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

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.

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.

We do sell receiver sets, which include the receiver, bolt and proprietary barrel extension nut. However, standard AR barrels are not a direct drop in option. Our uppers utilize a traditional style barrel that attaches like an AR barrel, but there is no gas block/system. If you used a regular AR barrel you would have to use our proprietary extension nut (for our 3 lug bolt ), have some machining work done, headspace it, and find a solution to plug off the gas hole. If using a barrel blank, the amount of work would be similar to rebarreling/rechambering a Remington 700. We strongly advise that only a qualified machinist/gunsmith complete this project. In addition, we can not guarantee the accuracy or functionality for uppers not completed in house.  If you’re looking for something different from our standard caliber or barrel offerings, we do offer custom options such as fluting, carbon barrels and other calibers. Give us a call and we can get you setup.

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