Cigar Guy Posted December 16, 2008 Share Posted December 16, 2008 Hi all, I'm trying to rescue a poor, abused Colt Series 70 9mm that came to me with an oversized .45 cal bushing comp that was so loose it pivoted in the slide and let the barrel rattle around inside it. 12" groups at 15 yards were the best it would do, so it has come a long way. The current configuration has a Nowlin barrel, now ramped, and a threaded 4-port cone compensator. I'm trying to get it set up for Bianchi competition, so it will run on 130 PF loads. It is a bit sluggish right now, likely due to the full weight slide. Ejection is basically just outside the port with no real distance on the fired cases. I'm currently running a 9 lb spring and iron sights for break in and reliability testing. After that, off with the sights, and on with a Gilmore shroud and red dot. I'm not opposed to cutting off one or two of the compensator ports, but think I might do better by lightening the slide. Any thoughts on how much weight to remove, or what the target weight for a slide in this configuration gun should be? Thanks. Scott Link to comment Share on other sites More sharing options...
want2race Posted December 16, 2008 Share Posted December 16, 2008 What main spring are you running? Should be a 15 or 17lb spring. You can change the profile of the firing pin stop as well. Link to comment Share on other sites More sharing options...
Action Pistolero Posted December 16, 2008 Share Posted December 16, 2008 Scott, We are running slides that are between 9.5 and 10 oz's. Spring weights are 17 lb mainspring and 7 lb recoil. If the mag sprinds are new you may have a problem there too. Kevin Link to comment Share on other sites More sharing options...
DougCarden Posted December 17, 2008 Share Posted December 17, 2008 Scott, you may end up cutting a port or two off of the comp as well. You just dont have a lot of gas with 130pf loads and the gun will not use much of the comp anyway. It is more of a weight out there at 130pf than anything else, but it will suck energy from the slide with the cone set up. Just food for thought! DougC Link to comment Share on other sites More sharing options...
Cigar Guy Posted December 18, 2008 Author Share Posted December 18, 2008 Mainspring is currently a 17 lb, but firing pin stop is factory profile. Thanks, I hadn't thought of that change yet. That's more of a slide timing issue rather than terminal speed though. I'll probably pull the slide here in a couple days, weigh it, and then cut slots. I don't necessarily want to cut through the outside of the slide, but will if I have to. I'll start with a ball end mill down the top of the barrel channel to thin that up. Do you generally have to cut in the rear as well to get down to 10 oz? Seems like the only place to cut there is into the extractor bore and deep into the opposite side all the way to the ejector. Otherwise, just really deep grasping grooves. 10 oz is also empty weight, correct? If that doesn't work, I'll lose the front port on the compensator. Maybe even lose it at the same time. Doug's right, not much gas flow on a 130 pf Bianchi load. I doubt it will hurt. I want the gun to run smoothly before I put the shroud back on it. Too much USPSA shooting has made my revolver trigger control unreliable for one match a year. I really need to shoot an auto at Bianchi in 2009. Thanks much Kevin, Doug, and Hacksaw Gunsmith whose real name I don't know. I'll report back soon. Scott Link to comment Share on other sites More sharing options...
Flexmoney Posted December 18, 2008 Share Posted December 18, 2008 Scott, Good luck. Keep us poted with the progress. And, look around for pics of lightened slides. Lots of options out there. Here is one place with pics: http://www.gansguns.com/ Link to comment Share on other sites More sharing options...
Cigar Guy Posted December 23, 2008 Author Share Posted December 23, 2008 Flex, Good pics. Thanks for the link. Those give me some ideas for modifying both the slide and compensator. Missed you at Summer Blast. As a related issue, I believe the factory firing pin stop is a 7/32" radius. That's the only spec I have been able to find, and it is for a .45 ACP 1911. Mine is still factory. I suppose I need to stick a radius gauge on this one to verify before I go cutting, but any suggestions for a radius to get the slide moving a little quicker? Kevin, what do your guns end up with for this radius? TIA, Scott Scott, Good luck. Keep us poted with the progress. And, look around for pics of lightened slides. Lots of options out there. Here is one place with pics: http://www.gansguns.com/ Link to comment Share on other sites More sharing options...
