slide to frame fit

[cletus9mm]

title says it all. many gunsmiths talk about and or guarantee a certain tolerance for a slide to frame fit. how do the gunsmiths building these firearms measure this fit? when a smith guarantees a fit of say .001, is this tolerance .001th per side or is it a total for the both sides meaning that each side has a tolerance of .0005? i would like to measure how much vertical and horizontal play one of my newer 1911's has and measure it again once there are a few thousand rounds on it to see how much it is wearing over time. not sure if this qualifies as "general gunsmithing" but i figure someone on here knows. thank you all for your time and ideas.

[ExtremeShot]

They are talking about a thou clearance between the slide rails and the frame rails (on each side). There's no good way of measuring it. When you hand lap the slide and frame, it provides about a thou clearance. That's what they are refering to.

D

[XRe]

There are ways to measure it, but it requires some tools... Depending on how the gun is finished, you can get a good idea of how well this was done, based on the wear pattern on the rails of both pieces... Not every hand lapped fit is the same Generally, though, you'd want a thou clearance all the way around as a starting point. The better the contact in the initial fit, the longer that fit will last. Realize, too, that too tight a fit can cause the gun to be unreliable, so... going tighter than that can be problematic until the gun shoots itself a little looser...

[CocoBolo]

If you have a fixture where you can solidly mount the gun you can use a dial indicator to measure the slide side to side walk and slide vertical walk. Measure it now for a base line then perform the same measurement later for comparison. I would say if it is fit within .001 you won't get a measurement. Slide slop can be a factor but more important is how the barrel locks up and that the bushing or cone comp is snug, so you might want to measure that baseline as well.

Edited May 27, 2010 by CocoBolo