1911WB
Member
My SA GI barrel bushing has a good fit to the barrel (about .002 difference), but its fit to the slide is rather sloppy (about .007 difference). How important is the bushing to slide fit from the accuracy standpoint? 
Semi-dumb question
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Pretty important. Remember that the barrel and slide are moving back while the bullet is still in the barrel and if things are sloppy in the barrel to slide positioning, accuracy will suffer badly. Normally, a target pistol bushing will be fitted to the slide so it cannot be removed without a bushing wrench, but for a more practical gun the bushing need only be a slip fit on the barrel and also in the slide.
Jim
Jim
ClarkEMyers
Member
You tell us, how does it shoot?
Mr. Keenan is of course correct. In particular barrel/slide is many people think much more important than slide/frame.
As an aside barrel/slide can't be completely right if the bottom end and the link aren't right. There are tales of guns with a barrel fit so as to stress (bend) the barrel in battery and the guns may poduce fine accuracy (for a while?) with odd dimensions.
Just the same, I'd say shoot the gun before worrying.
Mr. Keenan is of course correct. In particular barrel/slide is many people think much more important than slide/frame.
As an aside barrel/slide can't be completely right if the bottom end and the link aren't right. There are tales of guns with a barrel fit so as to stress (bend) the barrel in battery and the guns may poduce fine accuracy (for a while?) with odd dimensions.
Just the same, I'd say shoot the gun before worrying.
I don't think there is any doubt that the barrel-slide relationship is more important for accuracy than the slide-frame relationship.
When a 1911 type pistol is fired, the bullet begins to move forward and at the same time the barrel-slide unit begins to move to the rear. In spite of some erroneous pictures showing otherwise, the barrel and slide begin to move back together BEFORE the bullet leaves the barrel, so that any change in their relationship in that period can adversely affect accuracy. Remember the sights are on the slide. While a barrel pointing a bit off can be accurate and the sights can be adjusted to compensate, no compensation is possible if the relationship between barrel and slide changes from shot to shot. Such a change is entirely possible if the barrel and slide are not properly fitted to each other.
The relationship to the frame is not as important. But in a 1911 type pistol, the outside force that causes the barrel and slide to lock together and unlock is in the frame, in the form of the slide stop pin and the link. The frame thus controls the amount and timing of the locking of the barrel and slide, a very critical interface for both accuracy and safety, as well as wear.
So a very sloppy fit of the slide to the frame can cause variations in the locking and linkdown. It is for that reason, not simply tightness for its own sake, that makes slide-frame fit of importance.
Jim
When a 1911 type pistol is fired, the bullet begins to move forward and at the same time the barrel-slide unit begins to move to the rear. In spite of some erroneous pictures showing otherwise, the barrel and slide begin to move back together BEFORE the bullet leaves the barrel, so that any change in their relationship in that period can adversely affect accuracy. Remember the sights are on the slide. While a barrel pointing a bit off can be accurate and the sights can be adjusted to compensate, no compensation is possible if the relationship between barrel and slide changes from shot to shot. Such a change is entirely possible if the barrel and slide are not properly fitted to each other.
The relationship to the frame is not as important. But in a 1911 type pistol, the outside force that causes the barrel and slide to lock together and unlock is in the frame, in the form of the slide stop pin and the link. The frame thus controls the amount and timing of the locking of the barrel and slide, a very critical interface for both accuracy and safety, as well as wear.
So a very sloppy fit of the slide to the frame can cause variations in the locking and linkdown. It is for that reason, not simply tightness for its own sake, that makes slide-frame fit of importance.
Jim
BluesBear
member
Yes the slide to frame fit is important for functioning but barrel to bushing to slide fit is, in addition to affecting function, important for accuracy.
The sights will always be pointing where the slide points.
But if the muzzle is free to move around in the bushing and/or if the bushing is allowed to move about in the slide then the barrel will not always be pointing to the same place in relation to the slide.
The link, the lugs an the hood work together to position the breech in relation to the slide and frame.
The muzzle is held in position my the bushing. This leaves the muzzle as the end where the smallest change creates the largest change in point of impact.
This was the concept behing the Colt Series 70 Collet Bushing. Colt felt if the bushing could ensure the muzzle would return to a precise central location shot after shot that accuracy could be improved over a solid bushing without compromising function. The rub was trying to manufacture a collet bushing with enough flexibility that could stand the recoil forces.
The sights will always be pointing where the slide points.
But if the muzzle is free to move around in the bushing and/or if the bushing is allowed to move about in the slide then the barrel will not always be pointing to the same place in relation to the slide.
The link, the lugs an the hood work together to position the breech in relation to the slide and frame.
The muzzle is held in position my the bushing. This leaves the muzzle as the end where the smallest change creates the largest change in point of impact.
This was the concept behing the Colt Series 70 Collet Bushing. Colt felt if the bushing could ensure the muzzle would return to a precise central location shot after shot that accuracy could be improved over a solid bushing without compromising function. The rub was trying to manufacture a collet bushing with enough flexibility that could stand the recoil forces.
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