Googled it and can't seem to find an answer. I know what it does from an M4, but how about a rifle-length barrel?
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Googled it and can't seem to find an answer. I know what it does from an M4, but how about a rifle-length barrel?
deleted.
About 3,407fps from a 20" barrel. The info in the link shows an average velocity of 3,185 from a 16" barrel. Add 7% (M855 has a 7% higher velocity out of a 20" over a 16" barrel) for the additional 4" and you get 3,407fps.
http://smallarmssolutions.com/home/the-m855a1
I have heard that M855A1 has a faster burning powder so that the 14.5" M4 has almost the same velocity as a 20" rifle (hence the higher pressures). If that is true then could it essentially negate what we would expect to be a rather significant increase in velocity going up from a carbine to a rifle-length barrel?Quote:
Originally Posted by Red*Lion
That 3400-ish velocity you calculate would be awesome but I wonder if it is indeed the case?
Also wonder if the rifle-length gas system tames the effects of accelerated bolt wear and gas port erosion from those higher pressures?
Extrapolating and guesstimating velocity is well and good, but you’d need to shoot and chrono to have an answer.
3400 FPS from a 20” sounds optimistic as hell to me.
I’ve tested it in longer barrels. You’re not getting that velocity from a 20”, or perhaps anything.
Did your test include a chrono? If so what did you get?Quote:
Originally Posted by 1168
Also wonder, as I posted above, if the rifle length gas helps mitigate the higher pressure wear effect on parts.
It did. I cannot provide a number. I’d be cautious about the article posted above. It does not appear to be proofread very well, and contains info that was likely out of date at the time of publishing. It also includes the infamously over-hyped picture that older slide decks had. The author also did not sign his work.Quote:
Originally Posted by ABNAK
“M855A1 is at least an additional 200+ feed per second over the M855/M193 ball ammunition that the 5.56mm cartridge was designed around”.... oh, really? 200 more than M193, huh? Neat.
Edit: just checked that thread where I ran it in a 16”.... 88fps over m855. 3400fps with an unleaded projectile is encroaching into 26” 22-250 territory.
That was kind of the direction I was thinking in.Quote:
Originally Posted by 1168
Yeah no.Quote:
Originally Posted by Red*Lion
This guy is getting 3159 fps from a 22" bolt action, so I dont know what kind of crack he's smoking getting 3400 fps.
https://youtu.be/Qj9xzUVar-Q?t=217
I wish such a magical pixie dust powder that gives almost 6" worth of barrel velocity existed.Quote:
Originally Posted by ABNAK