Over Sized Luger Bores
 

Hi:

Is their any truth in the statement that Luger bores are typically over sized? A good friend claims that his bore is .360!!

Has anyone miked their bores? If so, what were your readings.

Thanks!

Bob

Bob, on many barrels they are marked 8,81, 8,82, etc., so that is in millimeters from land to land. And a 9mm equals a 36 inch, so his is the normal size, unless I am mixed up?

Google search:
INCHES TO CENTAMETERS - MILLIMETERS TO INCHES If you have Inches, multiply by 2.5 = Centimeters If you have Millimeters, multiply by 0.04 = inches

9mm x 0.04 = 36

Ed, this is one time that Google has misinformed you. 8.82 divided by 25.4 = .247244". Now add a nominal .008" for the depth of two grooves (opposite grooves of .004" depth each) and we have a groove diameter of .355". 9 divided by the same 25.4 = .35433" so .355" is quite close. Going by the bore diameters stamped on the barrels of most Lugers, I'd say they held tolerances quite tight as most I've seen are 8.81 and 8.82.

Having said that, when OTHER 9mm pistols are discussed it's not uncommon to find oversized groove diameters. I have yet to find a Browning Hi-Power less than .357" and most run .358 - .359". I've also measured many CZ-75 barrels and all of them have been .357" or larger. My own CZ-75 is .358" and it's a beautiful commercial model, deeply blued and new when I purchased it in England in 1985.

So I think it fair to say that many 9mm pistols will have oversize bores but most Lugers will not. At least that's my experience.

:)

thanks for the clarification, damn google :D

Doubs, sorry but 8.82 divided by 25.4 is 0.34724. I think you misprinted a "2" for the "3". I will agree with the rest of your calculations. :)

Probably used the google calculator :D

</font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Originally posted by Frank:
<strong>Doubs, sorry but 8.82 divided by 25.4 is 0.34724. I think you misprinted a "2" for the "3". I will agree with the rest of your calculations. :) </strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Frank, Ed is correct: Damned Google calculator!!
<img border="0" alt="[ouch]" title="" src="graemlins/c.gif" /> :)

Cartridge names have little or nothing to do with the barrel or bullet diameter. From the name "9 mm Parabellum" alone I would only deduce the diameter was somewhere between 8 and 10 mm. You have to dig a little deeper to find the mominal size and tolerances for these diminsions.

Examples:

400-360 Purdy .367 bullet
400-360 Westly Richards .360 bullet
600 Nitro .620 bullet
375 H&H .375 bullet
30-06 .308 bullet
308 .308 bullet
38 Special .357
44 Special .429
32 ACP .311
7.62 Nagent .295 (7.62 mm = .300")
7.62 Tokarev .308 or larger

etc.

</font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Originally posted by Doubs:
<strong>Ed, this is one time that Google has misinformed you. 8.82 divided by 25.4 = .247244". Now add a nominal .008" for the depth of two grooves (opposite grooves of .004" depth each) and we have a groove diameter of .355". 9 divided by the same 25.4 = .35433" so .355" is quite close. Going by the bore diameters stamped on the barrels of most Lugers, I'd say they held tolerances quite tight as most I've seen are 8.81 and 8.82.

Having said that, when OTHER 9mm pistols are discussed it's not uncommon to find oversized groove diameters. I have yet to find a Browning Hi-Power less than .357" and most run .358 - .359". I've also measured many CZ-75 barrels and all of them have been .357" or larger. My own CZ-75 is .358" and it's a beautiful commercial model, deeply blued and new when I purchased it in England in 1985.

So I think it fair to say that many 9mm pistols will have oversize bores but most Lugers will not. At least that's my experience.</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Dear Doubs:

Thanks for your excellent analysis and information!! If we can assume that all of the barrels had a total groove depth of .008, it should be easy to read the land diameter, stamped on the underside of each barrel, and simply add to it the groove depth, for the total bore diameter, just as you have.

