170 mm MBX magazine Problems

[Steelix]

This is my first new mag for my old 38s Para open gun. The first round I put in mag is loose as it will fall out, then I can only get 27 rounds in mag using a Maglula and it won't lock in with 27 only 26 and I have to hit it very hard. The gun won't feed every round i have to push slide close on maybe 4 rounds. I never had any problem with my old made in Canada mag's with DP base pads. the MBX mag lips are set at .353 front and .359 back and I run a 8# spring and oal length is 1.270 with a CP 134gr FMJ what's up with this mag as they as it will work with the old or new Para.

Edited February 11, 2016 by Steelix

[al503]

I don't know much about the Para platform but my guess is that your OAL is too long. The rounds might be dragging in the tube.

[mro111lland]

To get 29 rounds u must load it like they do on thete websight as far as not feeding mag catch might not b holding it hi enought in the gun

[Kingman]

Para mags, back down OAL to 1.2 and try. 1.25 may work.

[Hi-Power Jack]

The Plunk Test ...

[Steelix]

The para mags feed 1.270 just fine,just the MBX won't. The MBX does not want to feed when the mag is full, I cycle the first 10 rounds out then if feeds ok. The plunk test I can go to 1.280 with no problem.

Edited February 11, 2016 by Steelix

[BeerBaron]

yeah I agree the OAl may be the issue. assuming the gun is 38 super somewhere between 1.230 and 1.250 should be an OAL that will still enable the load you want, accuracy you want and feed well in both the mag and the gun. 1.270 is longer than than most running 38 super in a 2011/clone.

for the sake of testing load up 30 rounds at the shorter OAL and test them out. OAL thankfully is easy to adjust on most dies (except dillon).

[NickBlasta]

I had my 38 super loaded to 1.268 and they would nosedive all the time in MBX mags. They're just shorter front to back than other mags.

Edited February 11, 2016 by NickBlasta

[Hi-Power Jack]

OAL is easy to adjust on most dies (except dillon).

Off topic, but my SDB is very easy to adjust OAL .

I've never tried a 550 or 650 ...

[Bamboo]

I think he meant the dillon brand dies, and not the loading press.

I believe they use the same basic tube for the SVI/Para and as others have said 1.270 is too long. They want to see something like 1.235" for JHPs, and 1.250" for FMJ type bullets.

I've encountered this with the old vs.new Caspian mags, also. The old mags would take 1.260 OALs, but the new ones a will choke unless you run shorter OALs like the STI mags.

[Gooldylocks]

For my personal knowledge, why do people want to run 38 that long? That's longer than a 45, which is what the guns are designed around and why all the 9mm and 40 folks have issues, is it not? Wouldn't going past 45 oal bring problems as well? "

[Bamboo]

1.280" is the max per the SAAMI spec for 38 super.

1.275 is the max per SAAMI spec for .45

Back when major was major at 175+ pf some people loaded as long as possible (and often heavier bullets) to reduce pressures. Back in the single stack open gun days my favorite .38 super major load was a 130gr Remington FMJ at 1.265" OAL. When the double stacks came out they needed shorted OALs to function reliably because of the way the bullets stack in the mag and the shorter front to back dimension of the mags. The early Caspian and Para mags retained the longer front to back dimensions so they would still run the longer rounds, the modular guns needed a shorter OAL.

[Steelix]

Thank you Bamdoo yes these are older bullets just finishing off last 2k of them, they have large nose so I cannot load real short maybe 1.265. The bullets are not nose diving in mag, it's the angle there feeding into gun at. Maybe when I go to PD 124gr JHP it will feed right not sure. I know it's a old gun build for me in 1993, I need to use this gun until I can afford a new open gun.

Now to first question when I put one round in mag it falls right back out, there is no spring pressure to hold bullet in mag is this common on this type of mag.

[Bamboo]

No, having any rounds fall out is not a good thing. Something is wrong.

Do you have the right spring in there? I'd take the base pad off and make sure there is at least 2 1/2 to 3 1/2 coils protruding past the end of mag with the follower fully inserted to the top of the mag.

Also, you can try counting coils. Most 170mm mags have 13 coils...some cut 1/2 - 1 coil off to get an extra round, but it should have at least 12 coils total. If it is 11 coils, then it is probably for a 140mm mag.

[Steelix]

This is a band new MBX Para mag. I emailed MBX and Adrian said go shorter on the bullets too. He said mag will break after a few times using it. I'm just not sure how it's going to help the follower come up higher it the tube. The first round never push's down the follower. It's not a spring pressure it's that that follower will not go any higher. Right now I wished I'd saved my money and brought bullets instead.

[racegun9]

Sure sounds like the follower is hanging up or dragging in the top of the magazine.

Inspect the follower real good and make sure it doesn't have some left over plastic from

the molding. If you can see the dragging marks maybe sand them down a little. Shouldn't

have to on a new mag, but it seems like we have to tune things sometimes.

[cecil]

Steelix.... I'll buy your MBX mag if its 9mm/38... what u want for it ?

[Steelix]

Thanks guys, Adrian is sending me a new mag.