.308 blank comparison


#1

A friend picked these up off the ground while hunting around West Point Academy practice areas. The left one is LC87, the right is LC00. LC00 was on machine gun links marked M13 WM 4 and NATO thingy. Question: Why are these blanks so different? I understand when there are new approaches to crimps, projectiles etc because they affect the final goal, i.e. bullet delivered to the target. But a blank is a blank!!! Or isn’t it?


#2

I think it is pretty much as simple as “old” style vs. “new style”. Both are called the “M-82”. The new style does away with the small cardboard wad in the tip. This may be an ease of manufacture change or it may be that not having the wad makes the cartridge more “safe” if fired without a BFA. Back in the early 1990’s I ran across some of this “new” style blank ammunition packed on links for the M-60 MG. Up until this time, all we ever used was the “old” style. As I recall, the ammo can was marked as “M-82A1”, but I have not been able to prove my memory correct with any documentation!
When I opened the ammo can and took a belt out to load my M-60, I was surprised at the star-crimp tip and dark purple seal. My first thought was that these were of foreign manufacture (we were using Israeli made .45 ACP ammo at the time). I looked at the headstamp and it was definately new “LC” production.

AKMS


#3

The US persisted with the lacquered wad long neck blank in 7,62 calibre long after many other Countries had introduced the Star crimped blank.

The main reason for the change to a star crimp was the fact that in armoured vehicles, the constant vibration caused the wads to work loose, and the powder to spill out. Furthermore, the crimped cases ( as any Movie armourer will tell you) give a better powder combustion, thus converting the entire powder charge to gas to operate the mechanism.

Many countries stopped buying US Blanks in 30/06 for this very reason (wads falling out) back in the 1970s) as other producers could supply more reliable 30/06 and 7,62 blanks ( all star crimped.)

When I was in Armour (back in early 70s ) one of the major stoppage problems in out M1919A4s was Blanks with No powder left, due to wad fallout or fall back. ( .30 cals on M113A1 turrets).

The US (Lake City) went over to a crimped 7,62 Blank case when they finally disposed of all their pre-WW II “plate” filling machinery…in-line continuous production machinery works better with star-crimped cartridges, and the diameter of the “profile” is larger in a “M82A1” cartridge than in the earlier M82 wadded blank.
(the M82 original proflie is about the same size as a .243W neck, with a hole of about .200 diameter, the M82A1 profile is closer to a .284 neck (7mm), with a hole of about .270 diameter.
This allows for easier Powder filling (ball, very fine), and a thin but strong enough “neck” to crimp easily without collapsing the case.

(Experience from Movie reloading of oncefired M82 cartridges (old style)…
final crimp using a polystyrene ball in neck and taper crimp and lacquer…works OK for M60 and M14, just like the original M82).

Regards, Doc AV
AV Ballistics.


#4

Here’s a pic I posted in the past when I was trying to find out what the crimped M82 blank was. The M82A1 is at the bottom (of course)

I guess DocAV has answered my other question… why the extra roll crimp on the + WCC 62 headstamped round… I guess they were trying to stop the wad from moving.

Here’s the link to the original thread http://iaaforum.org/forum2/viewtopic.php?t=2329

description for the pic below.
Top to Bottom
Canadian Blanks

  • DA 58 (Standard blank for comparison)
  • DA 58
  • DA 66

American Blanks
L C 6 9 (Standard M82 blank for comparison)

  • WCC 62
    L C 6 9 (purple lacquer on the rose crimp) (M82A1)

Dose anyone have any information about why the different designs of blank?