Action Pistolero Posted December 23, 2008 Share Posted December 23, 2008 Scott, I use a very unscientific approach. I go to the grinder and create a taper from just below the hole to the bottom of the stop. I stop short of making the edge sharp and then round it off. I would put the slide on a diet. Since you are using a cone lockup you could make the slide look like that of a Beretta. I can try to post some pics when I get home if you want. Kevin Link to comment Share on other sites More sharing options...
Cigar Guy Posted December 23, 2008 Author Share Posted December 23, 2008 Scott,I use a very unscientific approach. I go to the grinder and create a taper from just below the hole to the bottom of the stop. I stop short of making the edge sharp and then round it off. I would put the slide on a diet. Since you are using a cone lockup you could make the slide look like that of a Beretta. I can try to post some pics when I get home if you want. Kevin Sounds like the stop has a huge radius at the limits of the part. If I cut through the top of the slide, I was thinking more along the lines of a Glock 34/35 rather than the full cut from a Beretta. Still reluctant to cut through the top. Into it, sure, but all the way through seems like it is asking for problems. The barrel locking lugs still need some metal to guide them back into place smoothly. Pictures would be great. Thanks. Link to comment Share on other sites More sharing options...
Action Pistolero Posted January 1, 2009 Share Posted January 1, 2009 (edited) Scott, Sorry it took so long. Attached are the pictures. I did some measuring and the radius on the firing pin stop starts 0.160" from the bottom. It's not going hurt the slide to cut all the way through it. I leave plenty of metal and have not had a problem with slides cracking. The slides in the picture on the right are all set up for light loads. The top two are from my action guns. The one in the middle is off of my new gun and is still in the white. The slide at the bottom is from my STI steel gun. I can run a big stick with 29 rounds in the mag and it functions flawlessly. I use a 7 lb spring. Kevin Edited January 1, 2009 by Action Pistolero Link to comment Share on other sites More sharing options...
speculatorking Posted January 1, 2009 Share Posted January 1, 2009 (edited) Action Pistolero, what kind of barrel are you using for your Bianchi guns? Just curious. Nice looking slide work. Looks like you are using a bushing comp on the top slide. Any benefit vs cone style? Edited January 1, 2009 by speculatorking Link to comment Share on other sites More sharing options...
Action Pistolero Posted January 1, 2009 Share Posted January 1, 2009 I've been using Kart's for the past 5 years. I use a bushing in all my guns that I use for accuracy work. The bushings are tight. I have to use a small hammer to get the bushing out of the slide. The bottom slide is set up for a cone. My gunsmith's philosophy has always been that you can replace a $15 bushing alot easier than a slide or cone comp. Link to comment Share on other sites More sharing options...
Cigar Guy Posted January 5, 2009 Author Share Posted January 5, 2009 Scott,Sorry it took so long. Attached are the pictures. I did some measuring and the radius on the firing pin stop starts 0.160" from the bottom. It's not going hurt the slide to cut all the way through it. I leave plenty of metal and have not had a problem with slides cracking. The slides in the picture on the right are all set up for light loads. The top two are from my action guns. The one in the middle is off of my new gun and is still in the white. The slide at the bottom is from my STI steel gun. I can run a big stick with 29 rounds in the mag and it functions flawlessly. I use a 7 lb spring. Kevin With the holidays, I found some time to work on my Bianchi auto and have it almost done. The slide ended up at 10.15 oz. I flat topped it, milled three 3/8 holes on the sides near the front, then laid them back about 30 deg, milled a 1/4" wide slot in the recoil spring guide, and cut a 1.5 inch slot 0.075 deep inside the barrel channel top. I also made some 2.5 inch long cuts on the radiused portion of the slide about halfway through the metal, 0.060 or so deep. Total weight reduction around 2.5-3 oz or so. Not too bad for a little time on the mill. The only problem was caused by Colt making the slide so hard. HSS tools just squealed against it. Carbide was the only thing that made metal move. If I need to take out more weight, I can still cut from behind the breech to the rear sight. I have some photos if somebody can let me know how to reduce the size so they are forum appropriate. I also swapped out the mainspring from my C&S action kit for a 17# ISMI spring. Apparently, the C&S kit spring is around 19# or so, because the trigger pull went from 2.25#, legal, to 1.75#, too light but really sweet. It still has a 9# recoil spring. I'm going to see how it runs with that combination, and will try an 8# and then a 7# if need be. Firing pin stop is still 7/32 inch factory radius. I might bump that to 1/4 inch radius after the next firing test to see if speeding the unlock will help a bit. Thanks for all the help. I'll keep you updated. Scott Link to comment Share on other sites More sharing options...
