eunichron

Primary Arms discount on the SR-762 lowers is up again. $69.99 while they last. I have all the receivers I need for the builds I want, so I won't be purchasing more. I did finally get a response from Ruger customer service regarding parts availability. They only confirmed that they no longer have parts available for purchase, and that any Armalite upper should mate with their lower. A few of the parts I ordered from Numrich/Gun Parts Corp arrived today. Pivot pins and bolt catch roll pins. The pivot pins are Ruger OEM part #NS01066 and measure at 1.3500" long, not including the head. They are .2745" wide. This matches dimensions I've seen for Armalite pins. I think it is safe to say any Armalite compatible pins are good to go for these Ruger lowers. The bolt catch roll pin is listed in the manual for both the SR-556 and SR-762, and it measures within spec for a standard AR15 bolt catch roll pin. I paid $7 each for these Ruger OEM pins, don't pay that much. Use whatever you can salvage from a parts kit or order them from McMaster-Carr (3/32" x 1/2" coiled spring pin part #91598A204). Next steps will be ordering one each of the Stag10 and DB10 uppers and some more Armalite small parts to see how they match up.

Numrich Gun Parts has Ruger OEM pivot pins in stock, so I ordered two. Armalite also uses a cut pivot pin, so the AR10 parts kits should include the correct pins, if not a slightly different length. I'm going to order one parts kit just for testing's sake. At this point I'm pretty sure all Ruger (i.e. Matrix) did was machine a receiver that's 60% Armalite AR10(A) (pivot/takedown pins, bolt catch [although it may use a B pattern bolt catch], SR25 magwell) and 40% AR15 (fire control group). Shouldn't be too difficult to finish the receivers now.

🤔 Almost every DPMS parts kit I've used has fully round headed pivot pins- CMMG and LUTH-AR parts kits, and the pins that come with MATEN receivers all use fully round headed pivot pins. The Panther LR-308 that I used to own had a fully round headed pivot pin. The stock photos for the BAD pins on their website also show fully round headed pivot pins, so I'm not sure where you get that statement.

I wouldn't mind protrusion, but on closer inspection the Ruger pivot pin is flattened on one side of the head just like the Armalite pins, so I don't think the BAD pins would fit regardless. I think between Numrich and EGP I should be able to piece together a mostly correct small parts kit. Just to confirm, I got my pin gauges from the shop and both receivers measured at a snug .277. I suppose I'll also order one each of a DB10 and Stag upper and see which one fits best. On further reading, I should be able to get away with using a DPMS barrel in the DB10 upper even with Armalite threads as long as I also use a DPMS bolt that headspaces properly. In any case, here are my current build plans: Mega MATEN receiver set: 6.5CM Ruger #1: 7.62 NATO battle rifle Ruger #2: 8.6BLK SBR I'll try to document what I can here since information on using aftermarket parts with the Ruger lowers seems scant. Gonna be an expensive year.

double post

I know some topics on other forums discuss Matrix being the OEM for both Ruger and Diamondback and that they're more or less interchangeable, but that was all pre-2021. It seems Diamondback has changed their uppers since then and they're now Armalite threaded. I'd really like to stick with DPMS threads on the upper for more compatibility. I know there are companies that will sell an Armalite barrel nut with their handguards. So that brings up something else I've never been clear on; barrel extensions and headspace. I know they used to be different between DPMS and the AR10B, but did Armalite go with DPMS dimensions on the barrels for the AR10A? I.e. will an 18tpi upper and barrel nut work on a DPMS pattern barrel? I don't know how much time I spent looking around everygunpart and didn't find those. Thanks.

From the information I have that points to an Armalite pattern lower parts kit... which Armalite doesn't sell direct anymore. Any guidance on where to find one, at least the pins, is most appreciated.

Got some measurements in. Won't be able to take a pin gauge to the holes to confirm the caliper measurement until next week, but I'm pretty confident in these measurements. Takedown/pivot pin hole: .2770/.2775 Receiver width at the pivot pin hole: 1.3335 Receiver width at takedown pin hole: 1.1325 For s&gs and comparison's sake I took some pics of it next to my Mega lower:

I'm on the road right now so can't gage the pin holes for a couple days, but I did test fit my MATEN upper (a newer Zev production) on the Ruger after getting them home. The Mega's pins are just slightly oversized for the Ruger's pin holes. They will fit with some force, so that leads me to believe the Ruger receivers are sized for Armalite pins. I'll know for sure come Friday. That was exactly my thought if I wasn't able to source an original lengthened spring. I did find this listing for BAD pins with an option for a rear location spring. I might just reach out to them and see if they'd be willing to send me a few springs.

Centurion got back to me and confirmed their Mk11 upper will not mate with the SR-762 lower. He did lead me on to the Stag10 upper, which I've seen mentioned in other forums, but no confirmations that it does mate with the SR-762. Looks like OpticsPlanet has a few Stag10 uppers in stock, might pick one up for some test fitting.

Hey all. So, I'm not new to this forum, been coming here for over a decade, but I suppose there was a backend change at some point and lost my account. Anyway... I (maybe stupidly) jumped on Primary Arms' recent deal on stripped SR-762 lowers. Bought a pair of them for some builds I've had in mind. I'm no stranger to building large frame ARs, and thought it wouldn't be too difficult to find parts to finish the receivers and find matching uppers even with the rifles being out of production for several years. My hope was to find some Ruger or AR10A small parts to do some further test fitting to see what sticks... Numrich has a decent amount of Ruger small parts, but no takedown pins in stock. I reached out to Ruger but have not received a response yet. No dice on any Armalite small parts A or B series. Down to brass tacks... I'm looking for a source on these parts in order to finish the receivers and build a couple rifles: Small parts in general, but especially pivot and takedown pins, including springs - the takedown detent spring is longer on the Ruger since it is installed through the rear of the receiver. Bolt catch - as best I can tell an AR10A bolt catch should fit Upper receiver with DPMS threads - I've looked at the Centurion Mk11 and HTX Concepts SR25. Both look promising. I know the likelihood of them using the same pin size is next to nil. Thanks.