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Guide to modifying .308 Gen3 P-Mags to work in DPMS G2


MickB

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I have a DPMS G2 Recon that I have modified to use in 3 Gun Heavy Metal. Modifications include a Dynamic Resistance muzzle brake, Samson 12.37" Evolution rail, SLR SA7 adjustable gas block, Hiperfire 3G trigger and Magpul STR stock on a Vltor mil-spec buffer tube.

Back in early April I bought some Gen3 Magpul P-Mags to use in the rifle. Once the components came together, I tried dialing in the gas system. No matter what I did, I could not get the bolt to lock back on an empty magazine, even with the gas block full open. Checked gas block alignment and it was perfect. Todd at SLR even sent a new gas block to try out.

It was with the new gas block that I discovered what the issue was. I happened to have a borrowed Gen2 P-mag with me which locked back fine with the gas block set at 5 clicks from full closed. Switching to the Gen 3 P-mag is when the bolt lock failures occurred again.

Manually locking back the bolt with the Gen 3, I would find that the act of removing the mag would cause the bolt to slam shut.

Basically what is happening with the Gen 3 mags is that the bolt catch actuation tab on the back of the follower is shorter compared with the Gen 2 mags. This means that there is little to no engagement of the bolt with the bolt catch. I contacted Magpul and explained the situation and they said they would look into it. I also spoke with DPMS and they were only just becoming aware of it.

After going back and forth with Magpul with still no resolution, I decided to try my hand at modifying the Gen3 followers myself.

What we are doing is making the follower come up higher inside the mag body so that the bolt actuation tab pushes the bolt catch higher.

In order to accomplish this, material needs to be removed from the follower directly under the right feed lip.

Step 1: First, mark the follower while still inside the mag.

Step 2: position follower in your bench vise and use a dremel tool with grinding wheel to remove the material.

Step 3: remove the flashing and test bolt catch engagement.

As you can see, you don't need to remove much material.

Mick

Edited by MickB
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  • 3 weeks later...
  • 2 weeks later...

Put 30 rounds of ball through the Lancer and GII Recon. I shot 10 loaded singly in the mag and then a full mag of 20. I did the same thing with my SIG716 and Ruger's piston 308. It worked like a charm.

So on the plus side we have what appears to be a durable and high quality magazine that will work without issue. On the down side, it costs 2x the price of the PMAG and doesn't come in a 25 round format.

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  • 2 months later...

I'm in the process of modifying a G2 Hunter that I just received last week for HM. The gun will be getting the typical mods for competition but in the mean time I took the rifle out and fired it in it's stock configuration using different ammo's. Accuracy was on par with various reviews I've read and I was using the new 25 round Pmags w/o any function issues. I don't have any 20 round mags to compare with but the 25's work great and provide a slightly taller "rest" for prone.

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The P-mags always functioned. The issue is with bolt lock back. Insert the steel DPMS mag and lock the bolt back and look through the ejection port and note how much of the bolt face the bolt catch covers.

Repeat for the P-mags and note any difference.

If you could post a pic of that comparison, it would be helpful...

Mick

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  • 1 month later...

Any updates? Any new owners of rifles and mags getting proper function without any modification?

Adams Arms is coming out with a piston gun built on the new DPMS pattern and Remington Defense is supposed to have an R25 GII coming to market. Rumor is SIG is also revamping the 716 to use this new pattern. So either these rifles will have a different bolt stop or Magpul is going to have to make a design change...

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  • 1 month later...

I just got a new DPMS G2 Recon (built 2/5/2015). I picked up some Magpul Industries Gen 3 PMAG MAG292-BLK 25 rounders. The problem still exists. The magazines don't push the bolt catch up far enough to reliable hold open on the last round fired. I've modified them as above with the exception of i used a flat file rather than a dremel. I filed them down enough that they catch as much as the factory mag.

I have some of the older 20 round MAG243-BK 308 magpul mags on order as well since I read that they don't have the same issues as the newer Gen M3 followers.

Magpul doesn't seem to care and DPMS just says it's a magpul issue. I've contacted both of them. Don't expect this issue to be resolved any time soon.

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  • 1 month later...

Just to add a follow up... I recieved the GenM2 .308 mags in the mail and they work great with no modification. They push the bolt catch up as far as the factory DPMS magazines. The only problem is, the GenM2 mags have junky followers in them and they don't have the same level of "anti-tilt" as the GenM3 magazines. Even though I have to file down the GenM3 magazine followers to get them to function properly in my DPMS G2 Recon, I'm still choosing the GenM3 over the discontinued GenM2 (that don't require any modification). The GenM3 is sturdier, there is almost no tilt in the follower, and the follower travel seems to be much smoother.

Edited by Rezolution
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  • 3 weeks later...
  • 1 year later...

No. I called up DPMS again about 4 months ago and re-explained the whole situation with both the Magpul G3 magazine follower and also the issue where brass hits left handed people in the face when it's ejected. The customer service rep told me to "buy a left handed gun". I explained to them that they don't make that modem in a left handed version and the customer service rep said "yes, I know." Then he said "well, you can put your own adjustable gas block on it but you'll void warranty". I asked about the newer model they're making for LEO/GOV where it has a 'working' extended shell deflector and he said, "we're not going to swap your lower out for brass deflection issues".

When I asked about the issue with the follower, he stated "That's Magpuls problem, not ours. If Magpul G3 mags don't work with our gun, just buy our magazines, they work".

So the bottom line is that DPMS gives ZERO Craps about their customers.

I talked to 3 guys at Magpul when they were at the Greater NorthEast NRA Outdoor show in PA. They all told me the same thing (well, two of them did, one was just a marketing guy). They know it has issues in the DPMS model, they make the mags that way so they are compatible with multiple guns. They don't want to alter it because it might cause issues with it working correctly in other models and they aren't going to make a follower just for the DPMS series of guns. They seemed to think that since it fed fine, and just didn't lock back, that it wasn't that big of a deal. I felt that it was because the follower left the bolt catch in a position where it can damage the bolt lugs. They just went back to, "well you can file it down".

So basically, this is not ever going to resolve itself, don't wait for a fix. If you want to use the G3 mags in the DPMS GII, you have to file or sand the followers down.

If you're left handed, expect to randomly get hit in the face with hot brass. I tried a brass deflector but it only made the gun less reliable. The only solution for me was to put a slightly longer magpul stock on it and also add the enhanced buttpad to it. Then, with that all the way extended, it takes my face and eyes mostly out of harms way.

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  • 10 months later...

Any updates a year later?

If DPMS and Magpul can't play nice with each other who else is making a G2 pattern gun that works with Gen3 mags? Not that I'm necessarily in love with Gen3 mags but they're cheaper and easier to find than pretty much everything else out there.

Sent from my SM-G930P using Tapatalk

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I had a Ruger SR 762 that ran the Gen 3 mags flawlessly. Later model with the magpul furniture and the updated 4.5 lb trigger. I also have a DPMS G2 Hunter and the Ruger is a far better rifle than the Hunter in my opinion.

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I had a Ruger SR 762 that ran the Gen 3 mags flawlessly. Later model with the magpul furniture and the updated 4.5 lb trigger. I also have a DPMS G2 Hunter and the Ruger is a far better rifle than the Hunter in my opinion.


I have an SR762. It is an older original gun that came out right when Magpul changed to the new mag format.

I like that gun. It shoots well. But it isn't as svelte as the DPMS.

What we need is for Ruger to adapt over to the G2 pattern...

Sent from my SM-G930P using Tapatalk

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