Barrel not plunking flush w/ hood

[MissionaryMike]

My original post is in the CZ section, but I'm double posting in hopes of getting more exposure and responses. I hope that's ok. I originally wrote:

"So I'm putting together loads, and my Accu Shadow will cycle dummy rounds at 1.125 with no problems at all, and it passes the plunk test (easy in, easy out). It'll even cycle 1.130 most of the time. However, the base of the case sits above the hood.

Should I be worried about this, or am I GTG as long my gun will eat the ammo?"

There seems to be much anecdotal evidence that CZs, including the Accu Shadow, have short chambers.

http://www.brianenos.com/forums/index.php?showtopic=220940#entry2460871

Edited September 4, 2015 by MissionaryMike

[MissionaryMike]

I'm using 147gr. Flat Nose lead bullets.

[jbarnett50]

Does the 1.13 pass the plunk and spin test? If not, you're begging for trouble if you shoot competition. My accu takes up to 1.16 with bayou 147 trainers.

[Matt1]

The "hood" isn't a traditional hood in cz's so it doesn't matter if the rim sits above it.

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[bfalcon00]

Some pictures of the problem would help.

[dillon]

First, do sized, empty cases drop in flush and freely fall out of the chamber? If yes, then load a few of the tested cases and recheck.

[MissionaryMike]

I've done pretty much everything you guys have questioned, addressed, and suggested.

Does the 1.13 pass the plunk and spin test? If not, you're begging for trouble if you shoot competition. My accu takes up to 1.16 with bayou 147 trainers.

Yes, 1.13 passes. In fact, up to 1.1350 passes. I haven't tried loading longer than that.

First, do sized, empty cases drop in flush and freely fall out of the chamber? If yes, then load a few of the tested cases and recheck.

This is the first thing I do after depriming and cleaning my brass. All the brass I'm using is gtg.

The "hood" isn't a traditional hood in cz's so it doesn't matter if the rim sits above it.


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After a week of testing over and over again, this is my conclusion as well. All the live ammo I make, up to 1.1350" cycles through my gun just fine. I've decided not to worry about the rim sitting above the hood for this barrel.

[bfalcon00]

Ok well let us know how it turns out for ya.

[glynnm45]

One question Mike; have you tried any factory ammo to see how they set in your barrel? You might be worrying about nothing.

[AirForce2]

I to have a cz accu shadow and since my olden days of shooting mostly 1911 barrels, was concerned that the sized case rim was above the hood thought this might be an issue only because I had problem with long ogive bullets loaded such as Montana gold hollow point OAL of 1.115 or longer would not drop in/out of my chamber.

I now know the cz accu barrel case rims "will" sit above the hood by appx 3/4 of the rim above the hood and this is ok. The hood doesn't fit the slide cut the same way a 1911 does. If you have issues loading hollow point bullets long, it's not the chamber that needs to be cut (mine was in spec). You will need to cut the "rifling" for longer hollow points, not the chamber. This is what I found out with my orig & replacement cz accu shadow barrel. I know because I thought I ordered a reamer that cut the rifling and it cut the chamber and "F'd" up my barrel. The top of the cz slide had a portion that sticks out at the top where a 1911 slide cut is recessed, hence the cz barrel hood is cut more forward and the 1911 barrel is flush w/rim for this reason. Hope this helps.

AirForce2

Edited September 20, 2015 by AirForce2

[MissionaryMike]

Thanks, everyone, for your responses. I've been testing out longish (1.120-1.130) reloads with my 147 flat nose bullets, and it all feeds fine. I'm not going to worry about the rim sitting above the hood anymore.

[Matt1]

Just to add to this topic. I picked up my CZ TS Orange yesterday and the test round the dealer have me sits flush with the hood in the .357 Sig barrel that I got extra with it. That barrel was reamed to Sig dimensions from a 9mm barrel. I then tried my rounds that sit above the hood in my other TS and they sit flush with the hood in the new barrel.

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[MissionaryMike]

After conducting the push test many times over, I finally settled on a Max OAL of 1.136. I subtracted the .015 (1.120) and load my rounds to 1.116-1.118 as an acceptable range for OAL. This is for match ammo. I allow a broader OAL variance for range days. The rounds still sit above the hood at these lengths.

[noylj]

My CZ-75s did not have short chambers.

I couldn't tell where the "barrel hood" was on my CZs, so I simply found the point where the empty case heads aligned with the barrel.

I establish COL by loading a couple of inert dummy rounds and check cycling (fit mag, feed, and chamber).

You can paint the bullets black and chamber the round and eject and see if there are rifling marks on the bullet from a COL that is too long. You can do this as part of the "plunk" test and see marks on the ogive near the bullet's bearing surface.

I like to work up loads with lead bullets just touching the lede/rifling and jacketed bullets just about 0.005" off the lede/rifing.

Not sure why so many want to shoot short COL, but they must know what they are doing.

[longbeard]

In my experiencethe OAL you can use in your CZ will be dependent on the bullet profile you use. Round nose bullets will load longer than flat point. I know this sounds short, but for LFP, try 1.1 and I think you'll see the gun cycles nicely and doesn't at all feel "notchy" when chambering rounds (which it does with longer OAL). I struggled with going that short, but 15K rounds later I've never looked back. No issues whatsoever, great accuracy. I use SNS coated