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Old October 5, 2008, 08:30 PM   #1
slickab
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Lockup

I need to know how to check the lockup of the barrel to slide in my 1911. Does and how does lockup effect the accuracy of a 1911? If lockup is not tight how do I fix the problem or is this a problem? I am doing a semi-build or you might could say I am replacing parts on a lower level 1911. Accuracy is improving and this is the next area I would like to address. Your knowledge will not be wasted. Thank you.
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Old October 6, 2008, 07:03 AM   #2
Harry Bonar
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1911

Sir;
The barrel fit on a 1911 needs to be, when in battery, supported by the bottom lugs on the slide stop pin and locked into the upper lugs with no down movement.
Much improvement can be effected by fitting a new front bushing but the real help would be to fit a new Kart or Bar-Sto barrel and a new bushing. Slide to frame fit doesn't do alot for accuracy but we all want that tight also.
A good trigger pull is nice too - about 4#.
But safety is paramount in operation!
Have fun.
Harry B.
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Old October 6, 2008, 11:42 AM   #3
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After checking the gun is empty, put it into battery with an empty chamber and grasp the front of the slide in one hand and the grip of the frame in the other and try to push the slide up and down. If that is rattling at all, you don't have tight lock up. Put a 7/16" wood dowel into the muzzle that reaches back to the throat, and with the empty gun in battery and while holding the grip frame, push the barrel up as far as it goes. Next, put your thumb on the back of the barrel through the ejection port and see if you can push it down? If you feel it move, you don't have tight lockup. A tight lockup won't be moved by the dowel and won't let the slide rattle in the frame.

Why this affects accuracy is simply that firm lockup is the only way to assure the sights are in the same position with respect to the barrel axis each time the gun cycles. Without firm lockup the back of the barrel could come up a little higher on one cycle than it does on another, or a little to the left or a little to the right from one cycle to the next. All these change the position of the barrel relative to the sight line. The effect on accuracy is the same as having loose sights that move around a little from one shot to the next.

Common estimates are that getting the barrel lock-up correct gets you 70-80% of all the mechanical accuracy improvement you will achieve. Fitting a tight bushing will get you another 15-20%, while tightening the slide and frame gets you maybe the last 5-10%. That all assumes you have good components and not a badly crowned or throated barrel or one with an oval cross-section (yes, I've seen that) or uneven rifling depth (I've seen that twice; can you spell keyholing?). Perhaps Harry can confirm or add some examples from his experience that widen those ranges, but they match what I've observed well-enough for government work.

But that was just the mechanical precision. The mechanical accuracy is only about half the story. You still have the practical accuracy component. That is comprised of the things that make the gun easier for shooter to use: better sights, better trigger, better grip panels, a grip safety that is more comfortable, parts that produce faster lock time, a square toe firing pin stop or a muzzle brake for reduced muzzle flip, and so on. For many shooters, the practical accuracy improvements constitute roughly half of what is responsible for actual hit improvements on their targets. In the case of speed disciplines with relatively large targets it can be 70% of what improves their score.
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Old October 6, 2008, 08:58 PM   #4
slickab
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Thank you both for your replies. The front of the slide moves up and down and back and forth and rattles when you shake it. The barrel is tight in the bushing and the bushing is tight in the slide as I recently fitted a NM bushing. The barrel can be pushed down at least 1/32", maybe more through the ejection port.

My next question is, how to fix this? Do I need to replace the barrel? If so, I need a recommendation. Say, a good barrel with enough material to be fitted without breaking the bank. I dont want to go overboard on a pistol I paid $568 for. I also would hate to create an unreliability from a gun that has 600+/- rounds downrange with no malfunctions of any kind. Once again thanks and help!
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Old October 6, 2008, 09:48 PM   #5
drail
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OK, I know some people will laugh at this but I would put a Wilson Group Gripper in it and shoot it until you're ready to fit a match barrel. If your bushing/barrel fit is good then the Group Gripper will tighten the rear end. Then you will be able to judge how good the barrel is. A lot of stock barrels are surprisingly accurate once the fitting slop is removed.
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Old October 7, 2008, 10:25 PM   #6
slickab
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Thanks drail. I have not heard of a group gripper and dont know what it is but if Midway or Brownells sells them then I will find out.
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Old October 7, 2008, 10:47 PM   #7
Slopemeno
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You'll see people at the counter of gun shops shaking and rattling 1911's in all kinds of ways. Heres how you do it: Check the gun to make sure it's unloaded. Point it in a safe direction. Pull the slide back and lower it. Don't dry fire it. With your off or weak hand press down on the barrel hood- did you feel it move? THATS the stuff you want to eliminate.

The vertical lockup is they key to getting a really good shooting 1911.