SharonAnne9x23 Posted January 5, 2009 Share Posted January 5, 2009 Scott, you mention trigger pulls, 2.5# legal, 1.75# too light. Legal and too light by what rules? for which sport? Link to comment Share on other sites More sharing options...
HSMITH Posted January 5, 2009 Share Posted January 5, 2009 If pull weight changed that much with a 2# mainspring change you have some geometry issues between the hammer and sear. Set your pictures up at 800 the big way if you need them that big, 600 should work for most. Sharon, Bianchi has a 2# limit now as I understand it. Link to comment Share on other sites More sharing options...
speculatorking Posted January 5, 2009 Share Posted January 5, 2009 Scott how about some pics of your lightened slide. Link to comment Share on other sites More sharing options...
Cigar Guy Posted January 5, 2009 Author Share Posted January 5, 2009 Scott, you mention trigger pulls, 2.5# legal, 1.75# too light. Legal and too light by what rules? for which sport? NRA Action Pistol rules, instituted about two or three years ago, mandate that all original safeties be intact and functioning, and that trigger pulls not be less than two pounds. I would love to keep it at 1.75# because it will only wear in. I'm using C&S Warp Speed kit with a really light hammer and disconnector. Oh well, have to bend a spring a bit. Link to comment Share on other sites More sharing options...
Cigar Guy Posted January 5, 2009 Author Share Posted January 5, 2009 If pull weight changed that much with a 2# mainspring change you have some geometry issues between the hammer and sear.Set your pictures up at 800 the big way if you need them that big, 600 should work for most. Sharon, Bianchi has a 2# limit now as I understand it. I'll check to see if they are mating correctly, but they are unmodified C&S parts. I agree, if one of the pins is out of round or not straight, I may have bigger problems. The sear spring may have just lost some tension in the reinstallation. I'm going to check parts alignment and bend the sear spring a bit before the test firing. Link to comment Share on other sites More sharing options...
Cigar Guy Posted January 5, 2009 Author Share Posted January 5, 2009 Scott how about some pics of your lightened slide. Trying to attach some now. We'll see if I can figure this out. I've tried to attach the top and bottom of the slide showing the cuts made. Link to comment Share on other sites More sharing options...
Cigar Guy Posted January 5, 2009 Author Share Posted January 5, 2009 Scott how about some pics of your lightened slide. That seemed to work okay. Here are two more, the first is the cone compensator. It had four ports all the same size as the front three, about 3/16 inch wide IIRC. I widened the back port to 3/8 inch, and drilled holes for side ports on the front three. I still haven't decided whether to cut the front port off. I'm leaning towards leaving it alone, especially if the gun runs with the changes I have already made. If it needs more mass removed from the end of the barrel, then the front port goes. When I originally started trying to rebuild this gun, I fitted a Bar-Sto standard, non ramped barrel with a seven port cone compensator. The weight of the comp would actually lift the rear of the barrel and cause it not to go into battery. Thus requiring the frame ramp cut and refitting a different barrel. The second photo is of the gun in test configuration, iron sights and all. As you can see, it has a scope mount already drilled for a Gilmore Bianchi shroud. If the gun runs in test mode, off with the iron sights and on with the red dot. It will probably get refinished at some point also. I'm getting blinded by all this shiny metal. Hardened Colt slides apparently get a nice polished look to them when you cut parts away with carbide. Sorry about the funky light flashes, but this was kind of like taking photos of a mirror. Link to comment Share on other sites More sharing options...
speculatorking Posted January 5, 2009 Share Posted January 5, 2009 Looks like you are pretty handy with the tools, looks nice. I changed my bianchi gun to a 3-port cone comp, from a 7-port. It runs much better on the light loads. Shooting 9x19 minor loads, I don't think requires such a large comp IMHO. Link to comment Share on other sites More sharing options...
