Quote:
Originally Posted by Justinmd
Gents, Recently a SOTIC instructor mentioned the desire for a rifle similar to an SR-25 (precision semi-auto .308), but with a collapsible buttstock and a shorter barrel (perhaps under 20") that could be used for assault if needed. Is this something you would find useful? If so, how would you spec it out?
1. Barrel Length (and/or desired effective engagement range)?
2. Weight (would you sacrifice a thick meaty barrel for more portability)?
3. Caliber cababitly (is .308 and its variants good enough or does it need to take the short mags as well)?
4. If it came with two barrels, say an 11" for DA and a 22-24" for long range precision, would you switch them out for different missions or just keep a medium length (16-20")barrel on all the time.?
5. Optic, what would you prefer for this type of setup.?
Ok thanks for the help gents. If all goes well, you may see something at SHOT show. Justin
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Justin:
You have no choice with what you are describing but to go with a AR-10 or SR-25 with all of its bulk and weight. Do you want a 7.62 based cartridge rim or not is the question. If you do, accept the weight and bulk of an AR-10 or accept shearing bolt lugs.
I was firing a JP 18" .308 upper on an AR-10 lower for the last couple of days and even though it had an exceptional compensator, the recoil was quite significant when firing issued M-118 Long Range ammunition. John Paul's compensator did reduce recoil but it would blow out a fellow's ear drums he he was standing next to the muzzle when fired.
You haven't yet given any really good physical criteria to detail your requirements. Such as penetration through a specific medium, engagement ranges for such penetration, terminal effects on the human body, etc.
IMHO -- you are asking for somthing bigger than the 5.56 but smaller than the 7.62. A issued service load in 7.62 NATO is pretty stiff -- M-118 or M - 80 Ball.
OK --- there are two relatively available cartridges that give you perhaps what you want and from an AR-15. The 6.8 and the 6.5 Grendel. There are also .30 caliber cartridges that are used with the AR-15 aside from the 7.62X39 but these cartridges are still pretty much wildcats.
Of the 6.8 and the 6.5 Grendel, one uses a bullet that is better in terms of teminal effects and one is better in terms of exterior ballistics to 350 yards which is what you said was your engagement range. Both have less than half the felt recoil of a full size SR-25 or AR-10 without compensators or muzzle breaks and both can be shot from the issued AR platform which is smaller than the AR-10 / SR-25 platform.
I prefer the Grendel believe it or not because I believe it offers a higher hit probability at ranges from 300 - 600 and IMHO if you put a 120 grain bullet into someone at 500 yards for example, it will put more kinetic energy into that person than a 63 grain, tungsten tip, 5.56 bullet at a lesser velocity (at that range) .
Both the 6.8 and 6.5 Grendel are high pressure cartridges for the AR platform and both will blast someone at ten yards as well as the other with half the recoil and at least 70% less blast than a carbine firing an issued 7.62 round.
It is my opinion that both the 6.8 and 6.5 Grendel will kill someone as readily as each other at ranges to 300 yards. However, my bets are on the Grendel in terms of hit probabilities at any range from 300 - 600 yards over either the issued 7.62 LR or M-80 or any loading of the 6.8 when fired from any platform while under stress.
I know why I say these things and won't get into someones pissing contest so you Grendel or 6.8 'Bots' out there -- if you think I care about your prejudices then think again.
That ought to stir the pot for you some. Maybe others have solid views too and that is how you will learn what is needed.
Gene