7.62x54r Safe Minimum?

[Josh Smith]

Hi All,

As some of you know, I handload for the 7.62x54 rimmed Russian with great success.

Most of my charges come from lots of trial and error, moreso than standard rounds because the data for this round is all over the place! One manual's minimum and is another manual's maximum for the same bullet, for example!

I have some bullets I just can't get to shoot without major stringing. They are 174 grain round nose and have extremely long bearing surfaces. They seem to heat up the barrel much more than the others I use, which are 150 grain soft point and 174 grain SMK. The 150 grain does around 1.5MOA and the SMK, sub-MOA. Yes, from a Mosin, five shot strings.

Anyway, I figure I'll do one more experiment with the round-nose bullets before giving up.

This load will approximate the original 7.62x54R load, which was a 212 grain bullet at around 2050fps. I figure I'll send the 174 grain RN at around 2100 to 2200fps to try to keep the heat down a bit.

Sooo... I'm looking at minimum loads now. As with max loads, the minimum loads are all over.

I'd like to use Varget as I have a bunch of that stuff and save the H4350 for the SMK.

I measured 61.5 grains of Varget as fitting into a 7.62x54r case, up to the neck, with a 70% starting load as being 43 grains.

This agrees with Hodgdon's starting load, but I'd like to seat the bullet the full length of the neck as was done with the original.

If I delete the case neck from the equation, I get a max fill of 54.7 grains with 70% being 38.3 grains.

This is in line with the more conservative manuals.

For the sake of consistency and safety, I'd like to avoid flashover (though I understand this is rare unless very light loads[/i] are considered). Consistent ignition is another issue.

While the Mosin-Nagant action is pretty strong (with one gunsmithing school finding a compressed charge of Bullseye will only stretch the receiver!), I don't want to get near these pressures. I'm used to standard or lower pressures, with most of my precision being found in the 2500fps range for my particular rifle.

Can anyone give me some guidance as to where I want to load this at? I intend to use the lightest load I can, as I stated previously, both for due to consideration for barrel heating and for safety's sake.

Thank you very much!

Josh

[Pete1979]

If you are going to slow down a bullet, you might do a better and cleaner job with 3031 or H4895.

[sunborder]

You may even want to consider using 2400 or red dot with that load. (ed harris, etc...)

If not, then your concerns about ignition might be solved by a magnum primer.

I find it interesting that the bullet with more bearing surface is proving to be less accurate. I'd have thought the opposite. I'm assuming you've slugged the barrel, corked or bedded it, and have done all the standard tricks for accuracy. Have you separated bullets by weight?

[Josh Smith]

I find it interesting that the bullet with more bearing surface is proving to be less accurate. I'd have thought the opposite. I'm assuming you've slugged the barrel, corked or bedded it, and have done all the standard tricks for accuracy. Have you separated bullets by weight?

http://www.smith-sights.com/article-accurizing-mosin-nagant.php

http://www.smith-sights.com/accurizing-the-mosin-nagant-a-year-later.php

I've not done anything with regard to weight, but I don't think at this point it would really matter. Not yet, anyway.

With the SMK loads, probably will once they're shooting like the other targets I've shot with Hornady Match. Only went to the SMK because the diameter, o.311", is a better match for my barrel, which slugs to o.299" x o.3105".

Regards,

Josh

[sunborder]

What's the diameter of the RN bullets that are giving you issues? I'm assuming it's jacketed.

[Bill Steele]

The "flashover", "shaped charge effects". etc. associated with downloading rifle powders are urban myth. Guys stick a bullet in the barrel with uber light charges and the second shot through kabooms the gun.

Lee in his 2nd Edition has many loads below 50% of start levels for 30-30, .30-06 and 308 Win, so there should be no concern downloading the Mosin. Just remember at some point you will start getting poor burn results and can stick a bullet. If you don't see a definitive impact, you need to check the bore after each shot.

As others have pointed out, maybe another powder will get you where you want to go with less worry. Fill the case with Trailboss and you will get an automatic download.

[rsrocket1]

43g Varget ought to get you close to 2500 fps and a peak pressure of about 3500 psi if you seat the bullet to 1 diameter 0.3". Further out gets you lower pressure and a slightly lower velocity, further in gets you higher pressure and slightly higher velocity.

The biggest hazard in using light loads with a slow powder comes from the primer pushing the bullet into the rifling before the powder gets going. When the powder finally ignites, the pressures go way up and cause a kaboom. Some people can prove it by simply tilting an under charged rifle load forward, then pulling the trigger. I've never tried it and don't want to.

The question is: why are you expecting sub-MOA results with a peasant gun make to kill enemy soldiers at 100 paces or less? If you want to squeeze the most accuracy out of a "sow's ear", you should throw all ground rules out the window and do whatever it takes to get that accuracy which includes lubing the bullets, seating for minimal jump, using bench rest primers or simply going with around 10 grains of a pistol powder and allowing for 50 yard max range.

My 91/30 takes over an hour to cool down. Even after just a few rounds, I still get cosmoline sweating out of the forearm of the gun. If I pour water into the breech even after a decent waiting period, the water still boils over in the gun.

[sunborder]

The question is: why are you expecting sub-MOA results with a peasant gun make to kill enemy soldiers at 100 paces or less? If you want to squeeze the most accuracy out of a "sow's ear", you should throw all ground rules out the window and do whatever it takes to get that accuracy which includes lubing the bullets, seating for minimal jump, using bench rest primers or simply going with around 10 grains of a pistol powder and allowing for 50 yard max range.

