Help by some one smarter than me. On Ruger M-77 .22 hornet

[viper]

Guys I bought a new Ruger M-77 in .22 Hornet. Went out to sight in and shot 35 grain Factory ammo. 1” group no problem. Tried Nosler Factory .35 grain and 3rd shot case separated back by rim about 1/16 inch ahead of it. Got nervous so sent ammo back to Nosler really nice but had no explanation. So I bought a head space set, Go -No Go gauge and neither would allow me to close my bolt. So that would seem to me that the head space is off. Does a Hornet head space off the rim? I have read arguments both ways! If it does head space off rim then does the shims in the 2 piece bolt adjust the head space? My action is snug to close and open but not crazy hard. Would to little head space shown by the GO gauge not closing cause this?suggestions?

 

[AWS]

The standard 22 Hornet headspace off the rim. There is too much taper and not enough shoulder to headspace off the shoulder. If you can't close the bolt on the go gauge and it is snug on the cartridge it sounds like the rifle is headspace fine. Measure your fired brass vs new brass and see if the chamber is too large. It would have to be extremely large to cause a separation on the first firing. You can fire factory ammo in any of the improved chambers, Kilbourn/Ackley to fireform.

Check your Hornady brass for evidence of impending case head separation. Nosler might have a batch of brittle brass. New brass is usually very malleable and rarely separates on the first firing. About the only time you see case separation on the first firing is with old military brass that has become brittle with age and fired in loose military chambers.

 

[Sgt_Mike]

With the K-Hornet I have the game changer was using small pistol primers. The Hornet "can" headspace off the rim or the slight shoulder.

Check your Hornady brass for evidence of impending case head separation. Nosler might have a batch of brittle brass. New brass is usually very malleable and rarely separates on the first firing.

Very true and spot on.

Best of luck with your hornet, great cartridge

 

[K22-hornet]

I've had my Ruger M-77 in Hornet since the early 1990's, and a buddy has a twin.

What AWS is saying.

I had one case separation, but it was my handload. The specs called for 10.2gr of H4227 (max), and I loaded 12.2gr.

I did not have a chrono yet, but I noticed the first shot of the 12.2gr seemed to get downrange noticeably faster than my previous loads. Shot #2 seemed faster as well, plus it was almost on top of the first shot. I thinking, WOW, faster and accurate! I'm in high cotton now.

3rd shot and smoke came out of the bolt area, and only the rim plus a little case came out, with the rest of the case stuck in the chamber.

To get the most out of the standard Hornet, reload for it, and use Lilgun or MP-300 powders. Much lower pressures and higher velocity than other powders. Your brass will last a long time using Lilgun.