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Mag extensions for MDT WSM/PRC mags?

Their +4's say they're only for ARC 308 mags on the website, good idea to call and ask though.
 
Buy 12rd 308 mags and bend out the lips.

Is that the only different between 308 and the wsm mags? no difference in feed lip length or anything like that?

I certainly have a 12 i could do that too if that’s the only diff. will check how many i can get in a 12 as-is.
 
Is that the only different between 308 and the wsm mags? no difference in feed lip length or anything like that?

I certainly have a 12 i could do that too if that’s the only diff. will check how many i can get in a 12 as-is.
My mags for short magnums are tuned up ARC 308 mags.

Area 419 makes extensions for them.
 
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Is that the only different between 308 and the wsm mags? no difference in feed lip length or anything like that?

I certainly have a 12 i could do that too if that’s the only diff. will check how many i can get in a 12 as-is.

I can't speak for MDT but I have 308 mags "converted" to WSM, all I did was bend out the feed lips. Obviously you'll want mags without binder plates.
 
was able to fit fairly 8 rounds in mdt 12 round 308 mag without tweaking feel lips. i could imagine extra height from feed lips -might- fit 9 but it aight be close.

not 100% clear yet a 2 round extender on mdt 12 would get to 10 rounds but seems likely.
 
7 round Accurate Mag and Area 419 extension gives you +3 for a total of 10.

Have them arriving Tuesday for me 300WSM.


 
Let me know how they work. I wonder if I bent the lips on my 308 12 rounder (that doesn't quite hold 9, holds 8 very comfortably) if I could manage to squeeze 12 in what would be a "16'er" for 308? Would be pretty long but 12 is becoming a standard number which sucks for a prc

The 10 round MDT fits 7 rounds, so pretty sure thats what they're selling with the lips adjusted.

Anyone used the altus +2's versus the 419's +4's?
 
Our 7 round WSM/SUAM/6.5 PRC magazines are the same height as our 12 round AICS, metal, SA magazines and there are more similarities than differences between them. You should have no issue adding a +2 or a +4 extender to these magazines, I just cannot guarantee that feeding, reliability and capacity increase will be as good as it would on the SA calibers.

In saying that, the short mag case designs are usually a very low taper, meaning that should be pretty forgiving to feeding issues that may arise. I would suggest looking into a +4 extender to attempt to get to 10 rounds of 6.5 PRC into this magazine, or we will be shipping the XM length magazines soon that will alleviate all of these issues, as long as you have an action/chassis/DBM that can accommodate it!

Josh
 
My mag and extension are going to be late. It got stuck in Detroit this weekend.

Will have a range report on how they work together this weekend. Weather is calling for high 50's and low 60's. Going to be good shooting weather, even if I won't have my steel by then.
 
I've got a +4 en route, will report back on how many fit with the MDT 10 and 12s and feeding after I rip some lips.
 
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I would like to know, why they don't make them 5 and 10. Instead of modifying and adding extensions to current offerings to get what we want.
 
I would like to know, why they don't make them 5 and 10. Instead of modifying and adding extensions to current offerings to get what we want.

The reason that we do a 7 round short magnum magazine is that we only really have to do a feedlip modification and a stamp change, which is much easier and quicker than making a complete tooling and laser pattern change for a dedicated 5 or 10 round short mag, magazine. Additionally, as short magnums have been predominantly used by hunters up until recently, there has been very little demand for a 10 round magazine that will reliably feed WSM/SAUM/PRC cases, especially seeing as it has to be a further few inches taller than a standard AICS or MDT 12 round magazine.

If the demand to do dedicated 5/10 round short magnum magazines is there, then that is something we can revisit and make dedicated tooling for though :)

Josh
 
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Nope, nope, nope. Got my 7 round Accurate Mag and Area 419 extension. Don't bother. The extension is nice, fits very well just like it should. HOWEVER, once you try and put rounds 9 and 10 in it, it gets extremely stiff. You have to use two fingers to get the rounds pushed down, and if you slide a round out, the follower hangs up. I tried several times cycling rounds, and rounds will hang up in the mag, nose dive, or it won't come up at all till you get to round 8. Playing with the follower in the extension, I noticed it hangs up on the front and back at the corners, does not slide smooth like it does in the mag. Not sure I want to return it, I want to make it work. Maybe if I use a Cratex tip and smooth it out some.
Not to mention I got the wrong color extension.

