8x58mmRD loads

[GunsNotPuns]

Last year I picked up an 1870 Husqvarna Rolling Block and finally got some CH4D dies for reloading last month. Problem? I'm having a bit of a time trying to figure out loads for this rifle.

It seems a lot of people use 30-40 Krag data as a starting point for 8x58mmRD loads but few of my manuals and online sources agree with each other about min/max loads. I have one manual whose minimum load is past another's max load!

So I come to you with the hopes that someone has figured this out already. I'm currently using 220 grain 8mm bullets in repurposed 8x56mm Mannlicher–Schönauer brass (much cheaper than the 8x58mmRD brass that Bertram sells). I'll be testing new loads ranging from 39.5 to 43.5 grains of H4831SC to see how that performs but if someone has a better suggestion(s) I am all ears.

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[bob q]

Have you slugged your barrel . That rifle with a 1st style barrel should have a groove of about .328 . If you give your land and groove size I can help you with some loads . I one won a military rifle match with back to back sub 1.2 inch 5-shot 100 yards groups with a 8x58r . 4831 is too slow a powder for a light load , more so if you are shooting .323 dia bullets in a .328 bore .

[GunsNotPuns]

I'll be honest with you, I haven't had a chance to slug the barrel. I've had limited opportunity to shoot the rifle and only got dies for it last month -- I've other project rifles on the go that I've actually been able to make progress on

That said, in talking to the lads at the local LGS at least one of them mentioned that bore size could be an issue and noted that he was casting slightly larger than .323 bullets for his Rolling Block.

What powder would you recommend over H4831 assuming the use of .323 bullets? On the shelf beside me I also have H322, H335, H4198, Varget and BL-C(2) available but I don't mind buying other powder if necessary.

[bob q]

When forced to use the wrong size components it can get tough to get one to shoot well . Also what velocity are you looking for ? Anything that will work well with small bullets will tend to be lower , 100 -200 yard target type load . With a .323 jacketed bullet I would use a flat base bullet with the most bearing surface and a lighter load of fast powder . With a groove size 209 grain bullet I used 27.5 of I-4198 for 1640 fps . with a smaller bullet you will need more . Bob Shell wrote a great article on reloading for a 8mm RB , it shows how to destroy the rifle with massive overloads and not even know why it happened . Do not use his loads !

[GunsNotPuns]

I'm looking for a velocity of about 2000-2100 fps which is similar to the Krag load -- I'm worried it's too much but I have no data whatsoever for the 8x58mm so I'm figuratively shooting in the dark right now trying to figure out where I should be going with this. Judging by what you shot very well with, it would appear that perhaps I'm too hot with my load, though at 1600 fps I saw keyholing on a few rounds.

Back to the drawing board!

[bob q]

What bullet are you using ? Also your bore size would be very helpful .

[GunsNotPuns]

At the moment I'm using Sierra's 220 grain 8mm bullets (.323 in size). Not my ideal choice as I would have preferred something with the wider base that you brought up earlier but after talking to a few lads down at the LGS they recommended I move up from the Hornady 195 grain bullets. There doesn't seem to be much choice in heavier 8mm bullets unless I start casting and my setup here doesn't lend itself to that at the moment.

I haven't had a chance to slug the bore yet so I don't have an exact bore size.

[bob q]

That bullet is a boat tail and will not shoot well in an oversized bore. That will be the main cause of your keyholes. I was using a .328 dia flat base bullet with the load I posted. The Hornady 195 sp is a flat base and should do better than the boat tail . But if your barrel's groove dia is close to .328 , none of the modern US .323 bullets are going to do that well . The original bullet was made as a long , cupped or hollow base for a reason , to let the bullet ride the lands and keep straight . Speer used to make a .323 220 -225 grain round nose with a cupped base , that bullet does work well in most of the big bore [ .327 - .334 ] 8mm's .