Del-Ton,or Model1 sales both have fairly decent kits,as far as a lower receiver it is the only part that has to be shipped to an FFL,my last builds were done with Double star receivers,but you can get "RRA rock river arms"or several others depending on price range you want to pay,some receivers can be bought for under $100.00+S&H
Check out Bravo Company Machine. Very good uppers at a great price for top tier quality.
Other places I would suggest would be Del-ton and Doublestar. I cannot suggest Model-1, I have some friends that have bought kits from them and the parts were questionable( weak steel), while others work fine.
I'm very satisfied with the results I got from a Del-Ton middy (mid-length gas system) kit built on a DoubleStar lower. No issues, no problems. The Del-Ton folks were good about pre-purchase questions and delivery was faster than projected at the time. Current price is still the same as when I bought mine a year ago. The 1 in 9 twist barrel included in the kit works well with a CMMG .22 conversion as long 40 grain or heavier ammo is used.
I would go with Del-ton for a kit. They've got the best customer service and responsiveness of any retailer I've ever dealt with. They're pretty well caught up now, from what I understand, and if you call and ask for it, they will sometimes build configurations not listed on their website.
I would recommend J & T distributing, they are partnered with Double Star. I own a Star15 carbine and I will swear by its quality. Thier prices are excellent and they will send you everything you need to build a basic rifle sans reciver for around $5-600. They give you a ton of options on how you want your upper built.
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