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A Look Inside: 7.62x54 Bulgarian light ball, 1954

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Zeliard
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A Look Inside: 7.62x54 Bulgarian light ball, 1954

#1 Post by Zeliard » Sun Jun 11, 2017 9:19 pm

Originally posted by carteach0.

Years ago I read an article. The subject was precision hand loading for accuracy.
This article appeared in a magazine devoted to hunters who typically shoot
at long distances. As might be guessed, the piece was all about the details
of building very special ammunition. The key to exceptionally accurate ammo
is keeping every factor, every component, as close to perfect as possible.

The title of this article was “The name of the game is the SAME”

In taking a ‘Look Inside’ the 7.62x54 Bulgarian light ball recently
available, I was thinking that another phrase might be more fitting.
“The name of the game is..... close enoughski”

In tearing down and examining various ammunitions I have come to expect
most to have some component, or some factor, less than perfect. With
few exceptions this has been true.

With this Bulgarian offering every single component and chosen measurement
factor had accuracy issues. No attempt is made here to be mean, and it must be
remembered that this is only 10 rounds, out of millions produced.

Let us take a look at the subject:

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As usual, components were weighed with an RCBS 10-10 scale. Components were
measured with Mitutoyu digital micrometers and a Central caliper. The bullets were
pulled using an RCBS collet type puller mounted in an Ammomaster press.

The components found:

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The ammunition is brass cased, and berdan primed. Neither bullet nor primer is
sealed in any way. The bullets pulled with very little effort, but erratically. This was
due to the case mouths being crimped into bullet cannelures inconsistently. On
most loading equipment the case mouth crimp depth is dependant on case length.
The longer the case, the heavier the crimp, all other things being equal.

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The components were measured in as consistent a manner as possible, but some
measurements were made two or three times. It’s easy to move along quickly
when each measurement is the same, but when they vary so much extra care
must be taken to be accurate.

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While making neck diameter measurements, something special was noticed.
It seems the cases were sized quite small, then the bullets were seated in a
non-concentric way. In other words, they are not centered in the necks.
On seating, the bullets stretch the case neck. In this example the necks were stretched
all to one side, to the tune of .003” off center. This proved difficult to photograph,
but here’s my best attempts:

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The neck diameters were also out of round by over .001”, but this was mostly caused
by the bullets varying at least that much in roundness.

Some data on case and cartridge dimension:

Over all length of loaded cartridges: From 3.000” to 3.020”, with a spread of .020”.
The optimal specification is 3.010 according to the Handloaders guide to cartridge
conversions.

Case lengths: 2.100” to 2.110” with a spread of .010”. Optimal is 2.050 based on
the same source. This case length variation accounts for the inconsistency of
case mouth to bullet crimp, in my opinion.

Cartridge base diameters stretched from .4821” to .4850”, with a spread of .0029”.
Case neck diameters varied from .3330” to .3358”, doing my best to deal with
the uneven neck stretch.

Once pulled down, the powder was checked and weighed. It’s a medium length
extruded grain resembling IMR 3031, but clearly not exactly the same.
Charge weights varied significantly, from 49.5 grains to 50.1 grains.
The powder appeared in decent condition despite its 50 year life
in an unsealed case.

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The bullets were interesting. They are a hollow base spitzer design. The indentation
in the base measured a whopping .160” deep. Bullet weight variations were on the heavy side
ranging from 150.5 grains to 151.9 grains, with a 1.4 grain spread.

The bullets have a lead core, with a copper plated mild steel jacket and a deep cannelure.

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Bullet diameters measured from .3092” to .3112” with a surprising range of .0020”.
That’s quite large by any standard I have ever seen. While these bullets should be safe
in any 7.62x54 rifle, accuracy of any kind would be amazing. Nominal bore
diameter in this round is .311”, with many hand loaders looking for .312” or even slightly
wider in the quest for accuracy. My own Mosin bores slug from .312” to .315”.
A bullet that much undersized must simply bounce down the bore.

There is a chance the very large indent in the base acts exactly like the one in the Minne
ball of civil war fame. Pressure pushes the bullet base walls outward against the bore,
sealing it and forcing it into the rifling. If this is the case, then accuracy might not
be horrendous after all.

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Also noted was the depth of bullet seating in the case neck. With variations, it averaged
a very short .217” deep. This is not even one bullet diameter. With rough
treatment the bullet will shift in the neck, once again damaging accuracy.
Treatment as ‘rough’ as chambering a round from the magazine might do this.

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Case weights were the widest ranging of any one lot I have ever seen. The lightest
was 145.6 grains, the heaviest at 152.5 grains, with a spread of 6.9 grains.
External measurements found no large difference, so I can only guess the
weight variation is due to case wall thickness.

A few graphs of the more interesting variations:

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My conclusions are.... well..... just mine. To be honest I am no trained scientist
nor do I play one on television. I don’t have a big sweaty brain. Heck, I’ve never
owned a pocket protector in my life! I’m just an interested hobbyist attempting
to understand my interests a bit better, and share my interest at the same time.

