split cases

[delmartin]

I just bought a used Cooper 57 in 17 hmr. Today I put a scope on it and sighted it in on a 150 yd target. I noticed that five out of twenty-five cases were split about a third of the way down the case. What is going on here and should I be concerned? Plenty of smoke around the necks.

 

[fdshuster]

Del: I had the same thing happen with a batch of remington 22 Long Rifle, standard velocity (target) years ago. Sent a handful of splits to Remington with the boxes showing the lot number and they denied there was anything wrong with the ammo. It was fired in a Douglas match chambered, Giles built High Standard bullseye match pistol. Then accumulated another handful, sent them those, and this time they admitted that lot had harder, more brittle brass than was acceptable. They shipped 2 bricks (1K rounds), "for my troubles". While this was going on CCI & Federal were trouble free.

 

[fdshuster]

Del: When the splits occurred, the sound was a "phffft", and of course the shot printed low on the target. Empty case did not eject, so I was able to save them for later shipment back to the big green "R". The split was from the case mouth all the way down to near the rim. Had a case of 5K of them so had to use for informal practice only, since they were not dependable for match use. When I sent the first batch back ( about 25 cases), they inferred there was something wrong with the pistol, and mentioned an oversize chamber. When the second batch was sent I told them it was a tight chambered Douglas match barrel, custom built. Then they admitted their metalergy dept. found the brass to be brittle. If you can use others brands without any of the problems, I would definately send the splits back to Hornady, along with the original box's.

 

[TRECustom]

I've had occasional problems with split necks, shoulders, and rarely the body of several different rimfire and some centerfire cartridges. The common thread was that nearly all were Winchester or W-W. About half of the centerfires were during fire-forming. Some of the chambers were factory and some were customs. No splits with Federal, Hornady, military, or Lapua brass. A couple with Remington.

I think the Winchester and W-W were just hard and thin.

Tom

 

[camac]

This was a huge problem with the 17HMR - check out rimfirecentral - threads date back to its inception. Main problem is the bad quality brass that came through but a lot of chambers seem to be a little "girthy" and/ or "long" causing bigger problems. Such that brittle brass couldn't stretch far enough. As suggested (unless you want to rechamber your rifle) try some different batches. If you want to look at the size of your chamber you will have to measure unsplit cases (as they form better to chamber than split ones). I lathed about 20 thou off the back of my barrel and looked at headspacing carefully to fix this problem in mine. - Much better took it down from 1.5moa to under 1.0 and into "the club".

Some guys had success with Hornady getting some replacements but it became a game of rifle manufacturers blaming ammo companies for bad brass and vice versa ammo companies blaming manufacturers for "sloppy chambers". You should really measure chamber and unfired shells to see which is closer to Saami specs before throwing rocks. In my opinion it is definately bad quality brass but some chambers leave a lot to be desired. I don't have a cooper but they have an excellent reputation.

 

[glbpmc]

I have a Volquartsen 17HMR and found 1 box of Hornaday brass split the neck and shoulder on about half the box. Odd that the next 3 boxes did not have a single split.

 

[CooperNV]

I had a 597 17 HMR, mine was POS. Trigger group fell apart twice and then started firing out of battery. I sent it back to Rem. and they gave me $400 credit on another rimfire, Ended up with a Marlin.
I have a Volquartson and a Magnum Research in 17 HMR, neither has ever fired out of battery. Stove Pipes at times, but nothing a cleaning won't cure. Keep the chambers clean and these will run very well. Remington ammo is still on the shelve. I have not experienced any slit case in 15,000 rounds of shooting since 2001. I have shot all brands of ammo but WW. Mostly CCI and Horny. No probs in my currant inventory of HMR's , Cooper LVT, Savage 93, Marlin HB, VQ Fusion and Magnum Research. Not much help but it must be the brass, most of my ammo was bought around 2005 when it went on sale.

 

[camac]

It is the brass quality primarily. But we had a few rifles here, one with a custom match chamber and did not see a split shell. WHilst from same batch I was splitting 1 in 3. Bad brass (work hardened or bad ratios) being asked to "expand" will split. Well annealed brass asked to do same will not. Bad brass in tight chamber does not have to move far so has much less chance of splitting. Some of the 17HMR chambers I have seen from factory rifles are "very" long. Mine had 30 thou too much in the shoulder length. A friends was similar (but not quite as bad). Similarly when we checked freebore they both had to jump 120-150 thou with the factory ammo. Simply put the reamers were sent too deep. I knocked 20 thou off the barrel and reset headspace - it helped a lot. (Must also check for adequate length in neck of chamber to do this)