Silly WWII 8MM question

G

Gunplummer

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Many years ago I came across a new surplus MG-34 barrel in some auction stuff I bought. I turned it down and stuck it on a receiver. To my dismay it shot like crap. I tried different loads and I had some 190 Gr bullets laying around and all of a sudden it shot way better. I bought some 250 Gr bullets and it shot great. Did the machine gun loads use heavier bullets and have a different twist rate in the barrels? I never bothered to check the twist rate once it was shooting well.
 
I have a book by Smith and Smith on military rifles from different countries. The book covers details about scuttle differences between rifles. You could have the book in your library.

F. Guffey
 
Well, you're up to something, so the 190 gr is close to the original. The 8mm Mauser IS (used in WWI) used the 150 gr S bullet. Then there was the 198 gr sS (schweres Spitzgeschoss) introduced in 1934 with the MG 34 which was used throughout WWII.
 
The 1934 iteration of the cartridge adopted a 195 or so grain bullet. The nomenclature translates to "heavy pointed ball."

Your MG 34 barrel would have been adapted to this cartridge.

What gets me, though, is that a longer, heavier bullet requires a faster rifling twist to stabilize than a shorter, lighter one.

Generally a shorter, lighter bullet will show OK accuracy in a barrel optimized for a longer, heavier bullet. The the difference between the two bullets really isn't that much.

Interesting that in your case the barrel didn't like the 150s.
 
Mike,

I wonder if the barrel was shot out and threads are pretty worn; the light fast bullet might skip the threads. The heavier slower bullets have more engagement surface and might follow true.

Jan
 
The threads?

You mean the threads on the barrel shank where it's screwed into the receiver?

Or do you mean the rifling?

If it's worn enough that it's not going to shoot well with a 150-gr. bullet, I simply don't see how 40 extra grains of weight and, IIRC, about 7mm extra length would make it shoot that much better.

Granted, we don't have a value figure for what constitutes "crap" and "much better," but if someone were telling me about that and then showed me a target, I'd expect the crap groups to be several inches larger than the much better groups.

But, that's my perception. Reality may be different.
 
We know that rifle barrels will shoot some bullets better than they shoot others, and even with the "proper" twist, some barrels will do things that you wouldn't expect, sometimes.

The standard German 8mm round used the 196gr spritzer, so that would be the what the barrel was made to shoot.

here are some possible reasons for the results you got..

#1) You started with a machine gun barrel. Generally speaking, machine gun barrels, even new, are not noted for having (or needing) the same accuracy as rifle barrels. In fact, rifle accuracy in a machine gun is considered by the military to be a detriment. They want a "cone of fire", not a small group. The way this is usually done is "sloppy" specs in the gun although not always. The US M2 .50 cal Browning went the other way, building the "dispersal" into the ammo specs.

#2), you "turned it down, and stuck it on an action". This could very well have an impact on how the barrel shoots, and with what. Somehow, I don't think the barrel harmonics now are anywhere near what they would be in an MG 34.

So, to answer your questions, the MG ammo was heavier (than 150gr) ALL their standard ball was heavier than 150gr. As to twist rate, I would think it would be the same as the standard rifle, BUT, the book I need to check that has gone walkabout, so right now, I can't say. When I find it, I'll let you know..
 
It was a new barrel, and I really do not remember, but think it was chrome lined. "Shoots like crap" is six to eight inch groups at 100 yards. I still have a 6.5 Arisaka that I re-cut to 6.5x55. With 120-140 grain bullets and untold amounts of different loads it KEYHOLED at 50 yards. With 160 grain bullets it is a tack driver @ 100 yards. I later learned the very early 6.5's had a different twist rate and very heavy bullets loaded for it. Just thought it may have been the same thing with the 8MM. I attached the only photo I had of the 8MM rifle. You can see by comparing the barrel to the scope that there was still plenty of meat on the barrel
 
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Yeah, 6-8 inches @100 is crap for a rifle (too big) and I think its also crap for a machine gun (too small). I'll need some time to find the right specs to be sure, but I think so..

