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Posted: 8/21/2006 10:40:04 AM EDT
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I used to hear tons about these but dont anymore. My question is are the mid-lengths much better than the Carbine lengths and why. Thanks! Riese |
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Longer iron sight radius. More rail space. More barrel covered. Slightly softer recoil impulse. Lower chamber pressures which make for not only a somewhat smoother cycling action, but it stacks the reliability odds in your favor. Couple of threads for you. www.ar15.com/forums/topic.html?b=3&f=118&t=291040 www.ar15.com/forums/topic.html?b=3&f=118&t=251611 |
That's better! |
Actually, the chamber pressure is lower as well. Less pressure being exerted inside the casing thus not forcing hte casing into the chamber wall as hard. Makes it easier fort he extractor to remove the casing from the chamber since it doesnt have to fight as much friction. |
Nope, has nothing to do with the peak chamber pressure, it is the same. Has to do with the residual chamber pressure and the timing to unlock. |
Its a slightly smoother and in theory, more reliable carbine. There is no doubt in my mind that it is slightly smoother, but a good carbine is very reliable to begin with, so I'm not sure what formal studies have been done to validate the reliability portion. |
Right. The unlocking of the bolt is slightly delayed (vs a carbine) thus giving the chamber pressure a bit more time to drop to a slightly lower level at the time of extraction. I never said anything about peak chamber pressures being different. Peak pressure will be the same regardless. |
Pretty sure Sabre Defence does as well. WIZZO |
Hmm, sounds like good stuff. Better than the other midlengths anyway. |
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Sabre's are great barrels and I run one on my mid-length. However they use the batch testing protocol the same as Bushmaster. Personally I like the BCM due to the extra insurance but I wouldn't hesitate to get another Sabre barrel either... 
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Proof load testing and MPI inspection do NOT make a barrel any better than one that's not been proofed and tested. Those tests DO make it a better TESTED barrel, but the tests do nothing to the quality of the actual barrel. Good and bad barrels exist in all batches. Testing helps remove the bad ones. What you are esentially getting is the confidence that it's not (likely) going to blow apart when you first fire it. I'm not saying that Proof testing and MPI is not necessary, it's just not the be-all, end-all in what makes a barrel good or not. Proof load testing PURPOSELY stresses the bolt and extension to MAKE it fail if there is anything wrong. It's also possible that it would partially fail and not show up in testing until several rounds later with regular ammo. It's not likely, but it's possible. |
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Doesn't the mid length sight radius make your click adjustments standards all meaningless? I mean... Not that anyone uses the iron sights anymore, but on a rifle 1 click is 1" at 1 hundred yards. 2 inches for the Carbean, etc. I guess it's not that critical once you zero the weapon, but still something to think about. |
Actually, I have a CMMG midlength on an A2 upper and if you use the IBZ (-2 clicks, zero at 50yds) then the click adjustment tracks closely enough that you can still hit silhouettes at 500yds. I don't normally do groups at that range so I can't say the elevation is perfect; but I can hit 10" steel at that range (provided you can see it over the front sight). I don't hit consistently (and considering I use 55gr XM193PD, no surprise); but I hit often enough that I know the elevation is correct. About the only issue is the click wheel is in meters instead of yards, so you need to adjust accordingly. I use 4+2 clicks and hold where I can see a sliver of the target above the front sight at 500yds using 55gr XM193PD. |
Even on my 20" A2, I can't just turn it to the number and expect to be on target. It took 20 min. up (2 clicks past the "7") to get into the black @ 600. Of course things like ammo and sling pressure probobly threw that # off. IIRC, I was using 77's. I'm putting a middy togather this friday. I have a feeling I'd run out of elevation on a detachable handle...would be interesting to find out though. |
Exactly. I'd rather buy one of the brands that takes the extra steps to insure that fewer bad ones are outbound. |
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