IG had mentioned a myth busting barrel length thread so I decided to make this. I have read many threads and there always seems to be someone spouting off as gospel that short barrels aren’t capable of long range engagements. Some even claim long barrels (20"+) aren’t capable of it!
As someone who has accurately shot a 10.5" issued Mk18 with a 4x PVQ31B using issued Lake City M855 out to 500 yards on a USMC Echo Target (20"x40") in 15-20MPH full value Hawaiian tradewinds winds I find the “maximum ranges” people talk about comical. I have also shot and trained others to shoot issued M4 Carbines (14.5" barrels) out to 800 meters also using the PVQ31B during my time as an instructor attached to I MEF / MNF-W in Iraq. I won’t even lie to you and say that the rifles are effective at that range, but hits can be made.
I know to some, having a 4 MOA group at 500 yards is unacceptable accuracy but I do not hunt varmints and these shots were not recorded for group size but for hitting the target. Since every round was an impact I suspect that it was indeed less than 4MOA although the rounds theoretically could have vertically stringed out more than 4MOA. My only regret is not having the guys in the Pits measure shot group sizes while I had the chance.
It did not help that proper use of the ACOG dictates kentucky windage either. There is no dialing in to compensate for wind, just hold overs. I’d also like to point out that virtually every US Marine can shoot a 14.5" M4 Carbine to 500 yards…with iron sights.
Using the PVQ31B (Essentially a TA31RCOM4 ACOG) the hold over for the 10.3" was not even noticably higher than that of the 14.5". Wind affected the round more, but I could still empty an entire magazine into the black from the prone unsupported. This means no sandbag, no mat, no rest, no shooting jacket. Nearly every Wednesday some US Marine with a chrome lined, M16A2, M16A4, or M4 using Lake City M855 is qualifying at 500 yards.
As a civilian I have made coke-can sized hits with my 12.5" BCM Stainless Steel upper at 400 yards. I zeroed my 10.3" SBR at 200 yards. Even if you are paper punching and measuring groups by the tenths of inches at 500 yards I can’t imagine anyone ever needing anything longer than a quality 16" stainless steel barrel. Of course this is just my opinion, and many people like the extra velocity (and thus the lack of wind deviation) that an 18" or 20" barrel provides. As far as combat accuracy goes, I don’t think I’ll ever buy an AR with a barrel longer than 12.5" ever again. again, thats just me.
I made this thread to mention real life no bullshit experiences with various barrel lengths. I feel that most people who make these assumptions do it because they have no experience with it. Assuming they can actually shoot, if they just get in a good position and move that target to 500 yards I think they’d be pretty surprised.
since it’s obvious that you can get hits at long range with short barrels, maybe it’s time to reframe the discussion as to the effective range of the 5.56 in a shorter barrel…
This. Its not about the ability of these short carbines to place rounds on a target at these long ranges, but moreso the ability for these carbines to incapacitate with a single shot at these given ranges. The fact is, with a longer barrel, you have more velocity initially and at impact, which equals more tumbling and fragmenting upon said impact.
Effective range is always a good conversation. I had saved the effective ranges of 75 gr 5.56 TAP where it stills fragments reliably and consistently from a few different barrel lengths. Using a fragmentation threshold of 2,250 fps, it was something like 50 yards from a 10.5", 150 yards from a 14.5", 185 from a 16" and about 230 yards from a 20". You can subtract about 60 to 70 yards from those numbers (except the 10.5") and that’ll give you an idea of the 75gr TAP in 223 as opposed to 5.56. Mk262, from what I understand, will be a little less, but we all know there are confirmed kills and much longer ranges.
TSX pretty much doubles these ranges where it’s still performing at or near 100%. the performance threshold for TSX is 2,000 for 50gr, 1,900 for 55 and 62gr and 1,800 for 70gr. So, that gives you an effective range where still performing at its max over 200 yards, nearly 4 times that of TAP.
FYI - I’m just repeating the results that others have already documented. Molon is a main source of that info as is Dr Roberts, of course. I’ll need to double check those TAP numbers though. I know they’re close, but not exact.
Keep in mind that these are just the ranges where they perform at their max. A member here, from what I understand, has at least a couple confirmed kills with a 10.5" and Mk262 at distances close to 400 meters.
TSX seems to be taking the 5.56 to a higher level over OTM bullets. It appears to be a great choice for all barrel lengths. Not trying to turn this into a ballistics and bullet choice discussion, but when talking about 5.56 especially, it’s very hard to not bring up specific ammunition.
For 5.56mm, I’d settle for any hit at 500-800 yards personally. I don’t know of any bullet that’s going to be traveling fast enough that far out that will perform as it would at say 100 or even 200 yards. With the drop in velocity I would be surprised if anything reliably fragmented or maintained a controlled expansion, and would instead expect it to either sloppily mushroom or just remain a .22 caliber icepick until it’s energy was expended.
Exactly. That’s what I was saying about the 10.5" with Mk262. It may perform at 100% only out to about 40 meters or so, but that same combo has definitely put some guys in the dirt at distances 10 times that.