160gr for the Swede is the original military bullet weight. I've seen a number of Swedes that would do ok, or sometimes rather well with the 140gr, or even the 120, but some just don't. I have never seen one that wouldn't do at least fair (better than crap) with the 160gr, and some are exceptionally accurate.

I've got a 1917 "long rifle" Swede, and with a midrange handload of IMR 4320 and the Speer 140gr SP, nailing the 400yd gong on the range is so easy as to be boring (and with the sights on their lowest setting!).

I'll do some checking on the MG data and get back when I have the info.
 
I think the 8x57 twist rate is 240mm (9.4") from the 1888 with 236 gr RN to the S 150 gr spitzer to the sS 196 boattail.
Kind of like the US 10" twist which worked for the 220 gr Krag and '03 to the '06 150 gr spitzer to the 173 gr M1 and long steel cored M2 AP.

Anything less than benchrest, stable is stable and rifling twist rate gets blame or credit for a lot of things it does not deserve; bullet design and quality, chamber throating, barrel harmonics, and the otherwise imperceptible differences that make a given barrel "like" one load and the next one off the production line do miserably with it.
 
My sources indicate the same twist rate was used in the MG34 and the 98k rifle. And in all the other 8mms they used. 1 in 9.25" or 9.49" depending on the source.

So, apparently, there was no special twist rate, or heavy bullet for the machineguns.
 
"So, apparently, there was no special twist rate, or heavy bullet for the machineguns."

No, there was no heavy bullet for the machine guns because the standard German 8mm round already used the heavy bullet, which had been adopted over the previous 150-gr. spitzer boattail design.

There are numerous discussions on the web that talk about the 190-gr. bullets shooting better than the 150s.
 
I've got a 1917 "long rifle" Swede, and with a midrange handload of IMR 4320 and the Speer 140gr SP, nailing the 400yd gong on the range is so easy as to be boring
Click to expand...


I have had the same experience with my 1917 Swede. 140gr Privi Partisan is eerily accurate at longer ranges. I got called a liar on another forum when I mentioned how easy it was to hit a gong at 400 yards offhand with that rifle. It is a little easier to shoot for me as it is a former FSR rifle with Swedish diopter sights.

My pre-64 M70 Winchester featherweight shoots 165gr bullets into a 1 1/2" group all day, 150gr bullets open up to twice that. I believe it is the length of the bullet vs the rate of twist that determines what combination shoots best.
 
Why one load shoots tighter than another bullet is always an interesting discussion...

In a mathematically perfect situation, shot dispersion would solely be due to environmental factors between the muzzle and the target. In reality, inconsistencies in powder charge, primer amount, brass capacity, bullet consistency, and barrel harmonics show that we are never dealing with a mathematically perfect reality.

Suffice to say, I've never gotten anything lighter than the 185gr Rem Corelokt bullets to shoot "tight" in any of my 8x57s. I haven't tried everything out there, but it seems to me that heavier is better in old Mausers.

Jimro
 
Years ago a friend of mine tried Hornady (I think) 125-gr. HPs in the bring back K98k that his Grandfather gave him.

It shot fine with surplus Israeli or East German milspec, both of which were 190 or so grain loads, but we were hard pressed to get the the 125-gr. load on a 3 foot by 3 foot target stand at 50 yards, and the ones that did occasionally hit showed every indication of starting to key hole.

At 100 yards we never did get a bullet on that target stand; we just kicked up dirt all around it.
 
Twist rate, ballistic coefficient, and that often overlooked factor, bearing surface. All have to be right.

An interesting piece of useless knowledge: Some years ago, Norma put out 6.5 x 55 ammo in boxes with stickers marked "Match Grade". It was OK, but nothing special. Then I found out that the only ammo in that caliber that did not have "Match Grade" stickers was their match grade. It shot some of the tightest groups I have ever seen from factory ammo. Go figure.

Jim
 
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