Author Topic: CZ 97 Barrel "Protrusions"  (Read 147 times)

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Offline Gunzanamo

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CZ 97 Barrel "Protrusions"
« on: March 13, 2018, 01:00:34 AM »
Hi, I recently snagged a CZ 97. They seem to be made of unobtanium so I was happy to get ahold of one.

First time out with factory hard ball was no problem. Managed to put 8 shots into 1 7/8" with 2 flyers at 12 yards. Very pleased for first time out.

I want to keep my shooting costs down by reloading and I particularly want some semi wad cutters. The manual says they are verboten. I tried some hollow points with no problem.

I bought a Lee mold that turns out to be a single radius round nose of 228 grains supposedly. I had done a fair bit of reading so I knew the learning curve would be fairly steep with pistol ammo. After much fiddling around I got my first reloads to feed and fire with a few failures to go into battery, A light shove from my thumb seemed to take care of it but still not ideal.

I bought some 185 grain Hornady JSWC's to try out and the learning came quicker second time around. I found that they would fit fine in the case length gauge but not in the chamber. Adjusting the bullet length and taper crimping lightly mostly took a care of that.

I noticed that the round would hang up on the case mouth on those small squarish protrusions on the upper back of the barrel. The left side one in particular. So I swallowed hard and stoned the left hand one a bit to radius the sharp bevel. With dropping the slide on them they seemed to chamber fine.

At the range I had about 3 out of 10 that FTF. A light pull back on the slide allowed them to drop into place and releasing the slide chambered them.

Today I loaded some 200 grain LSWC's. They are a bit longer and also seem to chamber OK. Better than the 185's. The test is in the shooting of course.

So now I have to expose my ignorance. What are those small protrusions on the back of the barrel for? I don't see what purpose they serve. I would like to do a bit more radiusing of them to get more reliable feed from the 185's just to broaden my bullet options. But I don't want to do any more until I know what function they serve. Hate to wreck a new gun and all.

Any help would be appreciated.
Professing to be wise they became fools.


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Re: CZ 97 Barrel "Protrusions"
« Reply #1 on: March 13, 2018, 07:06:54 AM »
Are you talking about the 2 protrusions on the upper rear of the chamber? If so Those are where the barrel locks up with the slide in back and I wouldn't stone those at all. If you are having issues with rounds chambering it's likely due to the bullet style your using and the fact that CZ barrels tend to be short throated. There are many threads on this forum dealing with the short chamber and "push test" for bullet seating depth.
I cast 200 gr lrn for my 97 BD and load 230 gr. jacketed ball as well and I also have no issues with any defensive type ammo. Never wasted any time with swc's as they can be an issue.
« Last Edit: March 13, 2018, 07:34:38 AM by SI VIS PACEM PARRABELLUM »

Offline Gunzanamo

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Re: CZ 97 Barrel "Protrusions"
« Reply #2 on: March 13, 2018, 10:27:49 AM »
Thanks for the reply, Pacem.
Yes, those protrusions above the chamber. Since they are already beveled on their lower sides I was simply rounding them very slightly rather than leaving a sharp edge on them. It seemed to work since the 185 grains went from 100% FTF to 30% FTF. I suspect that the longer 200 grains will be even better. It shouldn't affect lock up since those areas don't appear to bear against anything. I'm not shortening them or narrowing them.

Can you give me an explanation on how they accomplish locking up? I can't see what they do or really bear against. It is kind of dark and inaccessible in there.  I see nothing that they move into. The barrel tilts up and there is a ridge along the top side that would provide resistance to moving back under pressure. There is also the lug on the bottom of the barrel. But those protrusions are so small they don't look like they could contribute much. Maybe they provide some side to side resistance?

Here is a pic. Notice the protrusion on the left is slightly rounded on the chamber side.

To my unstudied eye they look like they could be removed entirely (not saying I was thinking of doing so) and still function.

Once it warms up and the icy winds stop blowing I'll try out the LSWC and see how they do.

Thanks for the input.
Professing to be wise they became fools.