Crimp groove & cartridge length?

[ljwarner]

Hi Veral,

A while back I had you make a mold for my Browning 53 in 32-20.  You recommended a crimp groove so the mold you made me produced a 115 gr FNGC with crimp groove and cast at .313" with w/w's.  All was perfect until I was setting up my dies and trimming my cases to length.

First, the Trim To Length according to the Lyman 48th manual is 1.305".  All my brass (winchester) was around 1.285" so that was the length I went with.  Upon making a dummy round to check for loading, cycling and chambering I found that during chambering the last tiny bit of bolt travel was difficult.  Ejecting the round found that there were rifling marks in the bullet "shoulder".  I had crimped in the groove so to be able to chamber a round, I had to seat the bullets deeper, beyond the groove.  All's fine-n-dandy but I been thinking lately about this and have come to a couple of different questions.

First, if I WANTED to use the crimp groove, would it be okay to trim the brass short enough to utilize it?  That would mean trimming the brass  to 1.235" give or take .005".  Would this be okay?  The Lyman manual says the trim length is 1.305".

Second, is have a new mold cut without a crimp groove?

Third, have a new mold cut with a crimp groove and just modify the "shoulder" of the bullet so it has more of a taper? 

Thanks for your response.

[ljwarner]

Well, we can scratch out the first question as the cartridge becomes too short to crimp the bullet in the groove, even with a LFC die.  So now it's to continue seating them beyond the groove like I'm currently doing or do one of the other two questions. 

[Veral]

  Your problem is why I try to avoid cutting crimp grooves for levergun cartridges.  The throat vary so much, and change with use, plus the variations in brass as you've encountered, make it near impossible to cut a crimp that is perfectly placed.
  Try seating without crimping, until the rounds chamber with light lever pressure, then factory crimp lightly.  This should solve the problem.  The only reason for crimping rifle cartridges is to prevent bullets being pushed deeper into the case.  With lever guns this is normally caused by the stack of cartridges slaming along in the magazine.  A light crimp fixes the problem.
  If crushing the Lee Factory crimp in makes the bullet move forward a little, because it is only catching the edge of the crimp groove, seat a bit deeper as needed so the crimping brings the bullet out to desired length.

  In my experiance, most rifles, of all chamberings, have chambers cut way longer than the sami specs.  I always leave my brass long if a throat slug indicates there is chamber room for long brass.  Sometimes there will be up to an eighth inch of space ahead of the case.  Even 1/16 inch gap between brass and beginning of throat can allow lead bullets to obturate out into the gap and damage performance, IF THE LOAD IS HEAVY ENOUGH TO OBTURATE THE BULLET. 

  Try the above solution.  Since I recommended the crimp groove, if it doesn't work, I fit the mold into my trash basket and make you another N/C.

[ljwarner]

Veral, thank you for your response.  You pretty much summed up what I'm trying to do.  I appreciate your offer but I was the one that said go ahead and put a crimp groove in.  It's not your fault that Browning likes everything short and tight.  All my Browning levers have throats like this.  I would gladly take them to a good 'smith and have them lengthened but as in my case, there's none close enough that I can drive to reasonably and shipping isn't an option with the good chance of damage or loss.

So, the mold you made me is still perfect.  I'll keep it and order a new one.  Besides I can always sell this one to someone with a handgun or an original Winny.  Not to mention, I also have an excuse to buy one in this same caliber.  A '92 carbine or USFA single action... hummm.

I'll be getting an order ready here in a little bit.

[Veral]

  So long as you are happy, I'll keep grining like a skunk in a dead horse!