Czechmate Reloading

[Lastcat]

I have owned Glocks and now my first CZ is this Czechmate. Love this gun. I've been to a few USPSA matches in Open Class, a few times. So my loads are for my gun and a power factor at MAJOR. Please be careful when reloading and know exactly what is only required for you gun. This article below is for my Czechmate and your reloads my vary, always use caution.



A week before this CM showed up, I read about the short length of the leade. Getting a reamer and do a +.05 cut, to allow longer loading for a round. It's common with a CZ and if that works for you, then make that choice. I decided to check the leade and see where it was at. I wanted to leave things as they were for my CM.

I have reloaded for 357 Sig for many years and found an article online about head spacing the shoulder (shoulder not the case mouth) on this particular case. I was a CNC Machinist for 16 years and have all kinds of mics, gauges, indicators, etc... What this article explained was to set the barrel on the crown end, insert a resized case and measure from the end of a Glock 32 barrel to the end of the case. Then resize the shoulder back until there was about .005 of clearance. Made sense.

So with this CM in 9mm Major, I knew the resized case would rest upon the step in the chamber. Using just a metal plate and my dial indicator, I was able to first measure a case in the CM barrel to establish Zero.



Now that I knew where zero was, I grabbed all the 9mm bullets I could find and loaded them into empty cases. I first loaded them long at about 1.180 and inserted them into the barrel and measured. This showed the profile of the bullet was sitting on the leade and not the case mouth sitting on the chamber end. Oh, and the chamber length was spot on. It's the leade that is cut into these barrels that are too short. I think they were made for FMJ's and not the profile of a JHP. If you can get a JHP at 1.170 to fit your barrel, congrats.

Below are the bullets I tested and found the correct length to fit my barrel. Left to right.

1) Xtreme 135 RNFP
2) Rainier 147 HP
3) Xtreme 147 HP
4) Rainier 124 HP
5) Hornday 147 HP
6) Montana Gold 124 HP
7) RMR 124 HP
8  Hornaday 124 HP
9) Montana Gold 125 HP



The only bullet that would work was the Xtreme 135 RNFP at 1.163. But in 9mm Major I wanted to only use 115 gr for gas to work the comp. And to also load as long as possible. Using Vhitavouri 3N38 at 9.2gr filled the case at 90%. Plus all that pressure in a 9mm case, loading longer helps to reduce some pressure. Loading short increases pressure. I was shooting for somewhere around 1.170 max to 1.140 min. Also dependent was Mags. I tested dummy rounds at 1.170 in all my Mags and that worked fine.

Here are the results below.



As you can see above, loading a Precision Delta 115 FMJ I can actually run 1.172 and still be off the leade by .010" What I did was to of course load a dummy round with a bullet at 1.200 in length and test this into the barrel. I would get to within .010. Meaning, the bullet is still resting on the leade and the case mouth has not rested on the chamber end. So in this pic below you can see exactly .010 to go before the correct length. But be careful, you want at least .005  to .010 clearance between the bullet and the leade.



At this point you can see the round is still .010 proud. Take the round measure the over all length (OAL). I was using the Precision Delta 115 FMJ and at this point it measured 1.192. I could take this OAL down to 1.182 and it would show zero on the Dial Indicator and the case mouth would finally be resting on the chamber end. But that meant so would the bullet be resting on the leade. I want some clearance, at least .005 to .010. So at this point the OAL is 1.192 and I could see the Dial is still .010 proud. Take .020 off the current OAL.

It gets the case mouth resting at the chamber end and it also gets the bullet .010 off the leade.

The final 1.172 OAL for this bullet, as pictured below.



Viola!

There are many ways to shave this cat, use what works for you.



As you can see above, I use Vhitavouri 3N38 and Silhouette. Testing the Precision Delta 115 FMJ and the Xtreme 135 RNFP. The best load for Major is highlighted in Red.

I did get a chance to test the:

Montana Gold 115 CMJ
9.2gr 3N38
Fed 200 Primers
OAL = 1.142
1480 fps

Very accurate out to 30 yards and consistent. Check my review here from a USPSA Match that I used this CM and MG 115 CMJ here:

https://www.czfirearms.us/index.php?topic=98021.msg758958#new

[IDescribe]

Nice report, sir. 

I do want to say something regarding loading shorter increasing pressure and longer decreasing pressure.  This is 100% true with the same bullet, but it's a little more nuanced when comparing different bullets.

What causes the increase in pressure when you seat shorter is that you are shrinking the initial size of the combustion chamber, or you decrease pressure when loading longer because you're increasing the initial size of the combustion chamber.  What this means is that the number you want to track when comparing different bullets is the seating depth -- how far the bullet base is seated into the case -- that's what controls the initial size of the combustion chamber.  And because bullets are different lengths, and because the bullets that have to be loaded shorter are also typically shorter bullets, the difference you see in OAL isn't necessarily reflected in the difference in seating depth.

For example...

If you were to check the XTreme 124gr HP, you might find that its max OAL minus .010 is 1.100.
If you took a Montana Gold 124gr CMJ, you might find its max OAL minus .010 to be 1.140.