Cigar Guy Posted January 5, 2009 Author Share Posted January 5, 2009 Looks like you are pretty handy with the tools, looks nice. I changed my bianchi gun to a 3-port cone comp, from a 7-port. It runs much better on the light loads. Shooting 9x19 minor loads, I don't think requires such a large comp IMHO. Thanks for the compliment. I'm still learning most of the tricks with the 1911. I took the C&S gunsmithing class in the fall of 2005 and built a fairly nice Government length .45 ACP almost exclusively with files. I bought a large and small mill, and a large and small lathe since then and am trying to learn how to use them correctly. I've done some other projects since then, and modified a few other guns in small ways. Most of my projects until now have been .45s, and much easier as a result. The gun was designed to run on full power .45 ACP with that slide weight. When you turn it into a 9mm, it has about half the energy available to drive the system. When you compensate it and start shooting light competition loads through it, you've bled off a significant amount of what little energy you have remaining. They really don't work well when they get to this point. In fact, almost every 1911 gunsmith I discussed this project with told me the compensated 9mm is the hardest 1911 to get running well. All wished me "good luck" in such a tone that I could almost hear "and you are going to need it" afterwards, although all were too polite to say so. Mine ran so slow after I got it back together with the slide still factory weight that I could almost outrun the slide. I tried every recoil spring down to 6# just to get it to cycle. I'll post and let you know how the firing test turns out. I'm thinking Wednesday evening if the weather holds. Scott Link to comment Share on other sites More sharing options...
SharonAnne9x23 Posted January 5, 2009 Share Posted January 5, 2009 Howard and Scott, thank you. I did not know there was a trigger wt lower limit for NRA AP Link to comment Share on other sites More sharing options...
speculatorking Posted January 5, 2009 Share Posted January 5, 2009 (edited) Scott one last word for you. I think you mentioned you were going to use a gilmore shroud. I have one, and they are great. Not many other options. Be sure the 1st port on the comp clears the end of the shroud, or you will be getting a face full of gas and powder when you pull the trigger. If the port doesn't clear the shroud the gases travel down the shroud and back towards you. This was happening to me, not pleasent. After I changed comps, I now have about a 1/4 inch or so clearance from the 1st port to the shroud. I no longer get a face full of gases. I have a 5 inch barrel and had a comp made with the ports moved up slightly on the comp to give me the added clearance. I think some guys are using slightly longer barrels (5 1/2 or 6 inch) and a bushing comp setup (like Action Pistolero's tack driver) which gives the relief you need. Hope this made sense. Good luck. Edited January 5, 2009 by speculatorking Link to comment Share on other sites More sharing options...
Cigar Guy Posted January 13, 2009 Author Share Posted January 13, 2009 Success!!! The combination Kevin gave me was enough to get the gun to run well. Many thanks. I finally got to the range tonight. It was dark and the temperature had already dropped to 20. The gun was basically dry after all the machine work, so I put a little cold oil on the slide rails, some on the hood, and a bit on the cone. Other than that, no lube. The gun ran flawlessly for the two magazines I cared to shoot through it. No feeding jams, and the ejection has moved from 2-3 o'clock barely out of the gun to 4-5 o'clock and about 2-3 feet away. Why only two magazines in the test? Did I mention it got really cold today? It was 50 this afternoon, 36 when I went to dinner, and 20 when I finally got to the range to shoot. Planned accuracy testing with iron sights was abandoned. So the winning combination for now is a 10.15 oz slide, a Nowlin W/N ramped barrel with a threaded cone comp, originally a four x 3/16 port, but with the back port now opened up to 3/8. Fp stop is still the factory 7/32 inch radius, which I may open up after more testing. Main spring is 17# ISMI, and the recoil spring is 9# ISMI. I will have 8# and 7# recoil springs for future testing, preferably when warmer, but I liked the slide speed in returning to battery. I also need to get a reference load and then check the other recoil spring weights to see if slide slap induced muzzle dip is happening. The trigger pull weight I hope to bump up a little over 1/4# by bending the sear spring. Barring that, I'll be back for a bit more advice and some suggestions. Presuming that the testing goes well, I then will knock off the sharp edges, and try it with the Gilmore mount and a PDP5 I found on ebay. I checked, and it does have clearance from the comp, even with the back port being lengthened. After a little sight in and accuracy testing at 25, 35, and 50 yards, the gun will go back to parts for a bit until I can have Ultra Coating put on one of their ceramic finishes. If applied heavily on the slide and frame rails, that can actually tighten up the slightly sloppy fit on a Colt series 70 gun without hammering the rails out. After that, I should be good to go for May. Further progress reports to come. Scott Link to comment Share on other sites More sharing options...
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