Do I need to take my buffer and spring out of my buffer tube in order for the bolt action to work?

No, but you can if you want to. We would suggest you try running it with and without and determine which you like better.

Do you make a Left Handed Receiver?

Not yet but we are working on them. We have prototype LH UPR-15s we are in the testing stages on but we have not gotten as far with the LH UPR-10 as of yet.

What Lower Receiver should I use?

For the UPR-10 it will fit any Gen1 DPMS pattern lower, the fit however will vary from maker to maker. We use Aero Precision or DPMS lowers for our rifles. The DPMS offers the best fit as far as looks go. As for the UPR-15 any Mil-Spec lower receiver will work, again fit and function will vary from receiver to receiver we try very hard to keep all of our parts as close to the same as possible but we have no control over the Lowers.

Do you sell just Receiver sets?

Yes. We sell receiver sets for both the UPR-10 and the UPR-15. They include the receiver, the bolt, and the barrel extension nut with a wrench. We do however encourage you to talk with the gunsmith you will have do the barrel work for cost estimates as this will be the same amount of smith work as re-barreling say a Rem 700. Also if you want something different than our standard barrel configuration we do offer extensive custom options such as fluting and carbon barrels so just give us a call if you’re interested in custom options.

Are you uppers compatible with standard AR-15 and AR-10 barrels?

No they are not. We use a Proprietary Barrel Extension nut with our uppers and there are no gas holes in our barrels.