Right. Effective range and the range at which you can make a hit are one and the same. Effective range is not the range at which the terminal performance of the round meets some X, Y, or Z standard.
We shot my 1/4" mild steel target at 600 yards Monday. 4 Rifles, and 4 calibers.
11.5 AR - made the usual lead splatter mark on the gong, and you could hear most of the hits.
308 WIN - 20" barrels with 175 SMKs. These put obvious Dents in the steel. Knocked it pretty good. Would definitely be more than effective at that distance.
3 and 4. 7mm Rem Mag and 300 Win Mag. I lumped these two together because we couldn’t tell which hits belonged to which caliber. But they both put massive dents in the steel and one of them actually penetrated.
We’d shot this same gong at 800 and 1000 before with no damage of any kind with any of the guns.
My comment was in no way to imply that 5.56mm isn’t lethal out to 500-800 yards because it obviously is. A sloppy mushroom is more than enough to put someone down in short order.
Since people have differing ideas of what “effective” means, I was just saying that at 500-800 yards I don’t know of any bullets that will perform as their design is intended/marketed. Some take “effective” to mean a hit, others take it to mean fragmentation/expansion, others have maybe more definitions.
There are also several Russian soldiers that were shot and killed at 300-500m by .22lr sporting rifle in Chechnya. Does it make .22lr suitable for use as combat weapon at distances of 300-500m?
5.56 even from 10" can be deadly at 1000yards or more, if it will hit in right place. If we use enough number of rounds and will try, eventually it will happen. Pure probability maths. But does it mean 1000yard is effective range for 5.56 round?
No. But, 5.56 Mk262 from an 18" barrel, you can definitely say it has an effective range of 600 meters. You can also say Mk262 has a range of maximum performance, where yaw and fragmentation are reliable and consistent, of roughly 200 to 250 meters. After that, it’s still effective with good hits.
I would consider an effective range with a particular caliber the point where You could no longer say you would incapacitate consistently. Those ranges will vary with barrel length and ammo used, but with a 14.5" barrel and quality ammo, it would be fair to say that 500 yards or more is a consistent effective range.
For effective range, personally I’ll take into account (an average) the level and speed of incapacitation per distance and the projectiles performance regarding wind and drop, which is also a consideration of the probability of making a good hit.
Fragmentation is only truly effective to about 160M or so. 200m is a stretch. The closer you get to 200m, the more likely that the round won’t fragment at all. That’s under ideal conditions. There are many real world cases where the round failed to fragment, to include conducting CQB. Regardless of range, shot placement is key, as many times as it takes.
What barrel length are you referring too? 75gr TAP 5.56 from a 14.5" is said to be consistent at 165 yards while it’ll stay consistent to about 100 yards with 75gr TAP 223.
According to Molon and the velocity threshold of 2,250 for 5.56 75gr TAP, we can expect consistent reliable fragmentation from a 16" barrel to 185 yards and 230 yards for a 20" barrel. 223 TAP 75gr from a 20" barrel will be about 165 yards.
This is not my testing, just repeating the results. The T2 bullet of the 5.56 TAP has better fragmentation properties. According to Hornady, if I remember correctly, they listed the threshold at 2,200, so Molon used 2,300 then lowered it to 2,250 to be conservative.
Either way, 150 yards is a safe bet and a good way to look at it. TSX on the other hand pushes the effective range where it still performs at its max quite a bit further. I’ve personally been moving away from OTM loads in my rifles.
M855 from a 10.5" should have a velocity around 2,630. At 500 yards, you’re looking at a velocity closer to 1,350. You’ll drop to roughly 1,250 at 600 and 1,150 at 700.
There will likely not be enough velocity from even the muzzle for fragmentation from m855. A 14.5" will only fragment m855 to 40 meters or so. Mk262 will only fragment reliably to about 12 meters from a 10.5" and 75gr 5.56 TAP to about 35 meters.
Out of a 10.5", it’s very hard to beat TSX, whether you choose 55, 62 or 70gr. The 50gr is probably the best of the TSX line for barrier penetration, but it’s not as effective at distance as the 55 through 70gr.
Keep in mind these are all estimates. Things like atmospheric conditions and different barrels of the same length can cause deviations in velocity. Just didn’t want anyone thinking I was trying to say this is exact info.
Shorter barrels are more accurate/consistent. I thought that little fact was starting to catch on. Maybe not if the ability to hit stuff far away with a SBR is so shocking.
Since we’re talking about the ability to hit targets in excess of 500 meters with M4 and shorter barrels, here’s a little perspective from the paper punching world. Most shooters don’t use a 20" service rifle for 1k matches because the .223 has vertical stringing issues at that distance. The issue isn’t that the round can’t group at that distance, it’s that the velocity is taking a beating and the rounds are plunging at a pretty steep angle relative to the target. Even very good shooters see their groups open up a bit vertically because even the smallest mistakes in sight picture translate into off call hits at 1k.