Re chambering by hand
- Thread starter DGY
- Start date
So I measure to case capacity difference between my 8x57 and the new 8mm-06, there is a 7.7gn of H2O difference, 12.45% increase in case capacity that give me just over 200fps more velocity on paper…. That means the 2550fps that I get pushing a 200 bullets out of my 8x57 should bring that same 200gn bullet to about 2775fps on paper anyway!! Will be interesting to see final results!
I went to the range today with 5 rounds(found out I went a bit light on the powder charge 53gn of IMR4350) anyway the gun shoots well and the chamber is almost perfect, need a little polishing but the brass came out quit nice already!
I will try and other load of five tomorrow!
I will try and other load of five tomorrow!
That 12.5% increase in capacity should give you a 3.25% increase in velocity, at the same pressure. This is fairly realistic. The 8x57 will push 200's to about 2650 and the 8mm/06 will manage close to 2750, again, at the same pressure. However, the 8x57 runs out of room, if using 4350, for instance, and the extra capacity allows the use of 4350 effectively. The use of the slower powder allows you to maintain peak pressure over a longer time, which boosts velocity. This means, with appropriate powders, the 8mm-06 will see an increase which is greater than it would otherwise produce.
I went back to the 8mm-06 loads I had for one of my custom rifles.
I started at 57.0 grains of H4350/196 grain bullets which gave appx 2675fps out of my barrel, a NOS K98
When I went over 58.0 grains I started getting cratered primers. I tried a few at 60 grains and started getting shiny rub marks on the face of the cartridge.
I also tried N160/H4831sc/Win 760 and H450.
I achieved the highest velocities with the Win 760, at just over 2700fps but it also gave the poorest accuracy, and the velocity deviations were the highest between shots, even with magnum primers.
H450 which is close to W780 didn't give any better velocities than 2600fps, so to slow.
Your choice of H4350 is a very good one. W760 might give better velocities and better accuracy in your rifle than mine showed.
I'm glad it all came about to your liking, after all is said and done, it's all about learning and having fun doing it.
I started at 57.0 grains of H4350/196 grain bullets which gave appx 2675fps out of my barrel, a NOS K98
When I went over 58.0 grains I started getting cratered primers. I tried a few at 60 grains and started getting shiny rub marks on the face of the cartridge.
I also tried N160/H4831sc/Win 760 and H450.
I achieved the highest velocities with the Win 760, at just over 2700fps but it also gave the poorest accuracy, and the velocity deviations were the highest between shots, even with magnum primers.
H450 which is close to W780 didn't give any better velocities than 2600fps, so to slow.
Your choice of H4350 is a very good one. W760 might give better velocities and better accuracy in your rifle than mine showed.
I'm glad it all came about to your liking, after all is said and done, it's all about learning and having fun doing it.
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Wildcats based on the 30-06 case have always been greatly underestimated IMHO.
The biggest issue is getting good-quality hunting bullets for the 8mm these days. Not so much in the past.
It was a definite toss up for me to stick with the 8x57 or 8mm-06 or its cousin, the Swede 8x63.
That's another cartridge for you to look at, to compare loads. The Swede 8x63. They used it in their GPMGs and had a few thousand bolt action K98s converted, which were mostly sold as surplus to Israel, where they were re-barreled to the 8x57 again. They had to fit a muzzle brake to the converted rifles because of the recoil with the 200+grain SBT cartridges that were interchangeable with the GPMG. Very stout loads, that were safe in 98 type actions. They used a Bofors powder #44 which was very close to IMR3031.
I eventually went with the 338-06 cartridge, simply because good bullets and similar velocities and energy were easily available.
I love the 8x57 and there are very few if any flies on the 8mm-06, right out to 300+ yards on Moose or Elk. I managed to get one Moose with my 8mm-06 before being talked out of it "right after" the hunt.
I've always intended to build another, but never could find a ''round to it"
I would like to take one more Moose and one more Elk before I get too old and decrepit to be beating around the woods, usually by myself, with my JR.
If I can manage to put a hunt together this fall, I will use my Ruger No1 chambered for the 338-06 with 225 grain bullets at 2600+fps. I will take along the vintage 8x57 sporter with the 50s dated Bishop stock or AA Walnut as a spare or depending on the conditions, maybe the primary rifle. I like them both.
Other favorites on the 30-06 case are 280Rem, 270Win, 6.5-06, and 9.3-06.
Have fun with your new build, that's what it's all about.
Thanks again, I love my 8x57, a Danzig built mauser 98 beautifully sporterized, I got it from my dad a few years back, a rifle he bought when he was 16 and now he is 82! The rifle shoot moa or better with my load and I did get my moose with it last fall! The rifle is 7.5lbs with scope on! A pleasure to carry!
An 8mm/06 just burns more powder to get only slightly higher velocities.
I have an 8mm/06 Ackley improved reamer. The increase in velocity is not worth the effort.
