saxguy
07-16-2014, 06:18 PM
I have only recently tried some Cerrosafe (low temp casting alloy) which I got from Brownells. I will say more on this later.
I recently acquired two no dash S&W 586 revolvers and a new Ruger SRH .44, and I cant tell you how happy that made me. Also I am setting up to start casting for these pistols and wanted to slug each of them.
Having not done this for many years, I thought I would refresh my memory and also take in all the information I could glean from the various forums etc. Back in 1980, when I bought my first S&W, the gunshop owner told me how to slug the bore, and get a sizing die to that exact measurement. Since then I have learned much about guns, ballistics etc, and I know that there is more to the subject than that.
I decided to firstly go through each handgun and assess them before I even considered ordering any sizing dies. I checked everything ie end shake, timing, alignment of yolks, barrels, chambers, headspace, cylinder to barrel spaces, bore size, chamber throat sizes, forcing cone/angles, borescoped the barrels etc etc.
All in all I had a great time. The written results and notes paint a picture of each weapon, and it has helped me understand the functioning and complexities and skill involved in not only the manufacture (especially the hand fitting of the S&W’s), but also the relationship between tolerance and function/accuracy.
I have put a few rounds through each gun, as part of the initial assessment. The Ruger was unbelievably accurate with ¾ full loads of jacketed 240g HP. In fact I couldn’t believe the results I was getting, seeing as it has been years since I owned a .44, and I was a little flinchy at first. The two Smiths, well I wasn’t so impressed with their accuracy, but then the ammo was second rate, some reloads from many years ago.
So, back on the bench, I found that the .44 had a chamber throat that was approximately .002” larger than the bore size. Specifically, the bore was showing .4295 and the cylinder throats were .4315” so there was a fair old squeeze as the boolits got to the bottom of the forcing cone and into the bore. But, as I said, the accuracy was amazing!
Regarding the Cerrosafe, after taking a cast of both the cylinder throats and the barrel, I put the barrel cast slug into the cylinder throats (each in turn) and it dropped in with a barely perceptible bit of wiggle room, in fact a smooth drop fit (being approx 2tho smaller). Thinking about it, this must be an ideal situation, as the boolit should be a tight fit in the bore, marginly larger than the bore in fact, which would be the case as demonstrated here. So that will be my new “guide” to a revolvers best relationship between its cylinder throat sizes and its barrel bore. So simple. If all things are equal (all chambers are the same etc), and the barrel is good etc etc, then if you make a slug from the barrel, it should fit just nice and loose (but not rattling around) into the chamber throats. A sizing die should then be made to the chamber throat dimensions/s.
Now, the Smiths on the other hand, well they were not as such. The first one (a 6” 586) when a bore slug was pushed into the chamber throats, it was a really tight fit. The bore measured .3575 and the cylinders measured only .358 although there seems a half thou when measuring, the bore cast plug did bind a little when trying to push it into each chamber throat.
The next gun, a 4” 586, well the bore on this gun measured approx .357 but no way would the bore slug fit into the chamber throats. I tapped in the slug using a brass hammer, and it shaved off about a half a thou around the slug as it went in. In other words, the cylinder throats are slightly smaller than the bore of the barrel. Interestingly enough, this was the least accurate of the guns at the range test. Yes, even allowing for the slightly shorter barrel.
Also, the cylinder/barrel space on this gun is off on a cant. Being 5tho on one side and sloping off to 12thou on the other, (this will be addressed later).
So, being the perfectionist that I am (I know, it’s a curse), I will be taking the cylinder throats out to .358 at a minimum, maybe even .3585 in both guns. In that way I will get a better boolit fit, and a one fits all sizing die at maybe .359
Anyway, that’s the story of my “getting my feet wet” for the first time with Cerrosafe. It is a great and fairly easy process, and to be able to actually “see” a casting of the barrel bore, and each chamber, it makes it easy to understand the relationship between the two, when you “pop” the cast slug into the chamber throats. A picture paints a thousand words as they say.
