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Trimming 45 colt brass

This is a discussion on Trimming 45 colt brass within the Reloading forums, part of the Firearm Forum category; Originally Posted by Iowegan Mark204, You asked so here it is: For semi-auto ammo, taper crimps are used for three reasons. The first being to ...


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Old February 12th, 2017, 10:58 AM   #16
 
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Quote:
Originally Posted by Iowegan View Post
Mark204,

You asked so here it is: For semi-auto ammo, taper crimps are used for three reasons. The first being to help secure the bullet in the case and prevent it from pulling out or pushing in during feeding. The risk when you don't crimp, or don't crimp enough is .... a bullet can get seated too deep while feeding and cause chamber pressure to elevate to dangerous levels. Sometimes the bullet gets pulled forward when the slide slams home. This can place the bullet against the lands and also increase chamber pressure. Either way, a bullet that is not secured tightly in the case will move forward or rearward .... maybe both, which will cause erratic chamber pressure with poor accuracy and possibly result in disaster.

The second reason is the very design of a semi-auto chamber. If you look closely in any semi-auto barrel, you will see a "stop" in the bore where the camber meets the lands and is just a little larger than bullet diameter. The concept is .... the cartridge will enter the chamber until the case mouth contacts the "stop". This is called head spacing on the case mouth versus a rimmed revolver case that headspaces on the rim. Headspacing is measured from the cartridge head to the breach face so the deeper a case is allowed to seat, the longer headspace will be. Typical handguns have about .010" of headspace (assuming SAAMI spec case length in pistols) Headspacing is one of the leading issues with accuracy in any gun so by controlling case length, you also control headspace and accuracy.

Last is your concept ... to assist with feeding. Cartridges feed much better when the sharp case mouth is not stubbing on the feed ramp or chamber mouth. Some pistols are more tolerant and feed pretty good even if the cases are not crimped while others gag and malfunction when cases are not perfectly crimped.

So how does trimming affect crimp? Both Roll and Taper crimping are sensitive to case length so when all cases are trimmed to the same length, your crimp die will apply the same exact crimp to each case. This solves all three of the above issues.

My cases get trimmed after the first firing. This makes all cases in the batch exactly the same length and results in very uniform crimps. Straight wall revolver and semi-auto cases do not "grow" much when fired .... less than .001" per time fired, unlike bottle neck rifle cases that grow about .005" per time fired. As such, I never trim them again. For match grade ammo, only cases that have been fired 3 times or less will qualify and those cases will maintain a very uniform length.

Is it a hard core requirement to trim straight wall cases? No, they will still function but they function just a little bit better when the brass is the same length so a uniform crimp can be applied. I guess it all depends on what accuracy you expect with your pistol and how much risk you are willing to assume for Kabooms.

One thing that has not been addressed is "over crimping". Many people think if they apply a harder crimp, it will hold the bullet tighter. With lead bullets, that is probably true but with jacketed bullets that don't compress, a harder than normal crimp means you will stretch the case and actually end up with less neck tension. This becomes obvious if you really over do it because the case will start to buckle like an accordion. A simple test after you complete a round will tell the tail .... measure the COL then grab a cartridge and push it nose first against your reloading bench with all your might. Measure COL again, if it is the same, you have a solid crimp. If COL is less, chances are you over crimped the case.
Quote:
Originally Posted by vaguru View Post
I thought that's what a taper crimp was for, eliminating trimming of straight wall handgun brass.

Shot hundreds of thousands of 38 spl and 45 acp in competition, never trimmed any. Guns shot 38's inside 1 1/2" and 45's shot inside 2" groups out of a Ransom machine rest at 50 yds.

Guess that was good enough.
Thanks for taking your time to go through all of that, but that I already knew.

My Statement was made of because of what vaguru said. In 30 years of reloading I have never heard of someone using a taper crimp to ELIMINATE trimming of a straight wall handgun case.

I have read what you wrote at least three times, and no where in the text do you say using a taper crimp will ELIMINATE case trimming. I wanted someone to explain to me HOW a taper crimp ELIMINATED case trimming.

I think you missed what I was saying initially.


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Last edited by Mark204; February 12th, 2017 at 11:38 AM.
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Old February 12th, 2017, 11:10 AM   #17
 
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I trim handgun cases to maintain uniform length so that I will get uniform crimps. Generally, I only have to trim once. I recently bought about 500 once-fired .45 ACP cases for practice ammunition and ran them all through the trimming process - most cases were barely touched (it did even up the case mouths on some), but there were a few that were significantly longer than the others.

With my .45 Colt cases, however, I generally load a batch at a time and all have the same headstamp; I haven't measured the difference between different headstamps.

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Old February 12th, 2017, 11:34 AM   #18
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Mark204, I think the issue is .... good crimps don't eliminate case trimming, they require it. If you "knew all this stuff", your knowledge sure isn't reflected in your post! Sorry I wasted my time trying to help you go beyond FTFs.
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Old February 12th, 2017, 11:42 AM   #19
 
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Mark204,

When I stated taper crimping eliminates trimming, it was not meant that over length cases don't need to be trimmed. It was a little "tongue in cheek".

