Problems with Zero 147gr JHP in SP01 mags

[Fantom919]

Hey all, I'm having an issue with Zero 147gr JHP's in my SP01 mags and was wondering if anyone has seen this before and how they fixed it.

When I load more than 12 rounds in a mag, as I shoot, the last round will get stuck in the mag catch slot. This stops the follower and I've got essentially 5 loose rounds in the mag until I unjam it.

This is my first batch of reloading these bullets and I load out to 1.15. I've loaded bayou 147's to 1.15 with no issue. Bayou 124 and MG 124 JHP also have no issue.

I've tried this in 2 of the mecgar mags I have and they didn't see the same issue.

I'm definitely going to try and shorten the OAL but don't want to push it too much. I use titegroup for my powder and am a little worried aboout pressure spikes.

Appreciate any feedback.

Thanks!

[MemphisMechanic]

You'll find there's pretty much no difference in velocity between a 147 loaded to 1.150" and 1.110" over 2.8-3.0 Titegroup.

Been there, done that.

The issue you'll run into is that some brass will bulge on one side halfway down if you attempt to shove a long 147 really far back into it - you'll have more case gauge failures unless you're running something like a Lee Factory Crimp die to push that wall back in.

Try 1.125 or 1.130" and see if you still have the issue. That's a pretty happy medium.

Edited November 11, 2016 by MemphisMechanic

[IDescribe]

I would be surprised to hear that that bullet will plunk test at 1.15.  Have you plunk-tested that bullet in your barrel?  If you're worried about pressure spikes with TG, loading that bullet too long so that it engages the lands when chambering is a sure way to get an unnecessary spike.

[Fantom919]

Thanks for the input guys.

I was surprised as well to find that the shape of this bullet allowed me to hit 1.19 when I did the plunk test. I did this on 10 different rounds with mixed head stamps. min 1.1845 max 1.1915 with std dev at .0031.

I decided to load to 1.15 since my moly coated bayous ar at 1.15.

 

I'll try 1.125. right now my load is over 3.4gr of TG.

[IDescribe]

12 hours ago, Fantom919 said:

Hey all, I'm having an issue with Zero 147gr JHP's in my SP01 mags and was wondering if anyone has seen this before and how they fixed it.

When I load more than 12 rounds in a mag, as I shoot, the last round will get stuck in the mag catch slot. This stops the follower and I've got essentially 5 loose rounds in the mag until I unjam it.

Still a little unclear as to exactly what's going on.  The mag catch slot is just lower than 5 rounds, so it seems like you are saying if you load 12 rounds, then after you fire off 6 of them, the bottom one catches the mag catch, pinning it and the follower, and the 5 other rounds are loose.  But with the problem occuring at the mag catch, just below the fifth round, it doesn't make sense you would have to get up to 12 rounds for this to happen.  Are you sure this doesn't also happen when you load 8,9,10, or 11 rounds?  

 

 

Quote

I've tried this in 2 of the mecgar mags I have and they didn't see the same issue.

To be clear, does are you saying this happens with ALL CZ mags that came with the pistol, but NONE of the Mecgar mags that fit the pistol?  

 

 

Quote

This is my first batch of reloading these bullets and I load out to 1.15. I've loaded bayou 147's to 1.15 with no issue. Bayou 124 and MG 124 JHP also have no issue.

Are you saying that you can load MG 124gr JHP to OAL 1.150?   If so, did you ream the chamber?  Or did you buy this used?

[Fantom919]

Sorry to clarify 5 was an estimate.

When I've loaded to 10 or 11 rounds you can feel there us a lot of binding going on but it does not catch in the mag catch slot. In the few tests of done of shooting and hand cycling ammo, it typically occurs if I load 12 or more. I had tried 14 round and about 75% of the time, the nose of the bullet would catch that slot.

I'm thinking that maybe as I load more, the force on the bottom round causse it to move forward in the mag. 

It also defiitely has to do with the ridges in the jhp round. If these were round nose, I don't think I would see the same problem. This is also supported by the fact that the flat point bayou 147's don't get jammed.

The mags that have the issue are all cz factory 18Rd sp01 mags. I have 8 mags that i tried yeaterday and they all have this issue. I just replaced the mag spring to wolf springs last night as well and both old and new spring exhibit the same issue. I didn't have a chance to measure the mecgar mags with a caliper to see if then spacing is different. When loading the mecgar mags, I don't feel the same binding or resistance as I do in the CZ mag.

Sorry to clarify, my MG 124 jhp load is loaded to 1.08. I have 2 accushadows and both accept these OALs.

 

 

 

 

[IDescribe]

1 hour ago, Fantom919 said:

When I've loaded to 10 or 11 rounds you can feel there us a lot of binding going on but it does not catch in the mag catch slot.

In the few tests... about 75% of the time, the nose of the bullet would catch that slot.

 

Why do you believe the ridge of the JHP is catching in the mag catch slot?    Can you see it caught, like ogive poking through the slot?   Can we see a closeup picture?

Also, can you get out the calipers and measure the link of the bullet itself, not a loaded cartridge?

 

[Fantom919]

1 hour ago, IDescribe said:

 

Why do you believe the ridge of the JHP is catching in the mag catch slot?    Can you see it caught, like ogive poking through the slot?   Can we see a closeup picture?

Also, can you get out the calipers and measure the link of the bullet itself, not a loaded cartridge?

 

Yes  I can see the ridge of the jhp in the mag catch slot. If I push on it with my thumb, it slip off the ledge of the slot and unlock it allowing everything to act as normal.

I'll have to take a picture after work but I do have measurement data of just the bullet for MG 124 and Zero 147. I measured 10 samples each

MG 124: min: .578 max: .5795

Zero 147: min: .6715 max: .6725

Difference is about .010 so I lose a little bit more case volume with the 147 bullet as well.

Edited November 11, 2016 by Fantom919

[MstngLX50]

The skives in the Zero 147 jacket catch the mag catch slot of the SP01 mags.  

1.10 was still catching, and attempts to chamfer the slot didn't help.

 

My solution was Mec-Gar mags.

[IDescribe]

Okay, no picture necessary.  If you say you can see the lip of the JHP crimps hanging on the mag catch, that's definitely it.  What's happening is either that the bullet is being pushed forward, or it's the noses of the bullets on one or both sides are being pushed outwards, or both, but whatever the combination, you're not getting enough force to push them far enough to cause the problem until you have 10,11,12 rounds in the mag.

I see someone above posted that they could not fix the issue.  If you want to try, you can shorten the load, but only so far.  At 1.150, that bullet base is seated .272 into the case.  You do not want that number to go deeper than .300, as at the point, the case walls start to thicken, and you will start to bow out the case walls, which can cause other issues. So I would say try a couple of different OALs between 1.12 and 1.15, and see how it goes.  It may simply be that those bullets will never work in those CZ mags, and Mecgar is your only option.

[Fantom919]

Thanks for all the help everyone. I'll try a few things but I think I'll have to go find another bullet. 

Any other 147gr jhp's out there?

[rowdyb]

montana gold rnfp 147's have always been excellent for me with zero issues in my press or gun.

[Fantom919]

So I loaded 8 mags with 11 rounds each and none of them got caught in the mag catch clot which is encouraging but still concerning. 

 

It seems like the first 6 rounds load fairly easily and then then the 7th round requires a lot more force. This pattern is also apparent with my 147 moly's loaded to the same oal.

 

I'm thinking of doing a test with an oal of 1.1 but thinking this may actually be worse since the shorter length may allow the bullet to tip up at a steeper angle. Thoughts anyone?