I have a Sako A111 action rifle barreled in 8mm/.338 and have been working with it, and have encountered some amazing velocities, with no signs of pressure, (ie) 3800+ fps. with 125 gr. I would like to talk with others who use this cartridge. David Wood
Does this cart head space on the shoulder, How is your accuracy, sounds like a shooter What powders are you using IMR/RE/Hodgdon? I like wild cats, a lot of fun working up loads know one else has, feel like the mad scientist LOL. Take care and good luck with your wildcat. Aim small hit small. RAMbo.
David, that sounds pretty hot! The .300 Win Mag (essentially the same case capacity if not a bit more) shows 125-130gr. bullets in the neighborhood of 3400fps, 3500fps tops. Although the 125gr 8mm bullets should be slightly shorter, resulting in more powder space/less friction, that's still quite a gain.
I'd suggest running the numbers through Quickload or something similar, just for a sanity check.
I didn`t mention it has a 28 in. barrel, that being said, my aged mentor friend helped me keep in the safety zone, all loads were worked up from extemely low levels, and with the use of printed data in the #9 Speer book page 299 and an old #2 P. O. Ackley book page 200 my friend had, incedently the Ackley book told of the man who invented the cartridge, I called him up and he was 94 years old and designed the cartridge for use in surplus 8mm German mausers which were cheap then the original name was 8mm PMM ( Poor Man`s Magnum) He was thrilled someone had looked him up about it, though he could hardly hear, his wife had to shout everything to him, too much shooting I guess. Any way the case has considerably less capacity than my 300 Win. Mag. and I got my book so I can give you the max. loads I have, so far, I was mistaken on some of the previous velocities I gave before, please pardon. 125 gr.Hornady 75.0 WC852 (H380 speed) surplus Avg. 3736 - 150 gr. Sierra 74.0 WC852 (H380 speed) surplus Avg. 3506 - 175 gr. Sierra 80.0 H450 Avg. 3226 (I killed a deer with this one at bragging range) - 180 gr. Nosler Ballistic Tip (still working) 200 gr. Speer 78.0 H450 Avg. 3078 - 250 gr. Hawk 80.0 WC860 (H870 speed) Avg. 2510 fps. and yes I did get into some high pressures but recorded them and backed up. Thanks for your interest I bought the rifle from a friends estate he built it and never got to fire it, sad David
I don`t know the headspace on this rifle I didn`t barrel it, there seems to be much opinion on belted mag. headspace this is what I know and do on my rifles. Traditional headspace gauges are .220 in. from the cart. base to the front of the belt and that is where the headspace is, but I measured many different cases and found they measured in the .210-.212 range so I had a machinist friend make me one at .215 in. some brands of brass with heavy imprinting on the case makes the bolt firm to close so I touch the high spots on the lettering with a file, and they are fine. Now phase 2 when the case is fired the shoulder blows out to match the chamber then it headspaces on the shoulder as long as you only neck size the case. My best accuracy load for my 8mm/.338 is, 80.0 grs. H450 Sierra 175gr. Avg. Vel. 3226 Std. deviation 4 Fps. extrme spread 9 Fps. on an Oehler model 35 clear day 78 degrees. This cartridge is dead center between a 7mm Rem Mag. and .338 Win Mag. but has bullet weights that span both calibers, (versitility) I am suprised it never was a factory cartridge, I feel my 28 in. barrel contributes to such high velocities, some of my loads beat 8mm Rem. Mag which is a huge case. David
Well, looking at the load data, you are definitely 'full throttle' but uniformly a bit above .300 Win Mag data (for the same weights). Although your 250gr. loads look to be a bit lower than what the .300 Win will do with the same bullet weight.
It does help that you are using standard-type bullets, nothing fancy or extra tough, like the X or Failsafe.
Of course I don't have any idea of how smooth the barrel is or how deep the throat is cut.
With the longer barrel... I would say that makes me feel a little better about the velocities you have published, but I'd wager the pressures are at least at SAAMI max for the usual belted magnums.
Still, it's true that every rifle is an individual, so good luck, and stay safe.
Thanks for checking me out! I know now this site is looking out for others safety, that means it`s not a smoke blower zone. As I said before these are the loads I stopped at, considering them max. some loads have smaller deviations way back down my list. The 175 gr. Sierra with4 fps. deviation is my favorite load,and I haven`t worked too much with the 250`s a friend gave me the box of Hawk bullets and when I found out how much they cost, I decided to save them for that once in a lifetime hunt someday. Thanks again David Wood
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