If the cases are within specs for length, then a taper crimp will give the same crimp at the base of the bullet regardless of case length. Will there be a "tad" more crimp on a case that is say .002" longer than the rest, yes, but not enough to worry about, or cause accuracy issues.

Now if we are using a roll crimp, and the case is .002" longer than what the crimp die was set for, then as Iowegan mentioned, you can get over crimping to the point of a bulge.

Taper crimps are more tolerant of inconsistent case lengths. Proved it many times over through a Ransom machine rest.

When I shot my S&W 52 competitively in center fire matches, all my cases were the same length, but for practice that brass was never trimmed. Groups out of the Ransom rest showed minimal difference in group sizes, usually less than 1/8".

So to sum it up, if cases are over length, yes they need trimmed. But if they are within specs a taper crimp gives better accuracy than a roll crimp.

Sorry if I confused you.
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Old February 12th, 2017, 12:09 PM   #20
 
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Quote:
Originally Posted by vaguru View Post
Mark204,

When I stated taper crimping eliminates trimming, it was not meant that over length cases don't need to be trimmed. It was a little "tongue in cheek".

If the cases are within specs for length, then a taper crimp will give the same crimp at the base of the bullet regardless of case length. Will there be a "tad" more crimp on a case that is say .002" longer than the rest, yes, but not enough to worry about, or cause accuracy issues.

Now if we are using a roll crimp, and the case is .002" longer than what the crimp die was set for, then as Iowegan mentioned, you can get over crimping to the point of a bulge.

Taper crimps are more tolerant of inconsistent case lengths. Proved it many times over through a Ransom machine rest.

When I shot my S&W 52 competitively in center fire matches, all my cases were the same length, but for practice that brass was never trimmed. Groups out of the Ransom rest showed minimal difference in group sizes, usually less than 1/8".

So to sum it up, if cases are over length, yes they need trimmed. But if they are within specs a taper crimp gives better accuracy than a roll crimp.

Sorry if I confused you.


Now that is funny........I took that at face value and to top it off I had the Iowegan up my a$$. He wrote a book, but all I wanted to know was how does a taper crimp eliminate trimming.

This statement makes sense, had you said this from the get go, I would have never said a peep.


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Old February 12th, 2017, 12:16 PM   #21
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vaguru, Your post pretty much goes against everything I learned. A taper crimp die will NOT provide the same crimp and neck tension with different length cases .... it's just not possible.

I'm used to dealing with match grade ammo that produces sub-half inch groups or better at 25 yards from a Ransom Rest and it takes a lot of effort to get to that level of accuracy. Your S&W Mod 52 is an excellent pistol .... I know because I used to have one. It is a 38 Special designed specifically for 148gr LHBWCs where the bullet is flush with the case mouth and barely has a crimp ... just enough to remove the flair from the expander die. That said, the Mod 52 is a very poor example for this thread because it is one of the very few pistols designed to shoot revolver cartridges .... ie cases that headspaces on the rim .... not the case mouth. In fact you could trim a 38 Special case way back and still develop excellent accuracy.

Roll crimp or taper crimp is not a candidate for a difference in accuracy .... it's primarily intended for crimping revolver cartridges with a roll crimp versus crimping semi-auto cases with a taper crimp. There are a few exceptions .... one being a 45 Colt when 45 ACP bullets are used. Semi-auto bullets do not have a crimp groove or cannelure so using a 45 ACP crimp die on 45 Colt cartridges with 45 ACP bullets is a decent solution. Also, many of the newer plated bullets do not have a crimp groove or cannelure so taper crimp dies can be used. If you try to apply a roll crimp to a non-cannelure plated bullet, it may cut through the plating and end up causing all sorts of lead fouling.
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Old February 12th, 2017, 12:21 PM   #22
 
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Quote:
Originally Posted by Iowegan View Post
Mark204, I think the issue is .... good crimps don't eliminate case trimming, they require it. If you "knew all this stuff", your knowledge sure isn't reflected in your post! Sorry I wasted my time trying to help you go beyond FTFs.
I'm sorry you wasted your time too...........something was here missed on both sides.

vaguru clarified his statement.



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Old February 12th, 2017, 12:28 PM   #23
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Mark204, Sometimes it pays to be a bit more informative with your questions and comments. I took your post #13 at face value .... no where did it say anything about taper crimps eliminating case trimming. It just said a taper crimp is used to eliminate FTF's in auto loaders .... true but only a small part of the reason. Sorry I went off on you!
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Old February 12th, 2017, 01:47 PM   #24
 
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This thread has been very informative, thank you all for your responses....
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Old February 12th, 2017, 02:16 PM   #25
 
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Iowegan,

I also loaded the 45acp for match use, using the same criteria. Speer 200 gr lswc, or Lyman 452488 cast bullets, taper crimped out of a Colt MK 4 Series 70 Gold Cup in a Ransom rest at 50 yds gave groups of 1 1/16" with matched case lengths, or 1 1/8" with unmatched lengths(none over max length though, they are hard to find).

I respect your comments but I guess we have a difference of opinion on this due to our individual experiences.

