah, no shit. It's like on some of the advice given of "Once you hit stiff bolt lift, back off 0.2gr and send it". LOL
Yeah some guys on LRH are ... interesting and taking credit for all sorts of stuff.. like the OCW test.. I called him out and asked if he knew Dan Newberry... ha ha he now has toned it down after he was called out
I am shooting a 1-9 to 1-7 left twist Bartlein now and getting 2920 with the 130 RDF’s, this barrel is also 22”. The problem with a longer free bore is you are not going to be able to chase the lands.
6.5 Super LR and 260 Improved Variants
RyeDaddy XFirst Sergeant Rating: 3.4/5 this site 1457 posts this site 6.5 Super LR and 260 Improved variants 11/23/2014 Last edited 11/23/2014 by RyeDaddy 6.5 Super LR Winchester brand 243 brass 43.7 grains H4350 CCI-200 primer 136 Scenar-L @ 2.285" base-ogive (2.885" OAL) 2890 FPS via 24"...www.snipershide.com
View attachment 7706443I
That seems pretty reasonable to me. I'm not sure where the "100 fps" claim came from.
I am not a fan of super long freebore either. For target rifles where i single feed, i would rather start with shorter freebore and shoot 120’s and 130’s in say a 6.5, wait for the lands to erode before switching to 140’s and eventually 147-156 gn bullets. Get maximum accurate life out of the barrel and save a few pennies. [As pointed out below, loading to mag length changes things.]
As i understand it, the +P throat modification is not the same as long freebore: The lands are still in the same place as before, and you can load to a short jump. The grooves are not as tall as before to reduce the engraving force on the bullet, so the bullet goes deeper into the lands before coming to a halt, waiting for the pressure to ramp up. Effectively makes the chamber volume a little larger, allowing more powder before pressure signs arrive. Thinner brass (like Hornady) does the same.
Every engineering change has pros and cons, and there are sure to be some trade-offs involved in this mod as well. Likely shorter barrel life, in exchange for more speed, because of the extra 3-4 grains of powder. And the lands might well move faster than before, as there is less material there. You might not have enough spare case capacity to load 3 grains more, and now you have to use drop tubes to pack more in there. Or abandon a good load and pick a different powder. But you might well find a higher node that shoots well. Might even be a wider node, with some luck.
Maybe if you spec your barrel nok to be longer, you will have the opportunity to cut off an inch, and rechamber twice, but that will of course cost you more speed. And money.
Trade-offs are inevitable in this game. But if it fun to play around with these things and see what you can accomplish. Did that with HBN, and found phenomenal speed, but eventually backed off to preserve brass life. Got pretty close to 6.5-284 performance, but it is somewhat challenging to get every batch of bullets coated the exact same amount. Only using HBN in one of my rifles.
As i understand it, the +P throat modification is not the same as long freebore: The lands are still in the same place as before, and you can load to a short jump. The grooves are not as tall as before to reduce the engraving force on the bullet, so the bullet goes deeper into the lands before coming to a halt, waiting for the pressure to ramp up. Effectively makes the chamber volume a little larger, allowing more powder before pressure signs arrive. Thinner brass (like Hornady) does the same.
Every engineering change has pros and cons, and there are sure to be some trade-offs involved in this mod as well. Likely shorter barrel life, in exchange for more speed, because of the extra 3-4 grains of powder. And the lands might well move faster than before, as there is less material there. You might not have enough spare case capacity to load 3 grains more, and now you have to use drop tubes to pack more in there. Or abandon a good load and pick a different powder. But you might well find a higher node that shoots well. Might even be a wider node, with some luck.
Maybe if you spec your barrel nok to be longer, you will have the opportunity to cut off an inch, and rechamber twice, but that will of course cost you more speed. And money.
Trade-offs are inevitable in this game. But if it fun to play around with these things and see what you can accomplish. Did that with HBN, and found phenomenal speed, but eventually backed off to preserve brass life. Got pretty close to 6.5-284 performance, but it is somewhat challenging to get every batch of bullets coated the exact same amount. Only using HBN in one of my rifles.
