22 Hornet to 17 Hornet

[inKYfromSD]

I've been using 10.0 grains of 1680 to form. Funny thing it's damn accurate with 20 gn V-Maxs. .4 - .6 groups at 100 yds. This CZ can really shoot.

[Mark527vARMINT]

Funny that is i form mine with about the same amount of powder.

[drewh]

2 extra tips that I am pretty sure I picked up from MontDoug and GLWentzl from some thread or another on this site:
Using expander mandrels to go up to 25 cal before necking down gives a nearly fully formed case before fireforming, and chamfering every step saves on the belling of the case mouth. Thanks guys.
Drew
On right, using expander mandrels, on the left formed "normally"

[56S]

Which made me think since the Hornady brass is commonly available the need to roll your own wasn't required anymore. I thought I've while away the the winter months reloading and decided to try the PRVI 22 Hornet brass for my 527A. One member over at RFC had good results one pass resizing with a Lee FL dies so I ordered one as well as 100 PRVI brass from Midway. LSS, I didn't need the Lee die since after experimenting I found my RCBS neck die and the Hornady FL die will both give good results on one pass of the 22 H brass. Trimming to the recommended 1.355" then annealing before another pass in the FL dies and off to primer and powder. Since I had oddles of 4227, 9.3grs was used as a fireform load. Initial results in accuracy were good with all 10 shots at 50yds gave a sub 1/2" group even though I had a 60% shoulder spilt ratio. Not good. More time under the heat reduced that to only two of ten shoulder splits with all the splits occurring at the shoulder to sidewall junction.

What I did find when measuring the cases was even though there was no visible bulging like seen on the Hornady factory loads, the generally smaller in diameter 22 H brass expands out to right around .3" fitting the sloppy 527 quite well. On the opposite end of the brass the neck tension is not near what I'd think should be but if precision in group size at the target is the metric, who cares. Since I had been crimping my loads all this time I think I've wasted my time.

My second firing of the PRVI brass was 10.0gr 4227, CCI 400, Dogtown 20gr HP and five shots gave me one small oblong hole at 50yds. Yesterday was cold and very windy here so no actual measurement and the 50 that 50yd groups are only for initial testing for function before moving out to the 100yd bench. Maybe today I'll get some actual 100yd group size.

[56S]

Very windy today but that shouldn't account for the less than stellar groups at 100 yards. Eight shots in slightly less than 1" Mostly horizontal stringing. So far using the Hornady brass 1680 and 4198 show the best consistency. I'll try those next and am on the hunt for some CFE BLK.

[Tilleyman]

Case trim length to 1.355" MAXIMUM is vitally important for initial fireforming so the danger of excessive length and subsequent pressure spikes are reduced.

SAAMI 17 Hornet nominal chamber length is 1.3565" +0.015"/-0.000" meaning a maximum chamber length of 1.3715"
SAAMI 17 Hornet nominal case length is 1.3500" +0.00"/-0.020" meaning a minimum case length of 1.3300"

Reforming from 22 Hornet and trimming to 1.355" for fireforming is 0.005" over SAAMI maximum case length but still 0.0015" under nominal SAAMI chamber length and 0.0165" under SAAMI maximum chamber length.

After fireforming trim length should be between 1.3300" and 1.3500"

https://saami.org/technical-informat...mber-drawings/

[JDHasty]

That is a good thing to highlight. That is the exact length I use, but I tell anyone looking for advice from me to check a half dozen cases by chambering them in their rifle to make double sure that it is not too long for their rifle.