Any experience running a Oly .45acp upper ?

[umwminer]

Pros/cons , problems , etc .
appreciate any actual hands on experience .
thanks

 

[theduke]

Had one , Never used it sold it.
Oly is no more.....Uzi 45 mags with the block were the originals.
Then Oly made the Plastic ones.

Not sure if someone bought out OLY and still makes these Mags.
I bought a bunch of spares for the 40 & 9mm uppers before they shut down years ago......was an election year...I'm thinking 2012?

 

[amphibian]

I bought an entire setup from someone. OLY .45 upper and MGI Modular lower with the rare Grease Gun magwell.
I had a GG magwell before and foolishly sold it so I bought this setup just to get the GG magwell back and I use it in conjunction with the CMMG RDB setup.
Here is a video of the upper before I got rid of it.

As you can see it worked fine but much prefer the delayed blowback CMMG in .45.

 

[strobro32]

I had a .45 upper that I shortened for a SBR. Ran fine but the blow back made it not a quiet host. They did produce there own 45 mags but they were limited to 17 rounds to fit the AR15 magwell. The mags are still available.

 

[SecondAmend]

I've had an OA K45 16 in. bbl. upper for more than ten years, but I only have the plastic body mags so some comments might not apply to the older IMI steel mags that have the magwell adapter welded on. As I hardly ever shoot .45 ACP with any firearm (due to expense), the K45 upper doesn't get shot much. Random thoughts that come to mind:

Some pluses about the K45 - it has a unique blowback system that is milder than "straight" blowback, but less mild than delayed blowback (using a 1928 Thompson delayed blowback for comparison). The mags include a last round bolt hold open trip, so that piece of hardware is not needed elsewhere. As an AR pattern upper, the there are numerous accessories for the upper and whatever AR lower one uses. In particular, the recoil system can readily be "tuned" for very tractable .45 ACP shooting.

Minuses include after winding down for a couple of years, what appears to have been the final demise of OA in early 2020. While Rainier Arms appears to still have K45 mags, the other sites I looked at show the mags as discontinued or out of stock. Other special parts might be difficult, expensive, or impossible to find. Ejectors come to mind. As is the case with other AR pattern uppers, full auto operation requires a bolt carrier that has a sear trip abutment (i.e., a "full auto carrier"). Such a full auto carrier was a special order, $85 item and OA required a copy of ones Form 4 before they would sell the item. That said, it appears that by tig welding and grinding to shape a couple weld runs, one could convert an semi carrier to a full auto carrier. The mags seem to be on the "fat" side and are a bit tight in some lowers that might not have been milled out as much as mil spec requires. I have not done so, but I've read that the long discontinued VM-Hytech magwell adapter with the ejector removed for bolt clearance can be used to hold Uzi .45 ACP mags such as those from IMI (expensive) or relatively low cost (ProMag); however, I don't believe that such an arrangement would provide LRBHO.

Neutral: Full auto rate of fire (rounds per minute) .45 ACP comparisons from own testing using American Eagle 230 gr. round nose ammo: Uzi: 680s; 1928 Thompson: mid 800s; OA K45 on M16 lower with carbine length buffer tube (lowest ROF buffer/recoil spring combination): 680s.

Best of luck.
MHO, YMMV, etc. Be well.

 

[umwminer]

I thank you 3 gentlemen for the info and your precious time .
I think I’ll go with a cmmg rdb outfit .

 

[SecondAmend]

I thank you 3 gentlemen for the info and your precious time .
I think I’ll go with a cmmg rdb outfit .

As you are undoubtedly aware, there are a currently couple vendors that make and sell so-called "direct impingement" (DI) gas operated systems for the AR-15/M16 pattern firearms which presents another viable option to direct blowback.
Of course, as is the case of the OA system and the CMMG system, a DI system, and any system for that matter, there are always design limitations and compromises.
Best of luck with whatever you decide to pursue.
MHO, YMMV, etc. Be well.

 

[umwminer]

I think that a DI upper would solve all my dislikes about running BB 9 & 45 on the M16 . I haven’t been paying attention for a while but the little bit of “research“ that I have done about the DI uppers seems to point to lack of gas volumes being a reliability issue . I would like to be wrong about that .

The OA shorty looks like a fun range toy . I wasn’t aware that it has it’s own version of delay until you educated me , SecondAmend . The lack of AOmags for it has me skittish . Would you Brothers know if the Macon magwell and mags would be a reliable drop in solution ?

 

[amphibian]

I personally do not like to use commonly abused term of DI in reference to the AR15 / M16 as it is technically incorrect as Eugene Stoner says himself here:

Stoner's patent also describes his system as using a 'stationary piston" in his patent: https://patents.google.com/patent/US2951424A/en

Regardless, I had a 'gas operated' 45 setup as discussed on my site here: https://c3junkie.com/?page_id=76

I have a friend with the Macon magwell and mags that he uses in an M16 and it works fine. He is also running it with a CMMG RDB in .45ACP.

Having owned a gas operated .45, and running almost 100% suppressed, I would still get the CMMG RDB.

I have a lot of experience tinkering with the CMMG RDB in 9mm, 40SW and .45ACP. I have a friend that also has it in 10mm. We are all running them in FA. Only the 45ACP version doesn't have the ejector spring failure issues as I have documented on my site here:
https://c3junkie.com/?page_id=164

 

[umwminer]

amphibian , you have always been my “go to “ AR subgun pro . I’ve been out of the game for a few years but we have corresponded about these issues in the past and I have always been gobsmacked by your detailed & documented work that you share with any of us that may be interested . Your c3junkie site is first class and on my favorites list .
Thanks again for the help .

 

[saxon]

+1 for CMMG RDB

 

[SecondAmend]

Historically, a recommended recoil system for so-called straight blowback .45 ACP AR-15 applications was the implementation of an A5 length buffer tube, a KynSHOT RB5015HD hydraulic buffer, a Blitzkrieg (2.5 oz.) steel spacer in the buffer tube positioned between the buffer and where the carrier rests, plus a flat wire rifle length recoil spring.

I personally use a similar recoil management configuration in connection with the aforementioned OA K45 upper.

Disclaimer: I have no affiliation with or financial interest in any vendor or manufacturer. I am not a competitive shooter or a blogger who receives any form of compensation or sponsorship for endorsements, or favorable public or private comments. I do not have a website, podcasts, webinars, or online videos; or books/magazine articles. Use of vendor and/or product brand names, if any, is for informational purposes only; and products or services were purchased by me from regular commercial sources.

Best of luck.
MHO, YMMV, etc. Be well.

 

[umwminer]

SA , thanks again for the eloquent help , info and time . I may fool around with the .45 this winter . Most likely a cmmg outfit .

 

[SecondAmend]

SA , thanks again for the eloquent help , info and time . I may fool around with the .45 this winter . Most likely a cmmg outfit .

You're very welcome, sir.
As "amphibian" notes, the CMMG RDB system is likely a good choice these days. As you might already know, CMMG originally developed their RDB system for the AR .45 ACP platform and added other calibers later.
And as you probably also already know, if at all possible, test shoot whatever systems you consider before purchasing; preferably, side by side for direct comparison.
Best of luck, and enjoy many safe and happy times shooting whatever you pursue.