[stubbicatt]

OK fellas. I'm about to embark on the development of a rough equivalent of the Finn D166 load for 7.62x54r. Of course I solicit any data or admonishments so that it works properly, and safely.

I do not have a Finnish Mosin Nagant, but I keep my eyes peeled. I do have an old Ishevsk 91/30 and a Tula SVT 40 which will be my workhorses. The SVT40 is a more accurate rifle, so the following is my plan.

The Lapua webpage posts N140 data for this bullet at 36.4 grains starting load and 40.0 grain as the max, also listed as their "accuracy" load. From the burn rate charts, N140 is only one digit faster than RL15. Data on RL15 in the 7.62x54r is sparse, but I intend to start at 36.4 grains with a max load of 40.0 grains of RL15. The bullet is the D166, 200 grain, rebated boat tail Lapua bullet. Brass is Wolf brand brass from about 10 years ago. I figured for primers I would use the CCI military #34 primer. I do not have a whole bunch of brass, so I have thought this through, and here is my plan.

PRESSURE TEST:

Fire one each 180 grain factory new round in each rifle. Mic the case head before and after firing, to gage expansion. This will be my primary method of evaluating pressure. The x54r (or x53r if Finnish) is a lower pressure cartridge, I think max is somewhere around 40 to 45K PSI, so gaging pressure signs in this cartridge will be more difficult I would think than say, a 308.

Full length resize the few fired cases I have, and mic them after loading. I do not expect that the web area will return to new, unfired dimensions, but it is a data point that may prove useful, I don't know.

Starting at 36.4 grains, load 2 cartridges each at 1/2 grain powder increments, until the 40 grain ceiling. First fire a cartridge of a given charge weight in the stronger, but less accurate, Mosin Nagant and examine for any obvious pressure signs. Then, assuming no adverse pressure signs, fire its companion in the SVT 40. Take velocity readings with the chronograph as additional data points. Mic fired cases to determine whether they are approaching my measurements for working max pressures.

Since this cartridge headspaces on the rim, I figure I'll use my Stoney Point case comparator tool to measure headspace using the .4" ring, as it were a 308, as an additional data point to gage pressure by how much longer the distance is from the case head to the case shoulder. I figure the lower pressure cases will stretch less in this dimension. --We'll see.

From the Vihtavouri website, they have some posted velocity figures for the ammo they produce, and I reckon I will use this figure as an indication of pressure.

ACCURACY

Once max pressure is determined I figured I'd load 3 each of bullets at whatever is determined to be max load, and ratchet them down in .3 grain increments until I reach a powder charge floor, arbitrarily set at 2 grains below maximum pressure, and gage these rounds for accuracy at 100 yards in the SVT40, as it is the more accurate rifle between the two I have. I realize 3 round groups are statistically inferior to 5 round groups, or better, 10 round groups. But with a chronograph, I figure I can at least get a pretty good idea of grouping ability and consistency in velocities.

Then, voila! With the remaining bullets I have, I should have a pretty decent accuracy load for the SVT 40. The one thing I think I will do at some point if I continue to handload for this rifle, is anneal the cases and buy a custom FL die for the SVT 40. This due to the relatively longer distance to the shoulder than unfired, or resized brass, exhibits. I figure to FL size this brass will lead to early case failure, seeing as the shoulder gets set back so far with a conventional RCBS die.

Seriously, though, I solicit any suggestions or advice which will help in arriving at an accuracy load for this rifle.