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Old 10-08-2012, 10:48 PM   #21
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Ouch, that sucks. I still don't understand why a short barrel "causes" this though.

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Old 10-09-2012, 12:13 AM   #22
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The shorter the barrel the less time the gunpowder has to fully ignite/burn. Rifle powders (unlike pistols) burn slower, so as to provide pressure for longer barrels. If you reload and use a faster burning powder you can eliminate this problem, but you may run into a myriad of other issues, so please don't use a faster pistol powder for your rifles.

See those streaks in the muzzle blast of the picture? Those are bits of gunpowder still igniting (and creating pressure)

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Old 10-09-2012, 12:23 AM   #23
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Quote:
Originally Posted by MCarter788 View Post
Ouch, that sucks. I still don't understand why a short barrel "causes" this though.
because the powder used in rifle cartridges is slow burning compaired to pistol powders which are considered fast burning. most of the heat energy should be created in the barrel to prevent damage to the supressor. when that heat energy is released in the supressor from a short barrel and slow burning powder damage to the baffles ensues. there are supressors made with advanced metals capable of withstanding that heat but it costs a lot.

the next thought is "why not use fast pistol powders??" the use of such powders in a rifle case cause things like detonation to occur. this is basicly releasing all the heat energy in case at once instead of burning the length of the barrel. the very large volume of even the 223/556 case can cause this when pistol powders are used. using enough pistol powder to not cause that and reach useable speed causes severe pressure spikes which can disassemble your firearm in a dramatic fashion.

thats why you see the trend in small case volume rounds with very heavy bullets like the 300 whisper and blackout.

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Originally Posted by Gonzilla View Post
Any chance we could get a look at ther research ? I have honestly never heard of a 1:7.7 twist. The problem lies not w 300 yd shooting but making the 5.56 an honest 800-1,000 yd cartridge.
556/223 doesnt fare well at that 800-1000 range. if i was going to shoot that far i would pick a different caliber and likely a different platform. it CAN reach out that far but its not ideal.

the info on the twist rate may be on their page. i just went with their suggestion. they have an outstanding reputation in barrel building.
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