.463 crimp

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Post by Lightfoot on 1/20/2020, 10:23 am

First topic message reminder :

I hear of so many people recommending crimping to .463" and it really baffles me.  At that amount of crimp the lead bullet IS being deformed and not just a little.  I'd like to know why this is helpful and how accuracy can possibly be achieved with an undersized projectile.  Technically leading should also be pretty sever since gasses should blow by and cut the lead.  

When I crimp to .468" I can measure a slight reduction in the diameter of a pulled bullet at the top driving band.  The bottom is still .452" though.  If I go lower than that, I see the bottom of the bullet getting skinny too.  .463" should swage the bullet down to .447" or so.  Not beneficial in my experience.
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Post by straybrit on 1/21/2020, 9:38 am

For me the beauty of the .463 crimp is more complete combustion with lighter loads (mandated for me by disintegrating body parts). I use them exclusively at the short line - where the lighter load also helps with recovery.

For long line I'm still using 4.1g BE with 200g lead and .468 crimp.  Both with the Lee factory crimp die. As with other people above I just get the top 1 - 1.5 mm of the case showing the crimp.

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Post by lablover on 1/21/2020, 10:03 am

Has anyone really compared recoil say with the 160s with like 4.2-4.5 BE as compared to like 3.6 clays and 200 gr swc?  Honestly to me the 200’s feel lighter to me.  Could be me? Or even 200 with BE
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Post by zanemoseley on 1/21/2020, 10:36 am

When I first started loading the 160's I loaded a magazine alternating the 160's and 185's. I could tell a reduction in recoil with the 160's, not huge but noticeable. Both loads were tuned to cycle my tight pistol Jon built with a 9000SC.

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Post by Wobbley on 1/21/2020, 11:00 am

BE Mike wrote:This was discussed a long time ago. Mr. Toyota is a big believer in the .463" crimp. I did some tests and through my pistols, the .463" crimped ammo produced much bigger groups from the machine rest at 50 yards. That being said, that was with my guns. I use a Dillon taper crimp die. A long time ago, the test for crimp was to just make sure that the bullet stayed in place under recoil. There were other articles that promoted a roll crimp for .45 ACP loads. I don't know for certain, but I think that it is likely that Mr. Dinan, Giles, Shockey, et al. used Star machines with Star taper crimp dies. One thing I don't see on here much anymore is accuracy testing at 50 yards. That's where the rubber meets the road!
While testing at 50 is very preferable, MD Waite of the American Rifleman staff in his article on developing pistol target loads stated that in his experience ammunition dispersion is proportional to distance for pistol ammunition at subsonic velocities.  My years of rifle shooting I tested my 600 yard loads at 300 yards.  The dispersion was just 2 times as much.  Now going out to 1000 things get dicey because the bullets go transonic.  

To be sure the rubber meets the road at 50, but the Highpower expression about “winning at 200 standing..”. Can be reworked for pistol as “ Matches are won at  the longline, but they’re lost at the short line.”  So if I have a pistol and load combination that shoots small clusters half the size of the x ring at 25, that load will very likely be good at 50.  And I can take that to the 25 yard line and be confident that points lost were on me.
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Post by PhotoEscape on 1/21/2020, 11:08 am

Jon Eulette wrote:I used 0.468 until I started shooting softer loads. Found I needed 0.465 to get them to run.
Land Variance I see for barrels is 0.442 to 0.443, so driving band still getting good contact in the rifling. Bases are 0.452 and sealing up the gases.
In my experience consistent crimp is more important than OAL or powder charge used.
Last year I loaded some 38 148 hbwc and did not roll crimp the cartridges enough. 50 yd groups were horrible. Added more crimp and they shot on call. 45 more forgiving but not enough crimp will open up the groups some.
I have not tried 0.463, I’ve always thought that to be extreme.
Jon

I suggest starting from paying attention to Jon's post and taking to account few things stated here by JackH.
Firstly - SAAMI spec for 45ACP bore is 0.442" with Rifling being at 0.450"
Secondly - the common wall thickness of the case for 45ACP is 0.009" to 0.01" (there might be variations to both + & - directions, keep this in mind)
Thirdly - SAAMI spec for OD of the 45ACP case is 0.4732"

Taking this as a premise, it is relatively easy to calculate MINIMUM crimp using formula - projectile OD plus two times wall thickness minus 0.04" (don't ask about where this number came from, I've seen it in several places, but nowhere I could find explanation. I guess, it is empirical number derived from experience of many generations of reloaders, so I took it as an axiom). With that and based on the above I calculate MINIMUM crimp for 0.452" projectile as being in the range from 0.466" to 0.468".

Next, I suggest, you need to keep in mind several particulars pertaining to your guns and reloading equipment. Chamber variations may necessitate using FCD type dies for proper chambering. FCD does go down the case beyond top 1/16" while crimping, and will swag bullet inside of the case, and that depends on type of the projectile. Obviously FMJ/JHP will be swagged less then lead/coated one. Consequence of this, - even with slight brass spring back there is, gases will go around bottom of the bullet and force opening of the top of the case in the crimp area. However regardless brass opening will seal the camber and there will be enough of gases to proper projectile through the barrel. So here is the reason for tighter crimp of the lead/coated and lesser crimp for FMJ/JHP bullets.

Now, I do not recommend this to anyone, but my own curiosity borders stupidity at times. So I've experimented with shooting squibs (no powder charge, only primer), and then pushing bullets back. Without much deliberation, with handgun bullets base swagging in 0.001 to 0.003 inch range by itself would not be making much difference. However in combination with bore diameter variations (and that would change based on the number of rounds through the bore!) it might.

