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View Full Version : Any real good reason to have feed ramps in a semiautomatic 6.8?



DaveInGA
12-10-06, 13:22
Howdy,

I've got a 5.556MM M4 to the point it's about finished and am planning my next build and I'm considering a 6.8MM SPC. The plan is to use these as both a medium range "Spotter's" rifle and as a part time hog/deer gun. In thinking this caliber through, there are some questions that have come up I'd like to see if I can get cleared up.

1. What is the realistic maximum effective range of this cartridge of a skilled rifleman? (Note: Assume magnified Eotech setup.)

2. What is generally thought of as the optimum barrel length? Is it 18 inches?

3. Is a BUIS a worthwhile setup with such a rifle? Would it be better just to use a standard fixed power scope such as a 6X?

4. Are feedramps on the receiver and barrel considered a "necessity" in this caliber due to the larger diameter bullet tip in the AR15 receiver? Would the rifle function as a "semiautomatic only" just as well without the feed ramps?

Thank you in advance for your assistance in the thought process.

Dave

FlyingHunter
12-16-06, 21:31
Good luck with the 6.8spc build. I have a 16 inch barrel PRI upper with a EoTech (No magnification) and have found that I can hit pie plates to 100yds every time and most of the time at 200yds while on some type of rest. I have not used a scope or shot any farther than 200yds. I'm not sure I would call myself a marksman, but it seems to shoot minute-of-deer pretty well. As far as the feed ramps...the PRI's come with them and it's probably digested about 150-200 rds this year with no malfunctions at all.

Stephen_H
12-18-06, 11:12
1. With a magnified EOTech (I will assume 3X), a skilled marksman should have no trouble making hits on man sized targets out to 500 meters. At that range bullet drop is going to be more than a meter, but the 6.8mm SPC is capable of outstanding accuracy.

2. I think that a 16" barrel with mid-length gas system would be ideal for almost any purpose.

3. I put BUISs on all my rifles, but that's just me.

4. I do consider the M4 ramp extensions essential to reliability across the full range of bullet shapes out there. If you only fire OTM or FMJ through it you might be okay without them, but it is too easy to just get them when you build the rifle.

HTH
Stephen