JonF

The .223 version should fit most any AR pattern PCC with a caliber larger than .223 and a long ejection port. Might not fit proprietary carbines though.

I like the concept of the hornady flag but im not sure i'd acutally use it to rack the bolt though. At least its rugged enough to last without melting or snapping. http://www.midwayusa.com/product/1165137689/hornady-rapid-rack-chamber-indicator-flag-aluminum-red

I like the concept of the hornady flag but im not sure i'd acutally use it to rack the bolt though. At least its rugged enough to last without melting or snapping. http://www.midwayusa.com/product/1165137689/hornady-rapid-rack-chamber-indicator-flag-aluminum-red

The flat nose is, without a doubt, more difficult in feeding and beats up the feed ramps. Short OAL's create even more of a hammering effect. When i switched from JHPs to RN fmj, i got rid of all my feeding, jamming and bending issues also.

I think there is a combination of factors/forces there. To characterize the movement, when cartridges are feeding from the mag, the bolt pushes them forward and as they slide from the mag feed lips, the nose of the bullet will strike the front wall of the magazine body where yours cracked. Since the cartridge is angled slightly upwards, it should begin to tilt and slide upward along the mag body front wall then transition over the mag body and into the chamber. Now to facilitate reliable operation (and knowing that the mag body will take this sort of repeated beating), glock themselves made sure to extend the inner metal shell up into the tab that acts as a feed ramp or guide in the mag body. Without it, the flimsy nylon would just bend or snap like yours did above. Supporting could theoretically help, but not even glock pistols are supported in that position. My old DDLES receiver is not supported there either. It also seems that there is more reciprocating mass, speed or force in the movement of PCC actions therefore the mag feed ramp takes a greater beating. While i only use oem glock mags now, i have in the past also tried KCI mags and can say that on occasion when i get a round that did not feed cleanly (or feeding blunt JHP or TC bullets), the round will sometimes nose dive during feeding and hammer so hard into the glock mag feed ramp that it bends it forward just a little. IT doesn't create a problem for feeding, however, it makes the mag NOT drop free so you have to yank it out and then hammer the ramp tab back into place. Doesn't happen very often when i use round nose so i dont get it much anymore but it does happen on rare occasion. So what ammo are you using here when it happened?

Then again you have an MPX which employs a gas driven recoil mechanism so a slower burning powder may benefit you. I have a DI 9mm carbine and i *have* to use a slower powder (3N37) to get enough pressure, volume and dwell time to get the bolt to cycle. I still only load for minor PF but that dwell time is critical for me. Understandably, the mechanics of a blow back and traditional delay lock breech pistols are different than gas guns so it going to be a different conversation and different solution (ie. fast powders for them). Of course the MPX is a factory gun built for factory ammo but it stands to reason that slower powders and dwell time may be amicable for its type of mechanism. Some anecdotal evidence is the folks with trouble cycling 147's load/poly reloads through the Sig which will have a non-trivial lighter powder charge than a 115gr FMJ factory load.

Frankly, unless you're one of the few people looking for a 223 AR training rifle analog for 3-gun practice, the GMR-13 is awfully clunky, front heavy and expensive. Its a fine gun and it does run, but they don't seem to be grasping the path PCC is forging on its own. There are plenty of alternatives now where you can build a PCC suitable for dedicated use (uspsa, steel, local outlaw) rather than one relegated to "practice" status.

I recently read some interesting discussion on this matter from the engineer from a company that makes AR compensators. It seems the issue of gas volume is the first and foremost that makes a design difficult to make effective, but there are additional less obvious factors that further compound the issue. Apparently in a PCC, and specifically the blowback AR9 retrofits that pervade the market, the recoil impulse is rather "lethargic" and its the timing of it that makes it difficult to time any possible thrust vectoring the 9mm could produce with the lazy recoil motion of the heavy reciprocating mass back and forth. Basically, if you could get any compensatory action from a muzzle device, its going to be challenging to time it to movement of the gun under recoil. And with folks using all sorts of springs and weights with little to no standard, forget about truly tuning this action.

I did exactly that. I took an Arredondo AR15 magwell, cut about 3/4" from the center to make it shorter font-to-back, pinned it back together and mounted it on my DDLES glock mag AR lower. Did a little contouring of the plastic "funnel" part inside to blend the transition from the magwell to the receiver. Did not need to fill at all with any epoxy this way as there's no wasted volume. Looks a little ugly, but it works really good though. Been using it for a couple years like that at steel matches before PCC was even a thing.

I use about 6 grains of Vihta Vuori 3N37. In a 16" barrel with a 124gr FMJ, this produces about 130 PF. The one thing to consider with using one load for both pistol is that while its convenient, you leave a bit on the table in terms wasted energy. A pistol load will often put up much higher velocities in a 16" rifle than from a short 5" pistol barrel. Just like when switching from FMJ to lead, you can download the powder charge to a much lower level and still produce the power factor you need all while producing less recoil and conserving powder resources. While its not essential, it is an potential optimization that is available to you for your application.

It is recommended to reload for this gun for a couple reasons. 1. factory 9mm is generally loaded with very fast burning powder such that the combustion is completed within 1-2" of bullet travel down the barrel. In order to prolong the combustion dwell time and provide sufficient pressure and gas volume to cycle the DI action, slightly slower powders are recommended to prolong the burn to 8-14" of travel (these kinds of things you can work out in QuickLoad). 2. You can tailor the load to the gun to optimize recoil. 3. you can use cleaner burning powders to reduce fouling in the DI system. 4. you can adjust the load OAL for better feeding in the long rifle action. I have found that factory (or normal minor PF pistol loads) can be used with the system after doing some tuning to the gun. Originally the gun comes with a full weight bolt carrier group and is made to work with a typical carbine recoil spring and buffer. Since it is using standard AR15 DI parts, i tapped into the lightweight parts market and put in a rubber city liteweight bolt carrier with adjustable gas key, taccom delrin buffer and wolff reduced power spring. because if this, i had to dial the gas system back considerably as the custom load i was used to using was now overgassing the system creating excessive and wasteful recoil. One side effect of this is that the lightweight carrier system can be more easily cycled reliably with normal pistol loads. Some experimentation may be necessary to see if it works with your specific load but it works a lot better than the old full weight recoil setup.

I have a Ron Williams DI 9mm upper. For all intents and purposes, it looks exactly like any typical DI AR15 system. Bolt carrier group with delay lock bolt, barrel with star receiver extension, gas block with gas tube. Only different parts are short gas tube system, bore/bolt for 9mm diameter, ejection port opened up slightly for better 9mm case ejection, bolt ramp is thinned for glock mag lip clearance.

My PCC isn't blowback, its a DI 9mm upper that uses a normal mil-spec bolt carrier group with a 5.45x39 bolt to clear the 9mm case head. Therefore i dont have any of the ramped/unramped nonsense to deal with. But your original statement of Geissele triggers require non-standard unramped bolts to function isn't accurate. Standard 223/556 mil spec bolt carriers have a natural built in ramp so of course Geissele triggers will be designed with ramping in mind. The question is whether the 9mm ramping you have is similar to mil-spec ar15 ramping.

Not sure why that would be, the Geissele triggers are made to operate with traditional mil spec design ramped AR15 bolt carriers that fire centerfire rifle cartridges. PCC is merely a retrofit to this platform. I have the SD3G and a traditional ramped bolt in my PCC and operation is 100% fine. Have also used the same trigger in a .223 AR with 100% function.

Amerigun is also selling a similar product. What's your pricepoint and is hardware included?