I have to say that the 5in. bbl is my favorite length. I have a J. Dewey 5in. bbl on one of my Lugers, and the looks and balance is just perfect to my way of thinking. GT is producing some handsome barrels, that look quite nice on these "target" Lugers. I await some range accuracy tests.

Back from the range today, the bbl. functioned perfectly on my shooter frame.
Shot both WWB ball and some hollow points, both fed fine.

I didn't fire for accuracy, as I need to work on the sights to be able to see them a little or even a lot better. The fine luger sights don't work well on a black bull with old eyes and sunglasses!

But that is for another day.

Nice work GT. The 5" soaks up what little recoil there is and is a pleasure to shoot.

Dick and Don -

What mainspring did you two use with your G.T. 'bull' barrels??? By that I mean what wire diameter and how many coils???

(Saying 9mm or 30 cal is pretty much meaningless these days - too many possibilities of mainspring swaps, clipped coils, Wolff springs, Sarco [Ha!] springs etc)...

Rich,
I'll have to open the frame up and measure and count.

I used the frame I had been shooting the 12" .30 cal on, clipped spring with about 14 lbs. pressure as I measure it.

Very similar to what I find in an un-molested artillery, but weaker than the "normal" 18-20 lbs I see in a 4".

As you say, just too many variables; add to that old springs vs. new springs; loose fit toggle/slide vs tight one, and one just has to try it out.

I am convinced that the 9mm is more forgiving of spring differences than the .30.

Helped a lot, didn't I. ;)

You pointed out a very neglected area - tight rails. I've had to lap two Lugers to eliminate binding, and just last week I had the same annoyance with two Sarco slides on 80% steel frames. On one, I actually had to use valve grinding compound - very coarse stuff, and required both rubbing compound and polishing compound afterwards to get it smooth again. Now it's like slipping on soap in the bathtub! :D

There was a forum member here about a year or so ago who wanted his Luger barrel worked on. I did the work, but couldn't test it because his barrel extension bound up on my 1939 Mauser frame. :(

Yes,
they didn't number the pieces just for the heck of it.;)

Mainspring Details
 

Howdy Richard,

Previously posted by GT.

"GT's Range Test
Well, just got back for the range where I tested qty. 2 of the new GTS/T-6 & qty. 1 of the GTS/T-4 versions... They all worked flawlessly on my byf test frame!!!! ... Yeah Team!!... Now, I did have an owners frame for one of the 6 inch versions, and, with that frame, it wouldn't always close?... So, I swapped out the mainspring, original DWM, with the longer, and seemingly stronger Mauser spring out of my test byf, and problem solved.... All good!"

I have not had the time to shoot my Navy GTS/T-6. My local range has been flooded. Nor have I had the time to take down the pistol to count mainspring coils or mic the wire diameter. Until I get to strip the Navy GTS/T-6 I hope GT's comments help.

Have a most excellent day,
Dick

Mainspring....
 

On testing all, I used a standard WW2 Mauser 22 coil byf 9mm factory spring... It had about 4K rounds on it, and when I range tested Dick H.'s GTS/T-6, I ended up installing that exact spring in his frame, as I knew it worked with all the others, and it work with his as well.... (prior to that it wouldn't always close completely... It's a real balancing act when the barrels get fat!?.... ;)... Best to all, til....lat'r..... GT

Rich,
the .30 12 inch bbl/frame has a spring of 0.0565 diameter and 17 coils.

I just changed the 5" bull to a different frame and will test fire it next week, and count/measure and report!