I see nothing in this ammunition that screams *unsafe* to me. In fact, I suspect
it will be completely dependable. My only criticism is from an accuracy
viewpoint. I fully expect this Bulgarian 7.62x54 to be as reliable as fifty
year old military ammunition can be. It’s probably 100% sure fire, I’m guessing
it will function perfectly. That said, I am as curious as a hound in a sausage factory
to see how accurate this ammunition is. I also want to run it across my chronograph
which I have found to be a good indicator of accuracy potential, or lack of.

I’ll report back after that range day....... this should be interesting.
There’s always the chance my conclusions are completely wrong.
This might be the most accurate ammo ever fired in a Mosin Nagant.

Stranger things have happened. There was the time I ate all those
bean burrotos.............. I was wrong then too.

***********************************************************
UPDATE UPDATE UPDATE UPDATE UPDATE UPDATE UPDATE
***********************************************************

An OUTSIDE look, for a change.......,

.....at a few of the cartridges examined recently in the ‘Inside look’ episodes.

The weather today was gorgeous. All the nasty global warming has melted from the
range and even the mud is not too thick. Chores are done, Mamma is happy, and
the planets seem to be in proper alignment.

Range day!!

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Goals today were to validate some thoughts on various mil-surp ammunition.

The velocity measuring device I use is a Pact Model 1 chronograph.
While it’s a little long in the tooth (ancient that is), it’s been reliable
for years. Features are scant, but it serves nicely.

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The setup is nothing spectacular. One simple box of electronics that’s nothing
more than a glorified calculator. Two ‘sky screens’ are mounted on a bar at a preset
distance from each other, then connected to the magic box via cables.
The biggest task is getting the sky screens in position so the shooter doesn’t
blow them to pieces. That takes some small bit of fiddling.

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First up, and the most surprising candidate, is the Bulgarian 7.62x54mm light ball.
I have recently made this ammo a subject of a ‘Look Inside’ article on surplusrifleforum.com. (NOTE: this is the information above this section )
In that article I noted many, many issues that all pointed to probable accuracy
problems. The only way to verify the findings is to put bullet to paper, sending
them over a chronograph on the way downrange.

I chose my Tula ex-sniper 91/30 for this test, as it’s my most accurate Mosin rifle.
I shot two five round groups of the Polish light ball as benchmark. I noted average
velocity, highest velocity, lowest velocity, extreme spread, standard deviation,
and average deviation for each group fired. Numbers are as follows:
Average velocity: 2699 fps
High velocity: 2705 fps
Low velocity: 2682 fps
Extreme spread: 22.6 fps
Standard deviation: 9.5 fps
Average deviation: 6.7 fps

These numbers are really not bad, especially for military surplus ammunition
from a communist block nation. I would not be upset at seeing numbers
like this from my own hand loads. This probably contributes to the
accuracy of this ammunition from the Tula.

The groups were fired at 50 yards, paying heed to my older eyes and wish not to run
down to the 100 yard back stop every fifteen minutes.

The Polish light ball turned in a predictable 1.5” and 2” group at 50 yards.
Not stellar, but not horrible for a $90 rifle with surplus ammo. This rifle will
plant them all under an inch with handloads.

After checking velocity and accuracy with the Polish, next up was the questionable
Bulgarian light ball. What I found surprised me substantially. The velocity data:
Average velocity: 2756 fps
High velocity: 2773 fps
Low velocity: 2741 fps
Extreme spread: 31.3 fps
Standard deviation: 11.5 fps
Average deviation: 8.3 fps

Notice the numbers do not vary from the Polish light ball by any large amount.
Average velocity is slightly higher and spread is a bit higher, but not enough
to cause any concern.

The real shocker was when I checked the target, looking through my
new Barska spotting scope. To be honest, if I hadn’t just posted fresh clean
targets I would not have believed what I saw. The group was TIGHT. How tight?
It was tight enough that I tried again right away. The second group of five
printed to the same point of impact and the same group size. Velocities were
within a few FPS of the first group.

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The Bulgarian light ball easily shoots every bit as well as the Polish light ball, at
least in my Tula ex-sniper.

I don’t find that easy to say. Everything I saw when tearing down this ammo
and inspecting it told me it should not shoot accurately. Theories abound, and some
pop out at me. That said, they are only theories. When the rubber meets the road
this stuff shoots pretty darn good through my Tula.

Am I going to order some more? I hope to order a few more cans just as soon
as I have the money to do so. Against all odds this blasted stuff shoots pretty
darn good!
Proud alumni of Transylvanian Polygnostic University. "Know enough to be afraid."

"Vertroue in God en die Mauser".-Faith in God and the Mauser.

"Send lawyers, guns and money." -Warren Zevon

VMASCIOP2000
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Re: A Look Inside: 7.62x54 Bulgarian light ball, 1954

#2 Post by VMASCIOP2000 » Sun Nov 05, 2017 12:19 pm

Great Job. Held my fascination from start to finish. Did you notice a blast and/or recoil difference (between the two), that was worth mentioning ?
I was R.L.E.V.M. on our old forum.

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