Crimp & neck tension

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Crimp & neck tension

Postby BD1 » Tue Jun 09, 2009 4:05 pm

Getting a good crimp is definately an issue with this cartridge.  On calguns I learned a technique some other guys had developed.  This basically involves cutting down a Lee 45-70 factory crimp die so that it will emboss a crimp on the body of the bullet, leaving the case mouth at the proper diameter to head space the round in the chamber.  I also turned some length off the crimp section of the collet to narrow up the crimp band.   I used this technique with limited success on the Nosler 250 grain JHP 43013, and the Hornady 250 grain FTX.  It helped significantly.  However, I'm still getting velocity ES over 150 fps, and SD of over 50, which IMHO indicates pretty poor start pressure consistency.When I drew the 300 grain cast RNFP boolit I wanted to try in this cartridge, I placed a lube groove at a point just .01" below the case mouth to give the "body crimp" an edge to stop against.  This has worked out well.  Velocity ES on the initial testing was 58, and SD was 18.  This is more in the range I'm used to seeing in something like the .44 mag.  With luck, the attachment will be a photo of the boolit and a loaded cartridge showing the crimp.  i have to say that it takes vice grips to pull the boolits when they've been crimped like this, (don't ask why I know that).I also feel that the expander in the hornady die is a bit to large for the .4505 and .451 jacketed bullets.  It works better with the cast boolits sized .452, but if I could get at it, I'd still polish it down a mite.  In my opinion the jacketed bullets would benefit from greater neck tension, and a real cannelure for the body crimp to "seat" into.  I have yet to see a factory loaded round, but I can't imagine thier as loose as what Hornady's dies are producing for me.  Maybe if we could standarize what we're using for a body crimp, we could get Hornady to put a cannalure on thier bullets?  BD
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Re: Crimp & neck tension

Postby MudBug » Tue Jun 09, 2009 7:20 pm

Very cool X's 2

Cool info and cool that the pic shows up like that, I had no idea that attaching a pic would actually show the pic.
Eric

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"War is less costly than servitude. The choice is always between Verdun and Dachau." - Jean Dutourd
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Re: Crimp & neck tension

Postby Siringo » Wed Jun 10, 2009 8:37 am

I have the following questions for those of you using the side crimps with lead bullets:

1. What does this do to the lead bullet as it passes by (lead being softer than brass)?
2. Does it completely iron out during firing (lead being softer than jacketed bullets)?
3. Can it end up reducing the bullet diameter before it hits the rifling (see #1)?
4. What do you think will happen to case life (stretching)?

I have used 45 Colt cases that had a similar crimp to prevent the bullet from pushing downward into the case (not crimped to the bullet) and I had frequent case failures after several loadings as compare to uncrimped cases.
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Re: Crimp & neck tension

Postby BD1 » Wed Jun 10, 2009 12:48 pm

Well, I pulled 40 rounds last night and measured them, (not the reason I pulled them:) . Boolits were all still .452. On the fired cases the crimp is blown out flat. I'm not sure that would allways be the case on "powder puff" loads, but on stuff loaded to around 40,000 psi it's ironed right out. Only time will tell as far as case life. I'm thinking that I need to polish the hard corners off the crimp collet to help prevent case loss due to cracks at the crimp. The ocassional annealing may be in order as well.
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Re: Crimp & neck tension

Postby slash2 » Wed Jun 10, 2009 6:04 pm

For what it's worth, I rounded off the sharp edges on my side crimper, hoping it wouldn't be as hard on my brass.

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Re: Crimp & neck tension

Postby Siringo » Wed Jul 01, 2009 5:57 pm

Today while traveling in WI, I stopped by LEE Precision. I talked to on of the managers about creating a factory crimp die for the 450B. They can make custom crimpers, but the backlog time is at least 6 months (he showed me all the files). LEE has doubled its production with new machines and personnel over that past year. I asked him to look up this site and Calguns to get an idea what we are trying to accomplish. He also suggested a "stab type" die that functions much like the side crimp. The stab type is used on some 45 ACP rounds and military ammo.

IF we all have a common crimp die made in a quantity of 25 or more, the cost would be $14.95 each.

I also suggested that they make dies, trimmers and such as a regular factory item. They were not up to speed on this round. As most in the firearms business -- they are plenty busy.
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Re: Crimp & neck tension

Postby MudBug » Wed Jul 01, 2009 6:55 pm

I would be in for one.

Siringo, let me know if you want a sticky thread about a group buy on these.
Eric

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"War is less costly than servitude. The choice is always between Verdun and Dachau." - Jean Dutourd
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Re: Crimp & neck tension

Postby Volt » Wed Jul 01, 2009 8:25 pm

I'll take one!
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Re: Crimp & neck tension

Postby BD1 » Thu Jul 02, 2009 6:40 am

I'd buy one as well. However, the delivery time on custom molds from Lee is currently over six months, so this is not a good option for someone in a hurry. It's really not to complicated for anyone with a lathe to make one out of a 45-70 FCD.
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Re: Crimp & neck tension

Postby MudBug » Thu Jul 02, 2009 11:42 am

BD1 wrote:I'd buy one as well. However, the delivery time on custom molds from Lee is currently over six months, so this is not a good option for someone in a hurry. It's really not to complicated for anyone with a lathe to make one out of a 45-70 FCD.
BD




Kind of a deal killer for many people.
Eric

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