Why I Crimp

stx

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I use the Lee FCD the same way I use sizing dies, powder charges and seating depth, It's a tuning tool for me that is just as important as anything on my bench, I do not use the Lee instructions as I set them up in a completely different manner and in my personal experience I have never seen it hurt a load, I've seen some the groups didn't improve ( although it did tighten up ES and SD's ) but I've seen a bunch that it helped, as I said this is the second time this has happened tom but this instance in particular the weapon had been loaded for two weeks and had been in and out of the truck to the field 40 or so times and dropped once, Like I said this is what works for me and once again I screwed up, Didn't hurt anything this go around as I was close by the house but I was disappointed in myself for not following my protocol from a lesson I learned 30 years ago
After reading all of this thread, I’ve ordered some of the Lee FCDs to see if I can improve accuracy in some of my loads that could use a little improvement. I’m wondering about pressure as some of these loads are pretty close to max! Will the crimp effect pressure enough to be concerned about?
 

CVCOBRA1

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Yes it will change pressure. In an old Lyman manual I have (copy write 1970) they tested for this and other variables. Took one load, a 30-06 with one bullet and powder charge all the same. They changed case brands, primer brands and threw in a crimp. Pressures went from 49,000 all the way up to 62,000. So care must be taken. What was really strange was that fps did not change much at all.
 

stx

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Case brands could change pressure quite a bit......just wondering about crimp alone!
 

CVCOBRA1

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Case brands could change pressure quite a bit......just wondering about crimp alone!
Yes, in that test the crimp alone did raise pressure. I will say that load was a compressed load charge but started out at a pressure that was in range and jumped to a dangerous level. And just changing case brands did change pressure.
 

cape cove

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I would imagine that a crimp would be somewhat similar to jamming in the lands. According to Quickload when a bullet is jammed vs a good ways from the lands pressure is increased by about 7000 psi.
 

ButterBean

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After reading all of this thread, I’ve ordered some of the Lee FCDs to see if I can improve accuracy in some of my loads that could use a little improvement. I’m wondering about pressure as some of these loads are pretty close to max! Will the crimp effect pressure enough to be concerned about?
As stated yes it will but if you use my method it's easy to control and read pressure sign's, and you would really have to crimp extremely hard to duplicate a load jammed in the lands
 

stx

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As stated yes it will but if you use my method it's easy to control and read pressure sign's, and you would really have to crimp extremely hard to duplicate a load jammed in the lands
All of the loads I want to try your crimping method on are already loaded so I think maybe I’ll just very light crimp a couple of each and shoot/chrono them watching for pressure signs! Your thoughts?
 

Ol' Red

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All of the loads I want to try your crimping method on are already loaded so I think maybe I’ll just very light crimp a couple of each and shoot/chrono them watching for pressure signs! Your thoughts?
I just loaded some .300 WM rounds to try at the range. A known good load, some with no crimo and some I did a light crimp with LEE factory crimp die. These loads are a couple grains down from max, but have been accurate. ButterBean was the one that got me interested in trying to crimp. I have been loading for over 35 years, but never crimped my loads. I probably won't chronograph loads, just test for accuracy. All that has to wait until after hunting seasons end in November. If I can wait.
 

ButterBean

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I just loaded some .300 WM rounds to try at the range. A known good load, some with no crimo and some I did a light crimp with LEE factory crimp die. These loads are a couple grains down from max, but have been accurate. ButterBean was the one that got me interested in trying to crimp. I have been loading for over 35 years, but never crimped my loads. I probably won't chronograph loads, just test for accuracy. All that has to wait until after hunting seasons end in November. If I can wait.
How are you Red ? if you do run them over a chrony you'll see that your ES and SD will have tightened up with the crimped loads, I hope all is well with you and yours
 

CVCOBRA1

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The only thing I have ever crimped were pistol loads and 30-30 for a tube magazine. Never had any kind of mishap in the field or at the bench.
 

Ol' Red

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How are you Red ? if you do run them over a chrony you'll see that your ES and SD will have tightened up with the crimped loads, I hope all is well with you and yours
I am good, as is my tribe. I am looking forward to a few weeks of pronghorn hunting and them deer season. The win model 70 in 25-06 is shooting lights out with the new trigger and it gets to go hunting. After that it's back to the range to play. Hope all is well with you and glad to see you stayed with us. Happy hunting, buddy.
 

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