So what is this?

[Elkeater]

Think I bought the wrong kind of upper receiver. No big deal. They're cheap and I can get a mil spec one. But what do I do with this one? What kinda of handguard fits this?obviously it's not milled out like a milspec.

 

[cohunt]

Ar10? There are "high" and standard

There is no real "mil spec" for ar10/ sr25 --- lots of proprietary parts in the "large frame" arena

 

[Elkeater]

No it's definitely a ar-15 pattern just not really milled. I'll be taking it back to the store.

 

[cohunt]

Actually the upper looks pretty standard--- what's going on with that seekins handguard? It shouldn't be "off set" unless itss for something proprietary

 

[rpol98]

Think I bought the wrong kind of upper receiver. No big deal. They're cheap and I can get a mil spec one. But what do I do with this one? What kinda of handguard fits this? obviously it's not milled out like a milspec.

any handguard that doesn't have the anti-rotation ears.

 

[rpol98]

Actually the upper looks pretty standard--- what's going on with that seekins handguard? It shouldn't be "off set" unless itss for something proprietary

it has anti-rotation tabs that are probably designed to mate with the profile of a Seekins upper receiver. Usually the mfr will have some kind of disclaimer that their product won't work with a billet or non-mil-spec receiver, such as this case. or not.

 

[cohunt]

it has anti-rotation tabs that are probably designed to mate with the profile of a Seekins upper receiver. Usually the mfr will have some kind of disclaimer that their product won't work with a billet or non-mil-spec receiver, such as this case. or not.

I see it now-- the anti rotation tabs are causing it to not sit flush with your billet style upper....the really "off" part is the difference in height of the rails...looks like ypu definitely have a "non-mil spec" upper there
I don't use handguards wirh rails though--

 

[Elkeater]

Actually the upper looks pretty standard--- what's going on with that seekins handguard? It shouldn't be "off set" unless itss for something proprietary

Yup all the above comments. Didn't really realize there were handguards that didn't have anti rotation tabs. Every one I've messed with had the anti rotation tabs and lined up nicely. Guess I'll just buy a new mil spec upper receiver.

 

[bultinkle]

Yeah I'd take that back and just buy a bcm/aero mil spec and roll on

 

[ARlife4me]

Not all ar15 parts work with each other, but the majority does. Some of F1 receiver sets (light weight 1's with the cuts) are not interchangeable with other brands. Ther's another mfg that I can't think of right now that's the same way. Geissele has tabs on their handguard (not sure if all do) that don't conform with other uppers. I know this because I had to Dremel to reform.

 

[Elkeater]

I ended up just ordering a new upper receiver for this particular build. I did keep this one though. I may try machining it with a drill press for a future build.