All of the above is IMHO, and based on me "playing". In short, my recommendation is to take all suggested / posted here and on other blogs / forums as a base, and then optimize for your own use. If suggestion works for you as is - GREAT! Otherwise you can understand why one ammo / recepie works great in one gun, and another one "hates" it.

AP
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Post by BE Mike on 1/21/2020, 11:27 am

Wobbley wrote:
BE Mike wrote:This was discussed a long time ago. Mr. Toyota is a big believer in the .463" crimp. I did some tests and through my pistols, the .463" crimped ammo produced much bigger groups from the machine rest at 50 yards. That being said, that was with my guns. I use a Dillon taper crimp die. A long time ago, the test for crimp was to just make sure that the bullet stayed in place under recoil. There were other articles that promoted a roll crimp for .45 ACP loads. I don't know for certain, but I think that it is likely that Mr. Dinan, Giles, Shockey, et al. used Star machines with Star taper crimp dies. One thing I don't see on here much anymore is accuracy testing at 50 yards. That's where the rubber meets the road!
While testing at 50 is very preferable, MD Waite of the American Rifleman staff in his article on developing pistol target loads stated that in his experience ammunition dispersion is proportional to distance for pistol ammunition at subsonic velocities.  My years of rifle shooting I tested my 600 yard loads at 300 yards.  The dispersion was just 2 times as much.  Now going out to 1000 things get dicey because the bullets go transonic.  

To be sure the rubber meets the road at 50, but the Highpower expression about “winning at 200 standing..”. Can be reworked for pistol as “ Matches are won at  the longline, but they’re lost at the short line.”  So if I have a pistol and load combination that shoots small clusters half the size of the x ring at 25, that load will very likely be good at 50.  And I can take that to the 25 yard line and be confident that points lost were on me.
I couldn't disagree more. Just about any .45 ACP load will group well at the short line, but absolutely doesn't translate to long line accuracy. I've verified this with my own tests with the machine rest. Rifle and pistol is comparing apples to oranges.
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Post by Vinkemulder on 1/21/2020, 11:30 am

straybrit wrote:For me the beauty of the .463 crimp is more complete combustion with lighter loads (mandated for me by disintegrating body parts). I use them exclusively at the short line - where the lighter load also helps with recovery.

For long line I'm still using 4.1g BE with 200g lead and .468 crimp.  Both with the Lee factory crimp die. As with other people above I just get the top 1 - 1.5 mm of the case showing the crimp.

I agree,  What are you using for your light load?
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Post by Richard Benoit on 1/21/2020, 1:57 pm

Many years ago I Ransom Rest tested groups at both distances by firing through a paper target w/o backing at 25 yds , the bullet continuing , theoretically w/o being deflected by only paper, to impact on a 50 yd target. I found that a tight , perfectly round group at 25 yds would translate to a group twice the size at 50 yds. If a round showed evidence of moving out of the group at 25 , it was likely to open up the group 3-4 times the size at 50 yds. A distinct flyer at 25 yds would be into orbit at 50. I concluded that it's very difficult to extrapolate 50 yd group size from 25 yd testing , once you lose a perfectly round group,YRMV , Richard Benoit

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Post by Jack H on 1/21/2020, 3:09 pm

In other words, if a bullet flies weird at 25, it will fly weirder at 50.
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Post by Richard Benoit on 1/21/2020, 3:14 pm

Jack H wrote:In other words, if a bullet flies weird at 25, it will fly weirder at 50.
Not the most technical description, but highly accurate.

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Post by PhotoEscape on 1/22/2020, 9:58 am

Richard Benoit wrote:Many years ago I Ransom Rest tested groups at both distances by firing through a paper target w/o backing at 25 yds , the bullet continuing , theoretically w/o being deflected by only paper, to impact on a 50 yd target. I found that a tight , perfectly round group at 25 yds would translate to a group twice the size at 50 yds. If a round showed evidence of moving out of the group at 25 , it was likely to open up the group 3-4 times the size at 50 yds. A distinct flyer at 25 yds would be into orbit at 50. I concluded that it's very difficult to extrapolate 50 yd group size from 25 yd testing , once you lose a perfectly round group,YRMV , Richard Benoit

Abstracting from gravity / ballistics effects these findings are supported by mathematics of Right Triangle.  Twice the length of AC side will translate into twice of the length of BC side.  Gravity / balistic's would affect this by pushing projectile down (mostly, unless firing is angled up), so print on 50Y target would be sideways and down in comparison with 25Y one.

As a follow up to previous posts, I thought about providing illustration and data for my 45ACP loads.  I load using three different toolheads on XL650 and one on Star.  Below is the picture of resulting ammo, and further down pertaining information.

.463 crimp - Page 2 45acp-10

Left to right:

JHP loaded on XL650 / crimp is 0.469" with Redding Competition die, 4.1gr BE
200 grain Coated SWC loaded on XL650 / crimp is 0.468" with Dillon die, 4.0gr BE
185 grain Coated SWC loaded on Star / crimp is 0.463" with Star die, 4.4gr N310
160 grain Brazos Coated SWC loaded on XL650 / crimp is 0.465" with Lee die (crimp die, not the FCD!), 4.4gr BE
160 grain Brazos Coated SWC loaded on Star / crimp is 0.463" with Star die, 4.4gr N310.

I have sporadic RR test data, that would take time to compile, and it was done with non-accurized Colt NM GC. If my memory serves me well enough, all the above held 10 ring at 50Y with occasional flyers. I plan of repeating testing as soon as weather permits to shoot outdoors.

AP
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