I'm needing to finish my pistol and I was wondering which bolt to order would be better
PSA premium or Aim surplus bolt.

Can I get a measurement from some one from their castle nut to the start of your sig brace.
No matter what I do I can't get that thing on past half way..

IMHO buy what ever BCG is cheaper shipped to your door I have several of each, none have given me any problems and function fine, quality is so close that I don't feel one is better than the other. If I were to pick one over the other I'd go PSA simply because the extractor and carrier key are tool steel... AIM offers both tool steel and investment cast, the cast are in the cheaper BCG's in both phosphate and NIB finishes. Investment cast is not necessarily a bad thing, if injected, final machined and heat treated properly they are just as good as tool steel IMHO. One very important factor may be shipping time... go AIM if you want it in a few days rather than possibly a few weeks to a month from PSA

Sorry, no help on the SIG brace... I run a CAA cheek rest on my KAK buffer tube.

Who's tube? I know some are significantly tighter than others and will even stretch the brace to where it won't fit well on some anymore, but never anyone say they had one that just couldn't work at all.

You ain't trying to stretch over a carbine tube are ya?

- OS

I bought a spikes pistol kit for it. I ordered the upper from palmetto state on the 17 and received it yesterday
Shipping time wasn't that bad.

It will go on all but  three inches I even used the baby powder trick and still fought it.

Push the lower into the brace with the brace supported from behind rather than trying to push the brace onto the tube. If that's how your already doing it, I have no clue other than push harder or get a buddy to help. I did mine this way with no powder or anything and it went on in one quick shove.

Got it where I want it.