The Original CZ Forum

CZ LONG ARMS => CZF RIMFIRES => Topic started by: gryphon on May 10, 2015, 12:56:12 PM

Title: Does the .17HMR tend to split cases
Post by: gryphon on May 10, 2015, 12:56:12 PM

I've asked this question in a couple of other threads after it was mentioned by one owner but I never got an answer. A member mentioned that after trying a few different makes of ammo in his new 17hmr barrel he had a number of split cases. Is this something the HMR's are noted for? Is it something the CZ's in that caliber are noted for?

Title: Re: Does the .17HMR tend to split cases
Post by: Jake G on May 10, 2015, 06:12:42 PM

I wouldn't think so and I have never seen it in my CZ 452 or Ruger with aftermarket barrel.  It could just be that lot of ammo perhaps.  I'd see if it does it with more than one brand/manufacturer and then contact CZ if it continues.

Title: Re: Does the .17HMR tend to split cases
Post by: SpinyNorman on May 10, 2015, 07:39:30 PM

It happens with my 452 Varmint fairly regularly (at least a couple of rounds per box). It splits right through the shoulder and neck.

Title: Re: Does the .17HMR tend to split cases
Post by: gryphon on May 10, 2015, 09:13:26 PM

Yeah, that's what the other guy was saying. He had 3 or 4 different brands of ammo and they all did it. Some worse than others.

Title: Re: Does the .17HMR tend to split cases
Post by: P.K.Hansen on May 16, 2015, 02:58:28 PM

I'm that other guy :-)
I didn't see your question - sorry about that.
I've seen quite a few threads regarding split cases, and it seems to be a commen thing, happening in all brands of firearms. Some think it is because the cases aren't annealed after necking.
A guy here in Denmark shot a box without a single crack. Next time out, nearly every third or fourth case cracked. Same lot.
The ones I had, all had cracks roughly 3mm long - 1/8" long

Title: Re: Does the .17HMR tend to split cases
Post by: SpinyNorman on May 16, 2015, 09:58:56 PM

I had a .17 HMR case rupture at the rim one time. It "inflated" the magazine in my CZ Varmint to the point where I had to drive the magazine through the window in the bottom metal to get it out. I squeezed the mag back into shape with a vise and it's worked fine ever since. The bullet ended up with just it's red tip sticking from the muzzle. Very odd.

Title: Re: Does the .17HMR tend to split cases
Post by: P.K.Hansen on May 17, 2015, 06:42:04 AM

Here's a pic of some of the cases. From left to right: CCI, Winchester & Hornady. The last pic shows two Hornady cases with very small cracks. Probably woudn't notice them if I wasn't searching.
(https://farm8.staticflickr.com/7757/17742674146_5e92b45f47_z.jpg)
(https://farm6.staticflickr.com/5325/17581454200_f3a538db6d_z.jpg)

Title: Re: Does the .17HMR tend to split cases
Post by: acsteve on May 17, 2015, 07:02:03 AM

is this a problem with chamber dimentions or imcorrect shoulder loacation on ammo?