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Gold Cup questions

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Post by NukeMMC Sun May 01, 2022 3:41 pm

So I have a couple early Gold Cups and had them out this morning to do some ammo accuracy testing and recoil spring tuning.

First is a 1971 GC (70N02118) that the prior owner worked into a wad gun.  It had been drilled/tapped for a Bomar/Clark rib, forestrap stippled, full-length guide rod, hammer bobbed, beavertail installed and a Kart barrel installed.  I sent it to KC Crawford who tuned the trigger (I had installed an EGW hammer/sear), installed a Dlask trigger and did some work to the barrel lockup and throating.  Apparently the barrel had been poorly fit and the chamber not cut right.  On top is a Matchdot in Vortex Pro 30mm rings on a Clark rail.
Gold Cup questions 20220512

Second is a 1965 GC (15679NM) that has the same EGW hammer/sear and Dlask trigger as above but a Wilson drop-in beavertail.  Everything else is original, including barrel and bushing with beveled recoil spring plug.  At 50 yds, it easily shoots 10-ring from sandbag rest.  This pistol SHOOTS for a factory gun.  This is my EIC pistol.
Gold Cup questions 20220511

My 50yd wad gun load is also my EIC load:
 - TZZ brass
 - Zero 185gr JHP at 1.215"
 - 4.3gr N310
 - FGMM LP primer
 - 0.470" crimp

Wad gun shoots this load with a 14# recoil spring but my 25yd load with 155gr SWCs needs a 13# spring. The top end of this gun (slide/barrel/optic/recoil spring/rod) weighs in at 28ozs.
EIC gun shoots it with a 20# spring!
I am using new Wolff springs.

Pretty sure the mainsprings are stock, but I will be testing with new stock and reduced mainsprings.

Both slides have the early lightening cuts internal to the slide, which are on either side of the firing pin housing/disconnector track and between the slide/barrel locking lugs and the bushing.  Apparently this amounts to about 3 ozs of weight loss to make them cycle reliably with the (supplied) 12# recoil spring and factory 185gr wadcutters at 730-750 fps.

Could 3ozs of slide lightening enable the above loads to cycle the 20#/14# springs?

I am thinking of dropping powder charge to 4.0-4.1 and checking for accuracy.  If I lose accuracy, I may have to go up to a 22/23/24# spring.

Thoughts?  Anyone have older Gold Cup experience like this?
NukeMMC
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Post by ermakevin Sun May 01, 2022 9:05 pm

i have a 1980 Gold cup w/ stock slide, new trigger 12lb spring, also match dot on slide mount, shoots well with 3.8 clays with 200g zero heads for 25 yards 4.1 clays with 200g zero heads 50yds, , holds 3 in at 50 yards, not the best for 2700, i use it for bullseye indoor comp 50 foot easy hold on 10 ring.  that's the only experience i have. for what its worth. 
good luck.

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Post by Fotomaniac Mon May 02, 2022 10:10 am

Personally, I’d leave the slides alone. Work out the loads and springs. All of my Gold Cups function terrifically with either 12# recoil spring for wadcutters with a dot, and between 16#-18# without. One thing you should be aware of is that by changing the hammers you have altered the functionality of the action. The geometry of the proper hammers are different than the standard “commander” or “Government” parts. Therefore you have removed a key feature that makes these pistols unique. Remember these were purposely designed for using wadcutters.

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Post by NukeMMC Mon May 02, 2022 11:46 am

Fotomaniac wrote:Personally, I’d leave the slides alone. Work out the loads and springs. All of my Gold Cups function terrifically with either 12# recoil spring for wadcutters with a dot, and between 16#-18# without. One thing you should be aware of is that by changing the hammers you have altered the functionality of the action. The geometry of the proper hammers are different than the standard “commander” or “Government” parts. Therefore you have removed a key feature that makes these pistols unique. Remember these were purposely designed for using wadcutters.
The slides in the pre-Series 70 and early Series 70 Gold Cups were lightened at the factory.  See below picture.

I don't plan on further lightening, just wondering if what was already done allowed reliable operation with a known-lower energy load and the high rate springs.

I didn't know about differences in hammer bearing geometry.  I have the original hammers and will compare against a couple GI and the EGW.
Gold Cup questions 60mach10
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Post by Fotomaniac Mon May 02, 2022 11:59 am

Yes, they lightened the slides on early models. The hammer geometry has to do with the positioning of where the strut attaches, allowing less resistance to the slide on recoil. Since you have two, put the original parts back into one of them and you’ll see/feel the difference when compared to the other.

