Crimp Pics

gltaylor

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Posts: 450		Jan 13, 2023 at 8:28pm riceman and lightthetower like this
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Post by BFD on Jan 13, 2023 at 8:28pm​

Took some close ups of the 137HH and 151AH while trying to establish seating depths with a crimp. I crimp with the Redding standard seating die.

308 Winchestershire
:D


137HH @2.760" Case trim length 2.005"
I have it right in the middle of the PDR saddle. That Redding Taper crimp really grabs over the PDR ridge:)



151AH @2.800"
I have it just barely over the PDR hump and prior to the saddle of first groove.
Red arrow shows the "saddle" or valley I guess its been called.
I wonder if crimping to the blue arrow would be of any benefit?








Last Edit: Jan 13, 2023 at 11:03pm by BFD
I fool around and find out!
 
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riceman
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Jan 13, 2023 at 9:10pm carsyn22 and BFD like this
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Post by riceman on Jan 13, 2023 at 9:10pm​

Great pics BFD.👍

I prefer your 137hh, looks perfect to me.
Here's a couple one 26n w/99hh that resembles your 137hh.
Second 25-06 with 92hh. With a bit heavier crimp.

I think personally either of your red/blue arrows
would be great.
 
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Posts: 450		Jan 13, 2023 at 10:57pm riceman, farleg, and 1 more like this
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Post by BFD on Jan 13, 2023 at 10:57pm​

riceman Avatar

Jan 13, 2023 at 9:10pm riceman said:
Great pics BFD.👍

I prefer your 137hh, looks perfect to me.
Here's a couple one 26n w/99hh that resembles your 137hh.
Second 25-06 with 92hh. With a bit heavier crimp.

I think personally either of your red/blue arrows
would be great.View AttachmentView Attachment

Thank you Sir!

You got a couple speedster cartridges there! I like everything about that 137HH so far! The Totem!
:)
Effortless ragged hole groups every time I hit the range. It didn't like being seated where I could crimp like the Totem round. So far the 151AH is only 100fps behind the Totem...
 
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Posts: 107		Jan 15, 2023 at 12:43am BFD likes this
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Post by rbtanzan on Jan 15, 2023 at 12:43am​

Personally, I like the blue line above, because I'm using a Lee Crimp Die for 151gnAH in 308Win.

However, the pics raise a parallel question that would be good to address, the more natural fit of a 'roll crimp'.

A roll crimp into the PDR valley would seem to naturally fit the slope of the PDR ridge down into the valley. But a Lee Crimp Die is more of a flat press down on to the slope.
Have any tested this out? Might the roll crimp be a better fit for the PDRs?
 
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Posts: 450		Jan 15, 2023 at 5:47am riceman likes this
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Post by BFD on Jan 15, 2023 at 5:47am​

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Jan 15, 2023 at 12:43am rbtanzan said:
Personally, I like the blue line above, because I'm using a Lee Crimp Die for 151gnAH in 308Win.

However, the pics raise a parallel question that would be good to address, the more natural fit of a 'roll crimp'.

A roll crimp into the PDR valley would seem to naturally fit the slope of the PDR ridge down into the valley. But a Lee Crimp Die is more of a flat press down on to the slope.
Have any tested this out? Might the roll crimp be a better fit for the PDRs?

I didn't see an accuracy gain at the 2.800" COL. (The previous pic crimp with red & blue arrows) So I moved it to the blue arrow.

This is a taper crimp. I had to look up the difference between roll & taper to understand them. However, yes the taper crimp really "hugs" that PDR profile! I know the Lee factory crimp die is the popular choice on this forum for Hammers. I don't see any problem with the taper crimp though.


I fool around and find out!
 
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Posts: 180		Jan 15, 2023 at 12:26pm via mobile riceman, carsyn22, and 2 more like this
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Post by lightthetower on Jan 15, 2023 at 12:26pm​

Correct me if I’m wrong, but the benefit of the crimp is simply to hold the bullet in the case a fraction of time longer, so that pressure can build in the case a bit before the bullet to land contact takes over and friction becomes the cause of pressure. Hammers have less friction in the barrel, so a crimp gets the whole process started a bit faster, and higher pressure results in more “push”, which corresponds to more speed. So, style of crimp is less important than location for “holding” the bullet in the case…🤷🏻‍♂️
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Posts: 450		Jan 15, 2023 at 12:33pm riceman, carsyn22, and 2 more like this
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Post by BFD on Jan 15, 2023 at 12:33pm​

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Jan 15, 2023 at 12:26pm lightthetower said:
Correct me if I’m wrong, but the benefit of the crimp is simply to hold the bullet in the case a fraction of time longer, so that pressure can build in the case a bit before the bullet to land contact takes over and friction becomes the cause of pressure. Hammers have less friction in the barrel, so a crimp gets the whole process started a bit faster, and higher pressure results in more “push”, which corresponds to more speed. So, style of crimp is less important than location for “holding” the bullet in the case…🤷🏻‍♂️

You nailed it. This is my understanding.
 
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Jan 15, 2023 at 12:47pm via mobile carsyn22, joe16, and 2 more like this
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Post by riceman on Jan 15, 2023 at 12:47pm​

I believe any type of crimp is good thing..
The cosmetics of a taper or roll crimp is in my opinion is definitely more appealing though.

I'm not sure if anyone has done a test to see if one version of crimp is better than another, velocity, es, sd...

There's been a few on various amounts of crimps and groups though.
 
As some would say, it's all coming out in the wash. It's going to be okay.
Check seating depth can very a little with each rifle. Just need to check and see what works best for you.

I think they are a great bullet, (Hammer-Bullets) some people, just run at the mouth hoping to build themself up by running something down; that's not how it works.

Blessing to all on this site.
Take care.
 
Does anyone know what type of crimp the Lee FCD uses?
My guess a taper crimp but it looks like a roll crimp when over a PDR band.

223/60gHH, lee FCD. I trimmed my case to put the crimp right over the top of the second PDR band.
1682912661054.png
 
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