For close to 5 years now I have been using a JP Enterprises Grade 1(older model) upper assembly on a lower receiver that I built up.
I really don't find it to be too terribly bad in terms of reliability. I've run this thing dry as well as wet while using it to bust squirrels and it's chugged through over 200-300 rounds in an afternoon without so much as a hiccup. It averages around 3/4 inch for 10 shot groups at 100 yards with one of it's more favorite handloads(my handloads are pretty basic).
Mine is a 24 inch barreled model set more for varminting/bench work but it still knocks the hell out of most things I want to do with it. I have the tank brake on my gun and wound up taking the thing off after a year or two of being fed up with not being able to properly clean the muzzle crown. JP now offers a non-standard post ban compliant thread now if I recall correctly, highly recommend either getting a removable brake or avoiding it all together. You would NOT believe how much crud was on my muzzle crown after close to 2 years of shooting and not being able to clean it properly. The tank brake is the most god awful loud assed muzzle brake you've ever had the displeasure of bearing witness to. No foolin, I've shot this gun exactly TWO times without hearing protection, first was a sort of deliberate thing to see if it was bearable(after which I swore never again) and the second time was purely by mistake.
From a low prone, the tank brake will pick up bits of dust and pebbles only to blow them into your face.
My gun is a bit unique, many of the more senior members of this board can remember back to 1998 when I was building it up. In it's final form it weighs in at 15 pounds unloaded and is 48 inches in overall length.
This gun was my first step into the realm of accurized rifles that have the potential to out perform the user. This was the rifle that I built before I knew what I really wanted or before I was truely educated on the world of accurate AR15s. Ofcourse back in 1998 there were fewer people in the market of making accurized AR15s of this magnitude. If I knew what I know now and had access to the amount of parts that are available now, it is likely my rendition of the ultimate varmint AR15 would be a different animal all together. I don't consider my JP gun to be a mistake, it was simply a learning experience.
Today, it is very easy to get a flat out accurate as all heck AR15. Can be as simple as getting an Olympic SUM barrel and throwing it together with the parts of your choosing, total price for the upper probably being a good 200-300 dollars less than a similar JP Enterprises upper that probably won't be any more accurate.
It's for these reasons that I believe that the Wilson and Les Baer AR15s are an even bigger rip off. Just johnny come lately types trying to hop on the bandwagon, worse the two previous companies seem to be basing their AR15 prices off of their reputation earned for building 1911s. AR15s simply don't require the type of tuning that a 1911 needs inorder to be both insanely accurate as well as reliable.
If you are looking for a 3 gun AR15 as well as one that can serve for varminting/target work, head out to a 3 gun or action rifle match and see what others are shooting. When I shoot 3 gun or action rifle, I yank my 20inch A3 upper off my Bushmaster and install it on my custom built lower of the accurized rifle. In that configuration I get a better fitting stock with superior trigger(the JP single stage trigger/hammer at 3 pounds) but get a reliable and lighter upper assembly.
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