Appreciable velocity loss from 20" down to 18"?

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[ARCHIVED THREAD] - Appreciable velocity loss from 20" down to 18"?

Posted: 1/6/2006 8:35:37 AM EDT

Thinking about replacing a barrel on an A2... What say you? Is it worth losing 2" (with a quality barrel)?

All things being equal... Would you rather have an accurate 20" barrel or an equally accurate 18" barrel?

TIA
jim

Posted: 1/6/2006 12:42:04 PM EDT

[#1]

Quoted:
Thinking about replacing a barrel on an A2... What say you? Is it worth losing 2" (with a quality barrel)?

All things being equal... Would you rather have an accurate 20" barrel or an equally accurate 18" barrel?

TIA
jim

What weights more, 50lbs of feathers or 50lbs of bricks?

If they are equally accurate, I'll take 2 inches less?

Posted: 1/6/2006 2:05:38 PM EDT

[#2]

Quoted:
Quoted:
Thinking about replacing a barrel on an A2... What say you? Is it worth losing 2" (with a quality barrel)?

All things being equal... Would you rather have an accurate 20" barrel or an equally accurate 18" barrel?

TIA
jim

What weights more, 50lbs of feathers or 50lbs of bricks?

If they are equally accurate, I'll take 2 inches less?

Ha... I was more going for the "loss in velocity" angle but in my limited research I haven't seen a reason not to go with the 18" barrel...

Posted: 1/6/2006 3:26:04 PM EDT

[#3]

i seem to remember hearing it was a 50 fps loss. the 18" barrels certainly handle better. but then every inch helps, like going down to 16" from 18" and so on.

here's a couple of my 18's

my current 18" rifle, this one is now wearing a DD freefloat rail

i recently sold the barrel but this was a bushy gov profile. it handled and shot great though, i just needed a heavier profile to support the silencer

Posted: 1/6/2006 6:57:18 PM EDT

[#4]

mr_h, thanks for the pics- very nice rifle!

I'm leaning toward the 18"...

Posted: 1/6/2006 9:29:23 PM EDT

[#5]

You can go all the way down to carbine length (16") and only lose a couple hundred feet per second. If you go to 14.5", you break the 3,000 fps barrier (the wrong way).

Posted: 1/7/2006 8:13:26 AM EDT

[#6]

I wouldn't worry about velocity between 20 and 18".

Posted: 1/9/2006 11:13:37 PM EDT

[#7]

I ran some quickload simulations at 62,000 PSI peak chamber pressure.
55gr sierra HPBT gets you 3320 in a 20" and 3240 in an 18" barrel.
75gr Vmax gets you 2900 in a 20" and 2840 in an 18" barrel.

Posted: 1/10/2006 5:20:03 AM EDT

[#8]

Quoted:
I ran some quickload simulations at 62,000 PSI peak chamber pressure.
55gr sierra HPBT gets you 3320 in a 20" and 3240 in an 18" barrel.
75gr Vmax gets you 2900 in a 20" and 2840 in an 18" barrel.

Wow, thank you Randall! I appreciate you running those numbers. The difference isn't that big.

[ARCHIVED THREAD] - Appreciable velocity loss from 20" down to 18"?

AR-15 » Rifles, Uppers, Lowers, Barrels, and more

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