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short bofors case
- Thread starter earni74
- Start date
This looks like a USA made case with Mk2 Mod1 and M22 primer.
What is the rim diameter. 51mm or the usual Bofors 61.7mm? There is a 40x235R with 51mm rim in Hawkinson's book.
Without the clip groove above the rim and longer case it may just be a case stage or the unknown 51mm rim case? I do not know.
What is the rim diameter. 51mm or the usual Bofors 61.7mm? There is a 40x235R with 51mm rim in Hawkinson's book.
Without the clip groove above the rim and longer case it may just be a case stage or the unknown 51mm rim case? I do not know.
charley777
Well-Known Member
This could be allied to the experimental post-WW2 UK AA guns.
Rim diameter would be 65mm because based on shortened Bofors 40/70 case.
I have 2 lengths.
40x237R and 40x278R (with some typical experimental purple paint ...of my memory is correct).
Note that mouth would be about 42mm because driving bands were inside the neck.
Will get them out and send photos if desired.
Definitely been covered on BOCN. But i am useless at searching .....lol
Rim diameter would be 65mm because based on shortened Bofors 40/70 case.
I have 2 lengths.
40x237R and 40x278R (with some typical experimental purple paint ...of my memory is correct).
Note that mouth would be about 42mm because driving bands were inside the neck.
Will get them out and send photos if desired.
Definitely been covered on BOCN. But i am useless at searching .....lol
Hi Guys, the rim is 61.85mm Diameter and the case mouth is 40mm as a normal L70 projectile fits snugly in the case as does a breakup projectile, rim thickness is 5.9mm, thanks for both your comments. Anyone know which projectile would have been used ?
Thanks
Thanks
Eggburt1969
Well-Known Member
Hmm, but there are a few problems with it being a blank/saluting charge case.
1) The unknown case has a neck, a shoulder and has, at some point, been crimped to a projectile. The blank/saluting cases have straight taper with no shoulder or neck. The unknown case is also missing the clip groove forward of the rim, which in drawings I have is present on blank/saluting cases.
2) If the unknown case was inserted into a standard 40/60 (40×311R) Bofors chamber and had been fired, it would have been blown out to a straight taper. This is because, for a 40/60 case, the distance to the shoulder from its base is ≈9.74" (≈247 mm), and the chamber is more of less of the same dimensions too.
For note, and according to early US documentation, the 40/60 case is 12.24" (310.9 mm) long. This length can be no more than 0.010" (0.254 mm) shorter than 12.24" if it's a MK 1 case, or 0.020" (0.508 mm) if it's a MK 2 (MK 3) case. The case has the aforementioned distance of 9.74" from the rim to the shoulder, and a rim diameter of 2.441" (62.00 mm). The rim can be no more than 0.020" (0.508 mm) smaller than 2.441" if it's a MK 1 case, or 0.015" (0.381 mm) if it's a MK 2 case. The rim thickness for both the MK1 and MK 2 (MK 3) case should be 0.240" (6.096 mm).
Mick I think I've seen that case on my travels.
Take a very close look at where the case wall meets the base. The one I saw was a cut down case but not with the top cut off, but with a section of the case removed and re attached to the base (head) of the case. There were some fine saw marks where it had been done. Shine a torch into the case and see if there's lead or solder in there.
Its not the first time I've seen a case where this has been done. There were a few German 4.2cm taper bore cases circulating a few years back that had been made from scratch in the same way with the bases attached.
I can kind of see the logic with someone trying to make a fake 4.2cm, goodness knows why they'd mess around with a Bofors.
Dave.
Take a very close look at where the case wall meets the base. The one I saw was a cut down case but not with the top cut off, but with a section of the case removed and re attached to the base (head) of the case. There were some fine saw marks where it had been done. Shine a torch into the case and see if there's lead or solder in there.
Its not the first time I've seen a case where this has been done. There were a few German 4.2cm taper bore cases circulating a few years back that had been made from scratch in the same way with the bases attached.
I can kind of see the logic with someone trying to make a fake 4.2cm, goodness knows why they'd mess around with a Bofors.
Dave.
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Spot on Dave, theres so much dirt inside i cant see anything, but cleaning the bottom of the case and rim i can see solder, naughty or what, thats saved me a red face when in the future i might have sold it as an "experimental" bofors case,thanks again Dave, Mick