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Shimming magazines

GrantA

Sergeant
Full Member
Minuteman
Jul 7, 2010
731
10
40
Thomasville, GA USA
I have a PTG Rem Military style DBM (which fits a BDL inlet) and it uses 3.775 mags. I got 1 mag with it (300wm) and bought 3 extras from another source. I just got the extras in and realize they are 3.715 (seller wasn't sure, I figured I could flip them pretty quickly worst case).
Looking over the two side by side the ONLY difference is the length. I put .060 of paper in the front of the mag well and the 3.715 mags fit fine.

SO my question- how crazy of an idea is it to attach (epoxy maybe?) 0.060 shims onto the front of the mags and have a dbm that can use 3.775 AND 3.715 AICS mags (just have to ship AICS mags). Of course I understand it would have to be snag-free, but if I've had too much kool-aid and should just go all-in one way or the other let me know that too
 
To my way of thinking, there was a saying when I was in the Army: If it's stupid but it works, it isn't stupid. I'd say try it. At worst, you end up with mags that don't work (like you already have now), but you could also end up with mags that work just fine, and with only a miniscule amount of shimming. Just my $.02
 
OK for anyone wondering this seems to work fine. I had a friend cut me off a strip of 16ga galvanized steel (just under 0.060") 3/8" wide and 6" long. It goes almost all the way to the bottom on the inside so there's nothing for the follower to snag on. I pinched the bottom together in the vise so it has tension, and it holds fairly well. It seems to lock in and it drop free while empty just as well as the 3.775 mag, this means the 10rd AICS mag could be used in the 3.775 dbm too.
This is the prototype, I'll use aluminum so it won't gouge the mag well, but this makes AICS mags an option for 3.775 DBMs
**I'll be using mine for 30-06 therefore losing .060 of mag length is no problem. If you needed that last bit of length you'd have to skip the wraparound portion.
Also I won't be able to tell until the gun is assembled but I assume the additional height at the front of the mag will be an issue, solved by filing down the front of the mag box so my shim can go a bit lower
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Well amazingly this exact thing just happened to me. Parts are not here yet. I am curious.. how do the regular AI mags fit without the shims? Is it just a loose fit or does it not lock in place at all?
 
My experience was that they did not lock in reliably at all, they're very loose. I bought one of the 3.775 DBMs from a guy that didn't know any better, he said "oh that's why they were loose" so apparently it'll work. You seemed worried about a mag falling out in the field in your other thread though so I'd say you won't like it being loose
 
Ya... figures. I am raging right now. Are there no manufactures of a bolt in dBm that takes AI mags for a 700 long action?
 
The reviews on midway clarify it, if you had ordered from PTG you would have gotten the right mags (assuming you are getting the wrong one, wait til you get it).
If this gets you raging, well...
There is no such thing as a bdl inlet dbm that accepts the normal ai mags. This has been said time and time again.

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Ordered from PTG and it is coming with the mag.
Was not aware it was such a commonly known fact. Thank you for clarifying!! :) guess I'll have to just to inlet for my m5 if i want AI mags
 
[MENTION=87759]BigCheese1[/MENTION] if you want to shim some AI mags I have 3 these sheet metal strips I'll send you, just shoot me your address in a pm
*the other option that I'd like to have investigated further, would be to build up the front of the mag well the same thicknesses, whether just with epoxy or with a piece of sheet metal, then it will take ai mags perfectly and just won't take the longer mags. Wait til you get it, the ai mags might fit just fine for you, mine were wobbly though.

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It wouldn't be tough to punch a couple quarter inch holes in those spacers and plug weld them into place. Hit the welds with a belt sander and call it good. Any decent welding shop should be able to do it in 5 or 10 minutes.
 
Cut a spacer / shim and TIG weld it in place and problem solved.

Fitting mags is sometimes a necessary thing to do, like converting 9mm mags for use in a .45 magwell.



 
[MENTION=87759]BigCheese1[/MENTION] if you want to shim some AI mags I have 3 these sheet metal strips I'll send you, just shoot me your address in a pm
*the other option that I'd like to have investigated further, would be to build up the front of the mag well the same thicknesses, whether just with epoxy or with a piece of sheet metal, then it will take ai mags perfectly and just won't take the longer mags. Wait til you get it, the ai mags might fit just fine for you, mine were wobbly though.

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[MENTION=40279]GrantA[/MENTION] I will surely let you know. I do not have any AI mags in yet. I am going to give the unit I ordered a go and see how it works and if I like the AICS mags. Because this is my dedicated hunting rig, I may even send it back and replace for an HS precision dbm so I can have mags that are flush with my stock. In certain positions I can see a mag getting in the way if I am resting my stock on my knees or am in a standing position and have a close grip with my elbow on my side with my hand right where the mag is going to be.
Shimming the mag well is a good idea. Hopefully someone someday gets a wild hair and makes a Drop in DBM for AI mags. I have no experience with either yet as this is my first project. The general consensus seems to be that AI mags are the way to go so it has thrown up red flags for me to go with anything else
 
[MENTION=87759]BigCheese1[/MENTION] I have made a mistake, allow me to withdraw my foot from my mouth. I forgot about [MENTION=6060]Hooper[/MENTION] Hooper Ordnance - Products
Long Action Rem 700 that fts in a BDL inlet (minor fitting might be needed, at home with a file) and is designed to accept AI mags

Go get em