LugerForum Discussion Forums - View Single Post - Guerrilla Gunsmithing # 3

sheepherder · 01-08-2012, 12:24 PM

Quick & dirty 7.65 Luger barrel for Colt Gov't Model

(Should be 'Gorilla Gunsmithing', as I take the brute
force approach...No fancy frills here...and I am not a gunsmith; just a
garage gun hack...)

This seems to be one of the few calibers/barrels not available for the
Colt Gov't Model...and since I had the first weekend off in 4 months
and nothing planned, and a member wondered what all had to be done,
I thought I'd give it a go...

I decided to go with what I was familiar with; making a screw-in stub
barrel for the Colt breechblock. I had a new 38 Super barrel with the
'straight' configuration that would not work with my beloved Series 70
collet bushings, so I used that as the donor breechblock.

First off is to bore out the chamber. I wanted it to be on center [duh!]
so I ran a 7/16" end mill through the chamber.

Then I sawed off the barrel and faced off the resulting breechblock face.

I drilled out the breechblock in 1/32" increments to 15/32", the hole
size for a 1/2" x 28tpi tap [NEF].

Tapping the breechblock. Incidentally, runout on the breechblock in my
3-jaw chuck was .001"...

Resulting threaded breechblock with cutoff barrel.

I selected a new barrel blank in 30 cal, and rough turned the OD on the
lathe...

Barrel blank threaded 1/2" x 28tpi for breechblock insert...

Nice tight fit into breechblock...Requires some exertion to screw it all
the way on...

Turning down the 'relief' in the barrel...

Turning the taper that the collet bushing rides on...

Clymer 30 Luger finishing chambering solid pilot reamer and 'floating'
reamer holder...

Start of chamber reaming...Keep an eye on the newspaper & the lathe
chuck...

Clymer used to have an instruction page on their web site,
but since the family sold the business, it's gone...but it recommended
high-sulphur content cutting oil [Ridgid makes some] and cutting at low
speed and in 1/32" increments, blowing chips out & re-oiling every
1/32"...

More cutting...this is a slow process, with all the blowing &
re-oiling...

Here's a shot of what 1/32" of chips looks like...The masking tape is
just a crude measurement of when I need to pay attention...

This is where I start cutting in thousandths...This is the final cut;
should give me .003" - .004" headspace when installed...

Here I'm cutting the 'liner' away from the barrel hood...

Semi-finished re-barrel in 7.65 Luger compared to my Colt Series 70 38
Super barrel & bushing...

Muzzle & breech ends of the two barrels...7.65 Luger still needs a lot of
hand-fitting; feed ramp, strange cut on side, fitting of link & pin (on
order)...

Comparison of headspace...

Another headspace comparison (installed)...

That's about as far as the machining operations go. My installed headspace turned
out to be .005". I'm waiting on a barrel link, link pin, and magazine from Numrich
for final fitment.

This is a quick & dirty barrel swap; not pretty, function over form...Call it a 'feasibility
study'...

I don't think that this is a barrel swap that can be done without a lot of
fitting of the mating parts. I was especially appalled at the excessive
headspace of the Colt 38 Super barrel...I try for .003" to .004"
headspace on my 'range shooters' (as opposed to .010" - .012" on my
'MilSpec' barrel swaps); this .038" is really mind boggling...but it
shoots OK; and has not failed to fire with Winchester +P 130gr FMJ
ammunition...but I will be looking for another 38 Super barrel...

BTW: This donor barrel was made of excellent steel...I use 4140 steel
for most of my projects and am familiar with how it machines...This barrel/breechblock
is way tougher than 4140...6000 series at least; maybe 8000 series...

01-08-2012, 12:24 PM	#1
sheepherder Lifer Lifetime Forum Patron Join Date: Feb 2009 Location: ...on the 'ol Erie Canal... Posts: 8,182 Thanks: 1,398 Thanked 4,440 Times in 2,328 Posts	Guerrilla Gunsmithing # 3 - 7.65 Luger Colt Gov't Model Barrel Quick & dirty 7.65 Luger barrel for Colt Gov't Model (Should be 'Gorilla Gunsmithing', as I take the brute force approach...No fancy frills here...and I am not a gunsmith; just a garage gun hack...) This seems to be one of the few calibers/barrels not available for the Colt Gov't Model...and since I had the first weekend off in 4 months and nothing planned, and a member wondered what all had to be done, I thought I'd give it a go... I decided to go with what I was familiar with; making a screw-in stub barrel for the Colt breechblock. I had a new 38 Super barrel with the 'straight' configuration that would not work with my beloved Series 70 collet bushings, so I used that as the donor breechblock. First off is to bore out the chamber. I wanted it to be on center [duh!] so I ran a 7/16" end mill through the chamber. Then I sawed off the barrel and faced off the resulting breechblock face. I drilled out the breechblock in 1/32" increments to 15/32", the hole size for a 1/2" x 28tpi tap [NEF]. Tapping the breechblock. Incidentally, runout on the breechblock in my 3-jaw chuck was .001"... Resulting threaded breechblock with cutoff barrel. I selected a new barrel blank in 30 cal, and rough turned the OD on the lathe... Barrel blank threaded 1/2" x 28tpi for breechblock insert... Nice tight fit into breechblock...Requires some exertion to screw it all the way on... Turning down the 'relief' in the barrel... Turning the taper that the collet bushing rides on... Clymer 30 Luger finishing chambering solid pilot reamer and 'floating' reamer holder... Start of chamber reaming...Keep an eye on the newspaper & the lathe chuck... Clymer used to have an instruction page on their web site, but since the family sold the business, it's gone...but it recommended high-sulphur content cutting oil [Ridgid makes some] and cutting at low speed and in 1/32" increments, blowing chips out & re-oiling every 1/32"... More cutting...this is a slow process, with all the blowing & re-oiling... Here's a shot of what 1/32" of chips looks like...The masking tape is just a crude measurement of when I need to pay attention... This is where I start cutting in thousandths...This is the final cut; should give me .003" - .004" headspace when installed... Here I'm cutting the 'liner' away from the barrel hood... Semi-finished re-barrel in 7.65 Luger compared to my Colt Series 70 38 Super barrel & bushing... Muzzle & breech ends of the two barrels...7.65 Luger still needs a lot of hand-fitting; feed ramp, strange cut on side, fitting of link & pin (on order)... Comparison of headspace... Another headspace comparison (installed)... That's about as far as the machining operations go. My installed headspace turned out to be .005". I'm waiting on a barrel link, link pin, and magazine from Numrich for final fitment. This is a quick & dirty barrel swap; not pretty, function over form...Call it a 'feasibility study'... I don't think that this is a barrel swap that can be done without a lot of fitting of the mating parts. I was especially appalled at the excessive headspace of the Colt 38 Super barrel...I try for .003" to .004" headspace on my 'range shooters' (as opposed to .010" - .012" on my 'MilSpec' barrel swaps); this .038" is really mind boggling...but it shoots OK; and has not failed to fire with Winchester +P 130gr FMJ ammunition...but I will be looking for another 38 Super barrel... BTW: This donor barrel was made of excellent steel...I use 4140 steel for most of my projects and am familiar with how it machines...This barrel/breechblock is way tougher than 4140...6000 series at least; maybe 8000 series... __________________ I like my coffee the way I like my women... ...Cold and bitter...