I had a customers Colt 1991 in the shop for work for an upcoming class, and I have to admit it felt loose. We did a beavertail, trigger job, etc, (but didn't address any accuracy issues) and sent the customer on her way to the clinic. I got a chance to shoot the gun at 50 feet that night, and it shot about 1.5" at 50 feet- THATS NOT BAD. Most of the time it's not the gun, it's the operator-have someone who shoots Bullseye shoot your gun.

If you want match grade accuracy, thats fine. I'd probably approach it by:

1) Match bushing. Dollar for dollar probably the way to go for most folks.
2) Weld up and match fit the existing barrel hood and bottom lugs.
3) Install a fitting-required match barrel.
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Old October 8, 2008, 12:14 AM   #8
Scorch
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Quote:
My next question is, how to fix this?
For less than $10 you can buy a package of oversized or undersized links. Read up on how to fit them.
http://www.brownells.com/aspx/ns/sto...0BARREL%20LINK

Group Grippers work OK, but I would still want the lugs fitted.
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Old October 8, 2008, 08:30 AM   #9
wjkuleck
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Quote:
Thanks drail. I have not heard of a group gripper and dont know what it is but if Midway or Brownells sells them then I will find out.
The "Dwyer Group Gripper" has been around for thirty years or more. It's currently available in both full-length-guide-rod and classic-spring-guide variations. The Group Gripper is comprised of a special link with a protrusion engaged by a short, strong leaf spring protruding from the rear of the recoil spring guide flange. The spring engages the special link, forcing the link, and barrel, upward into engagement with the slide.

Back in the day we didn't have barrels with oversize hoods and fittable locking lugs, so it was a matter of "crank up the welder." For those of us on a budget and lacking the skills and equipment to weld up a barrel and bring it back, the Group Gripper was a Godsend. I've had one in my "Patchwork Colt" (which actually started out as a 1918 Remington-UMC) for over thirty years now, and the accuracy improvement was remarkable with the GI barrel thje pistol came with from the DCM.


Today's pistols are generally fit a lot tighter than that DCM WWII rebuild, so the Group Gripper may not provide the same dramatic improvements as it did for us in the '70's. And, as someone stated, it's always good to fit the lugs. But for old GI pistols in particular, if you don't want to modify them, the Grip Gripper is worth a try.

Regards,

Walt
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Old October 8, 2008, 08:34 AM   #10
wjkuleck
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Quote:
For less than $10 you can buy a package of oversized or undersized links
Folks, please note that the link is there for pulldown only. The barrel feet, camming on the slide stop pin, are what push the barrel upward into engagement with the slide. The link isn't designed to do the job of the barrel feet.

Regards,

Walt
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Old October 8, 2008, 02:00 PM   #11
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True, but a lot of people try to do it anyway. Sometimes they get away with it, but often the long link jams the back sides of the link lugs up against the end of the frame channel in counterbattery, preventing the barrel from properly fitting into the cradle. That not only can mess up feed reliability, but in a bad case can jam the barrel against the slide and prevent proper operation. I've also seen at least one slide stop pin bent by the application of the "Armstrong method" to a gun with a tight link. Cheap slide stop, but it's not right to expect the holes in the frame to apply that much force, just the same. They could be turned oval.

The group gripper can make improvement in a gun with a standard recoil spring. If you have a bullseye gun with a lighter recoil spring, though, you may not have enough recoil spring force to overcome the Group Gripper's leaf spring. That will mean your gun doesn't always go fully into battery. My dad bought one to tune up a Goldcup with a light recoil spring once, and discovered that problem. He gave it to me. I had the same problem with it (12 or 13 lb spring for light cast bullet target loads, probably; I no longer recall). In any event, just be aware to keep an eye out for that.

Nick
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Old October 8, 2008, 03:03 PM   #12
RickB
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Of course, the specs for the M1911 don't call for the lower lugs to ride the slide stop pin, or for the upper lugs to have full engagement with the slide. Those are changes made to the original design for bullseye shooting, and they have become a very popular sort of alternate standard. The barrel, in a within-spec pistol, "floats" between the slide and the slide stop, and that's why a G.I. pistol shoots 3" groups at 50 feet and a match pistol shoots 3" groups at 50 yards.
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Old October 8, 2008, 04:33 PM   #13
wjkuleck
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Quote:
If you have a bullseye gun with a lighter recoil spring, though, you may not have enough recoil spring force to overcome the Group Gripper's leaf spring
Good post, good info, I learned something.

Thanks!

Best regards,

Walt
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Old October 9, 2008, 08:55 PM   #14
slickab
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Okay guys. I appreciate all of the input. I am more educated than before and will commit this information to memory as well as application. Thanks
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