CZ 75B 9mm chamber question.

[The Courier]

So I've been trying to set an overall length for some 124gr fmj round nose and I am running into a problem, even at minimum seating depth the rounds will not pass the plunk test. The data from lee states that for a 124 fmj round nose using Titegroup minimum COAL is 1.150, so first I thought the bell on the case was to blame but I dropped several unloaded cases in and they cleared no problem. After browsing CZ forums and discussions it seems I'm not the only one with this issue, some where saying they have to set their length at 1.10 for proper function. What bugging me is I'm trying to make a nice happy medium that works nice in my Glock 19 and my CZ and going below listed safe depth makes me a little nervous.
I understand that Glock chambers and CZ vary greatly in design and allowable length will be different as well. The only conclusion I can come up with is set charge at minimum and keep dropping the length until they chamber, Can anybody shed some light on this subject?

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[Jamie6.5]

Make sure there isn't any deposits in the throat area, like leading or carbon/copper build up that might be skewing the plunk test, before proceeding.

 

[Mistman]

I run my 125 RN @ 1.08, you can go shorter than 1.15. Look online for more data, the load I'm using states an OAL of 1.07. Just remember if you do shorten them up back off the load just a tad as pressure will be slightly increased. You'll probably find your o.k. with the load data you're using w/a shorter OAL. At 1.15 I have found I start to get an increase in FTF in some guns, others don't care.

 

[Wayne]

The data from lee states that for a 124 fmj round nose using Titegroup minimum COAL is 1.150

Keep in mind, that is not a minimum OAL, it is just what they used for their test, using their bullet,powder, and barrel. It is given as a "starting point".

 

[Mikej]

What projectile are you using? I use Montana Gold bullets in everything but .45acp, and they have an extra long bearing surface. For my Tanfoglio race gun in 9mm I must go down to 1.070 with 115 gr HPs. As said above drop back on powder. BUT, I also use a slower powder in 9mm. I like to have a larger range between min/max load, therefor I load 9mm and .40 with HS-6.



It would cause me some concerns as far as pressure spikes go using such a fast powder as Titegroup. HS-6 doesn't burn so clean and completely in larger cases but seem to work very well in the smaller cases of 9 and .40. Plus it fills the case more so you may be less likely to double charge.

 

[Mikej]

Keep in mind, that is not a minimum OAL, it is just what they used for their test, using their bullet,powder, and barrel. It is given as a "starting point".

This ^^ for sure! You need to look at these recipes not as "How to load your cartridge" but as "This was our result with this recipe with this gun/barrel length, primer, brass".

Ideally you really want to chrono your loads so you know what YOUR gun does with the recipe.

 

[Tilos]

With the barrel removed from the gun, drop a bullet into it, followed by a fired case over the bullet, pushing the case until it stops.
Then carefully push the bullet/case assembly out from the muzzle, carefully measure the overall length...that's your max length for that bullet/that barrel.

If the bullet is too loose in the case, slightly pinch the case oval to hold the bullet better.
In fact, putting the bullet in the fired case, and pushing the assembly into the chamber until it stops, will result in an assembly that represents the max overall length.
I then load to an overall length 0.010-0.020" shorter.
Either method has worked for me,
jmo

 

[thorborg]

I never ventured much beyond mid specs before I bought the chrony and found I was prudent to do so. Awareness of how a myriad of loading technique and component alterations can affect pressure beget its purchase. while it still won't identify pressure, speed plus sometimes telltale primer and case signs will educate most towards maximizing safe rounds.
Others here pointed me towards SAAMI. you should embrace it also.
Here it shows a 1.169 / 1.000 length spread which may enlighten your pondering some.

 

[Tilos]

...another option, this guy will recut the throat deeper for about $20
DaveGuy
45acp load problems

Here's his facebook
需要安全验证

 

[The Courier]

Thanks for all the info everyone! To give some more info the chamber is clean as could be, and the projectiles are from RMR and they look like they are from Armscor. I run my cases at .750 as it seems thats what most factorys run for case length I did trim some to .744 just to be sure the case wasn't causing the issue. I just loaded a couple and the max seems to be 1.139 for max so I set the length to 1.1375 to be safe.
Next question COAL is achieved but is shorter than tested OAL data, so for working up a load I usually load 5 rounds per .1gr increase in powder would 10 rounds be in order or more to be safe?

 

[Tilos]

Sounds like you're getting closer...

Here a site with a lot of 9mm data that can be searched by many different variables.
Just searching 9mm and 124FMJ will show many loads with a oal shorter than 1.150.
9 mm Load Data - Handloads.Com

9 mm Load Data - Handloads.Com

Some data has notes about what gun was used.
This data was submitted by shooters and should be cross referenced with other data from other sources, like powder mfg'ers sites found online.
Alliant Powder - Reloader's Guide

 

[jordanka16]

The best thing to do is to buy some cerrosafe, it's about $15 for a half pound on ebay, and make a chamber cast, then you can measure your actual chamber rather than guessing.

