I think I have read here before that it is recommended to only load 28 rounds in a 30 round P Mag for use.

Is this true and why.

Thanks

That is true for USGI mags. Not true for PMAGs. Load them all the way up.

With a fully-loaded 30 round USGI magazine, it can be really tough on some rifles to seat the magazine without the bolt retracted. Hence downloading those magazines by a round or two.

quote:

Originally posted by RogueJSK:
Not true for PMAGs.

Ditto.

Many people, through habit, download PMAGs.

I put 28 in any type of 30-rounder.

This message has been edited. Last edited by: striker1,

Thanks to both of you guys.

Never an issue with pmags, but I download lancers and usgi mags by 2 so I can seat on a closed bolt a lot easier.

It's funny that so many people only load 28 rounds into USGI magazines. In 17 years in the Army and through multiple combat deployments I've never loaded anything less than 30 rounds, nor have I ever been taught differently. The magazines are made to hold 30 and function perfectly doing so. YMMV I guess though.

Some magazines work fine fully loaded to their rated capacity, some don’t.

If the PMags I’m familiar with are loaded with 30 rounds and the top round is pushed down, the entire stack of cartridges will move down about half the width of a cartridge. That amount of free movement will permit the fully-loaded mag to be locked into a mag well with the bolt forward. It also means the rounds are not jammed into the magazine so tightly that the bolt will have trouble chambering the top round. Both of those problems can occur if the mag design doesn’t leave enough room for a little extra movement after the rated number of rounds are loaded.

It’s very easy to check: Load the rated number of rounds then push down on the top one. If it moves down about half the width of a cartridge, then there should be no problem. If it absolutely will not move, then downloading the magazine by at least one round is a good idea.

And of course check all that by chambering rounds and live fire testing.

An historical note: When I was in Vietnam we were definitely told to download our 20-round mags to 18. It was part of the official orientation instruction, not some barracks rumor. Was it really necessary? I don’t know. I didn’t know enough about how magazines feed ammunition and the bolt chambers the rounds to even think to check myself. I have some 20-round GI type magazines today, but because they’re not the ones I had in Vietnam checking them wouldn’t answer the question of 50 years ago.

I've never had an issue seating pmags fully loaded. 30 round USGI mags take a little extra shove to seat if fully loaded, but it doesn't seem like it's much more effort than to seat a full pmag. For whatever it's worth, my USGI magazines are of fairly recent manufacture (I'd say with the last 15 years), and I use Magpul's anti-tip followers I them. I think most all of my USGI magazines are either Okay Industries or C-Products.

I never put more than 28 rounds in any 30 round AR magazine.

I have experienced te issue of having a Pmag (loaded with 28 rounds) not want to lock back in the rifle that I took it out of. It's like a friction thing, with the rounds not wantnig to push back down into the magazine that little bit when the top round in a magazine contacts the underside of the bolt carrier. I think when the magazine is released from the rifle, a very slight bit of spreading takes place at the feedlips. It doesn't happen all the time, but it does happen from time to time. Consequently, I use Lancers and Okays now. I've never had this locking issue with either of those.

quote:

An historical note: When I was in Vietnam we were definitely told to download our 20-round mags to 18. It was part of the official orientation instruction, not some barracks rumor. Was it really necessary? I don’t know. I didn’t know enough about how magazines feed ammunition and the bolt chambers the rounds to even think to check myself. I have some 20-round GI type magazines today, but because they’re not the ones I had in Vietnam checking them wouldn’t answer the question of 50 years ago.

Was in the Army at that time. Since I was in an EOD unit right after the war ended we got tons of the code H ammo to destroy. Thousands of rounds of it got destroyed through the barrels of our rifles instead of the burn kettles. We used both the 20 and 30 round mags and we did occasionally have malfunctions when mags were loaded to capacity but never when loaded one or two rounds short. It was enough to convince me that when my life was on the line to always load a couple short. I could always insert a new mag faster than I could clear a jam. My experience carried over to today and I even download my pistol mags for same reason.

Today's magazines (Pmags, quality aluminum USGI <--- from reputable sources...and others) will work fine if you load them up to 30 rounds.

Here is some background:

In the old days, some 20 and 30 rd magazines would have issues with loading the last few rounds and/or locking back the bolt when empty. This was due to magazine follower design.

Today, the PRIMARY reason one loads a 30 rd magazine with only 28 rounds is to facilitate easier seating of the magazine on a closed bolt. If you compete with your AR and have to perform mag changes, or are Mil/LEO/Security/homeowner/etc using the firearm for duty/protection, then this is important. Again, I emphasize the fact that it makes it easier to seat the magazine. Yes, you can seat a fully loaded 30 rd mag on a closed bolt. Some are easier than others. Having 28 in the mag makes this a sure thing when things are not going well.

If you never anticipate having to perform a tactical reload, then it is a non issue.

Having loaded modern mags to full capacity hundreds of times...

Just load 30 round mags to 30, and 20 round mags to 20.

I've never had a malfunction in hundreds of loadings.

From what I hear this was in issue in the past (vietnam era) but with any modern weapon and mag I have not been able to duplicate it.

I haven't (in limited use) had any trouble loading the PMag 30s all the way.

This is why you test your gear.

In my book, ANY magazine that does not seat and function fully loaded is out of spec, and gets some spray paint and a "plinker only" designation.

Running an AR at speed in competition or training, I have seen many mags fall out because they weren't seated fully because they were loaded to full capacity. 28 in mine. Download GLOCK mags by one for the same reason.

loaded up my hex mags with 300 aac for the first time last week. When using in my dads x95 tavor, the first 2 rounds were making it difficult to insert the mag. after 3-4 load cycles of the mags (6 mags total), they now insert just fine.

Back in 2008 I had the same issue with the mags supplied with my sig 556 patrol swat. The black mags with the incorporated link into the plastic. I had to load those at 28 rounds max. Other than that. 30 rounds all the time.

Isn't the issue with Pmags that you can over load them to 31 and they will not seat?

(I seem to remember a friend doing this at a match about 10 years ago and really screwing himself)

quote:

Originally posted by cas:
Isn't the issue with Pmags that you can over load them to 31 and they will not seat?

I imagine that manufacturers have to walk the line between designing their magazines so they will accept the rated number of rounds, but not more than that for legal or practical reasons. Reduced-capacity mags for sale in commie states or during the Dark Decade (1994-2004) were often a very tight fit for 10 rounds.

The PMags I’m familiar with are a little generous in their room so that it doesn’t take gorilla fingers to load the last round or two. If someone does have that strength and determination, perhaps it would be possible to get 31 in a mag rated for 30. I would rather that a company decide it’s better to make it easier for the shooters who are smart and careful enough to pay attention to what they’re doing, including loading their magazines, than to make it impossible for the clueless to screw things up for themselves. But yes, if someone overloads a magazine, that could be the basis for the, “You gotta download these mags or they won’t work right,” belief and advice.

It wouldn't matter to me even if you could put 34 rounds in a 30 round magazine. Mine get 28. Always have, always will, and they lock into a rifle with a closed bolt a little easier than when loaded to 30 rounds.