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Post by tovaert Tue May 03, 2022 8:36 am

I inherited a '60's model. It was re-barreled at some point, not sure when. I use a WC 12.5 or 13# spring w/full length guide rod. With the lightened slide, 185 gr Zero or XTP JHPs at about 725-750 fps MV cycle well. I recently replaced the internal parts, and installed the WC beavertail as you did. Pretty soft shooting and accurate enough (for me). Would be fun to get some points with it Smile .

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Post by NukeMMC Tue May 03, 2022 7:56 pm

So here are (top-to-bottom), Gold Cup pre-70-series hammer, GC 70-series (bobbed) hammer, M1911A1 hammer, EGW lightened hammer.
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The GC hammer strut pins are clearly slightly below horizontal from the centerline of the hammer pin hole, maybe by about 1/32".
This should have a net effect of adding a preload to the hammer strut/mainspring, but not really affect the operating force.  On the other hand, the strut pin measures 0.030" closer to the hammer pin on the GC hammers.  This should have a net effect of increasing the force required to compress the mainspring as the torque arm is shorter.
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Post by Fotomaniac Wed May 04, 2022 10:52 am

Fwiw…the GC hammers are designed differently…also take notice of the half/quarter cock notches, and the sears. The struts should be identical afaik. There are a number of various differences between the GC and all the Commanders and Government models. Colt designed the Gold Cup to be a match pistol right out of the box. Even the frame is slightly different. Though many ditch the collet bushing (not all have/came with collet bushings), it does work very well. Remembering to back off the slide before you remove it will keep it from breaking. Those that don’t may live to regret it. I usually remove the slide whole, then break it down. 
It’s your pistol, do what you will…but you have some vintage items there that have intrinsic value. (Hang onto the original parts) Changing parts around will require tuning other aspects to make them work as well as you’re expecting. They weren’t made for hardball especially the lightened versions. Gold Cups are my favorite Colts…and I have been in and out of them for over 40 years. An experienced true 1911 smith should know the differences…

Oh and if it hasn’t been done already, make sure the front sight is secure. They have a tendency to get loose and disappear!


Last edited by Fotomaniac on Wed May 04, 2022 11:02 am; edited 1 time in total (Reason for editing : Added info)

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Post by GrumpyOldMan Wed May 18, 2022 12:34 pm

Thanks to ALL who have put info into this thread. I've worked with a rather early one which remains box-stock except for replacing a broken slide stop. Try getting a high-polish blued one of THOSE.

Made long before MIM parts, too. Snapped the ledge that rides inside the slide to keep it in place.

NukeMMC and Fotomaniac, another thing to note on the GC guns is the cross-pin that holds the earlier Elliason rear signts on. Even with shooting only wadgun loads, those would break and send the rear sight flying into the wilderness. When I inspected then replaced that with a short section of drill rod held in with Loc-Tite, the original was already bent and near to being sheared.

So, that's the second deviation from being box-stock...which I HIGHLY recommend that anyone with that type of rear sight do right away.

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Post by tovaert Wed May 18, 2022 4:16 pm

GrumpyOldMan wrote:Thanks to ALL who have put info into this thread. I've worked with a rather early one which remains box-stock except for replacing a broken slide stop. Try getting a high-polish blued one of THOSE.

Made long before MIM parts, too. Snapped the ledge that rides inside the slide to keep it in place.

NukeMMC and Fotomaniac, another thing to note on the GC guns is the cross-pin that holds the earlier Elliason rear signts on. Even with shooting only wadgun loads, those would break and send the rear sight flying into the wilderness. When I inspected then replaced that with a short section of drill rod held in with Loc-Tite, the original was already bent and near to being sheared.

So, that's the second deviation from being box-stock...which I HIGHLY recommend that anyone with that type of rear sight do right away.
I replaced my NM (factory) slide stop with an EGW HD blued .200 slide stop, mainly just to tighten it a bit, and preserve the original. I used a Dremel polishing wheel and lapping paste to try to get that same "mirror" finish. The flat surfaces look shiny but it's definitely not the original look and easy to remove the bluing from the edges with a polisher. IIRC the factory bluing went much deeper than what EGW does.

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