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Revolver cylinder location accuracy
penguin1
Member Posts: 97 ✭
I read of checking to see if one position of the cylinder is more accurate than others. Is this a common procedure?
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Comments
But, for safety purposes, I always check the alignment of each charging hole before buying a used revolver. I use a wood dowel. An alignment failure would shave lead, which would not only cause a flier but threaten the safety of the shooter on the firing point next to me. (I still have a tiny scar on my cheek from a friend's .22 revolver.)
Neal
Timing and alignment is checked with a precision range rod ( like the wooden rod but a better fit). There are other specialized tools- alignment mandrels for the yoke, frame rods to check alignment of barrel to firing pin hole, etc.
Actual machining can be defined in what's called 'Positional Tolerancing'. In pre-CNC days, tooling to control hole locations in cylinders was made and tolerancing allowed a plus/minus deviation. Cutting a hole in six locations in true position is not difficult- even without a computer to figure your radial and x and y locations. I'm not sure what the big gun companies used, but when we bored a cylinder, we had a special lathe fixture that indexed off a master hole location, and each subsequent hole located off it.
Later the concepts and underlying precepts were reinforced / confirmed by those in the cowboy action shooting field - SASS members...
Apparently it was common to find Italian reproduction revolvers were the diameter of the cylinder chambers varied not only from gun to gun but on a single individual cylinder...
Enough to noticeably impact accuracy and shot placement.
I was introduced to the practice of measuring and recording the diameters of each cartridge acceptance chamber on an individual cylinder...
The folk I was interacting with were having their cylinder chambers machined to closer tolerances - the end goal being each cartridge chamber on a cylinder having the same diameter - or having them as close to true / identical as possible...
The practice has been referred to as blue printing or truing...
Subsequently I had this modification performed on several of my own personal revolvers - and was pleased with the results...
Again my introduction was via 1851 Colt Navy reproduction revolvers made in Italy but with further hands on investigation I discovered that the inside diameter variance issue was present on a wide range of revolvers (make - model - age - COO - etc...)
I would humbly suggest that you randomly select revolvers from your own personal collection and perform a forensic investigation...
In addition I think you will find that on any given cylinder you will have cartridge chambers that not only vary in dimension but that such variances indeed do impact accuracy and shot placement / group size...
IMHO
Mike
The use of proper terminology is essential to understanding questions and providing answers. Hopefully you are asking about the alignment of the chambers with the barrel. If not, let me know and I'll delete this response.
Alignment and fitting of parts in a revolver are critical to the function of the revolver but contribute very little to accuracy unless the condition is gross misalignment such as lead spitting, as pointed out above. Revolver gunsmiths go to great lengths to make certain that all the parts of a revolver ARE aligned and that the chambers are the correct size. But this can become problematic when we discuss a used firearms. Getting the revolver to function correctly is critical.
However, accuracy of revolvers is based on a totally different idea. Here is an excerpt from Lt. Col. Douglas B. Wesson and his treatise 'Burning Powder':
With the machine rest we have demonstrated by actual test the fact that with proper alignment of the barrel and cylinder of a revolver, the distance that the bullet has to jump after leaving the shell and before entering the barrel, has, within reasonable limits of jump, no effect whatsoever on the accuracy of the arm. This accounts for the fact that with our K-.22 revolver we can make at 30 feet most excellent machine rest groups using the tiny CB caps, and with .38 S&W Special Mid-Range Wad cutter ammunition in our .357 Magnum at 60 feet we will secure six-shot groups that can be more than covered with a dime.
For those wishing to read the entire excerpt, here is the link:
http://sportsmansvintagepress.com/read-free/burning-powder-table-contents/smith-wesson-revolver-accuracy/
The complete book is also available for purchase at the end of the article.
Best.