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Posted: 2/26/2008 9:09:23 AM EDT
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Hi gang! I figure this 22 section would be most appropriate for this post. I have a basically new Marlin VS 17HMR. She's got maybe 100rnds through her. It has been cleaned numerous times. Here the problem.  I have only tried Hornady HMR ammo. I bought 2 500rnd cases at different times so it's not the same case lot #. I have not tried any other brand of ammo in the rifle. This doesn't happen every round, but at least 1 out of a few clips it does 
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| this is a common prob with all 17's, they are a hi pressure round, and the ammo companies still don't have it down yet. some do better than others, and you think hornady would, but they don't. None except eley, and they only make mach 2 ammo... there is a certain crimp pressure needed, there is a certain amount of run-out needed, and it is really not standardized at all. Also it doesn't appear that rifle chambers are perfect either; that being said, for low end , i think marlin has made them best, especially in their n.e.f. line, but even then, they proly don't get it right every time. Chamber specs are even tougher in themach 2. You would have to go high end rifle , to eliminate this problem, such as kimber,cooper, Anschutz, etc., for now , i would not worry about it. |
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I haven't had any split case issues with my single shot NEF 17 HMR, but that is common with 17M2 using any ammo except Eley or Remington. I've built a couple of AR15/M16 uppers in 17M2. CCI and Hornady will split/rupture cases all day long. Rem/Eley are OK. Several mods are required to keep things from going kaboom, especially in fullauto. |
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This was Hornady Ammo's responce: When they make the cases for the 17 HMR they make a straight walled case to start with. Then they add the priming compound in the rim of the case. Then they neck the case down to 17 caliber. When the case is size it down it puts stress on the case mouth and the shoulder. They can not relieve the stress from the case be cause of the priming compound. So from time to time you will get a cracked case. There is also some variation in the chambers on the guns. Some of them can be to the top of the specification so the case expands more. You may also find some lots that might crack more than others. Looking at the photo the crack looks to be a stress crack. Without measuring the mouth of the case it would be hard to tell if the chamber was a little large. Were both bricks the same lot or were they different? I see cracks in some that I shoot also but usually won't catch them unless I retrieve the case. I do check ammo to see if there might be a crack in the case before firing. I would not shoot any that were cracked before they are fired. The rounds that crack in the rifle should not cause any problems to the gun. |
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