10.5" build

[RomeoTango]

Hey, All.

I'm putting together a 10.5 shorty build. I've read in a few places online where some people have problems with the cycling and having failures with such a short barrel and long gas system. (Carbine length) while I'm still an amateur, and relatively new to wevo, I was wondering if you guys could help me out by giving me your input on the matter.
Busy schedule at work, so I don't get to get on here as much as I'd like, but will be checking this post later.

Thanks, fellas!!

[Calengor]

I have a 10.5 MK18 clone. Having said that, the reason I've seen quoted most often on the intertubes is 11.5 has significantly improved reliability. See Paul from BCM's answer below:

Q: Why BCM chose the 11.5" SBR over the 10.5"

I get this question a lot. It is a good one. When we spec our program we can build anything we would like, so we sat down and looked at the pros and cons.

First Statement: I know a good 10.5" SBR can run very well. I personally own a semi MK18 type and it runs great. No problems.

A: Dwell time.
Dwell time is the time that your gas operated weapon maintains pressure to continue the cycling of the weapon. It primarily exsists from the time the bullet passes the gas port in the barrel to the time the bullet exits the muzzle. When you pull the trigger and fire the weapon the movement of the bolt carrier group unlocks the bolt, extracts, and ejects the spent casing. Then it cocks the weapon, feeds, chambers the next round, and then locks again. One of the thing that can make SBRs finicky is the dwell time (or lack of).

The 11.5" carbine is approximately 4% longer weapon than its' 10.5" counterpart, but this extra inch gives the barrel a 40% increase in length for dwell time. IMHO, this is an excellent trade off. This additional dwell time (all other things being equal) will allow the carbine to be more forgiving to different ammo types, extremes in air temperature, weak or worn extractor springs, worn extractors, buffer weights, etc.

Last Statement: For those folks who have a 10.5" that works very well, I would reply; me too. (see first statement)

If I had to "go to war" with a AR15 Carbine, I would grab the BCM 11.5".
The BCM 11.5" Runs Like a Dream.

Hope this info helps,
Paul

[rob_s]

If meant as a host for a full-time suppressed gun, or possibly even part-time (where the "part" is >75% suppressed) with a switchable gas I'd opt for the 10.5" barrel.

Anything else and I'd look to the 11.5-12.5" barrels for most uses.

[Jerry R]

RT, wish I could be more help, but the two 10.5" uppers that I have are both piston and mid-gas. Having said that, they function flawlessly. I have not had any issues with the 6.8 or 5.56 running factory and reloads in these uppers.

[RomeoTango]

Thanks guys!! The actual oal of this barrel I have is 11". I'll try it out and see what happens. I was thinking of putting a slr adjustable gas block on it instead of running the a2 that I have, but I just think the a2s are sexy that far out on that barrel. Lol.

[Pyzik]

Well, this is all crappy news for me.
I'm (sort of) in the process of a pistol build as well. HOWEVER, here in MI the pistol cannot have an OAL greater than 26" (does not include removable parts; ie. muzzle device, sig brace).

So I am stuck with either a 7" or a 10.5". And I don't want a 7".

[rob_s]

I wouldn't sweat it. There's a difference between what's ideal and what's functional.

[toolboxluis00200]

i have a 10.5 and it run awesome never had a issue

[Soisauss]

i have a 10.5 and it run awesome never had a issue

Except when you rapid fire......then you get fail to eject because the barrel got a tad bit warm where you can get your eggs over easy.....

[GOST]

Over easy is how I order them.

[voodoo_man]

10.5 is a weird size.

11.5 is good to go - bcm / NOVESKE

10.3 is also good to go - DDmk18

Anything shorter needs to be piston - PWS

Anything longer can be whatever since itll run fine.

Totally depends on what you need.

[Kopis]

Well, this is all crappy news for me.
I'm (sort of) in the process of a pistol build as well. HOWEVER, here in MI the pistol cannot have an OAL greater than 26" (does not include removable parts; ie. muzzle device, sig brace).

So I am stuck with either a 7" or a 10.5". And I don't want a 7".

Why dont you want a 7.5" ? I have one that runs flawlessly. Whatever you decide on, i do recommend the extended buffer tube with the sig brace.

[toolboxluis00200]

Except when you rapid fire......then you get fail to eject because the barrel got a tad bit warm where you can get your eggs over easy.....

I mite trow some bacon on it lol

[UWone77]

Why dont you want a 7.5" ? I have one that runs flawlessly. Whatever you decide on, i do recommend the extended buffer tube with the sig brace.

I don't do Sig Braces...

Or white dots to cover serial numbers.

[toolboxluis00200]

Over easy is how I order them.

don't forget the toast and butter