So it LOOKS like the Montana Gold is closer to your ideal longer OAL, BUT..

At 1.100, that XT 124gr HP is seated .190 into the case, and
At 1.140, that MG 124gr CMJ is seated .205 into the case.

THIS means that your longer loading bullet actually leaves the smaller initial combustion chamber, meaning that if all else is equal, the 1.14 OAL cartridge would produce higher pressure than the 1.100 OAL cartridge.

NOW, before anyone jumps on me, all else is not equal in that example above because a .356 plated bullet is going to obturate better and contain gas and pressure better than a .355 jacketed bullet, so I really don't know in this case which would produce the higher pressure with the same charge weight or at whatever charge weight was needed to achieve the same velocity.

BUT the point is that you can't judge greater or lesser pressure with different bullets based on OAL. 

Basically, don't cross short-loading JHP off the list.  JHP have closed bases and will deposit far less lead in your comp than an open base RN.

IF you take a 115gr FMJ-RN and a 115gr JHP from the same manufacturer, and you load both to their max OAL, the FMJ-RN will almost always have the shallower seating depth and produce the lowest pressure at the same velocity, so without even doing all the math, I'll tell you that the MG 115gr CMJ is probably a great bet.  But I wouldn't exclude the 115gr JHP bullets without testing them.  Nor would I exclude the Zero or MG 121gr JHP, which were made for major.  I can't say for sure about the Zero, but the MG 121gr JHP is just their 115gr JHP with the hollowpoint cavity filled with lead.   

Good luck. 

[Wobbly]

Welcome Aboard !

Nice report. Just one question. How'd you get that horse on top of your CZ ?

[Lastcat]

IDescribe, yep I agree with you. The actual bullet itself hitting the leade was my findings with this post. Yes a Montana Gold 115 JHP @ 1.085 will work. Finding the longest OAL was my first goal and then 170 Power Factor. Then next would be accuracy, whether it be a MG 115 JHP, MG 115 CMJ, MG 124 JHP, Xtreme 115 HPCB or Precision Delta 115 JHP, etc..... More to come. 

In public Forums I did not want to express a shorter OAL was tried and trued, especially for 9mm Major. Just in case the info got misconstrued and someone took it for granted and made a major mistake.

[Lastcat]

Welcome Aboard !

Nice report. Just one question. How'd you get that horse on top of your CZ ?

Hahaha!!  That's totally funny, good sense of humor. Thank you very much.

I too love the smell of 3N38 at 9am, on Stage 1.

"Are You Ready?"

"Standby"

[Bossgobbler]

The FMJ are going to lead up your comp!

[IDescribe]

The FMJ are going to lead up your comp!

Yup.  Not from experience, but from reading others' experiences.  That said, CMJ-RN won't.  And JHP won't.

I'd be exploring 121gr JHP.  They're 115gr JHP with the cavities filled in.  And there is such a thing as TOO much gas.

[Crawl]

The FMJ are going to lead up your comp!

Yup.  Not from experience, but from reading others' experiences.  That said, CMJ-RN won't.  And JHP won't.

I'd be exploring 121gr JHP.  They're 115gr JHP with the cavities filled in.  And there is such a thing as TOO much gas.

I'm very confused by this comment. How will a FMJ deposit more lead than a CMJ? As long as it isn't an open back it's fine, right?

[Wobbly]

I'm very confused by this comment. How will a FMJ deposit more lead than a CMJ? As long as it isn't an open back it's fine, right?

Think that's what he's saying... the lead doing the fouling is coming from the base of the bullet. A simple FMJ bullet, having been filled from the rear, does have exposed lead on it's base. Whereas the base of a JHP bullet, having been filled from the front, has the sealed base. Plated and CMJ are both completely enveloped in copper, with no areas of exposed lead.

[IDescribe]

I'm very confused by this comment. How will a FMJ deposit more lead than a CMJ? As long as it isn't an open back it's fine, right?

As Wobbly said - - fmj IS open back.

[jameslovesjammie]

The FMJ are going to lead up your comp!

Yes.  Yes they will.  This is a picture of the comp on my Scorpion.  I've only shot Hornady FMJ's loaded with N320 for the last 1,500 rounds.

[Crawl]

What do you know, boxes and boxes of FMJ bullets, and I never paid attention to the fact that they were open back. I just went and checked two different boxes to convince myself.

I guess I'll stick with Berry's for now.

[Wobbly]

What do you know, boxes and boxes of FMJ bullets, and I never paid attention to the fact that they were open back. I just went and checked two different boxes to convince myself.

This is why you come here. To find out what you didn't know, that you already knew. 

I guess I'll stick with Berry's for now.

Or, Zero or Precision Delta JHP's !

 

[Crawl]

I just shot some Precision Delta 124 JHP that they loaded. Wasn't too impressed, but I guess the Czechmate was built around a 124 RN?

Also, Atlanta Arms 147 Major PF through a Czechmate is the most badass I've ever felt.