Hi guys, ouch, I have never experienced longitudinal cracks in my K Hornet brass, but do experience radial cracking around the web after several reloads. Not complaining as Hornet brass is very thin, and reading the contents of various forum postings, I do seem to achieve better case life than most.
For FF, strip even factory loading's, prep, anneal, reload. I generally load 8/9.5grn ADI2205, or have used 5grn AS50N (ADI shotgun powder), toilet paper wadded tight into neck over powder, or alternate, plastic disk over powder and filled neck to convex meniscus with melted candle wax, or, insert 0.22 Air Rifle pellet (18 to 22 grn) into neck, level with mouth, and then sealed with candle wax. Have lost no brass since using these techniques.
Howdy guys.
have a Sako M78 rifle in K Hornet. Most of the forum/s discussion is re standard Hornet, the K can hold 1/1.5 grn more powder. There is much discussion re "inaccuracy" (and case life) of the Hornet family. I have some observations, findings which may improve the accuracy of your rifle/s. The Sako M78 is factory (approx 50 years old), based on rimfire action, no front lock up, only fraction mm engagement bolt into chamber/receiver. View the ADI powder website, Australian powder maker, (producer H, IMR and others) you will see two targets of mine shot with the rifle at 100m posted on the ADI site. Four shot clover leafs, one 0.19 MOA, the other 0.2 MOA. these are centre to centre measurement, one raggedy hole (two raggedy holes).
The following may not work in you firearm, however after many, many hundreds of rounds with varying changes, these are the results. I seem to have found a load that is a cracker in my rifle. Not interested in speed, way more interested in accuracy, no accuracy without control!
Moved from Winchester brass to Sellier & Bellot, (fireform from standard Hornet to K). The 1.5mm flash hole seems to be a key, same loading with Win. to S&B, groups "much" improved (Win case 51 grn, 2mm FH, SB 55 grn, 1.5mm FH), slight change in internal capacity, therefore pressure, may have some bearing too. Remember, smaller increases/decreases in small capacity cases with powder charge mass/volume will have greater effect than with larger cases, ie +/- 0.5 grn in ll grn load is far greater change than +/- 0.5 grn in 33 grn.
Annealing cases for K forming or standard, to set headspace also seems to be beneficial. Appears to minimise/eliminate neck cracking. And that bulge/misshapen area that may appear at the web, leading to improved case reloading life. Fully prepped cases (do not have facility/tooling to neck turn/uniform etc.), annealed, trimmed length, flash hole de burr and chamfer etc.
Small pistol primers also appear to be a trick, have used many SRP's; Win., CCI, Fed etc., various SRP Magnum, way best accuracy achieved with S&B SP Primers.
Have tried many projectiles, 35/40 grn and heavier (have a target from mid/late 80's, field shot @ measured 87 metres, 53grn Hornady Match over ADI2205, 5 bullets one raggedy clover leaf, Win brass); Hornady, Berger, Sierra, Nosler etc. Far and away the best in my Sako, for general use, Hornady 40grn Z/V Max (view ADI website for target images).
Seating the projectiles 'long', I am something more than 2mm over magazine length, about 0.005" short of lands. My length, ogive to base with 40 grn Z/V is 39.85mm (approx. 49.6mm OAL, max. mag. 47.4mm). Neck size only; 2.5/3mm down from case mouth only.
Using ADI 2205 (check charts for equivalents, H, IMR) 11.5 grn. (This load may not suit your firearm/s, start 10% or more below and work up, looking for signs of over pressure etc.). I have tried many powders, Lil gun (inaccurate and dirty), W296 (humm), ADI 2207 (good), other rifle and shotgun powders, however ADI2205 has proven its worth. Hornady 40 grn Z/V Max (OH! Hornady bring back the Z Max, price point sensational). S&B Small pistol primer. S&B 22 Hornet case, fully prepped and FF, and leave the small flash hole alone! other than clean up.
I am achieving several reloads per case with the technique, Hornet brass is very thin, as we know. Annealing appears to be a benefit, (strip, anneal, prep, reload new factory load ammunition too), (only anneal if you know the correct procedure). Neck sizing only the first couple or three mm of the neck seems to help too.
The die set I use is near 50 years old, made by Simplex in Australia, Super Simplex (still made) 2 die set only, no special "inline" seater etc.
