I have original M98, Mauser Obendorf in Calibre 10.75 X 68mm. Barrel length 24 inches. As this is considered an obsolete caliber, I have had no option but to hand load ammo. Would you be able to provide a starting load for Hodgdon - Varget or H4350.

My results are given below:-
I have obtained Bertram cases and heads solids - 343 grains.

The heads are bore rider design, solid 70 �30 brass. The �driving bands� (large diameter- .422�) are groove diameter & the �grooves� (small diameter-.410�) is the bore diameter.

Powder available is Hodgdon - H4350 and Hodgdon � Varget.

I was able to load a few round with 59 grains of Hodgodon H4350.
Result � Velocity was 1367ft/sec, Mild recoil and primer was not flattened, however showed tendency to extrude out even at this low velocity.
Another observation was that all cases had residual unburned powder stuck to base of the case.

I carried out another test load of 4 rounds loaded with 59 grains of IMR 3031, bore rider solid head and Winchester Primer. (This data given in Barnes Cartridge�s of the World).
Result � Velocity varied from 1950 to 2007 ft/sec, recoil was heavy, primer was flattened and extruded out of the case.
I do not have access to any more IMR 3031.
In comparison I fired an old Kynoch round probably 60 years, Velocity was 1898ft/sec and the primer was not flattened and indicated normal pressure.

I require advice on :-

1) Why the primer tends to extrude out at a low velocity.
2) Why there remains unburned powder at base of case.
3) It appears that most European hand loader�s seem to be using a faster powder than H4350. As I have Varget which is faster, would it be a better a bet to try out loads?
If Varget is more suited, would you be able to provide a starting load??

Would appreciate advice on the above.

Thanks
Rhunu

[ 07-09-2003, 21:24: Message edited by: Rhunu ]

Sounds like you have excess headspace, allowing the primers to back out even at low pressure. You might open the neck up to at least .458" with a tapered expander and resize these expanded cases with the die backed out far enough to allow a crush fit in the chamber.

As to the unburned powder, with certain powders you will get this in a low pressure load (usually disappears when you get into the normal pressure range.

Once you have the headspace problem taken care of you should be able to start with 59.0 grains of Varget since it has a slightly slower burning rate than IMR 3031. Work up carefully from here, but be sure to look for any signs of excess pressure.

Jim

[ 06-26-2003, 22:18: Message edited by: mbogo375 ]

Rhunu , it's not the same result 59 grians of 3031 or 59 grains of 4350 , be carefull with fast powders and full loads as be carefull with slow powders and light loads , if you can get salvaged powder from GI 7.62 x 51 Nato , it's very similar to 3031 , the best ones the extruded , not the ball type , cases the best from Horneber in germnay , Bertram are to soft .
Saludos

Daniel

347 Grain Bullet

IMR-3031 From 54.0 grains to 59.0 grains
Winchester WLR Primer

I used to load the 10.75x68 quite a bit, but don't have my loads handy. Will try to look them up in my old notes from almost 30 years ago and send them to you by private e-mail.

In the meantime, let's discuss your primers backing out...there can be several causes:

1. You could have excess headspace in the rifle/ ammo combo, but that does not necessarily mean that your rifle has excess headspace. It is possible that in your normal sizing process, or even with the process of the Bertram factory, that the shoulder of the case is being set back too far.

Have you any factory ammo to fire in your rifle? Does the primer protrude from fired factory cases?

If not, it is almost certain the excess headspace, if any, is the result of your loading components/process. If it is the result of your process, try unscrewing your sizing die and just resizing part of the case neck. Then see if the sized case will enter your chamber. If not, keep screwing the sizing die into the press until the sized case will barely enter the chamber. Then, STOP, set the lock-ring on the die, and use that as you case sizing adjusted die setting.

2. The protruding primer may very well be due to too low pressure from lightly loaded cartridges...though your 59 grs. 3031 charge is not normally considered a light load.

When a cartridge is loaded to too low a pressure, sometimes a strong firing pin spring will force the case forward a bit, and there won't be enough pressure to initially shove it back against the bolt face. At that point, the primer backs out of the primer pocket.

