I sorta posed this question in a thread in the NFA forum, but I was wondering how one would convert a 16" KAC SR15 into an SBR? If I simply replace the upper, with say an LMT, am I good to go? What kind of adjustments/replacements are recommended for the buffer and spring? Thanks
I believe this subject has come about several times already but that could just be me getting confused with all the forum hopping. If you’re going to cut down a standard SR15 rifle the shortest recommended to go before you would have start adjusting the gas port is 14.5". If you swap out the upper for another shorter assembly then we recommend changing the buffer to a heavier buffer.
Cut-down was not an option. Has KAC released PDW uppers in 5.56? I’d prefer that route if available. Otherwise, I’ll drop in another manuf SBR upper and swap out the buffer. Thanks
The KAC PDW is a whole different animal. The only KAC available now is an 11.5" but you won’t be seeing separate uppers for a while, I’d assume.
You can buy any short barrel upper you’d like from any AR manufacturer in 5.45, 5.56, 6.8, 7.62x39, 300blk, etc. and put it on your lower AFTER you get your stamp back for the SBR. Sticking with 5.56, you’ll just need to switch out the buffer and you’re good to go.
If you’re going to cut down a standard SR15 rifle the shortest recommended to go before you would have start adjusting the gas port is 14.5".
With that long of a gas system you would cut the barrel to 14.5"? Has this been tried? That doesn’t seem like a lot of dwell time to me.
Form 1, when you receive your stamp just replace the barrel. Not hard at all.
Until that day,
Darkop
I really don’t see the point in making a SR15 into a SBR. One of the huge draws to the SR15 is the special balance of gas, barrel and buffer the design has. The SR15 uses a lightweight buffer, which IIRC is a tick lighter than a standard carbine buffer. Every part of the design is optimized to work with the others. Why would you want to upset that balance?
If you’re just looking for ambi controls, I would suggest buying another KAC lower and building a seperate rifle. By all accounts, the SR15E3 is a very good rifle. If I was going to buy a complete rifle you can bet that’s what it would be.
Knight’s Armament has said they’ll run fine at 14.5", but that’s the shortest they suggest cutting them while maintaining their gas system. You could also cut it to 11.3" and have it ported as a carbine gas system if you want to retain the e3 extension and bolt, though I think that’s a bit too much.