Check all your mags, especially PMAGS, but check all mags!!

[SgtStrykerUSMC43]

Are there any other concerns with these mags besides pushing the mag release up too far?

Yeah, but I don't think anybody wants to discuss the long term effects of UV, solvents, and heat/cold on polymer mags.

Too boring and I don't think there are many chemical engineers roaming around here...

[djv38]

Too boring and I don't think there are many chemical engineers roaming around here...

Not a chem eng, but yeah, that stuff does get boring. That's why I'm moving away from chemistry (got sick of it).

I'm not sure what polymer they used, but it may be UV resistant. The way most people use their mags, I wouldn't be concerned about UV related issues for a long time (unless you're tanning with them daily, but then there's other issues going on not related to the mags )

[SONYtec]

Black plastic tends to have less UV damage, except for the surface area, since the UV cannot get through the whole thinkness of the plastic. Translucent plastic suffers the worst UV damage.

I am speaking of Zip Ties BTW. Using Zip Ties outdoors, use black not white.

White Zip Ties break down from UV.

[SONYtec]

Oh, better living through Chemistry... wait, thats a different kind of Chemistry.

[Ferris2son]

[ultramarineblue1]

I like my PMAGs. Not only do they drop freely, but they really give a sleek look that complements the SCAR well.

Using a Dremel tool makes filing the edge of the PMAG a snap (and very clean).

[Strongbow]

Fantastic thread Strongbow!

EMags have the same problem on the SCAR.

Thanks for that!

[Strongbow]

A word to the wise, perhaps. Something to consider, regardless.

FN only warrants function with its magazines. What you are experiencing, if correct, would be caused by using aftermarket products, as opposed to OEM. You may face a problem with FNH USA since the fault is not with the gun.

If that happens, you are going to need to talk with Magpul.

Or write a check for a repair bill.

I could be pleasantly surprised if FN covers this, but one might not want to get one's hopes up too high.

I hope I'm wrong, or if I'm right, that FNH USA covers this anyway...just saying...hope it works out for you.

I bought one E-mag just to try it -- never have -- now, never will....

Brownell's STANAGs for me....

Hey, if you like the Brownell's mags, knock yourself out. Nothing wrong with them, they are a nice magazine (I have some myself). I just prefer PMAGs. With this fix in place, I don't anticipate any need for repair issues. But as with all PMODs (Peculiar Modifications), I realize I'm taking a certain amount of personal liability on. But given I'm SBRing my SCAR, I probably would have bigger issues with warranty work that using a non-OEM mag

I prefer PMAGs. I think they offer a step up over aluminum USGI mags. So I'm willing to tinker a bit to get them to work properly if I can.

[Strongbow]

OK, I thought this was definatley worthy of a sticky!!

Let me ask some questions so I can add them to the original post.

1.) Will the problem be fixed by simply notching out the Pmags to match the FN mag?

2.) Are there any other concerns with these mags besides pushing the mag release up too far?

I'm flattered! I'll give my opinions on your questions:

1.) It appears so... so long as you cut enough material that the bolt catch moves freely. The fix also works for the Lancer L5, but because of the design of the follower (the bolt catch tab is too narrow), the bolt catch can slip off the side and fail to hold the bolt open on the last round.

Ultimately we won't know if this problem caused the unusual bolt wear, and if this problem fixed it for a few thousand rounds and multiple users.

2.) Polymer mags can degrade under certain UV and chemical conditions. But they are less subject to deformation when dropped, etc. Ultimately magazines are replaceable wear items. When they degrade, replace them. My other area of concern is feed lip thickness. The feedlips are a little thicker than the OEM mags and clearance between the feedlips and the bolt carrier is pretty small. That might force the carrier up a very small amount. But it doesn't look like it to me at this point. I will be investigating further.

Edit: follow-up. Under normal conditions (that is, no pressure on the bottom of the magazine), both the OEM mag and the PMAG feed lips clear the bolt carrier as it comes forward. If, however, there is pressure on the bottom of the mag (as when using it as a monopod), both the OEM mag AND the PMAG very slightly interfere with the bolt carrier coming forward. I eyeball the interference as about .1 mm for the OEM mag and .2 mm for the PMAG. Neither one cuases significant interference and the carrier comes forward easily, even without the action spring pressure (I removed the action spring so I can move the bolt really slowly). Wheres the carrier being raised by the bolt catch when using an unmodified PMAG is obvious to me as I was observing the bolt motion, I cannot detect the upward displacement caused by this issue. It's probably there, just VERY slight. Unless you spend a lot of time shooting prone using brand new mags as a monopod, I don't think this will be an issue. Otherwise, your mags will quickly acquire a little lap wear and this won't happen at all.

[GULL]

Black plastic tends to have less UV damage, except for the surface area, since the UV cannot get through the whole thinkness of the plastic. Translucent plastic suffers the worst UV damage.

I am speaking of Zip Ties BTW. Using Zip Ties outdoors, use black not white.

White Zip Ties break down from UV.

Old story, Back in the late sixty's Goodyear Aerospace made a deal with the Phoenix Police Dept. to furnish all of our Motorcycles with bullet proof windshields. This was prompted by one of our officers being killed at a traffic stop. The bullet had gone through the clear Plexiglas windshields we were using at the time. The new windshields were very thick yellow tinted material, the same as used on fighter cockpits at the time. After years of service in the Arizona sun (don't remember exactly how many), we discovered that the material had lost it's ability to stop rifle bullets. Before this discovery, this phenomenon had not been addressed. It caused some changes in how the cockpits were protected from the AZ sun on the flight line and prompted some changes to the material itself.