Forming K Hornet from Factory Load

[rollinghills]

I recently purchased a 1949 mfg. Brno ZKW "Hornet" rifle.

On my first trip to the range, I was pleasantly surprised by the accuracy of the Federal American Eagle 35 gr. Tipped ammunition in my new rifle. Three five shot groups averaged about 0.85 M.O.A.

However, I was mildly disappointed to discover that it had been K'ed at some time in its history, making the 22 Hornet Forster Micrometer Seating Die I had bought for it somewhat superfluous.

My biggest concern with the K Hornet chambering is with fireforming the factory loads. The primers on the fired cases have backed out of the pockets and are sitting between 0.015" and 0.020" inches proud. I am guessing that means that I have fireformed in at least 0.015" of excess headspace, which eliminates one of the biggest benefits of the K shoulder.

How can I fireform factory ammunition without locking in this excessheadspace? My initial thought was to handcraft a 0.010" steel washer, or a thin rubber "O" ring, to sit on top of the rim which would force the brass to fireform with a low headspace geometry. Has anyone ever tried this strategy?

Thank you.

George

[JSH]

Neck it up and back down to form a false shoulder.
Use a cast bullet and jam it.
And, headspace may or may not be correct.

I have seen a couple of AI rifles chambered that the barrel was not set back on properly, both by the same "black smith".

[rollinghills]

JSH :

Thanks for the reply. I would like to use the factory loaded ammunition as is if I can. Any more thoughts?

[Bill K]

Originally Posted by rollinghills

JSH :

Thanks for the reply. I would like to use the factory loaded ammunition as is if I can. Any more thoughts?

Since you are wanting to fire form the factory case ( Hope you don't have hundreds of them, but) I would pull the factory bullet out enough to allow the bullet to hit the lands and hold the case against the bolt face. Then you should be able to fire form it without the issue of the loose case/headspace. Bill K

[JohnHenry]

I would suggest lightly lubricating the factory cases before fire forming.

[Bayou City Boy]

JohnHenry offers some good advice.

If you need to set head space for your rifles camber, the only good way to do it is with a false shoulder on the case to positively hold the case in place. Seating bullets longer is inconsistent at best as the primer strike tends to drive the case forward. Sometimes no two come out exactly alike as you really have no verifiable control on each individual case by seating bullets longer.

Get a good false shoulder on the cases and you should be OK for YOUR use. However, you might want to get the head space checked in your rifle to know if the chamber is AOK in case you ever try to sell the rifle.

JMO - BCB

[Daryl]

Originally Posted by Bayou City Boy

JohnHenry offers some good advice.

If you need to set head space for your rifles camber, the only good way to do it is with a false shoulder on the case to positively hold the case in place. Seating bullets longer is inconsistent at best as the primer strike tends to drive the case forward. Sometimes no two come out exactly alike as you really have no verifiable control on each individual case by seating bullets longer.

Get a good false shoulder on the cases and you should be OK for YOUR use. However, you might want to get the head space checked in your rifle to know if the chamber is AOK in case you ever try to sell the rifle.

JMO - BCB

Exactly! Lubing the cases, seating bullets out, is not a good way. As the primers are backing out excessively with a case that is supposed to headspace on the rim, the headspace of the rifle is very bad. Necking up and necking down again is the best method IF you don't want to ruin most, or all all your brass.
the Hornet case is the weakest commercial case on the market and will not take much stretch in the web before failing.

[rollinghills]

Thanks for all the feedback. It sounds like I will have to bite the bullet, so to speak, and pull the factory loads apart to make an artificial shoulder.

[rick w.]

The 22Khornet is a wildcat........which to me means, you are on your own. No SAAMI specs etc.

If one delves to the SAAMI spec for the original 22 hornet, I suspect you will see rim depths(headspace) of min/max of 0.065"/0.072". Brass rims will always be under the minimum, some a lot under. The SAAMI rim allows the case to be fired safely most times, but no accord for the reloader to reuse said brass necessarily or repeatedly.

So over the years I have discarded trying to headspace hornet whatevers with just the rim. Too many makers and rim thicknesses out there it seems, just my opinion.

The wildcat shoulder is there for a good reason, can handle headspace if fireformed correctly. For years, maybe generations we just loaded factory hornet up and blasted. You will get away with it for a while, but will surely have issues with separations sooner or later; unless maybe you are blessed with an abbynormal short chamber.

The idea of the bullet jammed, lubed etc etc is not my cup of tea, just again my opinion. I like the mechanical false shoulder induced by a mechanical expansion of the factory hornet case on its shoulder position. A long, smooth.........slick....polished....tapered expander is worth the money, kinda like fooling with a 44-40..........thin walled brass. Easy to crush. The false shoulder will hold the case in the chamber during fireforming regardless of the rim thickness........ie hopefully the rim thickness becomes a don't care.

You might measure the rim thickness of the brass you fired just for curiosity to see how thin relatively speaking to say 0.065". The ten you mentioned came from somewhere. I am not much of a washer fan.

Wildcat chambers are wildcat chambers..........rim depths do vary because of the depth of cut of the reaming to wildcat.

The BRNO is a fine rifle, I am a bit envious............enjoy it, it will serve you well many years after you get over the Black Knight woes...... .........and you certainly will.

[JSH]

Thinking, if the primer is backing out, sounds like there is a bit to much room. Headspace on the shoulder or not.