% burn of powder in a given length barrel

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mpallett
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% burn of powder in a given length barrel

Post by mpallett » Tue Jul 07, 2015 2:09 pm

So how important is % burn in the barrel for suppressor use?

When working on loads for a 45 ACP Encore (+P+) and a Bolt action 458 Socom, I was getting flame outs every 25 - 50 rounds as un-burned powder would ignite in the suppressor with a nice long pencil sized flame out the front of the suppressor.

Since then playing with Quick Load I've looked at the modeled % burn in the barrel.

For non suppressed use the % burn outside the barrel is flash.

For suppressed use, this is additional burning in the suppressor, flash, etc.

The question is, "How important is this?"

I would think that we would want 100% burn in the barrel for suppressed use to limit "flame out or detonation", reduce flash, and maybe reduce sound.

I'm working on loads for a 300 BLK at the moment and playing with quick load, I see that using the Holy Grail Powder A1680 there is only ~65% burn in an 8.5" barrel. Not sure I want this.

Discuss.
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Re: % burn of powder in a given length barrel

Post by T-Rex » Tue Jul 07, 2015 3:33 pm

All valid points.
65% burn, to me, means 35% wasted powder.
I have plenty of polyfill to make up that case volume.
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Re: % burn of powder in a given length barrel

Post by quiettime » Tue Aug 04, 2015 7:48 pm

mpallett wrote: I'm working on loads for a 300 BLK at the moment and playing with quick load, I see that using the Holy Grail Powder A1680 there is only ~65% burn in an 8.5" barrel. Not sure I want this.

Discuss.
It has been mentioned more than a couple times on 300blktalk.com that 1680 is NOT the quietest powder to use. But there's so many different combinations of parts and specs out there that 1680 has a foothold because of it's large volume of gas.

What does quickload say about H4198, A5744 and Reloader-7?

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Re: % burn of powder in a given length barrel

Post by Fulmen » Fri Aug 07, 2015 2:28 am

Silencer use is one of the few instances where % burned has any real value.
Most of the time it's a red herring as your main goal isn't to burn powder but to achieve a certain performance. If you want maximum performance you choose the powder with the highest velocity, if you're looking for economy you want the lightest charge that gives you acceptable performance. This also works for silencer use, generally speaking the lightest charge produces less noise and unburned powder.

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Re: % burn of powder in a given length barrel

Post by Fulmen » Fri Aug 07, 2015 7:59 am

As for the A1680 it doesn't seem like a good choice for silencers.
I ran a propellant table with the 240SMK through QL and the best choices seems to be powders like Winchester 296, Hodgdon Lil'Gun, Hodgdon H110, Vihtavuori N110, Ramshot Enforcer and Alliant 2400. Be aware that depending on your barrel and components these can reach maximum pressure before your target velocity, so use with care.

The best "fool proof" powders seems to be N120, ADI AR 2207 and Alliant Reloder- 7.

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Re: % burn of powder in a given length barrel

Post by Wicked » Wed Aug 12, 2015 9:33 pm

QuickLoad + OCD = insanity. Sometimes I just have to walk away. A mostly complete burn makes me feel better but I don't know how much of a difference it makes.

I usually attempt to achieve 95-100% burn with suppressed loads. Some of my +600gr Socom loads with Lil Gun or N110 burn up way before I run out of tube. If I get around 85% from unsuppressed loads when looking for extra velocity, I'm OK with that percentage. Any more than that, and I would want more barrel or a different combination of bullet/powder.
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Re: % burn of powder in a given length barrel

Post by Fulmen » Thu Aug 13, 2015 5:00 am

Why would you even care about % burned when not using a can? If you're looking for economy you need to look at charge weight and powder cost. I can imagine it could be a good indicator for muzzle flash, but even that seems to depend on the composition of the powder as much as % burned.

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Re: % burn of powder in a given length barrel

Post by quiettime » Sat Sep 12, 2015 12:24 pm

mpallett wrote:I'm working on loads for a 300 BLK at the moment and playing with quick load, I see that using the Holy Grail Powder A1680 there is only ~65% burn in an 8.5" barrel. Not sure I want this.
Any developments?

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