I don't have a lot of hand loading experience so I was suprized to discover my fired 22 Hornet brass now measures shorter than the trim to lenght I started with.

The rifle is a brand new Ruger K77/22-VHZ 22 Hornet.
Fired for the first time using my handloads.
New Winchester brass.
CCI 500 small pistol primers.
Hogdon's Lil'Gun powder (vaious charge weights up to 13 grains).
45 grain Sierra Hornet bullet.

The new brass was full length sized in a LEE Hornet die set.
Trimmed to 1.393" in my Wilson trimmer.

After firing I measured the cases and found the length has shunk smaller than the trim to length of 1.393" on about 20 of the 50 fired cases.
The other 30 cases stayed at the trim to length (another suprize), and a few grew about 6 thou (0.006) which is what I expected to happen to all of the cases.

I was suprized that all the cases didn't grow longer after firing as that has been my experience loading for my 375H&H the only other rifle I have.

I thought firing the cartridges fire forms the brass to chamber diemensions plus a little neck growth.

I have re-sized this brass using a Lee neck sizing die plus a 5/16" (0.056" thick)washer used as a spacer between the die and the shell holder.
I did the washer trick because I wanted to leave a small section of the case neck at the post fired size to help center the cartridge in the bore for the next firing.
The neck sizing didn't change the case lenght much, the short ones are still short.

I was thinking maybe I should partial full lenght size the cases.
If my die squashes the area at the pressure ring a little but not so far as to press on the shoulder I might gain some case lenght.
My goal here was to have beautyfull fire formed cases that just needed a little neck trim.

The body of the brass expands outward in the area behind the shoulder. This pulls the neck/shoulder back. When you FLRS the brass grows longer again. My 223 does this. The difference in the body is .005" larger after firing, when compared to a flrs case. Tighter chamber or a maximum loading may give different results because there is enough pressure to do both, expand out & forward.

sounds like you need Br-iagra(tm) in your polishing media!

quote:

Originally posted by jeffeosso:
sounds like you need Br-iagra(tm) in your polishing media!

Can't add that chemical, it would cause a dangerous interaction with the Roganium(TM) I already have in the polishing media.

Roganium(TM) is added to increase the hairyness of the chamber pressures normally associated with burning small quanties of Lil'Gun in a Hornet chamber.

The primer drives the case forward sometimes moving the shoulder back a scosh. With na light load the case stays foreard. With a hevier load
the case will break loose and come back stretching the case by theamount of the headspace. If you want cases the same length load harder, or oil the case with light loads.
Good luck!

hawkins,
does that apply in a rimmed case?

what?

I see two major issues

1. New brass is often not very uniform, particularly bulk Rem & Win brass. Full length sizing before the first load was the right thing to do. Did you take measurements after sizing the new brass?

2. The 22 Hornet is a real low pressure round with SAAMI spec of just 25000 cup http://www.lasc.us/SAAMIMaxPressure.htm. This low pressure certainly minimizes the lengthening of brass when firing. As already mentioned by others, the primary force is to expand the brass out & this pulls the neck back.

What primers do you use for the 22 Hornet? I have read that Pistol primers make a big difference in some rifles.

Good luck.

Does that apply to a rimed case?.
I have only played around witha fe of these
but it should apply. Most of the older rim
cases operate at pressures below those required to break yhe case loose. That was how Akley was able to fire a 94 Winchester without a locking bolt. It had nothing to do with the Improved
case .
Good Luck!

A brass case is somewhat like a balloon when inflated. A gain in diameter to fit the chamber diamter tend to shorten the length.

quote:

Originally posted by greenjoy:
I thought firing the cartridges fire forms the brass to chamber diemensions plus a little neck growth.

Your fired case will form to match the chamber (and then retract a bit, allowing you to extract it). Because the case expands, it will measure shorter when fired.

Only when you resize will you see case lengthening - due to the forced contraction of the brass (die), the material only has one way to move (largely) and that is forward...

- mike

quote:

Originally posted by hawkins:
The primer drives the case forward sometimes moving the shoulder back a scosh. With na light load the case stays foreard. With a hevier load
the case will break loose and come back stretching the case by theamount of the headspace. If you want cases the same length load harder, or oil the case with light loads.
Good luck!

The firing pin is said to drive the loaded round forward. A high pressure bottle neck type rounds neck/shoulder/front of the case will grab the chamber in the neck/shoulder area on firing. If there is excess headspace, the case body will stretch back till the head hits the bolt face. Rimmed head spaces on the rim. Rimmed brass blows forward for the most part, except for its excess headspacing between the rim and bold face. But on bottle necks the extractor MAY hold the brass that it does not get driven forward by the firing pin??? What if the bullet is jammed into the lands??? Something to think about.

I think the low chamber pressure that poster Nakihunter mentioned above is the source of the odd case expansion I am experiencing.

Because I have neck sized these fired cases I think on the next firing that the cases will expand in length as they are now already expanded width wise.

My new rifle shot my hand loads well.
The Winchester factory loads did not group as tightly as my hand loads.
I did notice that my groups tightened as the powder charge in the hand loads went up, best group was at 13 grs. of Lil'Gun the highest charge weight I tested so far.

I have high hopes for my next target session.
My second batch of hand loads will be launching their 45 gr Sierra's from fire formed (mostly) cases that have been neck sized only. With slightly increase powder charge weights and I now have the bullets seated to 15 thou. off the lands instead of the 35 thou. that the load recipe gave me.

Neck Sizing Only- At some point, you will have to FLRS. At least this is my experence loading with the Lee Hammer loader many years ago.