8x58RD loading with NOE 8mm mold......need some advice.

[Smokepole50]

I went out Saturday and shot my first cast boolits with Ben's Red in my 8x58RD rifle. My first impression of this NOE 8mm boolit is a good one. I was only shooting 25 yards, so as not to kill my new Chrony, the last one died from a cast boolit. The groups were basically a ragged hole so I have hopes it will be a good boolit for this rifle sized at .326, CG and weighing 224gr.

So, the powders I used were 2400 19gr thru 21gr and SR4759 19gr thru 23gr. At 23gr of SR4759 the RSI pressure trace indicated 19,000 PSI and the boolit velocity was just over 1600 fps.
If accuracy stays good and my alloy holds up I would like to push this boolit up to 1800-1900fps but I am not sure of the pressure effects of increasing 2400 or SR4759 past the loading I have already shot.

In past pressure testing with Norma 196gr Alaskan bullets I have found the 8x58RD pressure seiling of 28,000 PSI with a 44 gr load of VV N140 running around 2100 fps. Having not shot many cast boolit loads I am wondering if I can safely reduce the VV N140 powder load to say 38-40gr and shoot this 224gr .326 cast boolit to achieve my desired velocity of 1800 to 1900 fps without running into dangerous teritory of not having enough powder in my case. I really don't want to use a filler if I don't have to as I have read of pressure spikes associated from the use of fillers. So I am asking for experienced thoughts here concerning reduced loads. Precentage wise, what is the lowest case volume precentage that is usually recommended by powder manufacturers in a given case?

If you wish to see my RSI pressure data experiments for the 8x58RD before you coment you can find them here....

http://forums.gunboards.com/showthre...ss-Help-needed

Smokepole50

[Dutchman]

Keep up the good work, Randall. I'm glad you're here in this forum with us. You have a lot to add with your work on the m/1889 Swede rolling block.

Dutch

[Smokepole50]

Thanks Dutch

[dromia]

I have found N135 to do better than N140 with cast in this calibre.

[Smokepole50]

Are we talking N135 in a Swedish rolling block or a Danish Craig? Norma list N135 for the RB in their 1960's era Load Date book but I found it a bit to hot for my liking with jacketed bullets based upon pressure trace data(I may go back and test it again with lighter bullets). Do you think N135 being a bit faster then N140 makes it more suitable for cast boolits? If so I would be very interested to know what charge weigth and boolit weight you have fired using N135 in a Swedish RB. You can PM me if you don't want to list it on line. If it appears safe I will test it with a RSI pressure trace unit and let you know what the pressure is running.

[dromia]

Sorry for the delay in replying but I couldn't lay me hands on my load data at the time and then it drifted out of memory.

Anyway I moved to N135 in my Swedish rolling block as N140 was leaving unburnt powder, sooty case necks and the extreme spread was large at over 100 fps.

I am using the Swede Nelson G88 boolit at 0.325" 220 gn from softish BHN 12 range scrap alloy.

The best load giving 5 shot consistent groups of 3 1/2" at 100yrds was 35 gns of N135, a little bit over 60% case fill which I don't like going below with these slower powders, still a little unburnt powder and some slight sooting at the necks but the extreme spread was under 30 fps for an average velocity 1825 fps.

Some vertical stringing was evident in the groups but I think that was more a function of the open sights and my failing eyes rather than the load.

I was reasonably happy with that result and wanted to do some further tweaking but that has got sidelined as different rifles and calibres came in but will return to it as I do like the rolling blocks both smokeless and BP.

I would be interested in pressure traces, when I ran the load through QL it gave me a velocity of 1914 fps with a chamber pressure of 17501 psi. As my actual velocity was around 100 fps less then the chamber pressure would be little less than predicted.

[Donor8x56r]

Did you use any filler with SR4759 at all?I tried this powder in 8x50R Lebel under 200Gr cast but any load under 24Gr leaves soot on cases.

I was told to try the same load under 200Gr jacketed but I'm not so sure about that.

[pcmacd]

I read a careful investigation in Precision Shooting years ago that concluded no evidence found of barrel damage with natural fillers (kapok, cotton, etc.) but many instances when using a polyester or other man made material.

I'm thinking stuff a cotton ball in the case? A real COTTON one?

[Old Coot]

You are liable to start a fire with a cotton ball unless you are shooting in a very vegetation clear area.