Edit - I may try an MDT mag, maybe the follower won't be stupid when it is full.

Edit - 3 round AM it is still a pain to feed the mag, but the follower doesn't hang up. But doesn't work in an Oryx Chassis. Catch is to long hitting the extension and mag doesn't seat well.
Did notice on the 7 round, with the spring/follower pulled, that the front corners are protruding inside on the extension. So I think the rounds are pushing the corners of the follower into the extension, and that is also why it takes force to get the last two rounds in.
 
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Got my area 419 +4 and I'm pretty disappointed...

Its well machined, seems like a good design, follower doesn't bind, and yes - you can fit 10 6.5 PRC rounds in a MDT 10 round 308 (feed lips tweaked) with the +4 on it.

However, no magazine that I own has enough "spring height" to actually press the last round (or 2) to the top. Most end up at a totally goofy follower angle and even if you bend the shit out of the spring to give it more height, as soon as you fully load the mag it compresses the spring so hard that its back to its original memory position.

I'm a little surprised that -anyone- recommends these, for 3 different brands of mags (and both MDT 10 and 12 rounds) you couldn't successfully run the same number of round in it as you originally would have because it adds too much height to get the rounds to the top of the mag with sufficient spring pressure.
This seems like a fatal design flaw simply trying to do "too much", compared to a more traditional +2 base pad.

@MDT_Josh thoughts?
 
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Mine doesn't do that unless I'm fully loaded. I tried polishing and removing some material from the front for mine to work better. It did improve, but I eventually just pulled the Area 419 extension and binned it for now. Still plan to buy an MDT mag to try, but I single load when I'm out shooting on my range.
 
Got my area 419 +4 and I'm pretty disappointed...

Its well machined, seems like a good design, follower doesn't bind, and yes - you can fit 10 6.5 PRC rounds in a MDT 10 round 308 (feed lips tweaked) with the +4 on it.

However, no magazine that I own has enough "spring height" to actually press the last round (or 2) to the top. Most end up at a totally goofy follower angle and even if you bend the shit out of the spring to give it more height, as soon as you fully load the mag it compresses the spring so hard that its back to its original memory position.

I'm a little surprised that -anyone- recommends these, for 3 different brands of mags (and both MDT 10 and 12 rounds) you couldn't successfully run the same number of round in it as you originally would have because it adds too much height to get the rounds to the top of the mag with sufficient spring pressure.
This seems like a fatal design flaw simply trying to do "too much", compared to a more traditional +2 base pad.

@MDT_Josh thoughts?

Right, so here is what I recommend: install the extender on the 10 round metal magazine, but use the spring and follower from the 12 round metal magazine and see how many you are able to load up?

What is happening is that you are taking the magazine body and extending it by the internal height of the extender, but not extending the spring (unless you stretch it), which is why you're "running out of spring" on the magazines. Seeing as it is a +4 extender, you may be adding more internal height than the springs are capable of for the 12 rounder + extender, meaning that you would need a longer yet spring for that to work.

When ordering our MDT Mag Extender for a 10 round magazine, we recommend that you also order a Mag Extender Spring + Follower which is just a longer spring to take up that extra room. The fact that Area 419 doesn't have something like that also, confuses me a little.

Josh
 
@MDT_Josh So if I just order the 7 round WSM mag, with the extender spring, then things should work? WSM mag is just a 10 rounder if I understand from earlier correct?
Or do I need the 10 round 308 mag and adjust the fed lips for 300WSM. Still want to try and make my Area 419 extension work.
 
@MDT_Josh So if I just order the 7 round WSM mag, with the extender spring, then things should work? WSM mag is just a 10 rounder if I understand from earlier correct?
Or do I need the 10 round 308 mag and adjust the fed lips for 300WSM. Still want to try and make my Area 419 extension work.

If you order the 7 round WSM mag, then you want to add the extender to it, it will already have the strongest/longest spring in it. The problem is that the Area 419 extension is a +4 and not a "standard" +2, meaning that it is longer than most and that is why you're running into these fitment issues. We may be able to send you a slightly stronger (non-production) spring to try and get a little more tension out at the top end, but you'll have to get hold of our customer service team to order such a thing.

The MDT 7 Round WSM magazine is a 12 round metal magazine body, with adjusted feedlips and a different stamp on it, which has a longer body + spring than the 10 round counterpart :)

If you're starting with the 10 round magazine body, that is when you'd need to adjust the feedlips and order the longer spring.

