Lyman deprime/sizing die undersizing?

ASCTLC · Feb 21, 2017

Hey all,

My Lyman 38/357 mag depriming/sizing die was finished sizing my Starline brass all the way down to .372. I thought my cases looked pretty odd and when loading a cartridge (SWC confirmed at .358) it has a bit of an hour glass look to it.

I looked at my manuals and the spec is .379 outside diameter. I measured the carbide ring at .371.

So I called Lyman and spoke with a customer service lady and asked if there was an issue with the die or is there some possible way I might be causing this issue. She went off to speak with someone and when she came back she said they were sending me a replacement die.

I just got the die, deprimed & sized a fired .3795 outside dimensioned case......and it's all the way down to .372 with this replacement die too. Stubbornly I did it on a second case just to confirm and yep, .372

Long story short: the reloading gear I had prior to losing it all was comprised of this same Lyman 38/357 mag carbide 4 die set but purchased about 10 years ago. This new set purchased about a year ago (just now getting to reloading .357 mag again). I don't recall those previous dies doing this to my ammo. Now, the extent of hour glassing is readily noticeable with these new dies.

Here's my question: Am I nuts? Did I just not notice this before with my previous reloading experience (my lighting is completely different than before)? Am I doing something wrong? Or are these dies actually spot on?

Thanks for any of your thoughts and suggestions!!

Andy

243winxb · Feb 21, 2017

SAAMI is .373" minimum of a loaded cartridge. Maximum is .379"

Just measured my RCBS loaded 357 Starline brass ammo, loaded 2 times. Using a .3575" lead bullet.

Average over bullet .3773"
" Body .3753"
" at web .380"

When i size, there is a gap between die and shell holder , the thicknees of a nickel coin.

I dont see a problem with your die. Measure the brass in 3 days, see if it grows in diameter.

243winxb · Feb 21, 2017

My expander.

Wildfire · Feb 21, 2017

My fired .38/.357s come out of the chamber at .378".
After sizing with my RCBS dies they are .371" and once loaded with my cast bullets of {.358"} the case then is .378" to .380" where the bullets sits.
Yes you can at times see a bulge. It is pretty common.
Nothing wrong with the dies.

ASCTLC · Feb 22, 2017

Thanks guys! I see Walkalong's attachment response to the Lee FCD thread and that is what my finished cartridge looks like. Maybe a touch more hourglass shape but I'm guessing it must be the lighting that can affect just how mush it appears.

Andy

Walkalong · Feb 23, 2017

I just measured to OD of some sized .357 cases (I use the same sizer for .38 Spl and .357), and they are right at .373, so my sizer isn't as tight as yours. If you are uncomfortable with the sizer you can always buy another and see what you get. I bought another trying to get a slightly tighter one because for .38 Spl I feel like it is right on the edge of sizing enough (thinner brass), but the one I got didn't size any tighter. It makes ammo that shoots great though, so I quit worrying about it and just used it. The proof is on the target. If yours makes ammo that shoots great, you have no worries. The expander will (should) bring it out enough anyway.

Yep, quit worrying about what I thought the sizer should do to .38 Spl brass when it could give results like this. (Target at 7 yards shooting through chrono at 5 yards getting numbers.

ASCTLC · Feb 23, 2017

Thanks Walkalong. My concern was/is limited to unnecessary over working of my brass and prematurely wearing it out.

Zendude · Feb 23, 2017

My Starline 32 H&R brass has a similar hourglass shape after sizing and loading with Lee dies. Seems to work so I don't mess with it.

reddog81 · Feb 23, 2017

I use an older RCBS sizing die specifically because it sizes to .375. My Lee die was around .372 and I was having the same issue as you. I like to use cast bullets that measure .358 or .359 and don't want my cases to be sizing down my bullets. If your using jacketed .357 bullets it might not matter.

The RCBS die is a steel die without out a carbide ring. I use Hornady case lube spray and it is very easy to use. I just spray the pile of brass for sizing and everything works just fine.

As a side note the .375 bras doesn't have as much play in the cylinder. Take one of those .372 sized cases and put it in your cylinder. It can flop around. That can't be good for accuracy.

Walkalong · Feb 23, 2017

ASCTLC said:
Thanks Walkalong. My concern was/is limited to unnecessary over working of my brass and prematurely wearing it out.

I can only assume it would lessen case life to some small degree, but I guess the question is would it be enough to be a concern. I don't know.

Walkalong · Feb 23, 2017

reddog81 said:
I use an older RCBS sizing die specifically because it sizes to .375. My Lee die was around .372 and I was having the same issue as you. I like to use cast bullets that measure .358 or .359 and don't want my cases to be sizing down my bullets. If your using jacketed .357 bullets it might not matter.

The RCBS die is a steel die without out a carbide ring. I use Hornady case lube spray and it is very easy to use. I just spray the pile of brass for sizing and everything works just fine.

As a side note the .375 bras doesn't have as much play in the cylinder. Take one of those .372 sized cases and put it in your cylinder. It can flop around. That can't be good for accuracy.

People used to (Still do) load WCs long in .38 Spl thinking that being out in the throat would help alignment, and I still do that with plated buyllets out of habit and the fact they can bulge some cases loaded deeply. But most Bullseye shooters just loaded Lead HBWCs flush, and as far as I know still do. I doubt it would make a difference that I could shoot. Always something to consider though.

mdi · Feb 23, 2017

Yeah, yer nuts! (JK!

). When I was new at reloading I questioned the "wasp waist" feature of some of my cast lead bullet handloads. I first noticed the "problem" when I loaded some DEWC in nickel plated +P brass and they were a tight fit into the cylinder. Being "pre-web", I measured and measured, and shot a bunch. My final "test" was to seat a cast bullet (.358") crimp and then pull the bullet. When I remeasured the diameter of the bullet it had shrunk mebbe .0005"-.001", depending on the brass used and how deep the bullet was seated (I didn't try any of the DEWCs, just 158 gr, LSWCs). So I quit worrying...

Lyman deprime/sizing die undersizing?

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