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Seems to me it works the other way, at least when mag length is a constraint - longer nose length of the heavy match bullets, like the 145 - 150gr 6.5s, mean they can use a shorter throat than the lighter bullets, or more realistically, have longer jump at given OAL. In my experience anyway. Maybe different for some hunting bullets, especially older designs.
I don’t know about the effects on accuracy of this +P chamber thing, but as far as pressure is concerned it seems to me it’s the same idea as long freebore - a “soft start” - just implemented a little differently. Either way the bullet gets a bit of a run up before full land engraving, meaning it should down a lot less at that point and cause less of a pressure jump. Of course engraving the lands is one of the biggest factors in how quickly pressure builds, so this effect is pretty significant. I’m guessing the +P throat is an attempt to accomplish this without the potential accuracy compromises of long freebore, but that’s just my guess.
BTW long freebore can be cut to bullet diameter so it’s not necessarily loose and allowing bullet tipping - when the barrel is new. Of course it can erode same as if rifling were there, and then bullet tipping can happen as you describe.
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The lands are stepped. They engauge at normal length, however the diameters change. If I remember I'll chamber a spare barrel and cut it in half to show how I do, or previously did it.
You are of course correct, heavy high BC bullets loaded to mag length are pointy and will require less freebore. I should have added that i single feed in the bench guns that i shoot. I was referring to overly long freebore, like that found of a Weatherby Mark 5.
By the time i switch from 140’s to 147’s, i need the long shank of the heavier 147 bullet to get enough of the bullet to grip in the neck (trying to get one bullet diameter inside the neck). Like most folks, i pick freebore for a new build based on the heavy-for-caliber bullet i intend to shoot.
For a comp gun where mag feeding is required, chambered for say the very pointy 144 Berger Hybrid, the gun will be chambered with fairly short freebore, and you will most likely load for a small (optimized) jump, even if that eats into case capacity a bit. There is enough shank in that 144 to chase the lands for a long time - if you so desire, but most people would probably rebarrel when they lose 50-80 fps in speed.
My hunting rifles are all loaded below mag length. But they will probably last 3 lifetimes, as i shoot 10-30 rounds per yesr to confirm zero, and fire 3 to 5 crucial rounds a year at animals. It is a different game when you travel halfway around the world to shoot one must-get shot at a trophy animal.
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Not trying to give a busy guy work, but it would be fascinating to see a cutaway of an old barrel with this mod. When you have time.
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Talk to Kiff at PTG. He makes Bore Rider reamers for the larger stuff. 375 Chey-tac and up. think you need special bullets IDK!
Shitty attempt on the second one. 3 jaw chuck, didn't check, just rammed it in for an example. Hopefully you get the idea. Really can't be asses doing a proper quality one. It's 930pm, I'm going home.
Top one is a normal 308win. Bottom one is 308win+P throat.
Should look cleaner, but it was a bit wonky, so didn't cut clean, but for the example, you should hopefully see. The bullet will seat at the same depth touching lands. They are stepped out a diameter, and laid back more. Think .304 rather than the .300/.308 diameters, and instead of 1min30sec, it's 1min10sec angle (I think, I'd have to check).
For fuck’s sake, don’t ever talk to Kiff at PTG. If someone else has PTG stuff on hand, great, but there’s no reason to buy stuff direct from a company that about half of the Hide - including commercial vendors - has had an absolute nightmare of an experience with. There’s a mega thread on the subject.
@iceng Looks like it’s about half the angle for the throat engagement, which aligns pretty nicely with what other people have said. That does make it easier for the bullet to go into the rifling misaligned, though, so concentricity is critical for +P load accuracy.
The initial angle is 1-30 halfway down. Then it goes to a more gradual angle to major land diameter. The final angle can vary depending on what reamer your are using. Kiff was the guy that came up with the term (bore rider) At one time Dave offered it in smaller calibers. A friend of mine did one in 260. The lead (not freebore) was twice as long as most conventional 1-30 Dave offered at the time. The problem with smaller diameter calibers is that the throating end of the reamer is very long and delicate. I will say this reamer was nice. But it still scared the crap out me.
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If Kiff came up with the term bore rider then he stole/misused it, since “bore rider” has already been in use for well over 100 years to describe a long bullet with a nose fitting the throat, or a long freebore tightly fitted to the bullet.
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