I hope this is of some use to some of you guys.
Regards
I recently acquired two no dash S&W 586 revolvers and a new Ruger SRH .44, and I cant tell you how happy that made me. Also I am setting up to start casting for these pistols and wanted to slug each of them.
Having not done this for many years, I thought I would refresh my memory and also take in all the information I could glean from the various forums etc. Back in 1980, when I bought my first S&W, the gunshop owner told me how to slug the bore, and get a sizing die to that exact measurement. Since then I have learned much about guns, ballistics etc, and I know that there is more to the subject than that.
I decided to firstly go through each handgun and assess them before I even considered ordering any sizing dies. I checked everything ie end shake, timing, alignment of yolks, barrels, chambers, headspace, cylinder to barrel spaces, bore size, chamber throat sizes, forcing cone/angles, borescoped the barrels etc etc.
All in all I had a great time. The written results and notes paint a picture of each weapon, and it has helped me understand the functioning and complexities and skill involved in not only the manufacture (especially the hand fitting of the S&W’s), but also the relationship between tolerance and function/accuracy.
I have put a few rounds through each gun, as part of the initial assessment. The Ruger was unbelievably accurate with ¾ full loads of jacketed 240g HP. In fact I couldn’t believe the results I was getting, seeing as it has been years since I owned a .44, and I was a little flinchy at first. The two Smiths, well I wasn’t so impressed with their accuracy, but then the ammo was second rate, some reloads from many years ago.
So, back on the bench, I found that the .44 had a chamber throat that was approximately .002” larger than the bore size. Specifically, the bore was showing .4295 and the cylinder throats were .4315” so there was a fair old squeeze as the boolits got to the bottom of the forcing cone and into the bore. But, as I said, the accuracy was amazing!
Regarding the Cerrosafe, after taking a cast of both the cylinder throats and the barrel, I put the barrel cast slug into the cylinder throats (each in turn) and it dropped in with a barely perceptible bit of wiggle room, in fact a smooth drop fit (being approx 2tho smaller). Thinking about it, this must be an ideal situation, as the boolit should be a tight fit in the bore, marginly larger than the bore in fact, which would be the case as demonstrated here. So that will be my new “guide” to a revolvers best relationship between its cylinder throat sizes and its barrel bore. So simple. If all things are equal (all chambers are the same etc), and the barrel is good etc etc, then if you make a slug from the barrel, it should fit just nice and loose (but not rattling around) into the chamber throats. A sizing die should then be made to the chamber throat dimensions/s.
Now, the Smiths on the other hand, well they were not as such. The first one (a 6” 586) when a bore slug was pushed into the chamber throats, it was a really tight fit. The bore measured .3575 and the cylinders measured only .358 although there seems a half thou when measuring, the bore cast plug did bind a little when trying to push it into each chamber throat.
The next gun, a 4” 586, well the bore on this gun measured approx .357 but no way would the bore slug fit into the chamber throats. I tapped in the slug using a brass hammer, and it shaved off about a half a thou around the slug as it went in. In other words, the cylinder throats are slightly smaller than the bore of the barrel. Interestingly enough, this was the least accurate of the guns at the range test. Yes, even allowing for the slightly shorter barrel.
Also, the cylinder/barrel space on this gun is off on a cant. Being 5tho on one side and sloping off to 12thou on the other, (this will be addressed later).
So, being the perfectionist that I am (I know, it’s a curse), I will be taking the cylinder throats out to .358 at a minimum, maybe even .3585 in both guns. In that way I will get a better boolit fit, and a one fits all sizing die at maybe .359
Anyway, that’s the story of my “getting my feet wet” for the first time with Cerrosafe. It is a great and fairly easy process, and to be able to actually “see” a casting of the barrel bore, and each chamber, it makes it easy to understand the relationship between the two, when you “pop” the cast slug into the chamber throats. A picture paints a thousand words as they say.
I hope this is of some use to some of you guys.
Regards