FWIW I load 124gr JHPs at 1.110 and they pass the plunk test in my CZ85.

 

[The Courier]

The best thing to do is to buy some cerrosafe, it's about $15 for a half pound on ebay, and make a chamber cast, then you can measure your actual chamber rather than guessing.

FWIW I load 124gr JHPs at 1.110 and they pass the plunk test in my CZ85.

That is something definitely worth looking into, I know loaders personally who load just to make the pistol function where as I am loading for accuracy and repeatable consistency and especially for 9mm as the savings are not as much as 40,10mm,357sig etc.
One thing I haven't been able to pin down with a definite answer is loading pistol the same as rifle where longer is better? I've read many different opinions but with a cast of the chamber might be nice as the longest possible length could be achieved safely.

 

[The Courier]

Thanks to Mikej's comment I'm going to run three powders Titegroup,HS-6,and 700x to see if either has better accuracy and consistent pressure. I like Titegroup due to the fact it uses very little powder and I have 6lbs that I paid $18 for each container, but the one thing I don't like is it runs at a higher pressure than other powders.

 

[maddog]

What bullet are you using? Sierra 125 FMJ I use sometimes have a a shorter ogive and need to be seated to 1.10 in my SP01, while Precision Delta 124gr FMJ can be seated to SAAMI max of 1.169 (push test = 1.207 max in my gun).

As has been said earlier, it's prudent (necessary) to drop the powder charge a bit when loading shorter than published minimum oal. .2 to .3 grains seems to work out most of the time. You could kind of guestimate the reduction using some simple algebra:

1.169/5.2gr = 1.07/x

Now, all of that said, I do not like Titegroup, even though many people swear by it. It burns hot and violently, and it's extremely easy to double charge. And being a fast powder, the pressure spikes early. All of this does not leave much room for error.

My recommendation is to use a different powder with this bullet, reduce the powder charge, and carefully work up your loads. CZ's are great pistols, and their accuracy is due, in part, to their short throats.

These statements are what work for me and you may experience different results.

 

[Mikej]

Thanks to Mikej's comment I'm going to run three powders Titegroup,HS-6,and 700x to see if either has better accuracy and consistent pressure. I like Titegroup due to the fact it uses very little powder and I have 6lbs that I paid $18 for each container, but the one thing I don't like is it runs at a higher pressure than other powders.

If you're using an RCBS uniflow, you're going to HATE 700X!

I also run a CZ75, SP01, but in .40. I use a Hornady 49, and the Speer 14 that came with my RCBS kit. There is quite a range between min/max between the two books. I'm always running in the lower end on powder charges. I've pretty much settled on recipes, and have three recipes I use for three different 9mm guns due to chamber limitations.

When I first started loading for 9mm and .40 I couldn't see the slightest difference in accuracy between loads, note that I didn't see the need to go full maximum. I would generally load ten of each, and I would add .2gr per step. When testing loads I was at 50' because that is what our range requires. I did notice differences in recoil though, and heavier recoil may cause you to flinch in anticipation.

 

[Mikej]

Now, all of that said, I do not like Titegroup, even though many people swear by it. It burns hot and violently, and it's extremely easy to double charge. And being a fast powder, the pressure spikes early. All of this does not leave much room for error.

Agreed! Save the Titegroup for .38sp and .45ACP, and ALWAYS check the brass good after charging, before seating bullets.

 

[The Courier]

Titegroup worked well with Berry's 115 plated but I keep the charge right in the middle of min and max.
Now that I'm looking at the jar of HS-6 it has a load of 6.8gr with sierra 124 fmj and a COAL of 1.090, obviously thats a different bullet but the depth looks promising as a good powder.
I've been running 700x in 40S&W as it's a lower pressure but good lord it meters terrible for me so I have the charge just below what my target is and adjust the charge by adding powder to perfect weight. Takes an eternity to get rounds loaded but very consistent shot to shot.

 

[Mikej]

I bought a couple pounds of that 700X stuff when I was still checking out different powders....If the book had recipes for a powder in multiple calibers I was going for it! I learnt, and sold the 700X promptly. 9mm is pain enough to load if you've got good size man hands to begin with, don't need that crunchy stuff to deal with on top of that!

 

[The Courier]

I started buying it because Bi Mart had it at $17 a peice and I figured it would be a pain but HS-6 at $23 or Bull's-eye at $28 seemed a little spendy for 9mm. One thing I like about the HS-6 is it loads 357sig quickly and still produces good velocity.