If the load then builds enough pressure to blow the case back over the primer and up against the bolt face, the primer may be unduly flattened at the edges. If it blows the case only part way back over the primer and not quite up to the bolt face, the primer will still be protruding somewhat when you remove the case from the chamber. This is fairly common when working up loads where one has no data for that cartridge and rifle. One may start too low, in trying to really be safe. In that instance, a little higher pressure, often with a little faster burning powder, will eliminate that problem.

3. Your rifle may actually have excessive headspace for factory loads or good handloads. In that instance, if you need to use the iron sights mounted on the barrel, you are likely to have to have the barrel set back and rechambered. (Or, if the barrel has a long enough reinforce and you don't mind a single shot, you might be able to have the whole rig converted to .404 Jeffrey, but likely not.)

If you don't need the iron sights and are going to only use a low-powered scope, you can have the barrel shortened a few thousandths at the breech end and the barrel shoulder moved forward the same amount. That will cause the sights to not come up plumb at 12 0'clock, but if they are removable and you use a scope, it is the cheapest way to go.

Anyway, good luck.

I'd spend the money to get a couple of collector's cartridges first, fire them, and see what factory ammo looks like after firing.

It can tell you a lot. If it looks like excess rifle headspace, then I'd get a knowledgeable person to make a chamber cast for me, or do it myself. Measurements from that could tell you everything you need to know.

Good luck,

AC

[ 06-27-2003, 04:33: Message edited by: Alberta Canuck ]

You can begin with 60 grains of Varget and work your loads up, increasing 1 grain at the time. Try neck sizing only.

Pantanal

The German RWS-manual says best Rottweill powder is R902 or R903. IMR 3031 is in that class as well as H322 an H335. Therefor H4350 should be (far) too slow-burning and even Varget is on the slow side.
According to the RWS-manual the original factory ammo was loaded with a 347 grains round nose bullet at a Vo of 2250 fps.
Hope this is of some help.

Dutchgus
i have a email buddy that lives in the Netherlands the same as you.He isn't a gun man and told me there are no gunshops in your whole county,is this true????
Ben is a tennis player and has no interest in guns, so maybe he is wrong.Let us hope and pray he is for your sake!
just curious
muskrat
live free or die!

Muskrat,
Of course there are gunshops in Holland, if not, where were we to get our equipment? There are some 30.000 hunters and probably the same numbres of sport-shooters in Holland.
As I live close to the border, I also do a lot of my shopping in Belgium.

DutchGus
i will make sure my tennis playing friend knows about this then! when i asked him if he ever looked at any guns in the sporting goods store, he said they didn't sell guns in the Netherlands!
Not having been there i had no way of knowing?
Now i will have to make sure Ben knows this!He lives in this town, hertogenboosch,do you know it?
muskrat
live free or die!

Muskrat,
Tell your friend to stand in front of the cathedral in 's-Hertogenbosch and then cross the street. He will be in the gunshop 5 seconds later!

Alberta canuck is right on with his explanation!! When a bottleneck cartridge is fired at very low pressures, the force of the primer can actually drive the case "off the face" of the bolt, setting the shoulder back, and permitting the primer to protrude from the case head. That is one reason why people are cautioned to never use cases that have been fired with low-velocity (usually cast-bullet)loads for full-charge ammo afterward! That is probably what you are seeing with these protruding primers - the load you used generated too little pressure!! It does NOT mean that there's anything wrong with your RIFLE'S headspace, but those particular cases NOW HAVE EXCESSIVE HEADSPACE, due to the action of the primer!!

[ 07-06-2003, 19:03: Message edited by: eldeguello ]

347grs Woodleigh SN
66grs Rottweil R902
RWS cases
Vo: 2250ft/s at 24" barrel

My best group was under 0,75" at 100m.

Well gentleman, thanks much for your advice.We have had heavy rain in the last week and I have been out of action with an attack of flu!! I await better days to try out loads and revert back. Many thanks to all of you!