17 Mach2 case splitting

[greer]

 I have hunted with a CZ 17 Hmr for a few years now and recently purchased a CZ 452 in 17 mach2. While trying it out with a few brands of ammo I noticed that with Hornady and CCI ammo the cases would often split and of course accuracy wasn't great. With Ely ammo the cases never split and accuracy was better. I thought sure I had a rifle with a bad chamber. Just for the heck of it I shot some of the same ammo through my buddies CZ 452 and had the same results, cases split on the Hornady and CCI. It would be odd to get bad batches of Hornady and CCI ammo at the same time I would think. I need to try some different lots. Would like to know if anyone else has had the same experience with the CZ's or the ammo. I know that some have had trouble with the semi autos blowing cases when the chambers get dirty. I guess both of our rifles could have chambers that are a little sloppy but that would be odd too. His rifle shoots pretty good with the Ely which is all he has shot so far, and this new one of mine shoots decent with Ely. Also I noticed that some of the newer CZ's have pinned barrels, including this new one of mine. Are these barrels still threaded or are they pressed in? I may rebarrel my 17M2 if I can't get it shooting the way I want. My 17 Hmr used to be a 22 mag and I rebarreled it before CZ offered a 17 Hmr. It is very accurate and I want an equally accurate 17 mach2. Thanks for any input. greer

[tlyne]

There has been stories on the web that CCI & Horndy 17 HMR & 17 Mach II brass cases are not being annealed, but Ely ammo is annealed. American ammo has been having split cases but not Ely. I got rid of a 17 Mach II because of splits before I found out it was caused by US ammo. Don't get rid of your CZ just yet. Follow  up on US Ammo not being annealed before loading. I don't think you have a bad chamber. Best of luck.

[dorothy daily]

would not be unusual since both are manufactured b.y the same company

[greer]

 Thanks alot for the responses. That's exactly the kind of information I was loking for. I've got some more Hornady to try that was made earlier. I'll see if it splits also. I really enjoy shooting the quieter Mach2. I can't imagine a better squirell cartridge when the leaves are gone. Before I fired the first round I bedded the action, floated the barrel and worked on the trigger. Hopefully I'll get it to shooting to the barrels potential.  Thanks again.     greer

[S.S.]

Never had one split?

[Ladobe]

Never had one split?

Same here and I do shoot only Hornady ammo.    Maybe it's because I bought a lifetime supply of the ammo early on, all in the same lot and that lot is one that is not prone to splitting (or bulging as was seen with some early ammo in specific chambers - like early factory TC barrels). 

[S.S.]

the only real problem I have seen is people mistaking 17 aguila
for 17 mach 2. These cases didn't even split that I remember but they were
deformed and difficult to extract.

[greer]

 I tried some earlier Hornady ammo the other day and had no splitting and good accuracy. I guess it was just a coincidence that I had lots of CCI and Hornady that both split. The brass may have come from the same factory. The rifle seems to be shooting better as the rounds pile up. Another bonus is that it puts the first shot right where it's suppose to after the barrel cools down which for hunting is more important than group size I believe.  greer

[S.S.]

An accurate cold bore shot is what separates good rifles from great ones.