Case separation

[LowerRiver]

I had this issue in my 77/17. Hornady had a lot number of factory loads that had lots of problems. It’s possible your brass is from that lot???? Hornady replaced mine with no issue.

[SmokinJoe]

Since we're talking about Hornet brass, and I haven't seen this discussed, the current Nosler made in USA brass looks really nice and weighs 56+ grs, so it is on the heavy end of Hornet brass.

[B23]

Maybe I missed it, but are we talking about the 17 Hornady Hornet, K-Hornet, or Ackley Hornet??

[GrocMax]

I'm not understanding how a rimmed cartridge has a CHS.

[SmokinJoe]

My contributions are regarding Hornet brass in general since that is where all these cartridges start from.

Groc, What is CHS?

[cosh]

I think he is referring to this subject/article -

http://photos.imageevent.com/badgerd...ce%20_CHS_.pdf

[Bill K]

Originally Posted by GrocMax

I'm not understanding how a rimmed cartridge has a CHS.

Any cartridge, even though it is head spaced on the rim, rebated or other types, must also be seated on the shoulder supported in length also, or you can get brass stretching, which in turn will cause the case to begin separating, usually as mentioned in the CHS article and how the OP first posted, that his did.

[Bayou City Boy]

Laidler, when he mentions CHS in his article, he is referring to cartridge head spacing for a rifle chamber and particular cartridges.

CHS can also mean case head separation which is what the OP asked about. And yes, a rimmed cartridge can suffer from CHS (case had separation) if not sized properly with the shoulder touching as Bill K related.

-BCB

[B23]

I can't speak to anything chambered in 17 K-Hornet or 17 Ackley Hornet, but I can to those with 17 Hornady Hornet as I have two of those, both being CZ 527 Varmint models.

As mentioned, both of my 17 HH are CZ 527's, both were bought new and still wear their factory barrels with the exception, one of them I sent to Kevin Weaver to be set back and rechambered with his PTG 17 Hornady Hornet reamer, shortly after I bought it. Out of the box, depending on the particular Lot# being shot, they both shot .5 - .75 at 100yds. Occasionally a little better and even sometimes worse, but generally with factory ammo .5 - .75 was expected and with hand loads the avg. would be tighter.

I don't know about other brands, although I think they're similar, but the chambers in the CZ 17 H Hornets are generous and plenty long.

New unfired brass as well as new factory loaded 17 Hornady Hornet ammo all measure 1.046 - 1.047 to the shoulder datum, which is exactly SAAMI spec. BUT this stuff grows a lot upon firing. A lot as in 11 - 12 thou. My brass, from my two 17 HH as well as the brass from a friends CZ 17 HH measures anywhere from 1.0505 - 1.057 and none of the brass I've measured ever had the shoulders moved so far forward that it wouldn't rechamber or even give resistance closing the bolt so I'm not sure how far it needs to stretch before it reaches zero headspace and needs to be pushed back.

With these long chambers, if you're pushing the shoulder back at all, when you are FL resizing, I can see why people are getting case head separation and if anyone is pushing them all the way back to SAAMI spec of 1.047 I think you are pretty much guaranteed to get case head separation in only a couple firings.

Having measured a lot of different Lot#'s of 17 Hornady Hornet brass, I highly recommend people keep them in their own Lot #'s, as well as, consider buying a bushing die because the neck thickness on this stuff is alllllllll over the map. It seems most of the newer stuff is 9 - 10 thou and the older is as much as 13 thou.

Also, for the 17 H Hornet shooters, the Federal American Eagle 17 HH ammo tends to shoot better than the Hornady 17 HH ammo, which is really odd, considering both are made by Hornady and to the same spec.

[Bill K]

Having measured a lot of different Lot#'s of 17 Hornady Hornet brass, I highly recommend people keep them in their own Lot #'s, as well as, consider buying a bushing die because the neck thickness on this stuff is alllllllll over the map. It seems most of the newer stuff is 9 - 10 thou and the older is as much as 13 thou.

Have shot any of the factory ammo, other than some Hornady 15.5 NTX, for the brass to start with. Now Hornady brass is easy to locate and I have found that the average of the neck thickness, on what I have is running .011 , and it is working just fine. But then again I size to just touch the shoulder and do not set it back, after it is fire formed into my chamber. Bill K