My 2 Uppers are 85% identical. Both 14.5 with pinned muzzle devices... 1 with FSB, 1 without, rocking Aimpoints PRO/T1
If I went for a 3rd, I'd go for a MK12 set up with Can
My 2 Uppers are 85% identical. Both 14.5 with pinned muzzle devices... 1 with FSB, 1 without, rocking Aimpoints PRO/T1
If I went for a 3rd, I'd go for a MK12 set up with Can
I know the 18" barrel is popular with the 3-gun crowd, but it makes no sense to me. The 18 inch barrel is a bastard length between the 16 and the 20 with out any of the advantages of either. No practical velocity advantage over the 16 but no handier than the 20
[QUOTE=CleverNickname;1932191]You do realize that you can get SBRs in Illinois now, right? The law changed recently.
I didn't know that. Now I have to figure out iof I want to actually mess with the paperwork & pay the $200
In one test, M855 ammo made 3000 fps in a 20 inch barrel. Velocity in an 18 barrel was 2900 fps. In the 16 inch barrel velocity was 2800. This is fairly typical. Often, the loss in velocity is greater between 18 & 20 than between 18 & 16, depending on ammo type.
http://sadefensejournal.com/wp/wp-co...02/barrel6.jpg
If the thinking is, why not trade 100 fps to reduce barrel length from 18 to 20 for a slightly handier rifle, why not just trade another 100 fps to cut the barrel back to 16 inches and get a truly handy rifle? A 16 inch will do anything an 18 inch barrel will.
But what if you want more velocity than a 16 inch barrel? 18 inches only gets you 100 fps, isn't as handy and the 16 inches will still do anything 18 will. If you're going to trade handiness for velocity, might as well go 20 inches for a velocity gain that worth it. The 18 inch barrel also gives you the complication of gas port location. If equipped with a midlength system, blow down time is longer which can lead to over gassing. Rifle length has a shorter blow down time and the rifle becomes particular about ammo. An intermediate length system could be used but then you need to use a proprietary length gas tube. (Personally, I think the proprietary parts thing gets blown out of proportion.) A rifle length handguard can be run with a 16 inch barrel as well. I plan to cut the FSB of a 16 inch carbine and install a rifle length free float tube.
It's not that the 18 inch barrel is a bad choice, it's just not as practical. It's a tweener without the handling advantage of the 16 inch or the velocity advantage of the 20 inch and the bad habits of both
Can you cite your source for that information about muzzle valosity? It seems a bit suspect because that chart is saying 11 has a highter validity than 12. Just wondering.
http://sadefensejournal.com/wp/?p=1093
I take velocity information as a guideline, not an absolute. In this case, I suspect (but do not know) that there may have been a couple of tight spots in the test bore. There are other variables that can cause fluctuations in velocity & pressure as well
Now knowing what I prefer in rifles, I would go with a BCM 14.5" ELW Fluted middy and a 20" A4 with a free-floated stainless barrel.