Thanks again!!

Bob

Waitaminute, have I been misinformed all my life, or did we just enter an alternate universe? The "total bore diameter" is land-to-land, is it not?, with rifling depth (groove diameter) being solely an engineering/design consideration, not having anything itself to do with the caliber designation...

--Dwight

</font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Originally posted by Dwight Gruber:
<strong>Waitaminute, have I been misinformed all my life, or did we just enter an alternate universe? The "total bore diameter" is land-to-land, is it not?, with rifling depth (groove diameter) being solely an engineering/design consideration, not having anything itself to do with the caliber designation...

--Dwight</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Hi Dwight!!!

Caliber is measured from land to land, in the UK and US anyway. In Europe, the designation is from groove to groove. The 9MM Parabellum is measured from groove to groove, as the bullet is 9MMs in diameter.

No, I don't think that you have entered a new universe quite yet. Ha!!

A cast lead bullet must fit snugly against the groove to assure premium accuracy. Without a snug fit, the soft lead bullet can simply strip over the rifling, thus yielding very poor accuracy.

The actual reason for my question is that I am designing a truncated cone bullet, just like the DWM original military bullet, except of cast lead. To yield maximum accuracy, they must fit the groove of the Luger properly.

Bob

They rarely seem to use the actual caliber in the name of the cartridge. I still remember how confused I was, when I found out that the .218 Bee, .219 Zipper, .220 Swift, .221 Fireball, .222 Remington, .223 Remington, .224 Weatherby Magnum, and .225 Winchester all used .224 diameter bullets. Apparently none of the so called .38 cartridges used .38 caliber bullets. They actually are smaller than .36!!! What is going on, I thought... Advertising..

HOLD UP THERE DOUBS BABY!!!

YOUR ABSOLUTELY CORRECT!!!

"Having said that, when OTHER 9mm pistols are discussed it's not uncommon to find oversized groove diameters. I have yet to find a Browning Hi-Power less than .357" and most run .358 - .359". I've also measured many CZ-75 barrels and all of them have been .357" or larger. My own CZ-75 is .358" and it's a beautiful commercial model, deeply blued and new when I purchased it in England in 1985."

I just remembered that I had the original blue prints for the Luger Pistol hidden somewhere in my basement. These are from the Bravarian military archive, as discovered and reprinted by Goetz.

All of the dimensions for the barrel are given.

Minimum groove is: 9.07mm X .03937 = .3570859

Maximum groove is: 9.11mm X .03937 = .3586607

Your fine M-35 and CZ-75 are, indeed, within original spec!!!

Thanks again!!

Bob

The bore is the land to land diameter. many people incorrectly use it to mean the groove to groove diameter. It is the diameter the barrel is "bored" to before the rifling is cut.

The caliber designation also refers to land to land diameter but is abused as often as the term bore.

Cartridge designations have even less to do with diameter. They have more to do with what looks good in the advertsing copy.

The 38 S&W does not have the same diameter as the 38 Special which does have the same diameter as the 357 Magnum, the 357 Supermag, the 357 Maximum, and the 360 Dan Wesson. Just to confuse the issue even more, if you have a Dan Wesson 357 Supermag, chambered for the 357 Supermag, it will say 357 Maximum on the side, a different cartridge. Go figure.

The 44 S&W does not have the same diameter as the 44 Russian, 44 Special, 44 Magnum, and 445 Supermag, all of which have the same diameter.

The 45 Colt has a groove diameter of .454 or .451 depending on whether it was made before or after WWII. And it's not the "45 Long Colt" although there is such a thing as the 45 Short Colt. (The 45 Short Colt and the 1909 Colt 45 share the distinction of today being the two most obscure cartridges the US Army ever issued.)

Bottom line is you just have to go dig and find out what its really supposed to be. And take that with a grain of salt.

I'd hesitate to call Luger barrels oversized anyway, it's the original barrel and hence all others are copies of it.