Josh
 
@MDT_Josh So if I just order the 7 round WSM mag, with the extender spring, then things should work? WSM mag is just a 10 rounder if I understand from earlier correct?
Or do I need the 10 round 308 mag and adjust the fed lips for 300WSM. Still want to try and make my Area 419 extension work.

Don't go buying anything just yet....

@MDT_Josh - I'm one step ahead of you but didn't want to crowd the thread with permutations initially.

10 round mag with 10 round follower/spring, +4 extension : not enough spring height to pressure the last round or two, but does fit 10 rounds snugly

12 round mag with 12 round follower/spring, +4 extension : not enough spring height to pressure the last round or two, fits 10.75 rounds but not quite 11

10 round mag with 12 round follower/spring, +4 extention : plenty of spring height to pressure the last round, however the extra spring is enough that it no longer fits 10 round, you can only get 9 in there and its pretty tight.
 
What we seem to need (which gets honkin tall) is a 12 round mag body, with a slightly taller than 12 round spring/follower, with the +4. It seems like there is enough room that the extra "spring space" when compressed would still allow 10 to fit and give enough up-pressure to feed the last round or two.

@MDT_Josh is the spring/follower in the WSM 7 mag different/taller/stronger than the 308 12-round spring follower?
I could imagine it might be if you can only fit 7 in that WSM branded mag and I can pretty easily fit 8 in my 12-round 308 (no +4).
 
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Well, back to an odd number of rounds no matter how its sliced.
I'm pretty sure the AM world work, if it just didn't have so much issue with the follower jamming in the extension. Because like I said, round 8 is great, inserting 9/10 it sucks, and the follower sticks not pushing the full stack tight to the lips till you give it a smack, but round 9 jams when you go to cycle the action so it either nose dives or you rife over the top.

I blame the large radius corners on the extension.
I'm here at work looking at my shops ancient end mill looking for small enough bits to reduce the radius. It's so deep though I don't think I have anything long enough. I'm past the cost of this thing though. If I trash it, oh well.
 
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What we seem to need (which gets honkin tall) is a 12 round mag body, with a slightly taller than 12 round spring/follower, with the +4. It seems like there is enough room that the extra "spring space" when compressed would still allow 10 to fit and give enough up-pressure to feed the last round or two.

@MDT_Josh is the spring/follower in the WSM 7 mag different/taller/stronger than the 308 12-round spring follower?
I could imagine it might be if you can only fit 7 in that WSM branded mag and I can pretty easily fit 8 in my 12-round 308 (no +4).

Nope, same spring and follower in the WSM mag as the standard 12 round offering. We did do a stronger spring at one point, but like @loveha said, you'll run into issues with the spring compression and taking up extra space.

One thing you could look at doing would be to file off the bottom of the legs on the follower to allow it to get down a little lower in the magazine when under load and **maybe** increase your capacity back up to 10 with the +4 extension.

Josh
 
That was actually @anotherwannabe that discovered that. He's working with MDT mags, I'm working with an AM mag. Two of us trying to get to the same goal at the same time it seems.

If filing off the legs on the follower work then I'll pick up the 10 round mag and get the spring.
I may still see if I can get the extension milled first though. Found an 1/8th inch bit, but it may not reach far enough inside.
 
Not PRC/WSM, but I just stretched the spring out in a no binder MDT to run the area 419 extension.

No issues so far.
 
Not PRC/WSM, but I just stretched the spring out in a no binder MDT to run the area 419 extension.

No issues so far.

A 10 or 12 rounder? Mine wants to return to original height after being compressed.
 
I can confirm that stretching a 12 round spring out -does- appear to give enough pressure to fit 10. If you try and hork an 11th in there it will "rebend" the spring however, so its right on the edge.

For now I'll run a 12+4 (holds 10) and a 10 (holds 7) as my backup.

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Slight topic change but since folks here are using MDT stuff. If you want to run a binderless mag in the MDT ACC chassis you either need to have a notched feedlip or bed the action forward .100. By "default" the recoil lug will put a standard length feedlip right on the 2.860 mark for a bindermag.

If you run binderless like that you will catch the tip of a 2.950 PRC round every time. Thankfully they put enough oblong in the action screws that you can run a WSM mag-well sized action and move the action forward that additional .100 and fill it with bedding compound.

