LR308 vs AR10

[QuinnBayArea]

Just now discovering there's a difference between the two with the upper to lower fitment. I have a complete DPMS lower, and a complete JL Billet upper. After getting the upper home tonight I discovered that the upper BARELY doesnt fit. The front pin goes in fine, the rear one is off by a butt hair. Do I need to buy another lower for this upper, or can I make it fit with some grinding/sanding/what have you? Is there a danger to making it fit? Or do I need to know buy another lower that fits properly?

[Quiet]

Just now discovering there's a difference between the two with the upper to lower fitment. I have a complete DPMS lower, and a complete JL Billet upper. After getting the upper home tonight I discovered that the upper BARELY doesnt fit. The front pin goes in fine, the rear one is off by a butt hair. Do I need to buy another lower for this upper, or can I make it fit with some grinding/sanding/what have you? Is there a danger to making it fit? Or do I need to know buy another lower that fits properly?

There is no standardization with AR308 platforms.

Some manufacturers are proprietary and some manufacturers copy others.
There's enough variations in the builds that they make it so they are not compatible.

You need to pick a single manufacturer and stick with them.

[C.G.]

Just now discovering there's a difference between the two with the upper to lower fitment. I have a complete DPMS lower, and a complete JL Billet upper. After getting the upper home tonight I discovered that the upper BARELY doesnt fit. The front pin goes in fine, the rear one is off by a butt hair. Do I need to buy another lower for this upper, or can I make it fit with some grinding/sanding/what have you? Is there a danger to making it fit? Or do I need to know buy another lower that fits properly?

I looked up the JL Billet lower, it is not an AR-10 lower, but an LR-308, so it should be a semi-fit. Unfortunately, LR-308s are not standardized especially if billet, always best to buy the lower and the upper as a set. You could probably make it work although I would have a gunsmith (unless you are machinist) do it as I've seen too many Dremel hack jobs.

[ar15barrels]

I have a complete DPMS lower, and a complete JL Billet upper.
After getting the upper home tonight I discovered that the upper BARELY doesnt fit.
The front pin goes in fine, the rear one is off by a butt hair.
Do I need to buy another lower for this upper, or can I make it fit with some grinding/sanding/what have you?
Is there a danger to making it fit?
Or do I need to know buy another lower that fits properly?

Sometimes the parts are just barely off from each other and you can either find a smaller takedown pin by measuring several different brands.
Another option is to line-ream the takedown pin holes in both receivers while they are pinned together with the pivot pin.
Grinding or sanding should not be options to consider as you will be fighting anodizing.

[SloChicken]

Just now discovering there's a difference between the two with the upper to lower fitment. I have a complete DPMS lower, and a complete JL Billet upper. After getting the upper home tonight I discovered that the upper BARELY doesnt fit. The front pin goes in fine, the rear one is off by a butt hair. Do I need to buy another lower for this upper, or can I make it fit with some grinding/sanding/what have you? Is there a danger to making it fit? Or do I need to know buy another lower that fits properly?

Make sure that isn’t a panther lower as if I recall correctly it is on the CA ban list.

But yeah, your realistic fix here is either a dpms upper (they have both high rail (pre 2009) or low rail (post 2009) as well as gen 2 308 and rhat is a whole different animal.

End all, I have built up more than a few AR/LRs (still have 3 of them ...) and have found I am bette off and happoer with my FAL, M1A or even a G3 clone.

[tabascoz28]

Yeah, sorry that's why I just bought the whole thing from PSA. And when I bought another upper I made sure it was from the same company. This is the time when everyone is trying to win the standard fight so you're going to get non standard parts. I now finally own a glock for that reason as there are tons of aftermarket parts that just fit without research, although there's a gen4 and gen5 discrepancy too. I started with the AR15 and was very lucky they are very standard. I think 1911s are too but be aware there's now something called a 2011 which is just a double stack mag model.

[Fang415]

Get a aero m5 and call it a day

[PachecoFTW]

Lol, ever since I was 18 and learned this I said no ar10 for me! Never did buy or build one.

[67Cuda]

Get a aero m5 and call it a day

I had a similar situation with a Colfax 80% lower that I used with my DPMS .308 Oracle upper.
Using standard pins, no way it would go together, so I turned the take down pins and made it work. It worked well.
But, I didn't register it, didn't want to go through the hassle.
So I bought an M5 lower and it fit perfectly. Done.

[Zzyzx85]

Yeah, putting together an AR308 was fun. There's no such thing as a "milspec" AR308 so it's almost a free for all. However, most manufacturers settled with either AR10 or LR308.

I built mine using a JD Machine billet upper and lower set, which used the LR308 design (rounded rear lower end of upper receiver).

Fun rifle but I wished I built it with a shorter and/or thinner barrel.

[Robert1234]

The only AR type rifle I ever bought co.plete was an Armalite AR10 (whatever model is on the roster). It takes P Mags, which is nice. I had to add a free float handguard, muzzle brake, and better trigger. Looking back, I'm glad I did it this way, the various .308 ARs seem to be a pain to build, and more expensive (including gun, trigger, brake and handguard I think I'm into this one around $1,200.00. It's a nice gun, but even with the thin, 16" barrel, it's heavy.

[2Aon2wheels]

Always get matched upper/lower sets whent building 308 ARs.

[Devilock04]

[sigstroker]

End all, I have built up more than a few AR/LRs (still have 3 of them ...) and have found I am bette off and happoer with my FAL, M1A or even a G3 clone.

Why is that? Spill!

I like my FAL and M1A, but they are not good for scope mounting. At least an AR pattern is good for that.

[QuinnBayArea]

Can you elaborate on the ban of the Panther? So if it says "Panther" its banned? Do you have a link to wherever it says its banned? I know it says DPMS I will have to check what model and whatever when I get home.