Sloppy Slide-to-Frame Fit & Accuracy...
This is a discussion on Sloppy Slide-to-Frame Fit & Accuracy... within the General Firearm Discussion forums, part of the Related Topics category; Hello. Now and again the topic of how "tight" or "loose" a slide can be before accuracy is meaningfully affected. Some report that tight fit ...
November 18th, 2006 11:27 PM
1951 - 2011
Sloppy Slide-to-Frame Fit & Accuracy...
Hello. Now and again the topic of how "tight" or "loose" a slide can be before accuracy is meaningfully affected. Some report that tight fit is essential, not only between barrel and slide, but also between the slide and frame. Others advise that the former is the more important of the two.
I have never personally cared for "crush fit" type lock up, ie: where the gun has to "kerchunk" into lockup. I have always much preferred the slide to "glide" into the firing position without it, but admit preferring minimal slide-to-frame wiggle and especially with regard to the barrel resting in the slide.
In most instances, the guns I've fired which had minimal or no perceptible movement in barrel-to-slide setup shot better groups, but not always. It seems that the key may be how consistently the barrel moves shot to shot. If everything closely replicates itself, it seems that one can get tight groups.
Perusing my pistols, I found that my old '84 CZ-75 has pretty loose fit between the slide and frame but no easily found slop in the way the barrel is fitted to the slide. I had not shot this particular pistol in a good while so I decided to take it to the range and see what I might be able to do with it on paper. (FWIW, most of the CZ-75B pistols I've examined have had better slide-to-frame fit than any of my Pre-B guns.)
This '84 vintage CZ-75 was today's "test" gun...although I will admit that I sort of knew the outcome in advance as I've shot this one for over 20 years. It has what I would call "sloppy" slide to frame fit but the bbl-to-slide fit is rock solid. The barrel is the same one it came with from the factory. The hammer spur was bobbed and the gun's guts and frame were hard chromed decades ago. The slide is a matte blue. It has had no accuracy work done. I forget the gunsmith's name, but he was big in CZ's in the '80's and in Colorado that made the grips. It has a Wolff 18-lb recoil spring as the one that came with it felt undersprung and was replaced years ago with the Wolff's. The only other alterations to this gun from factory trim was that I removed, straightened, and replaced the magazine brake so that magazines would fall free when released.
The CZ was shot with Fiocchi and Winchester 115-gr. FMJ. I also fired it using some of the old original Triton 125-gr. JHP +P, Winchester 127-gr. +P+, and Corbon 115-gr. DPX +P. I also fired a bout 3 dozen 124-gr. Hornady XTP handloads.
I only fired at 15 yards and did so seated and with my wrists braced.
The sights were dead bang "on" with Corbon's excellent DPX load.
The same was try with Winchester's RA9TA 127-gr. +P+. The shot
outside the bullseye was me slapping the trigger and I knew it would be out of the group immediately upon firing it.
None of these groups are outstanding or target match caliber, but they are tight enough for my purposes.
I have experienced similar results with Hi Powers and 1911's as well. That a particular pistol might have somewhat loose slide-to-frame fit doesn't necessarily mean that it is destined to be inaccurate from what I've observed. Having said that, I do not agree with the idea that a nicely-fitted but smoothly cycling automatic is necessarily doomed to jam after a few shots are fired.
This Caspian home-build has a very closely fitted slide and frame as well as bbl-to-slide. I've not subjected it to any "torture" tests but quit worrying about it malfunctioning due to firing after running roughly 700 shots through it w/o cleaning the interior. I did wipe off the exterior of the gun between shooting days. I have no doubt that this one is capable of better mechanical accuracy than the CZ, but I doubt my capability to wring it out of the thing, especially under field conditions.
A pistol with looser slide-to-frame fit probably will not beat one more closely fitted if fired from a Ransom rest. The reason is simple: The pistol is not aimed for each shot. Shot dispersion is negatively impacted under such parameters. It seems to me that IF the slide and barrel are properly aligned and the slide-to-bbl fit is consistent, aimed shots are capable of landing in a small group.
My thoughts are that a nicely fitted pistol that operates smoothly is more desireable than one that is not so nicely fitted, but I honestly believe that so long as the bbl and slide lock up firmly and consistently shot-to-shot, the pistol is capable of more intrinsic accuracy than most of its shooters are.
Often I find that a particular handgun shows a distinct preference for a particular load or bullet weight. Such was not the case with this CZ. It shot the Winchester USA 115-gr. FMJ and Fiocchi about the same as the two high-performance loads mentioned. The same held true for some Hornady 124-gr. XTP handsloads and the old Triton ammo.
Unless we are going into formal bullseye competition, in which case we likely wouldn't be using a CZ or Hi Power, concerns about slide-to-frame fit are probably overblown for most purposes.
I believe that Col. Townsend Wheelan said that "Only accurate rifles were interesting." I sort of feel the same way about handguns, but
believe that a goodly number can "outshoot" their owners, including me. I suggest that our money and time might be better spent for decent ammunition or handloading components and serious range time than seeking to immediately "accurize" the particular handgun.
November 18th, 2006 11:39 PM
Excellent thread Mr. Camp!
I remember wondering when I went to Massad Ayoob's LFI in NH on August 1996 whether I should get a Bar Sto barrel and slide tightening for my BHP Mark II 9mm. Good Mr. Ayoob quickly answered by self-imposed question when he proceeded to cut a ragged one-hole group on the target at distance slightly longer than 10 yards off-hand with S&B 115 grain FMJ.
USAF: Loving Our Obscene Amenities Since 1947
November 19th, 2006 12:16 AM
VIP Member (Retired Staff)
Steve - another welcome contribution! Thank you.
Heck - I love every thread you offer us - always interest and practical results.
My take re slides is - wait for it, very technical description coming up - ''Tight but not too tight'' - haha - make of that what you will.
I do think ultra tight tolerancing can be prejudicial but it does seem that even some good ol AI Gov 1911's which seem sloppy are in fact ultra serviceable and for sure - will not be affected too much by ambient crud.
I do think in the end the greatest accuracy factor will be that resulting from in general terms, ''bushing'' issues. Strikes me that if on lockup the muzzle is well secured in relation to slide and frame then - in combat terms at least - any adverse accuracy effect will be minimal.
I'd rather have a smidgeon of detectable float than none at all. That said my 226 is pretty tight but I discovered too that grease with crud added is far from useful - and so slide lube now is oil.
Chris - P95
NRA Certified Instructor & NRA Life Member. "To own a gun and assume that you are armed
is like owning a piano and assuming that you are a musician!."http://www.rkba-2a.com/
- a portal for 2A links, articles and some videos.
November 19th, 2006 02:27 PM
A few years back, Larry Vickers reported the same thing as Stephen Camp for 1911s. If the sights align with the barrel as the barrel is locked into the slide onto which the sights are mounted, then the fit to the frame isn't a significant part of accuracy. You aim with the sights that are on the slide the is locked up with the barrel.
If the sight is a scope mounted to the frame, as in some race or hunting guns, then slide to frame fit is critical since sight alignment is tied to the frame and not the slide. The frame must have a proper fit to keep the slide uniformly aligned to the frame, the slide that locks up the barrel.
The key is having a good lock and alignment between whatever sighting you have and the barrel.
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