Best lower for a precision BBL build

[Holyfather12]

The time has come to build myself a lower before all the stocks dry up as the election comes near. I was looking at the CMT Tactical UHP15 Billet lower for $185. Heard good things about Aero and Seekins as well. Anyone have this lower or recommendations? It will be mated to a VLTOR MUR upper. Plan to put a Giessele SSA-E trigger, Ergo grip and Luth-AR MBA-1 Stock on it.

[mongoosesnipe]

i have a sun devil lower on may precision ar, its billet and it was the first one to come out with the set screw to tighten up the upper lower fit so you didn't have to use a wedge, this was several years ago and since several other companies have adopted the same setup seekers being one of them, i also like that all the springs are held in the seekers with screws and that it has Bambi bolt release.... if i were building another precision rifle i would probably get a seekens that said any in spec lower will shoot fine as the ar15 design does not require a tight upper lower fit to be accurate

[LRRPF52]

PF's billet sets are crazy tight and well fit.

Seekins makes top notch billet sets.

AA has a side charger billet upper kit.

I like the new ADM billet lower with ambi bolt hold open and release, very streamlined and intuitive.

[am4966]

Hell PF's forged lower with a Aero upper was crazy tight! Imo, I don't think you need a billet lower. I believe that a billet upper and forge lower will give you the same results as a billet upper/lower set. If I'm wrong someone please enlighten me since I'm going to be building a precision Grendel in the near future.

I have a couple uppers and lowers in mind.

[Keep The Change]

am4966,
I have a billet upper LH Side Charger (WMA/Holy City Rifleworks) with a Seekins forged Lower. There is some play between the 2. I'm contemplating putting a wedge or using the JP rear tapering pin to snug the rear up. This is a long barrel gun built for distance, and if I had it to do over again, I would've bought a billet pair. At the time there was a rush on lowers and the billet sets were outrageous.

[454bore]

I got a mega billet lower and like it for my side charge upper.

[Maplebacon]

I've never been able to understand the concept of a loose upper/lower fit not affecting accuracy. It goes against the practice of bedding actions in other rifles for accuracy.

[mongoosesnipe]

I've never been able to understand the concept of a loose upper/lower fit not affecting accuracy. It goes against the practice of bedding actions in other rifles for accuracy.

it does affect accuracy but since the sights are on the upper it doesn't have as much affect as you would think think about a loose slide to frame fit on a pistol that has a tight barrel to slide fit, and since most of the time the barrel is free floated you don't have to worry about contact points causing stress which is the principal reason for bedding in most rifles but all things being equal a tight upper to lower fit is better...

[Keep The Change]

If there is a little play vertically or laterally I could see it impacting accuracy. Because the reaction force is going aft and forcing the carriage to compress the buffer spring. That aft momentum would make the aft end of the upper could go down or side to side, thus moving your muzzle during this process. Am I missing something.

[mongoosesnipe]

If there is a little play vertically or laterally I could see it impacting accuracy. Because the reaction force is going aft and forcing the carriage to compress the buffer spring. That aft momentum would make the aft end of the upper could go down or side to side, thus moving your muzzle during this process. Am I missing something.

you said yours has a little play are you consistently getting vertical stringing?

[Holyfather12]

Has anyone used the AA stripped lower for any of their builds? Or know if it is a billet or forged? At $110 its pretty cheap for a lower from a quality manufacturer. My guess is forged.

[LRRPF52]

The AA lowers are forged, and a very nice forging at that. The are always snug to the upper in my experience.

[Maplebacon]

it does affect accuracy but since the sights are on the upper it doesn't have as much affect as you would think

Aren't sights on the "uppers" of pretty much all rifles? I have a JP adjustable pin, so mine is nice and snug. Personally I feel every bit of looseness has an impact on accuracy.

I simply do not understand how the AR upper group is any different than a bolt gun upper group or pretty much any other rifle. I am hard pressed to think of a rifle where the sights are somewhere other.

since most of the time the barrel is free floated you don't have to worry about contact points causing stress which is the principal reason for bedding in most rifles

I have never heard that as a reason for bedding.



In any event, back on topic: My LMT Defender 2000 lower had some slop with the LMT upper, but my newly built grendel upper with Mega Billet upper is nice and snug (even before using the JP pin)

[mongoosesnipe]

Aren't sights on the "uppers" of pretty much all rifles? I have a JP adjustable pin, so mine is nice and snug. Personally I feel every bit of looseness has an impact on accuracy.

I simply do not understand how the AR upper group is any different than a bolt gun upper group or pretty much any other rifle. I am hard pressed to think of a rifle where the sights are somewhere other.



I have never heard that as a reason for bedding.



In any event, back on topic: My LMT Defender 2000 lower had some slop with the LMT upper, but my newly built grendel upper with Mega Billet upper is nice and snug (even before using the JP pin)

most traditional firearms only have one receiver but yes the sights are going to be on the "upper"
in a bolt gun there is only 1 receiver/action and the trigger is attached,if you had a loose a stock to action fit and a heavy trigger you could in theory move the action as you pull the trigger so bedding makes for a snug fit and you will also either raise the action a bit or inlet the stock to float the barrel so there is no other contact or stress to cause issues as barrel temp changes

im not saying slop is a good thing as much as saying it is not as much of a factor as a bolt gun as the barrel is already free floating and the upper is a separate piece its kind of apples/oranges but you don't typically see a lot of emphasis on bedding when the bolt gun is in a chassis