Burn rate to barrel length

[NoFail]

Hi guys. I have become cognizant that at some point powder burn rate becomes a factor which I had not really considered much if at all. Just been distracted trying to nail down much else in this art of handloading I find myself involved in.
So I just load for one rifle, a .308 gasser. Actually a carbine at 16". Would I be better off using a faster powder being the barrel is short? That is faster than CFE223 which I think may be on the slower end, and IMR 4064 which I think is a little faster than the CFE. I'm just wondering if afaster burning powder than those two, which is all I've tried so far, would be a good idea to try for a 16".n

Thanks

 

[turbo54]

Re: Burn rate to barrel length

A faster powder can maximize potential of a shortish barrel.

For a 16" gas operated 308, I STRONGLY suggest you give H4895 a try. Not IMR4895, mind you, <span style="font-weight: bold">H</span>4895.

Good luck.

 

[BuzzBoss915]

Re: Burn rate to barrel length

Barrel length should always be considered in choosing an optimum powder. Had two different 6MM Remingtons, one a 700 and the other a 600 with an 18.5 " barrel. Once, at night I grabbed the wrong ammo and it was a flamethrower, the powder ignites, but outside the barrel. I developed a system after that, one gun used spitzers the other HP's. That solved it.
Anyway, generally speaking, you have to use a slightly faster burning rate powder in short barrels in order to achieve pressure and velocity. It will never make up for being short but it will get as much performance as possible out of a short barrel. 4895 is a good suggestion, depending on bullet choice?

Who to ask, is somebody that shoots a hand cannon like a Wichita.
BB

 

[NoFail]

Re: Burn rate to barrel length

Awe H4895. Yeah ok I was gonna give Varget or IMR 4895 a go next when I get more powder. But then i just started thinking about burn rates. So Hodgdon H4895.

I have this list in a Basic Reloading Manual given me at a show where I bought the CFE223. There is a list with Relative Burn Rates of 120 different powders, from fastest to slowest #1 being NORMA R1, fastest is #120 VV 20N29.
Indeed, H4895 is faster at #69. IMR 4895 is #71. IMR 4064 is #76. Varget is #81 & CFE223 is even slower at #84.

 

[NoFail]

Re: Burn rate to barrel length

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BuzzBoss915</div><div class="ubbcode-body">Barrel length should always be considered in choosing an optimum powder. Had two different 6MM Remingtons, one a 700 and the other a 600 with an 18.5 " barrel. Once, at night I grabbed the wrong ammo and it was a flamethrower, the powder ignites, but outside the barrel. I developed a system after that, one gun used spitzers the other HP's. That solved it.
Anyway, generally speaking, you have to use a slightly faster burning rate powder in short barrels in order to achieve pressure and velocity. It will never make up for being short but it will get as much performance as possible out of a short barrel. 4895 is a good suggestion, depending on bullet choice?

Who to ask, is somebody that shoots a hand cannon like a Wichita.
BB </div></div>

Thanks BuzzBoss!! And you also said H4895 good suggestion, depending on bullet choice? I have 1-10" twist. I have 178 gn Amax on hand & also 168 Amax. I have some ladder tests of both of those loaded up over the CFE. I will run those thru and see what they do. Still not set on any bullets either though. Thanks for the help guys I really appreciate it!!

 

[RyeDaddy]

Re: Burn rate to barrel length

You're on the right track. I switched to faster powder in my 16.5" gasser and got a boost in velocity and softer muzzle blast. I think for the 178's H4895 is a good choice, and with the 168's and smaller you could try IMR 8208XBR like I did if you don't find what you're looking for with your other choices.

http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=2818521

 

[Greg Langelius *]

Re: Burn rate to barrel length

It may help.

For a gas operated semi, the key issue is port pressure. Any clear evidence of extractor damage to case rims should be a good indicator that pressures are too high.

While faster burn rates can help allay that, it's not a complete answer.

