Loading for S&W model 52

I have been loading 148gr HBWC for the model 52 with WST for around 4 years.  I am getting ready to load another batch and was looking at some old data when a couple things that dont make sense popped out at me. 

1.  I get lower standard deviation (velocity) with lighter crimps. (.371")

2.  Most people on this forum load with 2.6 to 2.7g WST and get around 710 fps.  I load with 2.5 and get around 710fps.  (with a .367" crimp). 

I am thinking this might have something to do with how I measure crimps.  I measure at the very end of the crimp just before the caliper falls off the crimp.  I am not sure if others measure this way.  It seems to be a good way for me to compare different crimps that I make, but perhaps it is not a good way for me to compare to crimps others make

Am I doing something wrong?

Doug




my loads are:
2.5 to 2.7gn WST
.367 to .371 crimp
Star cases and Winchester cases
Rem primers and CCI primers
Zero bullets

Crimp, and even sizing die internal diameter affects velocity. Tighter crimps improves combustion efficiency; you get more pop. Factory loads added a cannelure that bites into the skirt adding more bullet pull force. Hard to do that at home.
I'm thinking a lighter faster bullet would help with the slow twist in this gun. Been a while since I played with that. It's true in the 32; the Old Hornady 90 gr hbwc was superb at 50 yards and meh for the 98

I load for my 52 using a roll crimp.   I’ve found it extremely difficult to get a measurement with the crimp given by my dies with an external measurement.  So I “crimp” an unloaded case then I drop in a pin gage to give an idea of what the crimp is trying to form.  I have pins in .354 .352 .350 and .348.  It isn’t so much to get a real value but to set up the die to the same level between loading sessions.

bruce martindale wrote:Crimp, and even sizing die internal diameter affects velocity.

Bruce,
I hadn't thought about the internal diameter of the case.  Maybe my case diameter is too small.
For Zero bullets I use a standard 38 special sizing die.  Then I expand the case to fit the zero bullet with a Lyman M die and a special insert for the M die to fit the zero bullet.  Perhaps my insert is too small (or worn) and dosent expand the case enough.  That would increase the pressure explaining why I only need 2.5 grains WST and everyone else uses 2.6 to 2.7 to get 710fps.
Doug

Wobbley wrote:I load for my 52 using a roll crimp.   I’ve found it extremely difficult to get a measurement with the crimp given by my dies with an external measurement.  So I “crimp” an unloaded case then I drop in a pin gage to give an idea of what the crimp is trying to form.  I have pins in .354 .352 .350 and .348.  It isn’t so much to get a real value but to set up the die to the same level between loading sessions.

Wobbley,
I am using a profile crimp die.  Its basically a roll crimp die that also  reduces (slightly) the case OD.  To get a consistent crimp I found that I had to trim my cases to the same length.  So far I have only had to do it once, when i first obtain the brass.  I also on load only one case type at a time.  That way I (hopefully) keep the entire lot of brass the same length.  Do you trim brass too?  I am only referring to brass for the model 52.  I am not so anal about ammo for other guns.
Doug

Try unresized cases for fun. Use a 45 die to deprime  See what you get. The bullet should start in 1/16 " by hand. If not, you're swaging it during seating

djw1cav wrote:

Wobbley wrote:I load for my 52 using a roll crimp.   I’ve found it extremely difficult to get a measurement with the crimp given by my dies with an external measurement.  So I “crimp” an unloaded case then I drop in a pin gage to give an idea of what the crimp is trying to form.  I have pins in .354 .352 .350 and .348.  It isn’t so much to get a real value but to set up the die to the same level between loading sessions.

Wobbley,
I am using a profile crimp die.  Its basically a roll crimp die that also  reduces (slightly) the case OD.  To get a consistent crimp I found that I had to trim my cases to the same length.  So far I have only had to do it once, when i first obtain the brass.  I also on load only one case type at a time.  That way I (hopefully) keep the entire lot of brass the same length.  Do you trim brass too?  I am only referring to brass for the model 52.  I am not so anal about ammo for other guns.
Doug

Doug:  I segregate brass by make and (roughly) by times fired.  I generally load in 1000 round batches.  So, I’ve never trimmed brass.  My 52 is accurate enough for 25 yards without that and I still have enough 38 WC from the 1980s to satisfy my 50 yard requirements.  

That said, with a profile crimp I might still use the gauge pin technique.

bruce martindale wrote:Try unresized cases for fun. Use a 45 die to deprime  See what you get. The bullet should start in 1/16 " by hand. If not, you're swaging it during seating

Bruce,
I tried inserting a bullet in an unresized case and it did go in about 1/16". 
Doug

Now shoot a bunch using unresized cass