Tight AR magazine well - Sandpaper fix?

[marklbucla]

I thought I remembered seeing someone say something about using sandpaper to open up a tight AR magazine well. I tried searching just now, but couldn't find the info I needed. What are the specifics about this?

Are there easier ways of getting the mags to drop free?

 

[Hanzerik]

Have you tried a different Mag?

 

[marklbucla]

Yes. It's the lower, not the mag.

 

[RecoilRob]

Before you start sanding on it, please make sure the mag latch is properly adjusted. You can make it release farther which might just get the mags dropping the way you want.

 

[Trempel]

So, the mags are stiff going in even before they contact the mag catch? What brand magazines and what brand lower do you have?

 

[Tokugawa]

Check for a misalignment between the upper and lower reciever.

 

[marklbucla]

It's the lower, not the mags, nor the magazine catch. Some lowers like Olympic and DPMS have tighter mag wells than others like Stag. Thus, not all lowers are created equally.

It's a little tight getting the mags in and they don't want to drop free.

Well, I just bought a $3 sanding block from Home Depot. I'll try that and see if it works

 

[DMK]

The only problem with sanding is you will be removing the protective anodizing.

 

[Andras]

Take a hammer to the hump under the magazine catch slot on your mags, I had a DPMS lower that was tight on 6 of 15 magazines, I hit the humps 4 times with a claw hammer and they work fine.

 

[Trempel]

The only problem with sanding is you will be removing the protective anodizing.

I don't think he'd need to sand down that much to get through the anodizing. Even then, the inside of the magwell is not such a high-wear, critical part that lack of anodizing would be a cause for concern.

 

[TexasRifleman]

Type II Anodizing is only about .0005" thick so it doesn't take much to go through it but there are other types, like 0002" to .001" thick.

 

[Bartholomew Roberts]

I think the better solution is to contact the manufacturer and ask them to replace the lower in question.

 

[plexreticle]

axle grease ftw

 

[nico]

Not to hijack the thread, but is sanding the mags OK? I realize that it'd remove the finish, but they can always be refinished, and it's not like aluminum is likely to corrode. I'm also concerned about rubbing off the anodizing inside my magwell.

Here's a post I made in another thread regarding this problem:

I have two surplus LE/Gov't marked Center mags (with marked floor plates fwiw) [that are tight in the magwell]. They're both very tight to insert into the mag well and have to be pulled pretty hard to get them out. They're longer front-back and the back of the mags seems to rub on the trigger guard. When inserted in the mag well, they have zero play front-back, as opposed to the three Okay mags I have that wiggle a fair amount.

I just got out my calipers and measured the relevant dimensions, and from front-back, the Center mags are ~2.746" long, while the Okay mags are ~2.716". The wall thickness (total thickness at the front of the top of the mag divided by 2) is .035" for the Center mags and .030" for the Okay mags.

I haven't been able to get to the range, so I don't know how either mags function, but I'm really tempted to try and shave off some of the extra thickness of the Center mags.

I have two NHMTG straight 20 round mags and a D&H curved 20 round mag w/ teflon finish coming this week for comparison, and am going shooting this coming Sunday, so I'll find out if there are any functional issues with any of the mags.

 

[Bartholomew Roberts]

I've got mags that are as shiny as a nickle with less than 10% of their finish left that show no corrosion at all. Other than that, I couldn't comment on whether sanding mags would work.

 

[ocabj]

It's the mags, not the lower. The majority of my 30 round magazines don't drop free. These are Colt, Okay, Adventure Line, and other USGI mags in my rifles.

All of my 20 round straight body Colt magazines, on the other hand, drop free perfectly fine in all my rifles.

 

[Cesiumsponge]

Aluminum "self-anodizes" with exposure to air. Anodizing = artificial method to produce aluminum oxide, aluminum oxide = "rust". Anodizing basically forces aluminum to form an extra thick rust layer. Aluminum immediately oxidizes when it's freshly exposed so it won't further deteriorate (unlike iron, which rusts and flakes away so continuously new metal is exposed)

 

[Bartholomew Roberts]

Aluminium can corrode. There are no shortage of Vietnam and Central American M16 receivers that have corroded to the point there are actual holes in the receiver.

I would also disagree with the characterization that anodizing is similar to the bauxite salts that form when bare aluminium corrodes. It is like comparing parkerizing with rust. Both are protective layers of corrosion; but one is a lot more effective at preventing further corrosion.

 

[DougW]

On my last Stag lower build, some mage were tight. I found the problem was the folding trigger guard was hitting the back of the mag. !st rule is to file on the cheapest part, so I dremmeeled the swinging trigger guard and all mags now slip in and out easily.