MDT METAL MAGAZINES - SHORT ACTION 12 Rounders

Maple57 said:
So I confirmed with my Cadex the bolt is in fact riding over the rounds as they come out of the mag.

I did some measuring on some of the metal AI pattern 308 mags I have...

The distance between the feed lips is as follows...

............................................................Width at back of mag lip....... Width at front of mag lip
Accurate Mag supplied with Cadex rifle..... 0.416 .................................. 0.417
MDT 12 round metal mag ...................... 0.404 ....................................0.393
Ruger Accurate mag ............................. 0.419 ................................... 0.400
Real AI mag # 1 .................................. 0.380 ................................... 0.395
Real AI mag # 2 ................................. 0.376 .................................. 0.395

Interestingly the real AI mags have the closest feed lips.... and they are wider at the front to create a little "up" attitude... I have not tried them yet in the Cadex... I feel like a dummy as I type this BTW... I should have tested all the mags. But they have always worked in other rifles.

Anyway... I did as RGV suggested above ^^ to widen the feed lips on the MDT 12 round metal mag.

I put a couple paint stir sticks between the lips and jammed a screwdriver in between. I gave it a little twist and tried a few times, but I got it.

The lips are now 0.417 apart and rounds seem to feed just fine so far. I hope they prove out well in time as the MDT 12 rounder would be my fist choice for the extra capacity and ease of loading 10 rounds.

So thank you RGV for the suggestion.

BTW the Ruger accurate mag is narrower at the front of the feed lips, and that mag was a fail in the RPR. Rounds would get stuck between the feed lips like they were too far apart... and I could not drive the rounds hard enough to feed them. I'm sure I'll have to give that mag a little attitude adjustment as well.

If there's anything can draw from this is the feed lips should be wider at the front than at the back. If the feed lips are closer at the front, then the rounds can bind or misfeed.
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Glad you got it sorted out!

The best tool for feed lip adjustment is to get an old chainsaw bar and cut a 2” chunk out of it. The way you describe opening the lips risks bowing out the body rather than just bending the lips in or out.

As you said, opening the front slightly wider than the rear can help with cartridges like the creemoor with very little body taper. Parallel usually works fine for 308 based cases.
 
lavino said:
$10 extra just to fit 2 more rounds doesn't sound too good of a deal to me. I am happy with my 10 rounder metal one. If feed much better than the polymer one.
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I get where you're coming from, but shoot a match and you'll see why they help ;) You'll never know when a round will have an unexpected failure or you'll run into a 12 round stage! Cycling your bolt is much easier than coming off the gun to find your extra rounds out of a holder next to your action.
 
In Remington 700 clones, you are almost always safe to run non-binder plate magazines. Some guys have had luck with the 6BR in the 12 rounders with a weak spring, but you will almost always need a spacer kit. I have heard there is one in the works ;)
 
Kudu said:
In Remington 700 clones, you are almost always safe to run non-binder plate magazines. Some guys have had luck with the 6BR in the 12 rounders with a weak spring, but you will almost always need a spacer kit. I have heard there is one in the works ;)
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Do any of the 6BR spacer kits work in the 12 rounder?
Or should I wait for the “one in the works”...
 
Savage with ESS stock, they work great.
When loaded to 12 rounds, chambering the top round requires effort,
Then the other 11 are smooth.

For NSCC it’s great, 10 round matches with the 2 sighters in the same mag.
 
I just bought my 3rd MDT 12 rounder and I had to adjust the feed lips on every one of them for the Cadex in 308..

All were narrower at the front than at the rear of the feed lips and gave the round a nose down attitude. I think it would be even worse if running a round with less side wall taper.

I'm not suggesting that I'm not pleased with the MDT 12 round mag, because I actually like them a lot, really I'm just highlighting the point that depending on the caliber and rifle you have, there's a good chance you will need to adjust the feed lips. So go into the venture with that in mind.

MPA sells a tool to bend the feed lips but you can make one 2 ways...

1) Get a chunk of steel around 1/2" thick and 1 to 1.5 inches wide and make a saw cut about half way through with a hack saw with a low tooth count to get a good wide cut. Home made version of the MPA tool.
2) This is easier... Get 2 flat pieces of cold rolled steel about 6" long, 1/8" thick and 1 to 1.5" wide clamp then in a vise and drill a 1/4" hole about 3/4" from the end. Put a nut and bolt through the hole and use it like a clamp to manipulate the feed lips.
 
Maple57 said:
I just bought my 3rd MDT 12 rounder and I had to adjust the feed lips on every one of them for the Cadex in 308..

All were narrower at the front than at the rear of the feed lips and gave the round a nose down attitude. I think it would be even worse if running a round with less side wall taper.

I'm not suggesting that I'm not pleased with the MDT 12 round mag, because I actually like them a lot, really I'm just highlighting the point that depending on the caliber and rifle you have, there's a good chance you will need to adjust the feed lips. So go into the venture with that in mind.

MPA sells a tool to bend the feed lips but you can make one 2 ways...

1) Get a chunk of steel around 1/2" thick and 1 to 1.5 inches wide and make a saw cut about half way through with a hack saw with a low tooth count to get a good wide cut. Home made version of the MPA tool.
2) This is easier... Get 2 flat pieces of cold rolled steel about 6" long, 1/8" thick and 1 to 1.5" wide clamp then in a vise and drill a 1/4" hole about 3/4" from the end. Put a nut and bolt through the hole and use it like a clamp to manipulate the feed lips.
Click to expand...

For optimal performance, you usually need to tweak the feed lips a little, and a little sanding with some fine grit sandpaper on the feed lips really helps to make feeding butter smooth. Pretty much all AICS pattern mags benefit from this.

I picked up a 12 round MDT 6BR mag for the wife's 6BRA rifle - tweaking the feed lips helped a lot. Spring comes really stiff, so I'm leaving the mag loaded up with 10 rounds for a few weeks to soften it up some.
 
kthomas said:
I picked up a 12 round MDT 6BR mag for the wife's 6BRA rifle - tweaking the feed lips helped a lot. Spring comes really stiff, so I'm leaving the mag loaded up with 10 rounds for a few weeks to soften it up some.
Click to expand...

Interesting that you found it stiff...

I found the MDT 12 rounder much less stiff than real AI and Accurate 10 round versions.
 
Maple57 said:
I just bought my 3rd MDT 12 rounder and I had to adjust the feed lips on every one of them for the Cadex in 308..

All were narrower at the front than at the rear of the feed lips and gave the round a nose down attitude. I think it would be even worse if running a round with less side wall taper.

I'm not suggesting that I'm not pleased with the MDT 12 round mag, because I actually like them a lot, really I'm just highlighting the point that depending on the caliber and rifle you have, there's a good chance you will need to adjust the feed lips. So go into the venture with that in mind.

MPA sells a tool to bend the feed lips but you can make one 2 ways...

1) Get a chunk of steel around 1/2" thick and 1 to 1.5 inches wide and make a saw cut about half way through with a hack saw with a low tooth count to get a good wide cut. Home made version of the MPA tool.
2) This is easier... Get 2 flat pieces of cold rolled steel about 6" long, 1/8" thick and 1 to 1.5" wide clamp then in a vise and drill a 1/4" hole about 3/4" from the end. Put a nut and bolt through the hole and use it like a clamp to manipulate the feed lips.
Click to expand...

Just stop by a saw shop and ask for a junked chainsaw bar, cut a section 2” wide and you have a magazine lip adjusting tool
 
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