Let me say at the very beginning that this is not a recommendation of any type. It is simply a method I used to develop a handload that worked very well in one particular rifle. The results may not be the same for you. Handloading can be a hazardous activity if not approached correctly. Please do not try this yourself!
The 1891 Russian 7.62×54 rimmed cartridge is still in service in some parts of the world, serving as ammunition for such varied pursuits as sniper rifle usage, and squad level machine-gun ammunition. Not bad for a round that turned 100 years old in 1991. 7.62x54r ammunition is available in a lot of types, and from a lot of places, and if you choose to fire it, please make sure that your firearm has been checked by a competent gunsmith before doing so.
I purchased a Finish M-39 to add to my military rifle collection. It was not one of the older lot, but seems to be one that was re-purposed in the 1970’s. For those of you who may not be familiar with this weapon, it is built on a Russian M-91, or M-91/30 Mosin Nagant receiver, which is not the best action for a sporting rifle.
The problems of the rifle
Mosin Nagant accuracy suffered from a long and heavy trigger pull, and several other factors. The rifle fires the Russian M-1891 rimmed cartridge, which fires at velocities and distances just slightly below the venerable 30-06.
The Fins used them because they were available as captured or conscripted Russian weapons. On this model, unlike the earlier M-28, the Fins removed the original Russian stocks, and replaced them with nice finger jointed stocks. Like the M-28, they removed the barrels, and added heavier, better made barrels, and made other modifications to improve trigger pull, sighting, and other factors. The end result is a weapon that, although a little bulky and clumsy, functions well, and is capable of extreme accuracy with the right ammunition in the hands of someone who knows how to use it.
The ammo problem
The problem was, that this one was a little finicky. No 7.62x54r ammunition that I tried would produce the results I wanted.
I had already gone through the sequence I use for checking a rifle, like making sure that the stock bolts are tightened correctly, the barrel to stock clearance was right, that there was nothing putting pressure in the wrong places, no barrel warp or bulges, and still, with the 4 different types of military Mosin Nagant ammunition, and the 3 different types of commercial ammunition, the groups were just too big at around 6 to 8 inches at 100 yards.
Solving the ammo problem
I set about developing a hand load to make it work. I used both Sellier and Bellot, and Norma cases, several different primer brands, a variety of bullets in differing weights, and countless powder combination, I tried every conceivable cartridge, bullet, powder, and primer combination, and still, nothing better. I did this by fits and starts over a 2 year period, and still no significant improvement. I kept careful notes.
Developing the solution
I came by a case of 2 spam cans of 440 rounds each of ammunition which has been popularly called “Russian sniper ammunition”, but which I suspect was really intended as PKM ammunition for the older Russian squad level automatic by Kalashnikov, but I have no valid evidence for either theory. Either way, I had a lot of well stored ammo dated 1986, with potassium perchlorate primers. If you are new to this field, pp primers are corrosive. They deposit potassium chloride into a hot barrel, and suck moisture into rust your tube. Meticulous cleaning is needed after using them, preferably with ammonia, the minute the shooting stops. The weapon with which I had intended to use the ammo was a Tokarev rifle, and if you have ever field stripped one of these, you will know that cleanup, especially the meticulous type needed for corrosive primers, is intense! I hate corrosive primers, so I decided to try a little experiment.
Working out a load
I took some of the Soviet made ammunition, disassembled it, used Sellier and Bellot cases, and CCI primers, and used the same powder that the military cases had held, reduced by 5% from the original load. I started with the 5% reduction, and loaded 5 cartridges, made 5 more with one grain added, made five more with another grain added, and so on until I reached the original charge.
Just for kicks, I made 2 extra five round bunches, dropping each at one grain below the five% reduction, and went to the range.
I fired each in sequence at a 25 yard target, checking after the first round of each for primer flattening. The lowest charges exhibited almost no flattening, and the highest was never fired due to the flattening that occurred on the next to last batch, which, although not severe, or dangerous, indicated a little more pressure than I wanted to use in a rifle receiver manufactured in 1915.
The process produced some amazing results! Every batch was better than any of the factory ammo, and most were very good. One selection shot 5 rounds into a ragged hole about the size of a dime! This was a great starting point.
Using my Lee Classic Loader, I loaded 10 more rounds of the best performer for further testing. I continued with 5 rounds at the hundred yard target after making a slight adjustment to the windage, and repeated the initial 25 yard results with 5 rounds slightly under an inch! I advanced to the 200 yards with similar results. The only other guy at the range was also shooting at the 200 yard target, so after firing we retrieved our targets together. He tried to buy the rifle from me.
I tried a few more rounds the next weekend, this time I made half the rounds with a lee factory crimp. the results made a slight improvement. This was followed by several other trips to the range at longer distances, each one exhibiting sub MOA groups for the distance.