My 91/30 takes over an hour to cool down. Even after just a few rounds, I still get cosmoline sweating out of the forearm of the gun. If I pour water into the breech even after a decent waiting period, the water still boils over in the gun.

Um, The Mosin is used as a target rifle in North-Eastern Europe. Accurizing them is not exactly rocket science. He's expecting MOA results because with two other bullets he's gotten MOA results. Hell, I can get 2.5 MOA using crappy surplus czech light ball with NO accurizing on my "off the rack" Big-5 Mosin special.

Lots of people have wicked-accurate Mosins. Most don't, but that's because they are shooting crappy ammo, and have never bothered to use the standard Mosin accurizing methods. Others have rifles with the rifling completely shot out. The OP's rifle, though, has already shown accuracy potential. His only problem is load development.

And pistol powder loads are good up to 200 yards if you do your part, even with cast bullets. Ed Harris did a lot of experimenting with this. He tended to use 13-18 grains of various pistol powders.

Seriously, sounds like you had a bad Mosin experience. That doesn't mean the OP can't get good results out of a proven rifle.

[sunborder]

43g Varget ought to get you close to 2500 fps and a peak pressure of about 3500 psi if you seat the bullet to 1 diameter 0.3". Further out gets you lower pressure and a slightly lower velocity, further in gets you higher pressure and slightly higher velocity.

Um, the reduced Lee loads show lower fps and much higher pressures at 43 grains of Varget in the .308 and 30-06 with a similar bullet weight. I'm not sure how you could get both those numbers to go in opposite directions...Do you have experimental data to back that up or are you going off of load development software? (not that Lee's data is always the most accurate)

[Josh Smith]

What's the diameter of the RN bullets that are giving you issues? I'm assuming it's jacketed.

Hello,

o.312".

Here is a Hornady Match o.312", five-shot group:



I'm sorry this was only at 60 yards; I was having trouble seeing the target. Come to find out that I have 20/55 vision in my good eye. I had to work for this group (open sights) and have since begun wearing my glasses again.

Here is another, shot with surplus, a bit further out:



The SMK is ready to be ladder tested:



I think the long bearing surface is what's messing with the round nose bullet. It's like shooting two or three SMK or 150 grain Speer soft-point through it at once:



The bore slugs to o.299 x o.3105, which is perfect for a Mosin. I've started shooting only o.311" bullets through it, and the o.312", while they won't hurt a thing, just don't provide the best performance in this rifle. While about as precise, there is increased recoil for that zero gain in precision.

As for the whys and wherefores of this load, it's 1) an experiment to learn from and 2) an exercise in fireforming. I bought up a lot of PPU once-fired from a gent here. I usually buy loaded PPU cases (Wolf Gold, Prvi Partizan) and plink with it to make my fireformed cases, but this deal was just too good to pass up.

I usually keep some pulled surplus around to fireform with, but am down to like 10 bullets. I am going to buy some from another gent on this forum, but whenever I think about sending the money order I'm already in for the night! Darnit. I've been spoiled by paying for stuff online.

Thank you,

Josh

[Bill Steele]

Some of the BR guys use fast pistol powder and wax to fireform. Fill the case and plug with wax, bang, fire formed case. Best maybe to read up on the proceedure before blasting away.

[Pete1979]

Josh, I'm no expert but the round nose bullet is not only a flying brick compared to the HPBT but the long bearing surface and increased diameter are probably driving the pressure (heat) up. The heavy RN is designed to transfer maximum energy into the animal, not to group well on paper.

[sunborder]

Josh, I'm no expert but the round nose bullet is not only a flying brick compared to the HPBT but the long bearing surface and increased diameter are probably driving the pressure (heat) up. The heavy RN is designed to transfer maximum energy into the animal, not to group well on paper.

^^^^^This.

Given the 3 factors here (bullet shape, long bearing surface, bullet diameter), I'd say the oversize bullet diameter is probably your biggest problem.

Longer bearing surface is usually a trick to improve accuracy with worn out rifling, but it doesn't help much if you are shooting an over-sized bullet, where you are REALLY engaging the rifling. It probably is partially responsible for the perceived recoil and the barrel heating up faster.

The bullet shape shouldn't make that big of a difference, especially at such short ranges. You are not going to see a huge drop in velocity with either bullet inside of 200 yards or so. Out at 400 yards, yes, this will make a difference, but not this close. That said, the bullet itself may not be constructed to the same tolerances, since it is "just a cheap hunting bullet."

There are guys shooting 1.5 MOA at 500 yards in black powder silhouette shooting sports with round-nose lead bullets (without gas checks!), so it's not necessarily bullet shape that is the problem, more the tolerances to which they are made.

Also, at such short ranges, you may actually be getting WORSE accuracy than you would in the 100-200 yard range. A lot of bullets don't stabilize until they get a bit further out. Someone who knows more about barrel twist in 91/30's and bullet weights should chime in on this. Basically, think about how an arrow bends almost completely in half when it is launched from a bow, but after a certain distance, you can get repeatable accuracy from it (once it stabilizes in flight). The same thing can happen with bullets.

If you can, try your load testing at a minimum of 100 yards/meters. If the eyes are a problem, then make a trip to the optometrist for a new prescription. I had to do the same a couple years ago. Either that, or mount a good scope on it.

Personally, for outdoor shooting I like the mojo microclick sights with the dual apertures. Costs about the same as the rifle, but they are nice target sights. For indoor or low-light shooting they suck big fat donkey gonads, but I've shot much better with them than the original iron sights. Just make sure your target is a dark color (black bullseye).