Monday 28 April 2014

Sub-Calibers ! 9MM & .40" S&W in GLOCK 20 10MM ?

 Just call me "irresponsible":

I did something very dumb once (- only once ?): Many years ago I had both my Glock 17 9mm and my Glock 20 10mm on the bench at the firing -line and several loaded magazines for each. - I was comparing the two calibres split-times on a standard exercise of two low-centre shots and one higher (! - in New Zealand we are strongly discouraged from naming targets or target parts as relating to body components) on IPSC targets. - I picked-up the G20 - slapped in a mag and 'bang' - but the gun didn't cycle and I thought "Uh Ohh - I've cocked up my reloads again". So, dropped the mag, racked the slide, and - " what the f**k is that?"


          Yeah, - You've guessed it right -'that' is a 9MM shell that's been fired in a 10MM gun.

Now, coming forward - down the range the other weekend with Jxx & 'Cutters' - we were having a laze, sitting around - swigging chilled coffee and chewing the cud - and I 'fessed-up'  that I'd probably done more stupid things than they had - and told the tale about how mathematically - nine does go into ten at least once.

*WARNING WARNING*

*DO NOT TRY THIS AT HOME*

  - I am only telling you what we did: This is NOT in any way a suggestion or instruction - DO NOT do anything like this - Got it ?

Well, things being how they are, and even 'past-their-best', overweight old farts still have a sense of adventure, - and there being, right there to hand a 10mm, a 9mm, and a .40" Glock - guess what happened next !

 1/-  The left-hand case is a 9MM fired in a Glock .40"S&W.
 2/-  The right-hand case (with the small split) is a 9MM fired from a Glock 20 10MM.
 3/-  And the top shell is a .40"S&W fired in the 10MM G20.

The two 'nines' of course did not cycle the bigger guns - but the projectiles did penetrate the target downrange. - Yes folks - the 9MM projectiles left the 10MM barrels and went through the paper target - but only travelling at around 330ft. per sec. instead of their usual light re-load velocity of 1000ft. per sec. The G17 magazine does not fit in the G20 - certainly it goes in , but tends to drop-out at every opportunity.

- But the .40"S&W round did cycle the 10MM - and eject ! - So we had to try more to determine if you could run a semi-auto 10MM on .40"S&W.

- Now - what's that you are thinking?  "I know that .40" S&W  works in a 10MM Revolver using full-moon clips (a bit like a .38"Special in a .357"Magnum) - soooh?" - But the revolver doesn't rely on the power of the cartridge to operate it - whereas a semi-auto needs a matched power and recoil force to run properly.

- Well the .40"S&W rounds did feed and cycle (& reload) through the semi-auto G20 10MM each time they were tried (using the 10MM magazines) - supposedly 'head-spacing' on the extractor - the primer face of the cartridge being "clipped" in place against the breach face and firing pin by the extractor hook. But they lost about 100ft. per sec. on their normal velocity. We are not sure if that is because of the longer G35 .40"S&W barrel (5.31" against 4.61" G20) or the increased chamber space in front of the round.

** DON'T  DO  IT.**

- Just because it fits is NOT a good reason to do it !

- but it's interesting anyway.

Marty K

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