Howdy folks - Love my PSA products, wanting to build and AR9 but would really like LRBHO functionality which the current PSA AR9 completes do not offer. Does anyone know if a PSA AR9 complete lower has compatibility with a CMMG 9mm upper? And if the lower impacts the LRBHO function? Having trouble finding info on compatibility across makers. The AR9 world feels very fickle compared to its bigger brothers… Way less info out there.
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It is best not to mix brands with AR9’s much like it is best not to do the same with ar10s. I personally would not mix the two just to get lrbho.
I have a Quarter-Circle-10 ten (small Mag) lower with LRBHO.
Sometimes it locks the bolt back on the last round…sometimes it doesn’t.
I’ve had it for years and I love it. To be honest I like it….and enjoy shooting it….and whether the bolt is locked back or not on the last round is not that important to me any longer. At first it was important….and it was one of the reasons that I chose that receiver for my build….but as time has gone by….and thousands of rounds have gone through it…. I have found that the bolt lock isn’t really that important. I shoot recreationally………if it was full on competition shooting….you may benefit from LRBHO. You decide….but really the reliability, fun factor, and the realistic training that it provides……for a fraction of the price of my 5.56 or 7.62….cannot be understated. Get one……use it……have fun……you will get more Smiles per Hour out of it than the bigger rifles…….but the bolt hold open….it’s not that big of a deal.
Appreciate this much thank you and great points. Re lrbho, my thought is that this weapon would be home defense primarily. I know the arguments for the rifle calibers but have 2 little kids and am trying to mitigate wall penetration / noise as much as reasonably possible while also being ballistically competent. Does this impact your assessment of lrbho?
If you have to worry about changing a 30+ rd mag in a home defense situation you have bigger issues than lrbho.
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Lol, yeah fair point, well, this steers thinking toward lrbho doesn’t really matter
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The lower does usually impact the LRBHO. Usually the mechanism is built into the lower to pop up and lock open the bolt. However there are other options. If you were to use a standard AR-15 lower, you can look at MEAN’s Endomag. It is a 9mm insert for a traditional AR-15 Magpul Magazine. This will give most AR users a more familiar magazine to manipulate, and it has a LRBHO tab in the insert that will interact with the traditional bolt catch. We dont carry them at this time, but they could be worth looking into.
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I have a PSA Gen 4 9mm upper on a standard AR lower that I use with the Mean Arms Endomag adapters, I like them. I bought three, one of them kept hanging the bolt on the ejector after doing the recommended break in procedure. I ended up having to shave a little bit at a time off the ejector until it ran properly. I contacted Mean Arms about the issue before I trimmed it and they said they would exchange it but the shave fixed it so I never took them up on swapping it out.
I like the look of the larger mags vs the little sticks so this solution was best for me.
I really like shooting the 9mm since I can take it to the indoor range if the weather is bad and I want to shoot. The look on people’s faces when you run a silhouette target out to the end of the rail (it’s a 25 yard range indoors) and rip a 1.5” hole in it is priceless. They peek around the side of the booth to see what the heck kinda pistol can do that.
I think you will like it no matter what you choose.
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Thanks Josh. If go the route of standard AR w/ endomags or the like, I need to get a 9mm upper correct? Obviously. And any of the pre-built 9mm uppers on the PSA website will fit the PSA lower I have. Sorry for these dumb sounding questions…
Not a problem, its a great question! Yes, our PSA AR-9 uppers will fit on our PSA AR-15 (PA-15) Lower Receivers.
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Thanks Josh!
PSA gen 4 upper kit paired with a mk9 CMMG lower with LRBHO
like josh said the hold open mechanism is in the lower and magazine. The CMMG mk9 lower has last shot hold open it uses colt mags. which have a little tab that pushes up on the bolt catch just like your standard AR in 556. im using ACS mags and it has worked flawlessly. plus i personally like the colt mags , they are easier to load. drop free and look cooler than glock mags , just my opinion.
My PSA AR9 lower has a LRBHO, have they been discontinued?
We stopped producing the model with the LRBHO a few years ago. I remember building them and hated it. I’m not sure the reason we discontinued them though.
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New reply to an old thread. Aero EPC uppers with a standard PSA lower works great for LRBHO. Worth the $90 to $130 ( depending on sale prices) for the Aero upper with LRBHO. They look pretty good together, too.
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I’m glad you commented, I was wanting LRBHO for my PSA AR9 and was curious if all I needed from Aero was just the upper receiver and if that would be all I would need?
Yessir. That’s it. I’ll be honest and say you may be able to get the EPC lower for less than the PSA lower, too. Aero has been selling them for around $100 or $110 at times. If you already have a PSA lower, you’re still good to go with just the Aero EPC upper for LRBHO. Have fun!!
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I have a PSA AR9 upper on a standard AR15 lower and started with the EndoMags. They worked fine and never had any issues with it not holding open on an empty mag. The only issue about the EndoMags everyone should realize is that if you have a round in the chamber and you need it out of the chamber, the magazine needs to be empty and in the mag well before you can eject the round out. If the magazine is not in the mag well it will not eject the round. I did not like this fact and went with a Stern Defense mag well adapter for that reason alone. It was more of a safety issue for me than anything else. I enjoyed what they did and what they allowed for a minimum cost. The one thing you need to think about with mag well adapters is the mag release is moved and you don’t use the standard release anymore. Different adapters eject in different ways so do your research before you go this route. In my research the Stern Defense had the best reliability ratings but cost a little more. In the end I went with reliability over cost. I haven’t had a lot of range time after I have switched. I was able to shoot a few different magazine brands with different ammo types and only had issue with one. I hope this helps someone.
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I beg to differ on this. I run the same setup, PSA upper on a standard lower with EndoMag adapters. You can use either a loaded or empty EndoMag to eject a round in the chamber. Insert the mag, pull back the charging handle and lock the bolt open, then remove the mag before you release the bolt.
I will agree that method will work, in the end that was an extra step I felt that could have been eliminated. In a high stress situation, this would probably cause more problems than needed. Is the average person going to be running this set-up during a high stress situation? Probably not, but for me I felt it was a safety measure I was willing to spend the extra money to eliminate. I however do recommend the Endomags for someone getting into a budget build and can certainly upgrade later if they want. I certainly had plenty of fun using them while I had them.