I have one of these and have misplaced the manual! I want to get an extension for the SIG brace but I think this is a piston not DI. If it's a piston there is no buffer tube, right?

Can anyone help with this?

Yes, an LWRC Piston gun has all the same parts as a direct impingement gun with the obvious exception of the gas block, gas tube and gas key on the BCG. Other than the gas system/piston parts the upper, lower and stock assembly are the same as any other AR.

I have an LWRCi M6A5 and it's my favorite AR.

FYI, LWRCi's customer service is AWESOME. I purchased mine second hand but the duffus, who may have never actually shot the gun (good) didn't save any of the box/paperwork/accessories (bad) that came with the gun. So, I called LWRCi up and was going to just buy all of that. I was told that while they could not send me a new box that they would simply send me the manual and all accessories that originally came with the gun... for free! It would be an understatement to say that I was pleasantly surprised.

I just recently decided that I should also have a couple replacement gas piston springs on hand, you know, just in case. I emailed them asking about which one that I needed exactly and they responded promptly with a link to the specific part on their web page and simple, yet detailed instructions on how to pick the correct part. Very nice touch.

LWRCi is top knotch!!!