My first AR build questions. 7.5"

[JohnXDm]

Pistols use carbine buffers and springs.

[Rngr188]

Pistols use carbine buffers and springs.

Yea, figured I had the wrong spring.

[JohnXDm]

Not sure what you mean by standard spring. Just measure and count what you have.

Below is from Wing tactical

A standard carbine spring is 10.5" long and has from 37 to 39 coils. The standard rifle spring is 12.75" long and has either 41 to 43 coils. Over time, with every shot, the buffer spring will weaken and should be periodically removed and measured.

[Rngr188]

Not sure what you mean by standard spring. Just measure and count what you have.

Below is from Wing tactical

A standard carbine spring is 10.5" long and has from 37 to 39 coils. The standard rifle spring is 12.75" long and has either 41 to 43 coils. Over time, with every shot, the buffer spring will weaken and should be periodically removed and measured.

Riffle spring, 43 coils.

[JohnXDm]

At least springs are one of the less expensive components. Here are two more pictures of the Fortis Control Shield

20180430_130946.jpg

20180430_1309403sik.jpg

[JohnXDm]

Always how it goes..

Here are two more pictures of the Fortis Control Shield.


20180430_130537.jpg

20180430_130957.jpg

[Rngr188]

My barrel came in today and I went and bought a BCM (might put on my 6920) charging handle, Aero BCG, torqued and staked my buffer tube castle nut. Now I need a new spring, handrail, BUIS, muzzle device, and a decent model price optic. It'll be on hold for a bit but while I do some more research and let my wallet settle. I'm not wanting to dump a whole lot of money into this build. Once this is done I think I'll do a Mk18 build as close to spec as possible and probably register it as an SBR, this is just a pistol only build for fun.

[rockapede]

The bottom build there is a 7.5" pistol built on an Aero upper with a BA 7.5" Hanson barrel. Sionics LPK, BCM BCG, H2 buffer, and BCM carbine spring round out the function parts. It's been totally reliable over about 1500 rounds (mix of .223 and 5.56 pressures) which ain't a lot, but neither is it nothing. It's functioned hot and dirty just fine. From purely a reliability standpoint (and being well aware the reliability envelope is narrower than it would be with either of the other builds) I'd rely on it. It's purely a toy just because of the blast (though the BRT Covert Comp does seem to help with this) and general neutering of the ammo, though. It's a hoot at the range.

[TEAM V SEVEN]

I have an Aero upper and lower that I bought stripped. I've assembled the lower minus tube and the upper I've installed the forward assist and dust cover. I've ordered a KAK shockwave with their dimpled tube. I'm considering the Balistic Advantage Hanson barrel with gas block installed, thoughts on this barrel.

https://ballisticadvantage.com/7-5-i...ce-barrel.html

I still have a lot of decisions as far as had guard, thinking DD Omega 7, BCG, and muzzle device. Any advice would be appreciated.



Thanks.

Short 5.56's can be very fun. I have made and properly tuned 6.5",7.5" and 8.5" 5.56 barrels over the years and with the proper port (smaller than most imagine) they will run in the proper cyclic rate and be reliable. You do loose some significant velocity so don't think about it as a 20" high velocity 5.56. It sits some where between a 5.56 x 45 and the FN 5.7 x 28 in these short barrel lengths, still a decent and effective round for sure for short range. I typically recommend slightly lighter projectiles to insure bullet disruption due to the lower overall velocities in these short barrels, my favorite round is the Hornady 50gr V-max out of my 8.5", its pretty fun and effective. Good luck and have fun.