Sizing 10 mm with powder coat

[W.R.Buchanan]

Good advice overall, except that a crimp to .417 would be excessive. Anything beyond .422 with Starline cases will turn the case mouth into the bullet. No bueno. With a 401 boo lit, anything narrower than 423 is more than straightening the bell. Brass thickness .011x2 + 401 = .423".

I heard what you said, but I disagree totally. The purpose of the crimp is to hold the boolit in place and to prevent boolit setback. Relying on case neck tension is not always enough to insure that setback doesn't occur, and especially on calibers like 10MM where the cycling of the gun is more violent than lesser calibers.

You are one of the people who only uses the crimp die to remove the case bell. I consider this to be very risky and especially on a High Pressure Cartridge like the .40 S&W/10MM.

I use the crimp to actually penetrate into the boolit and create a step to prevent boolit setback when the pistol is cycling. If you look closely at Factory Ammo that is what you will see. Also there is still enough case mouth exposed to headspace reliably.

Boolit setback causes pressure spikes which in the case of these high pressure rounds is really no bueno !

I got that .417-.418 number directly from and article on loading .40 S&W by Brian Pearce in Handloader Magazine. Since the .40 is nothing more than a shortened 10MM the same holds true for it. I have loaded and fired literally thousands of rounds like this both on a Dillon SDB and a 550B and fired in two different Glocks and a Kel-Tec S2K rifle.

But,,, and I want to emphasize this,,, Comparing your reloaded ammo to Factory Loaded Ammo is one of the best things you can do as a reloader. If you can compare your ammo directly to factory ammo and it measures the same and looks the same, as long as your powder charge is not too much,(which is really the only variable) your ammo will run reliably and be safe.

Here is Pic of a Winchester NT Factory Loaded Round. The case mouth is .418 on the nose with my calipers. Just for giggles I went down to the shop and measured it on my Optical Comparator. .41765

One of the problems that arises is actually getting a good measurement right at the case mouth with dial calipers. It is difficult for many, including myself, who has been a machinist for 35+ years.

There is a reason why the factories load ammo the way that they do, and it is pretty simple really.

It is the safest ammo you can obtain. If they didn't need the crimp do you think that over the course of literally billions of rounds that they wouldn't eliminate it. It would save a bunch of money, and they are definitely doing this for the money!

The only subtraction from that money would come from lawsuits.

We as reloaders are only trying to duplicate that level of safety as much as possible in our homes and garages. But we don't have the resources to test our reloads beyond shooting them.

Many people do as you suggest, many do what I have laid out.

This is America and you have a choice! And of course YMMV

Randy

[popper]

I load on a single state press and do the eating and crimp is separate steps. When seating I can feel a loose boolit. When I crimp (just get a shiny ring at the mouth), again, by feel. I don't trim pistol brass so I get a proper crimp independent of case length. I don't bother separating by H.S. I plunk test every round that goes in a S.A. - don't like surprises. Every once in a while a hard alloy or thicker case will bulge and I just run it all the way down in the RCBS seater/crimper. I use those for plinking and sometimes I get leading but the next (good) one cleans barrel pretty good.

[Taterhead]

I heard what you said, but I disagree totally. The purpose of the crimp is to hold the boolit in place and to prevent boolit setback. Relying on case neck tension is not always enough to insure that setback doesn't occur, and especially on calibers like 10MM where the cycling of the gun is more violent than lesser calibers.

You are one of the people who only uses the crimp die to remove the case bell. I consider this to be very risky and especially on a High Pressure Cartridge like the .40 S&W/10MM.

I use the crimp to actually penetrate into the boolit and create a step to prevent boolit setback when the pistol is cycling. If you look closely at Factory Ammo that is what you will see. Also there is still enough case mouth exposed to headspace reliably.

Boolit setback causes pressure spikes which in the case of these high pressure rounds is really no bueno !

I got that .417-.418 number directly from and article on loading .40 S&W by Brian Pearce in Handloader Magazine. Since the .40 is nothing more than a shortened 10MM the same holds true for it. I have loaded and fired literally thousands of rounds like this both on a Dillon SDB and a 550B and fired in two different Glocks and a Kel-Tec S2K rifle.

But,,, and I want to emphasize this,,, Comparing your reloaded ammo to Factory Loaded Ammo is one of the best things you can do as a reloader. If you can compare your ammo directly to factory ammo and it measures the same and looks the same, as long as your powder charge is not too much,(which is really the only variable) your ammo will run reliably and be safe.

Here is Pic of a Winchester NT Factory Loaded Round. The case mouth is .418 on the nose with my calipers. Just for giggles I went down to the shop and measured it on my Optical Comparator. .41765

One of the problems that arises is actually getting a good measurement right at the case mouth with dial calipers. It is difficult for many, including myself, who has been a machinist for 35+ years.

There is a reason why the factories load ammo the way that they do, and it is pretty simple really.

It is the safest ammo you can obtain. If they didn't need the crimp do you think that over the course of literally billions of rounds that they wouldn't eliminate it. It would save a bunch of money, and they are definitely doing this for the money!

The only subtraction from that money would come from lawsuits.

We as reloaders are only trying to duplicate that level of safety as much as possible in our homes and garages. But we don't have the resources to test our reloads beyond shooting them.

Many people do as you suggest, many do what I have laid out.

This is America and you have a choice! And of course YMMV

Randy

Off topic, so what I had written here originally is deleted. We're just going to disagree on a few points.

[cwlongshot]

Slugged my Glock 20 barrel. .398 on low side and .402 on the high side. I just ordered the Lee 6 cavity TC mold which is .401. I'm hoping powder coating adds enough dimension to add some to it. Was curious of what sizer die I should order. Going to use a push through bushing from NOE. Any suggestions would help. Coot sent me some lubed .402 and they leaded the barrel pretty bad. No ones fault but mine. I stripped lube off and they come out about .405 powder coated. Hard to seat at that thickness. Just trying to keep from buying Lone Wolf or KKM barrel.

Did you discover the solution to your issues here?

I have shot allot of 10mm. Thru five different guns two where glocks and in those two three different barrels including a LW and a KKM.

I shoot PC from six different designs and all get sized to 401. Hard to soft mild to “Wild”.

CW

[Lloyd Smale]

I size after I coat and size all my 10s and 40s to 401. Glocks, smiths, and sigs. Now im not going to tell you that's absolutely the best size for accuracy because I quit benching black guns years ago. I might sit and shoot 10 shots out of a new gun just to make sure its expectable but there not target guns and if I want tiny groups ill take out a 1911 or a revolver. Add to that a bigger bullet is just more likely not to run a 100 percent. It might run fine for you in a clean gun but after a 100 rounds it just might make it choke. Little bit to much of a bulge and the one time you need it to run it might not. Reliability is more of a concern with black guns to me then small groups. Don't bother with the wolf barrel. I bought one for my 20 and it was to tightly chambered even for 401s and didn't shoot a bit better with cast then the factory barrel. Id say it was a waste of a 100 bucks but I got 75 out of it used.

[scotner]

Don't write off black plastic guns for accuracy. This was my first outing with boolits from the Lee 6 cavity and sized with the Lee .401 sizer. These were the starting loads for Bullseye, 231, Unique and AA #5 using data for the Lyman 401638 from Lyman 47th manual. AA #5 looks promising. Shot from a sandbag at 15 yards with the XDm 10 OSP. It was 95° yesterday and this was supposed to be mostly a coating test so I did not spend a whole lot of time out there. The smaller holes dispersed around the target are 357 Sig from a Glock. Not sure yet how that one is going to work out.