7mm STW Hornady vs Nosler Cases

[Douglas A. Twitty]

Thanks to everyone for the replies. I will check the Hornady cases for cracks when I get back home tonight. Working up loads using both brands to see if there's a difference in accuracy, and so far there is none (Most accurate load so far = Federal Magnum Match primers, Barnes 145 grain LRX over 76.3 grains IMR 7828SSC) I'm ordering more Nosler cases for this rifle and will likely settle on that brand after the next outing or 2. May contact Hornady for their opinion on the case appearance

Let us know what Hornady says about the "rings" on the brass I've seen them on my 7mm STW also.

 

[RomeoJim]

Just spoke with Jordan at Hornady regarding the "rings" that I've found just above the belt on Hornady 7mm STW after a single firing. He told me that by my description that ring appearance is almost always a headspace issue. He suggested comparing the lengths of the fired versus unfired brass and if the difference is greater than .008" that also indicates a headspace problem. He also suggest that I try cases from one of my other boxes od new Hornady brass, provided the are a different Lot # and try firing some of those to see if there's any difference. The rifle and ammo is presently at our cabin in northern Michigan and we won't be back up there until June 1st for me to measure fired vs unfired case length. (I know that the fired cases are longer but can't remember by how much) I will also measure the case length difference between the fired and unfired Nosler cases to see how much they stretched during firing compared with the Hornady cases. I also plan on ordering a Hornady headspace guage from Midway to check it for myself when I get back up there. Once I've done my analysis I will post my findings.

 

[Douglas A. Twitty]

Thank You for the update!

 

[RomeoJim]

Tell us a little more about your gun, custom, Factory, barrel twist, etc. What were your two case lengths (base to mid shoulder) lengths before firing and after...

My first STW had a 1/10 twist and loved the Barnes 145gr LRX pushed with Re 25, if I remember right just shy of 3,450 fps... (It now has a Proof 26" CF Sendario 1/8 on it for 195 gr Bergers)
I mostly shoot Nosler, RP, or Win in my STW's, equal loads will show more pressure in Nosler cases sooner. IMO

I'm not certain of the barrel twist on this Blaser 93 but will check it (along with case dimensions fired vs unfired) when I get back up to our cabin

 

[RomeoJim]

Over this past weekend, I checked about a dozen each of my Nosler and Hornady 7mm STW fired and new cases, using a Hornady Headspace Guage. I found out that the difference between the fired and new cases measured at the shoulder by the Hornady Headspace gauge is .014" for both the Nosler and Hornady brass. The tech
support guy at Hornady states that they consider this too much headspace, which is likely the reason for the ring showing up just ahead of the belt and with someone having mentioned previously that he found the Nosler cases to be thicker that likely explains why there seems to be less of a ring on the Nosler cases, even though the measured expansion is the same. Corsair4363 mentioned previously that he has found variances in increased headspace in various rifles that use belted cases and it sounds like that's probably the case here as well. This rifle is a Blaser Model 93, which was lightly used by it's previous owner. I have yet to determine the barrels rate of twist but will do so soon. The load that I've recently worked up for it is very accurate at 100 yards, but I've yet to try it on the 200 and 300 yard range at our club.

 

[RomeoJim]

I just checked the rate of twist on this Model 93 Blaser and found that it's 1 in 10"