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I'm looking for pros and cons to either a 10.5 or 11.5 223/5.56 barrel on an at pistol build. I saw one place that said the velocity out of an 11.5 is about 300fps faster on average than a 10.5. I still want to be able to shoot to 200 yards with it so I like that velocity gain. I also think the 11.5 is more reliable all around. But I like the PSA deal for the FN 10.5 barreled uppers. Do I go quality of functionality? What do you guys think? Pros, cons, suggestions? Thanks!
 
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I'm looking for pros and cons to either a 10.5 or 11.5 223/5.56 barrel on an at pistol build. I saw one place that said the velocity out of an 11.5 is about 300fps faster on average than a 10.5. I still want to be able to shoot to 200 yards with it so I like that velocity gain. I also think the 11.5 is more reliable all around. But I like the PSA deal for the FN 10.5 barreled uppers. Do I go quality of functionality? What do you guys think? Pros, cons, suggestions? Thanks!
here is some data I gathered on velocity .....27gr of 335 is above published data max so work up if reloading. You would be looking at around 50 to 80 fps gain with an 11.5 over a 10.5 depending on propellant .
HNDY 55gr FMJ 27gr H355
18" 3135 fps
10.3" 2767 fps
8" 2452 fps

CBC M193 55gr FMJ Factory
18" 3212 fps
10.3" 2682 fps
8" 2509 fps

HNDY 55gr FMJ 24gr IMR 3031
18" 2902 fps
10.3" 2351 fps
8" 2167 fps

if everything is right there should be no reliability factors between the two. Technically the 11.5 has another inch of dwell time after the gas port but its negligible in factoring reliability, if the gas port and buffer/buffer spring weight are proper then there is no reliability advantage .

Both will serve you well out to 200 yards.
 
Last Edited:
I'm looking for pros and cons to either a 10.5 or 11.5 223/5.56 barrel on an at pistol build. I saw one place that said the velocity out of an 11.5 is about 300fps faster on average than a 10.5. I still want to be able to shoot to 200 yards with it so I like that velocity gain. I also think the 11.5 is more reliable all around. But I like the PSA deal for the FN 10.5 barreled uppers. Do I go quality of functionality? What do you guys think? Pros, cons, suggestions? Thanks!
Go 10.5 if you plan to run it suppressed, otherwise I'd say 11.5 or 12.5 is the sweet spot. I have a 10.5 as my home defense but it's got a can mounted to it all of the time.
 
I went with 11.5 because it's one inch extra of burning powder which might give my first baffle a little longer life. Probably negligible amount of difference, but in my head it makes sense.

I don't think you can go wrong with either.
 
A lot depends on where the gas port is, what size it is and what you plan on doing with it. My Ballistic advantage 11.5 1:8 has a MID length gas system so I get about half a C hair of dwell time, so the port is BIG. This means that its ridiculously over gassed with my suppressor. So a Bootleg adjustable BCG and an H3 buffer fixed it, but something to consider, especially if you want to suppress it. If the 10.5 is carbine or pistol gas, you'll be good- but its gon' be snappy. With my handload training load, Im getting 2680ish FPS with my 11.5", using a conservative amount of win 748. 2200 I believe is the threshold for permanent wound cavity and 2400 is what you want for terminal effect past 200, I think. Barrel length is less important than twist and bullet weight in regards to accuracy. Although the PSA may have an FN barrel, consider the quality of the rest of the parts. Are you going to have to lap the receiver to get 1moa? is the BCG reliable? Maybe just build your own?
 

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