I've been running a 10.5" for a couple years with many thousands of rounds and no issues. Using TSX, like the 50gr Black Hills, you can expect reliable, consistent expansion out to a little past 100 yards. That decreases dramatically when using TAP (about 40 yards with 75gr 5.56 for reliable fragmentation), FMJ (can be literally just a few yards for reliable fragmentation) or other ammunition like Mk262 (less than TAP's fragmentation).
Now, this doesn't mean it's not effective past those ranges, it's just not performing at its optimum. There have been many badguys put to the dirt at ranges far beyond the reliable frag range of 75gr TAP and Mk262. For comparison using 5.56 TAP 75gr as an example, you can expect it to reliably fragment to roughly 160 yards from a 14.5" and about 110 yards from a 12.5" compared to 45 from a 10.5". These are not exact numbers, but close. They're also not the maximum range of fragmentation, but the point where it still fragments reliably at its max.
So, for any defensive use, the 10.5" will be very effective. Especially with proper ammo. It'll also be very reliable if you go with a quality manufacturer and don't start experimenting outside the recommended buffer weights and ammunition.
Having said that, the 10.5" fills a bit more of a specialty role and will likely need parts replaced sooner than longer barrels. The 12.5" is a good general use rifle and what many consider a sweet spot for the rifle and caliber. My next will likely be an 11.5" or 12.5".
On a side note, the M4A1 CQBR and the Mk18 Block 2 use either the MaTech rear sight or the KAC standard rear sight along with the KAC standard flat dark earth front sight, not the micros. The rear doesn't matter much to me, but I prefer the standard KAC front as its protected when folded. I've broken two URX II front sights on my SR15's and the thought of the unprotected micro when folded down gives me a little less confidence than the standard front does.
Last edited by jonconsiglio; 09-22-12 at 17:08.
Proven combat techniques may not be flashy and may require a bit more physical effort on the part of the shooter. Further, they may not win competition matches, but they will help ensure your survival in a shooting or gunfight on the street. ~ Paul Howe
Bookmarks