Author Topic: 9mm Minimum length question  (Read 3820 times)

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Offline jimny

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9mm Minimum length question
« on: December 19, 2013, 02:58:54 PM »
I have some "Missouri Bullets 124 gr Small Ball" cast bullets to try in my CZ 75B 9mm. Doing the push test for the correct length I ended up at 1.090" , and decided to use 1.070 for my overall length. The minimum is listed as 1.095 " according to M.L.Mcpherson in "Metallic Cartridge Reloading" 3rd edition. . Only problem is the test bullets won't chamber in the barrel until I got the OAL down to 1.035". What Happened??? It's not the crimp., that was the first thing I checked. Other brands of 125 cast bullets have been around 1.125" in the same pistol. Any CZ forum members used these with similar measurements ? Are these going to give pressure problems ? I searched the forum and didn't get any results I could use.

thanks,

Jim

Offline levellinebrad

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Re: 9mm Minimum length question
« Reply #1 on: December 19, 2013, 06:39:57 PM »
Can you post a picture of the cast bullet?
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Offline jimny

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Re: 9mm Minimum length question
« Reply #2 on: December 19, 2013, 06:48:46 PM »
No pictures, but they are on the Missouri Bullet website as 9mm 124 gr "Small Ball".

 

Offline Old Rocket

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Re: 9mm Minimum length question
« Reply #3 on: December 19, 2013, 07:53:51 PM »
 Try a push test with more than 1 bullet and take the shortest OAL and subtract your .015. When I've done that I have never had a problem with chambering.
 In looking at the profile of that projectile I would say you need a short OAL in a CZ. 1.035 wouldn't surprise me at all. The shorter OAL would cause me to start with the minimum recommended load and work up using a chrono. Test to see if you have feeding issues and if you don't load them up.
 I personally wouldn't order any more of those and would look for a better profile that is more user friendly in a CZ. I don't like loading shorter than 1.060 myself but that is me.
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Offline 1SOW

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Re: 9mm Minimum length question
« Reply #4 on: December 19, 2013, 08:54:04 PM »
The nose shape---where the straight sidewall of the bullet 'starts' is usually the cause of needing short oals. 

Borrowing one of Wobbly's great pics illustrates the differences between bullets:

Offline jimny

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Re: 9mm Minimum length question
« Reply #5 on: December 19, 2013, 09:42:23 PM »
Thanks for the replies, I'll give them a try at starting load of HP-38 and see what the chrono tells me. I also think they are a little short, that's why I was asking .

Offline armoredman

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Re: 9mm Minimum length question
« Reply #6 on: December 19, 2013, 10:16:55 PM »
I had to do the same thing with Berry's plated hollow point, being so wide, and I went down to 1.025 to get them to work, so I feel your pain. :) No worries, start low and work up.

Offline steel

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Re: 9mm Minimum length question
« Reply #7 on: December 19, 2013, 10:19:02 PM »
Small Ball has a profile much like a FMJ bullet.  The push test revealed a maximum of 1.075 in my Shadow and Compact L.  I've loaded 2,000 at 1.060 and shot over 1,000 with no problems.  They are accurate, reliable, and relatively cheap (when ordered in bulk) in both of my CZs.  My only objection is that there is a lot of smoke with Titegroup.  Unfortunately it was the only powder I had access to at the time.  I plan to use Clays with the next batch that I order.


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Offline Wobbly

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Re: 9mm Minimum length question
« Reply #8 on: December 19, 2013, 10:32:54 PM »
Welcome aboard !

You got some great info from the guys. If the 'push test' (run with several bullets) says they will fit at OALs shorter than 1.090" then you can believe it. The push test is not some hockus-pokus magic trick, but the actual measure of the bullet in the chamber. If it works with the static push test, then is must work in action if your brass is good and the crimp is OK.

By the way, just for grins, what is your crimp measuring ?

 ;)
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Offline jimny

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Re: 9mm Minimum length question
« Reply #9 on: December 20, 2013, 10:55:20 AM »
Mr. Wobbly, my crimp is measuring between .377-.378 on my dial caliper. Very consistent on all my test bullets.(I'm impressed with my consistency) When I was doing the push test I had a hard time finding a fired case that would accept the bullet, like 1 out of 6 would work. I did use 3 different cases and bullets - tried many times to get the numbers ( Overall length = 1.070) in my first post. So I was surprised when the test bullet would not seat in the chamber for  .035 less than the push test.

Thanks for adding your expertise.

Jim

Offline Wobbly

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Re: 9mm Minimum length question
« Reply #10 on: December 21, 2013, 08:41:27 AM »
When I was doing the push test I had a hard time finding a fired case that would accept the bullet, like 1 out of 6 would work.


Since a lead bullet is typically .001 to .002" larger, the issue you encountered is to be expected.

You might gain something from purchasing a 9mm "cartridge gauge" from Wilson Tool, or other. There are numerous reasons why a cartridge will not allow the slide to go into battery, and only about half of these reasons are detectable with a caliper.

 ;)
« Last Edit: December 21, 2013, 08:54:42 AM by Wobbly »
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Offline jimny

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Re: 9mm Minimum length question
« Reply #11 on: December 23, 2013, 11:21:15 AM »
We had a few warm days on the frozen tundra of upstate NY, so I packed up the pro chrono digital and headed to the club. Set up in 6 " of snow, but it was overcast and about 42 degrees. Fired 2- 10 shot strings with the "small ball" at 1.035" with Win brass, Fed primers, and a starting load of 3.9 grains of HP-38. The 75B fired these with no problems, no jams, no stovepipes, etc. It has always digested everything I feed it. The average  was 1073 fps, ES =14; SD =5. This load is a little warm, and all the primers were flattened. I intend to drop back on the HP-38 and try again. 

Jim

Offline kobus

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Re: 9mm Minimum length question
« Reply #12 on: December 23, 2013, 01:36:14 PM »
your es and sd is very good with those loads.   try 1.055 with 3.7gr of HP38. you should get close to the same velocity with a bit less pressure.
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Offline Wobbly

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Re: 9mm Minimum length question
« Reply #13 on: December 23, 2013, 07:31:42 PM »
We had a few warm days on the frozen tundra of upstate NY, so I packed up the pro chrono digital and headed to the club. Set up in 6 " of snow, but it was overcast and about 42 degrees. Fired 2- 10 shot strings with the "small ball" at 1.035" with Win brass, Fed primers, and a starting load of 3.9 grains of HP-38. The 75B fired these with no problems, no jams, no stovepipes, etc. It has always digested everything I feed it. The average  was 1073 fps, ES =14; SD =5. This load is a little warm, and all the primers were flattened. I intend to drop back on the HP-38 and try again. 


Glad to see you were able to settle on an OAL.

Federal primers will always "flatten", even with moderate loads, so that's not an indicator of much of anything. Certainly not a good/bad indicator of pressure.

Done good.   ;)

In God we trust; On 'Starting Load' we rely.

 

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