Agree. I've found M855 is inferior to M193 for most applications. M855 is generally less accurate, doesnt penetrate armor as well as M193 and doesnt fragment as well at range. For hunting coyotes, the 50gr varmint tip has dropped them all where they stood, regardless of barrel length (11.5"-20"). I'm not against 20" barrels, but much like the .308, the velocity difference between barrel length isnt nearly as pronounced as many of us have been taught over the years.For civilian application, I don't see much purpose in designing around M855.
Edit : At any rate rather than chase our tails on a quest for a FPS at a speed that we can both agree on with an ammo I'm generally not using for anything but plinking lets just say the reason I went with a 20" inch AR is for the increased wounding performance.
Fragmentation is going to be more pronounced with a 20" barrel than with a 7", a 10.5", a 12" inch, a 14.5" inch, a 16" inch or an an 18" inch while still retaining something that's maneuverable. To me a 26" isn't maneuverable at all. So a 20" inch it is.
Me either.I'm with you on the 20 inch rifle though. I love them. Having actually used the M16A4 rifle my entire enlistment (even when I was a machine gunner I still had to qual on a rifle) I dont find them to be the hindrance that many people make them out to be. Im keeping my 20 inch with irons sights for it to be my "I dont have to worry about batteries or banging my scope off zero" gun. I can grab it and without worry Im good from 0 to 500 meters.[/B]
The gap between 14.5" to 24" tends to follow ~43fps per inch with this load, almost linear.
Meant to reply to this (as I agree with far more that I disagree), didn't get around to it.77smk's over H335 follows 45-50fps per inch in 14.5-24" as well.
For general purpose with a twist of long ranges, 18-20" has proven to me (and my customers) to be the most versatile lengths. Enough speed to keep the 69-77grn pills stable out to 700yards and beyond, but not as burdensome to carry as the long tube rifles. Just short enough to still be manageable with a full size suppressor. I've had a lot of folks want to live on a "two rifle" plan, one 16" carbine or SBR, and one long gun in the 22-24" ballpark, but a large majority of them end up coming back to get an 18-22" at some point, because they love how their carbine handles, and love the extra range of the long rifle, but don't like the length of the long gun, and want more range than their carbine - all in one rifle. I know everybody loves their particular rifle and their barrel length is the best, and everybody else loves saying the application dictates the design, but a DMR is a general purpose rifle with a moderate range expectation. It's NOT a "sniper rifle," it doesn't need to be a long range weapon which carries like a boat anchor.
If I'm honest, if I were building one away from the mantra of military/NATO compatibility, I'd most likely build one in 6x45 or 6-6.8 instead of 5.56 to give me a little more thump at range. I built my "DMR type" rifles for myself in Grendel and SPC, doing it again, after building a few 6mm AR's the last few years, I'm heavily favoring them.
Though I have no qualms using M855 for defense. I dont. But if it was all I had I wouldnt think twice about it. A lot of people talk bad about the round, but Ive seen it put a lot of dudes in the dirt.