scooter123
Member
Are there any gunsmiths offering these for sale?
If not, how many would be interested in having this option?
Things are slow enough at work that I am currently on a 4 day work week. However, we do have 2 vertical CnC machining centers and a CnC lathe. I also have a 620 in very good condition sitting in my safe because it's 6 bucks a box cheaper to shoot 40 Ss&W in my 610. So, I have been doing a bit of pondering. Why not get in a few bars of 436 stainless and running off a batch of 9mm moon clip cylinders for my 620? As for making the moon clips, there are a lot of EDM shops in the Detroit area that are starving for work, having some moon clips cut won't be a problem. I talked to the company owner about this and he's mildly interested.
The problem is the cost of fixturing and programming the machining centers. That would run about 3000-4000 dollars. So, to do this would take a minimum quantity of at least 100 cylinders sold. I also don't know if a firearms manufacturers license would be required to build parts for a handgun and sell them, if so it's probably a no go.
If it looks like a go, here is the plan. I take the cylinder from my 620 and do a full dimensional layout of it and build a 3D model of the cylinder. Then use that model as a basis to design a 9mm specific moon clip cylinder using 0.025 inch thick moon clips. The extractor star and ejector rods would be purchased from S&W. The extractor star would be recut for the moon clips using dedicated fixturing and carbide tools on the CnC machining center. Currently the flange that is recessed into the cylinder measures 0.077 inch thick, so removing 0.025 inch for the moon clip will leave a 0.052 thickness which should be adequate. The cylinder itself would be unfluted (a cost cutting measure) and feature a brushed finish to match the current finish on the stainless S&W's. Bore in the chamber mouths would be reamed using a 0.3565 carbide reamer, exactly 0.001 inch smaller than the bore for the 357/38 spl.. I may also look in double cutting the lead in to the stop notches to eliminate the turn line that every S&W gets when it's used.
Now for the cost. Parts from S&W run about 60 dollars on their current parts list. Assuming 100 units sold, amortizing the tooling and setup would add another 40 dollars. Cost of the material would be 10 dollars. Cost of machinging the extractor would run 25 dollars. Cost of machining the cylinder with all the steps and setup required would run about 100 dollars. Finally, hand checking each cylinder to insure the stop notches were properly "timed" to the cylinder bore would add another 15 dollars. Finally, the cylinders would have to be heat treated to match the heat treat of the current 620/686 cylinder and they would require finishing after heat treat. Cost for that would probably be in the range of 15 dollars. Add in a 40% markup and the total selling price would be in the range of 370 dollars. Add in shipping and packaging and we are probably talking about 400 dollars total.
That is not cheap. However, at a 10 dollar per box cost difference, which is about what I have seen when comparing 38 spl. and 9mm locally, the break even point for a shooter would be about 2000 rounds down range.
For that money, what the customer would get would be a cylinder that would just drop into the yoke and hopefully not require any fitting. Great care would be taken to produce a cylinder that would a near perfect match to the length on my 620 which produces a 0.005 B/C gap.
There is also the cost of the moon clips, which I suspect may run as high as 15 dollars each. One area I would experiment with is if they could be laser cut and then tumbled because a laser could produce these very cheaply. However, a laser cut would produce a rougher surface texture than EDM and that may be a serious issue.
So, I throw it out to my fellow members. Too expensive? Possibly, I am sure that S&W could do the same for around 220 dollars. However, they are not doing this. I'll also state that I have no plans currently for doing a 6 shot version, on an older 6 shooter they would probably require fitting which I do not want to get into.
If not, how many would be interested in having this option?
Things are slow enough at work that I am currently on a 4 day work week. However, we do have 2 vertical CnC machining centers and a CnC lathe. I also have a 620 in very good condition sitting in my safe because it's 6 bucks a box cheaper to shoot 40 Ss&W in my 610. So, I have been doing a bit of pondering. Why not get in a few bars of 436 stainless and running off a batch of 9mm moon clip cylinders for my 620? As for making the moon clips, there are a lot of EDM shops in the Detroit area that are starving for work, having some moon clips cut won't be a problem. I talked to the company owner about this and he's mildly interested.
The problem is the cost of fixturing and programming the machining centers. That would run about 3000-4000 dollars. So, to do this would take a minimum quantity of at least 100 cylinders sold. I also don't know if a firearms manufacturers license would be required to build parts for a handgun and sell them, if so it's probably a no go.
If it looks like a go, here is the plan. I take the cylinder from my 620 and do a full dimensional layout of it and build a 3D model of the cylinder. Then use that model as a basis to design a 9mm specific moon clip cylinder using 0.025 inch thick moon clips. The extractor star and ejector rods would be purchased from S&W. The extractor star would be recut for the moon clips using dedicated fixturing and carbide tools on the CnC machining center. Currently the flange that is recessed into the cylinder measures 0.077 inch thick, so removing 0.025 inch for the moon clip will leave a 0.052 thickness which should be adequate. The cylinder itself would be unfluted (a cost cutting measure) and feature a brushed finish to match the current finish on the stainless S&W's. Bore in the chamber mouths would be reamed using a 0.3565 carbide reamer, exactly 0.001 inch smaller than the bore for the 357/38 spl.. I may also look in double cutting the lead in to the stop notches to eliminate the turn line that every S&W gets when it's used.
Now for the cost. Parts from S&W run about 60 dollars on their current parts list. Assuming 100 units sold, amortizing the tooling and setup would add another 40 dollars. Cost of the material would be 10 dollars. Cost of machinging the extractor would run 25 dollars. Cost of machining the cylinder with all the steps and setup required would run about 100 dollars. Finally, hand checking each cylinder to insure the stop notches were properly "timed" to the cylinder bore would add another 15 dollars. Finally, the cylinders would have to be heat treated to match the heat treat of the current 620/686 cylinder and they would require finishing after heat treat. Cost for that would probably be in the range of 15 dollars. Add in a 40% markup and the total selling price would be in the range of 370 dollars. Add in shipping and packaging and we are probably talking about 400 dollars total.
That is not cheap. However, at a 10 dollar per box cost difference, which is about what I have seen when comparing 38 spl. and 9mm locally, the break even point for a shooter would be about 2000 rounds down range.
For that money, what the customer would get would be a cylinder that would just drop into the yoke and hopefully not require any fitting. Great care would be taken to produce a cylinder that would a near perfect match to the length on my 620 which produces a 0.005 B/C gap.
There is also the cost of the moon clips, which I suspect may run as high as 15 dollars each. One area I would experiment with is if they could be laser cut and then tumbled because a laser could produce these very cheaply. However, a laser cut would produce a rougher surface texture than EDM and that may be a serious issue.
So, I throw it out to my fellow members. Too expensive? Possibly, I am sure that S&W could do the same for around 220 dollars. However, they are not doing this. I'll also state that I have no plans currently for doing a 6 shot version, on an older 6 shooter they would probably require fitting which I do not want to get into.