Greg

 

[NoFail]

Re: Burn rate to barrel length

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: NoFail</div><div class="ubbcode-body">Awe H4895. Yeah ok I was gonna give Varget or IMR 4895 a go next when I get more powder. But then i just started thinking about burn rates. So Hodgdon H4895.

I have this list in a Basic Reloading Manual given me at a show where I bought the CFE223. There is a list with Relative Burn Rates of 120 different powders, from fastest to slowest. Fastest #1 being NORMA R1, slowest is #120 VV 20N29.
Indeed, H4895 is faster at #69. IMR 4895 is #71. IMR 4064 is #76. Varget is #81 & CFE223 is even slower at #84.
</div></div>

Edit; that list I had it confused originally, Norma R1 is fastest, VV 20N29 slowest

 

[NoFail]

Re: Burn rate to barrel length

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Greg Langelius *</div><div class="ubbcode-body">It may help.

For a gas operated semi, the key issue is port pressure. Any clear evidence of extractor damage to case rims should be a good indicator that pressures are too high.

While faster burn rates can help allay that, it's not a complete answer.

Greg </div></div>

I've seen these signs before. This time with the CFE I'm doing new ladder test but starting with lower charges. Well that's with the 168 Amax. The 178's I started with 44.4 gn CFE223, and stopped at 46.2, i think I'll do round robin on that batch. CFE223 being new powder we don't really have a long chronology on it. I want it to work for me but we'll see, just giving it one more try. Going to range after a new scope gets delivered here.

 

[wilecoyote]

Re: Burn rate to barrel length

The right powder,on the fast side,on a semiauto end even more on a military semiauto,coupled with the correct setting of the gas valve,when available,has more than only a ballistic bonus:it's the correct way to avoid some major damage at the rifle_This effect will be really consistent when the function of the rifle perform thank to a gas piston_

 

[NoFail]

Re: Burn rate to barrel length

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: wilecoyote</div><div class="ubbcode-body">The right powder,on the fast side,on a semiauto end even more on a military semiauto,coupled with the correct setting of the gas valve,when available,has more than only a ballistic bonus:it's the correct way to avoid some major damage at the rifle_This effect will be really consistent when the function of the rifle perform thank to a gas piston_ </div></div>

Well, I do have adjustable gas block from JP. The barrel JP Super Match 16" 1 in 10".
JP LMOS BCG, Slash's CAR 10-XH 6.5 oz. buffer and modded Armalite spring. Non gas piston though.
Lots of dough in there it should do ok when I figure it all out.
The valve is set more open than not right now, I need to address that again too this next time out.

 

[wilecoyote]

Re: Burn rate to barrel length

On the limits of my 7,62 FAL only experiences,I never go slower than Vihtavuori N135 or equivalent,with ball weight not over 155grs.,on semiauto mode_(I'm happy you never must worry about binding the gas rod,too)_

 

[BCP]

Re: Burn rate to barrel length

I use varget all day long in my 308 16". No problems and good velocities. I've tried faster powders like TAC and AA2460 but didn't get any higher speeds.

edit: 168nosler 175SMK 178AMAX

 

[NoFail]

Re: Burn rate to barrel length

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: wilecoyote</div><div class="ubbcode-body">On the limits of my 7,62 FAL only experiences,I never go slower than Vihtavuori N135 or equivalent,with ball weight not over 155grs.,on semiauto mode_(I'm happy you never must worry about binding the gas rod,too)_ </div></div>

And N135, at #72, just below IMR 4895 on this list I have. I haven't tried any bullet below 168 grains.

 

[NoFail]

Re: Burn rate to barrel length

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BCP</div><div class="ubbcode-body">I use varget all day long in my 308 16". No problems and good velocities. I've tried faster powders like TAC and AA2460 but didn't get any higher speeds.

edit: 168nosler 175SMK 178AMAX </div></div>

IMR 4064 has been problem free for me up to 43.8 grains under 168 Nosler SBT, 168 SMK & 168 A-Max. That's hardly a max for those bullets & 4064, I just haven't bothered to go further.