Thanks for being forward thinking on that MDT - another chassis I've got does not allow that and would require milling the action screw holes to make it work which I don't want to do.
 
I can confirm that stretching a 12 round spring out -does- appear to give enough pressure to fit 10. If you try and hork an 11th in there it will "rebend" the spring however, so its right on the edge.

For now I'll run a 12+4 (holds 10) and a 10 (holds 7) as my backup.

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Slight topic change but since folks here are using MDT stuff. If you want to run a binderless mag in the MDT ACC chassis you either need to have a notched feedlip or bed the action forward .100. By "default" the recoil lug will put a standard length feedlip right on the 2.860 mark for a bindermag.

If you run binderless like that you will catch the tip of a 2.950 PRC round every time. Thankfully they put enough oblong in the action screws that you can run a WSM mag-well sized action and move the action forward that additional .100 and fill it with bedding compound.

Thanks for being forward thinking on that MDT - another chassis I've got does not allow that and would require milling the action screw holes to make it work which I don't want to do.

You're welcome, however, I would highly suggest that you notch your feed ramp rather than spacing your action forward in the chassis. If you were to space the chassis forward, you will have to permanently add a block made of something hard and incompressible to ensure accuracy is maintained. Additionally, you are not only moving your action and mag well further forward, but also your trigger/hanger and other features on the bottom of your action, which could lead to further issues.

Long story short: the best solution is to notch the feed ramp on your action rather than spacing it at all.

Josh
 
I'm surprised to hear you suggest that people notch a (usually expensive) feed ramp rather than just bed the action appropriately if your action allows it.
.100 isn't much for a devcon/epoxy bedding and well within the tolerance of the action screw holes.

Maybe you mis-understood me and thought I was just going to have the action screwed in with no recoil lug contacts... which would obviously be a bad idea!

If your action magwell is meant/has room for a WSM based mag no reason to grind an action that doesn't need it. At least on my Borden actions with a WSM length bottom cut you can shift the whole thing forward and there is still clearance within the trigger cutout of the chassis, at rear of mag for the bolt, and at the feed lip. Obviously all this stuff needs to be checked before you bed something.
 
I'm surprised to hear you suggest that people notch a (usually expensive) feed ramp rather than just bed the action appropriately if your action allows it.
.100 isn't much for a devcon/epoxy bedding and well within the tolerance of the action screw holes.

Maybe you mis-understood me and thought I was just going to have the action screwed in with no recoil lug contacts... which would obviously be a bad idea!

If your action magwell is meant/has room for a WSM based mag no reason to grind an action that doesn't need it. At least on my Borden actions with a WSM length bottom cut you can shift the whole thing forward and there is still clearance within the trigger cutout of the chassis, at rear of mag for the bolt, and at the feed lip. Obviously all this stuff needs to be checked before you bed something.

Nope, I understand, but I still would not endorse that you add something between the chassis (which is precision machined and held to a high tolerance) and the recoil lug of an action. As for the cutout in the action, it depends on how the manufacturer decided to "grow" the magazine well cut to allow for non-binder plate magazines. Most manufacturers "grow" their magwell forward in their action cutout to clear the binder plate, rather than adding more room at the back. That is why when we design the chassis for use with magazines, we stop the upwards travel (where possible) of the magazine when inserting, on the front of the action rather than the rear, and leave room in there so that you could run non-binder plate magazines if you so wish.

I don't personally have any experience with the Borden actions, but I have heard great things about their design and construction, so if they added .100" extra mag well room away from the recoil lug rather than towards it, I would be a little surprised. Unless that is for use with a specific magazine box like the Wyatt? Doing a little reading, it also looks like Borden makes the Rimrock series of actions, which are essentially an XM length (3.200") magazine in a SA footprint action? Depending on what action you have, you may just need a very specific stock/chassis for that action?

Josh
 
Just to follow up here. I machined a shim to get the feed lip to line up with the mag and it was a .055 thickness. So I've bedded it forward with a little piece of shim to provide a solid stop when tapping it back towards the lug and working the epoxy squeeze out and its drying as we speak. My other MDT bed job worked out great, so hoping this one follows suit.

The action I'm using is a Borden Mountaineer w/ integrated lug - not XM length - with a wyatt cutt that gives a 3.070 bottom well opening. Just to put in your mental storage if it ever comes up again.