UBR 2.0 on a LR308/SR Buffer Question

[ShooterwithNoName]

Hey guys, so I wanted to ask about this, I didn't see anything directly related to this question so my apologies if this has been asked before.

So I picked up a UBR for my Stag 10 here on the hide. Got it installed today, awesome solid stock. I started playing around with buffers for it and found this:

Before the UBR I had a standard AR15 buffer tube with a short 308 buffer installed. I installed the UBR, which comes with a spacer that fits down inside the buffer tube to make up the difference in length between the UBR tube and a standard AR15 length tube, as the UBR tube is longer.

I dropped the spacer in, dropped my short 308 buffer in on top of the spacer. The bolt wouldn't cycle back all the way, it would allow the bolt stop to catch the front of the carrier but wouldn't go back far enough to allow the bolt head to go past the bolt catch.

So I pulled the spacer out and put the short 308 buffer in by itself. The bolt would now go past the bolt catch and catch on the bolt face as it is supposed to. But now the carrier will go too far back into the buffer tube and would strike the back of the receiver and front of the tube.

So I left the spacer out and installed a standard Spikes AR15 length buffer... Perfect. The standard AR buffer WITHOUT the spacer is allowing my bolt face to catch on the stop and the bolt carrier is stopping about 3/16" short of hitting the back of the lower/ front of the buffer tube when bottomed out on the standard AR buffer...

So... for you guys running the UBR on a LR308 style rifle, have you found that a standard AR15 buffer is what works? Just thought it was worth asking and talking about here. If anyone here us running a UBR on a 308, may want to verify that you are running a standard AR15 buffer. The short 308 buffer minus spacer will cycle but would be hammering the back of the receiver/front of the buffer tube correct?

Thanks...

 

[DRAM40A1]

The UBR tube is 3/4 longer than a standard carbine tube. I’m using an Armalite H3 buffer and spring. Works great on my 308.

 

[DRAM40A1]

I also have Slashes XH Carbine buffer and Armalite spring if I need more weight.

 

[ShooterwithNoName]

Good deal... I'm glad that I can use a standard AR buffer now. That and this thing is way easier to charge now. Like charging on an A2 stock. Ill probably have to re-tune my gas block but that's no big deal. Going from that stiff carbine spring to this should make it a bit smoother shooting too.

Thanks DRAM40A1 for the reply...