It varies by a number of factors. It can be totally negligible, or it can make up for an inch or so of barrel, which may or may not be significant.Originally Posted by Wake27
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It varies by a number of factors. It can be totally negligible, or it can make up for an inch or so of barrel, which may or may not be significant.
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Like the person above said, a number of factors can result in a suppressor adding a noticeable amount of velocity to a rifle (if any). In this case, I was basing it on the fact that Strikefirst was reporting a 208 fps increase in average velocity going from 12.5" to 13.9". That's a bigger difference in velocities between those two barrel lengths than I have ever seen, so I was wondering if the suppressor he was using on the 13.9 was possibly contributing to some of that increase in velocity.
Triarc published some velocity data on their barrels a while back that showed around a 100 fps increase in average velocity going from 12.5 to 13.9, so 200+ fps would be a really nice increase in velocity if its due to the barrel length alone.
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Ofcourse go to the range to chronograph and zero 7 ARs and the stupid magnetospeed 3 wouldn't read the bayonet. Atleast I got them zeroed but I still need to chrono. Got a sporter magneto that still works so just have to use that till I get the V3 sorted out. Not sure it is the cord as I tried a spare cord and still would not read the bayonet. May have to send it in to see if they can sort it out.
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Finally got to the range
11.5" Expo Heavy barrel with Banish 223 suppressor
55 TAP reload 2700
55 FMJ reload 2570
75 Hornady reload 2270
12.5 BCM cutdown Gov mid w/YHM T3
55 Tap 2833
55 FMJ 2678
75 Horn 2457
13.4" BCM cutdown mid ELW w/YHM T3
55 TAP 2810
55FMJ 2767
75 Horn 2477
14.5 BCM ELW mid w/YHM old TurboK
55 Tap 2904
55 FMJ 2773
75 Horn 2500
16 Green mountain mid unsurpressed new barrel
55 Tap 2929
55 fmj 2824
75 Horn 2511
18 WOA 3 gun interm gas w/YHM Turbok
55 Tap 3100
55 fmj 2960
75 Horn 2643
My TAP load is a 55 vmax with 24.7 Benchmark
My 55 Hornady FMJ is 25 XBR for matches
75 Hornady is over 24 varget or 26 CFE 223.
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Thats much more in line with expected results.
RLTW
Whats New button, but without GD: https://www.m4carbine.net/search.php...new&exclude=60 , courtesy of ST911.
Disclosure: I am affiliated PRN with a tactical training center, but I speak only for myself. I have no idea what we sell, other than CLP and training. I receive no income from sale of hard goods.
Senior Member
Looks like 12.5 is kind of a sweet spot for the heavier projectiles.
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My 12.5 is my oldest barrel brand new being 18 and 16 with only a few sighters rounds through.
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Velocity loss/gain per inch of change steepens under 12.5. It is moderate between 12.5 and 16, and fairly flat 16- 24 or so. As we look at medium length barrels like 13.5 or 14.5, an inch in either direction makes very little or no difference, but down in the 10.3 region, an inch can be a big change in noise, flash, trajectory/ballistics, reliability, and silencer wear. In the opposite extreme, there is almost no difference between an 18 and 20 barrel, in practical terms. As in, you really need a chrono to see the difference.
Handling difference between a 12.5 and 10.3 is nil.
In my view of general purpose rifles, which is merely my opinion, the sweet spots are:
11.5-14.5 for silencers (Mk18/M4 role),
12.5-18 for A2 flash hiders(M4/M16 role),
16-20 for light support weapons (M27/M38 roles).
Last edited by 1168; 04-22-24 at 08:29.
Senior Member
I'm very fond of the 12.5-13.9" with a K-can.
I very much regret selling my 12" but I'm loving my 13.7".
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