AR 9 using the Endomag conversion

[Rangegod]

This is a report on my observations and results using a standard AR lower with Endomag converted Pmags to assemble a 9 mm PCC.

I currently have four “Glock Mag” compatible 9 mm carbines. These include the KT Sub 2000, the Ruger PC Carbine, a Micro Roni with a dedicated Gen 3 Glock 19 and a 10.5” AR built on a PSA Glock LRBHO lower. Of these, the only one that I am not 100% happy with is the AR.

First, although it has been basically 100% reliable feeding ball ammo from Glock, KCI, Magpul and ETS mags, the LRBHO has only worked semi-reliably with the ETS mags. This is not a major problem as many 9 mm AR’s do not even feature a LRBHO. In addition, to prevent breaking the bolt catch, the bolt over travel must be reduced by either spacers in the buffer tube or a longer PCC specific buffer.

The second issue is of much greater concern. This is because I do not trust the gun to safely feed and fire HP ammo. Early on when working with this gun, I realized the design required the cartridge to make a large unsupported jump from the mag to the chamber. I found with HP’s it was easy for a bullet nose to catch the chamber edge and misfeed. It could also however, due to the heavy spring and buffer used in the PCC, drive the bullet deeply in to the case during the feeding cycle. This, as I learned from experience, can cause extreme over pressure and a case head failure, with many (trust me) unwanted results. One might say, just don’t use HP’s, but this seems like a terrible limitation on a defense carbine which can share your carry gun mags and ammo.

Enter the Endomag. Simply put the Endomag conversion allows you to convert your standard (Gen 2 or 3) Pmag to a 9 mm mag. Installation take only seconds and the mag’s original configuration can be restored just as fast. Just remove the mag floor plate, remove the spring & follower, then insert the Endomag conversion (one piece) and reinstall the floor plate. I ordered a 3 pack of the conversions a few week ago and last week received my new PSA SBA3 lower ($179.99 on sale!).

To test proof of concept, I mounted my 10.5” 9 mm upper on the new lower after installing a heaver buffer and buffer spring borrowed from my KS47. At the range this morning I ran 100 rounds of HP’s (50 Berry 115 gr TCHP, 50 Win 115 gr HP) and 45 ball rounds. I am happy to report 100% feeding and function. The Endomag provide an excellent feed ramp built into the longer Pmag body. They also provide very positive actuation of the AR bolt hold open catch (maybe better than the standard mags). Feeding was extremely smooth and positive. Loading the mags is also easy as the rounds can be pushed in from the top just like the standard 5.56 rounds.

Overall I think this is a very viable option for someone who wants to build a 9 mm PCC without the expense (and some of the drawbacks) of a dedicated pistol caliber lower.

Sorry this got a little long.

[stagpanther]

Wait til the first time a case fails to clear--pop! bye bye goes the flimsy plastic ejector--weapon down.

[MagnumWill]

Polymer PMAG followers take a pretty good beating from the bolt over the years, I'd absolutely be willing to give it a try if they come out with other calibers (already have a pretty sweet 9mm AR pistol). I would recommend this is definitely used for training, rather than something in an HD gun.

That'd be a really cool idea for cartridges you typically don't see in an AR format. .44 mag anybody?

[Mobuck]

"Polymer PMAG followers take a pretty good beating from the bolt over the years, "

In what way? Mag followers hardly ever contact the bolt in an AR. Even then, it's not the impact that a loose case in front of the cycling bolt would cause.

[stagpanther]

How ANYONE can possibly believe a flimsy piece of plastic has any business in the cycling of cartridge in an AR (let alone a 9mm blowback) is a complete mystery to me--yet interviewers everywhere have fallen in love with these things.

[Rangegod]

Wait til the first time a case fails to clear--pop! bye bye goes the flimsy plastic ejector--weapon down.

No one is suggesting that this should be your first choice for your next Afghanistan deployment. The Endomag allows you to have a fun, cheap to shoot 9 mm understudy/trainer/plinker, with all your current AR upgrades (triggers, grips, bolt releases etc.), with just the addition of a 9 mm upper.

Plus, IF (big if) the ejector fails, a simple mag change (part of clearing the malfunction) installs a new ejector, so no weapon down. Trust me, my case head failure when using my "Glock" mag lower DID cause a weapon down situation (not to mention mag destruction, extractor damage and 3rd degree burn).

I had this same argument back in 1985 when I bought a flimsy plastic pistol just to prove it would never survive 1000 rounds. Thirty-four years and 13 Glocks later, I've yet to break one.

I'm going to continue shooting the converted mags, and if a problem occurs, I'll test the Endomag lifetime warranty.

[stagpanther]

Whatever--no harm in having fun. I maintain my opinion that the whole notion of a flimsy piece of plastic for an ejector is absurd.

[Rangegod]

I put another 175 rounds (320 total) through my PSA 10.5”, 9 mm AR yesterday with zero issues. After my initial testing, I installed the Kaw Vally 7.5 oz. 9 mm length buffer and their extra power PCC/.308 buffer spring. This combination makes for very smooth operation by, slowing the action to increase dwell time and preventing violent ejection, while reducing bolt over travel to prevent damage to the bolt stop catch.

During the week since my initial post I have seen several comments from this, and other forum members and continued to research many online reviews. There seems to be a common theme to most of the problems encountered. This can basically be stated as “tolerance/clearance” problems.

Due to all the various upper, lowers and 9 mm bolts available on the market, there are literally hundreds of possible combinations of parts. This makes some tolerance conflict between parts inevitable. Most of these issues can be identified and/or resolved by following the manufactures instructions to test mag fit on closed bolt and checking (and maybe correcting) bolt/feed lip clearance on the closing bolt before installing the conversion kit. Instead I watched one on line reviewer prove Einstein’s definition of insanity by destroying three mags in succession, while expecting different results.

As to the plastic ejector, after 320 rounds (over 200 on one mag) I can see no signs of any ware. This was a surprise and force me to think about the engineering (something I don’t do much of since retirement). The ejector’s sole purpose is to initiate the pivot of the case off the extractor hook. This change in force vector and the velocity imparted by the bolt throws the case clear of the action. Although it is counter-intuitive, the ejector is in reality a relatively low stressed component. The amount of force require to initiate the case pivot off the extractor is minuscule and applied for only a millisecond. In addition, the mass of an empty 9 mm case striking the ejector is very low. This makes damage to the ejector during normal operation of little concern. Damage by tolerance conflict is another issue as discussed previously.