Gunboards Forums banner

1 - 8 of 8 Posts

·
Platinum Bullet Member
Joined
·
2,800 Posts
Discussion Starter #1 (Edited)
This is the third time I have posted this, but on both previous occasions I was just in time for two successive "Eclipses of the Forum", and neither posting was visible for more than an hour or two before it disappeared into the ether. So I am trying once more, with apologies to those who managed to catch it earlier:

Some interesting results chronographing three different types of 7.9 Kurz ammo. It has been suggested that the new brass-cased NC Privi Partisan ammo marketed under the FNM brand may be underloaded.

According to info printed on the box, PP/FNM has an 8.0 gram (124 grain) BT bullet loaded to give 660 m/s measured @ 25 meters. That works out to 2165 fps @ 83 feet.

The WWII-issue German ammo is said to have been loaded with an 8.1 gram (125 grains) BT bullet with a velocity of 690m/s measured @ 6 meters (2264 fps @ 20 feet).

Since these figures may or may not be accurate, and in any event are not strictly comparable because of the different measuring distance, I decided to chronograph the PP/FNM against two other lots available, all at the same time, with the same instrument and at the same distance. The comparison ammo, of course, was steel-cased:

1) E. German dated 1961 (headstamp "04" & "61" @ 12/6 o'clock); the laquered cases were gray-colored, primers were yellow with black annulus.

2) WWII Pistolen-Patr. 43m.E., "aux" code (Polte) "71", dated 1944. Box labels included the identifiers "Nz.R.P. (1-0,8/0,2)" and "rdf/9-1,57g." Primers were 30/40 (non-corrosive) made by "eem", lot 193. Cases were olive-colored, blue primer annulus.

I am going to break down samples of all three to confirm bullet type and weight, but have not yet done so.

Ten rounds of each were fired through a PACT II chronograph @ 10' from the muzzle. All firing was done with the same rifle, a standard StG44 made in 1945 with an excellent bore. There were no malfunctions.

Type- Average velocity- Extreme spread- Mean avg. deviation

PP/FNM 2161 fps 92.5 fps. 19.9 (cv= .92%).
WWII Polte: 2160 fps 62.7 fps 16.8 (cv= .77%)
E. German: 2296 fps 36.3 fps 11.8 (cv= .51%)

Here are the HI and LOs:

PP/FNM: 2211 / 2119
WWII: 2197/ 2134
E. Ger. 2315 / 2279

It can be seen that the E. German comes closest to the design specifications, though the absolute numbers may be subject to variations in instrumentation accuracy and measuring distance (measurement at 20 feet was not possible with the PACT II); the comparative ranking is more significant. PP/FNM is not underpowered when compared to the current performance of 63-year-old WWII ammo, though it is about 135 fps slower than the E. German, which is now 46 years old, and by far the most uniform. The fired cases of the E. German are hurled about 6 feet further out. The PP/FNM was the least uniform of the three.

The E. German and PP/FNM primers showed slight to moderate cratering. The WWII showed none --perfect indents, suggesting exactly the right primer cup hardness.

M
 

·
Registered
Joined
·
255 Posts
Thanks for reposting this. I was very happy to see it on the old boards. Could you explain what you mean by cratering?
 

·
Platinum Bullet Member
Joined
·
2,800 Posts
Discussion Starter #3
Primer indents are said to be "cratered" when there is a raised fringe around the circumference of the concave impression. It is the result of rearward extrusion of the primer cup (from chamber pressure) into the firing pin hole in the bolt face.

M
 

·
Registered
Joined
·
135 Posts
Great info. Thanks for doing the tests and posting the results.

Jay
 

·
Registered
Joined
·
3,923 Posts
Mike, any chance of you having some unwanted fired 7,92Kurz casings lying around? EG or WWII.

Eli
 

·
Registered
Joined
·
255 Posts
Standard barrel length is either 16" or 16.5" I forget.

MGMike, any chance you can get a comparison picture of the cratered primer vs. the noncratered primer? I'd be interested to see the difference.
 
1 - 8 of 8 Posts
Top