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Old February 12th, 2017, 03:55 PM   #26
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vaguru, No offence but we aren't playing from the same deck. About 10 years ago, I decided I needed a super accurate 1911 so I went to my friend in LeClaire, IA ... Mr Les Baer. He sold me a nice stainless target model for a mere $1600 that was guaranteed to shoot 1/2" groups at 50 yards from a Ransom Rest. After I bought the gun, one of Les' snuffies took me to the range and proved my new gun would indeed hold groups under 1/2" at 50 yards. When I got home, I tried to replicate the load ... the best I could do was about 3/4" @ 50. I weighed each powder charge, use high quality Speer bullets that did not vary a tenth of a grain, and I was using Winchester large pistol primers. When I chronographed these loads, the max velocity spreads were under 10 fps from fastest to slowest in a 10 shot string. That's when the lights came on .... I was using new Starline brass .... known for its good quality but when I checked case lengths, I was hard pressed to find more than a dozen out of 500 that were at the true SAAMI max length of .898". Nearly all the new Starline brass was .005" .... a few as much as .010" too short. I dug through my resources and found a bag of once fired GI 45 ACP cases with a WCC 86 headstamp. Most were at the SAAMI max or just a few thousandths more. I ran a batch of them through my case trimmer set for exactly .898" then went on to load up a test batch. Sure enough, that did the trick .... just that .005~.010 extra headspace caused a considerable difference in accuracy. Granted, if I didn't have something to prove to myself, I would have been plum tickled with 3/4" 50 yards.

What I learned from this exercise was ... headspace can make a notable difference in accuracy. Using this same logic, I tested my CZ75b 9mm pistol and found headspace with a full SAAMI length case (.754") was about .005". Most 9mm pistols have .010" or more headspace, assuming full length cases .... which means the CZ is pretty tight. I sorted through a bunch of once fired range brass and came up with about 25 that measured the full .754". I loaded these with Nosler 124gr JHPs and off to the range I went. I've never seen a 9mm pistol shoot better than 1" at 50 yards by my CZ did .... my best 5-shot group was just over 3/4".

On to my next adventure .... my 10/22 build. I had improved accuracy tremendously by installing a Green Mountain 20" bull barrel, 3~10X Nighteater scope, and a Fajen target stock ... plus a very light trigger pull. At 50~70 yards it is a "one holer" but at 100 yards, even with the best match grade ammo, about 3" was the best I could muster. I measured headspace (Ruger factory bolt) and found it was excessive ... about .030" too much. I machined the face of the bolt until I got headspace down to .005" .... a bit tighter than I intended. Wow! At 100 yards with Wolf target match ammo and shooting from a sturdy bench rest, I was pounding them in the bullseye with groups measuring about 1". Wow, a 1 MOA 10/22 .... at least on a very calm day!!!

I guess the point of all my rhetoric is ... excessive headspace allows the cartridge to move in the chamber and its movement will cause the bullet to enter the bore at a microscopically different angle. This results in minor bullet damage .... virtually no difference at 50 yards in my 10/22 but at 100 yards it really showed up .... just like a handgun at 50 yards. Is this level of accuracy needed? Absolutely not! When the Les Baer 1911 was in my hands, I doubt if I ever shot a group much under 1" at 25 yards. That said, my shooting buddy could shoot one tattered hole at 25 yards so a few years later, he became the proud owner of the Les Baer 1911 ..... and my old Ransom Rest that I bought new in 1979.
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Old February 12th, 2017, 05:05 PM   #27
 
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Originally Posted by Iowegan View Post
Mark204, Sometimes it pays to be a bit more informative with your questions and comments. I took your post #13 at face value .... no where did it say anything about taper crimps eliminating case trimming. It just said a taper crimp is used to eliminate FTF's in auto loaders .... true but only a small part of the reason. Sorry I went off on you!
Not a problem. My post was in regard to post 12 (thought I highlighted it), that's were it was stated.

vaguru stated he thought a taper crimp eliminated case trimming, (which he cleared up). I said a taper crimp is used to eliminate FTF in auto loaders, it has nothing to do with trimming.

Without going into as much detail as you, I opted to say a taper crimp is to eliminate FTF's, because that's what probably 70%of the people I know associate it with. I don't know of anyone who links a taper crimp with case trimming.

That's what I was questioning.


At any rate it's water under the bridge now.



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Old February 13th, 2017, 06:49 AM   #28
 
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Iowegan,

I agree, different deck. My experience dates back to the early '70's, where Giles made custom 45's for competition and guaranteed them to shoot 3" or better at 50 yds, 10 ring size.

Really upset a couple of guys at the range that had Giles guns when my Gold cup, out of the box, cleaned and put in Ransom rest, ran its first 10 shot group ever at 1 1/6" with my smiths practice loads. Those loads did not have matched cases. Back then that was considered excellent results.

Your example with the Les Baer, kind of reinforces my point though, only a 1/4" difference in group size at 50 yds for case length, with a gun capable of 1/2" at that distance. To me that is negligible, when loading thousands of rounds for practice.

Have a nice day.
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Old February 13th, 2017, 09:07 AM   #29
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vaguru, By definition, any handgun that shoots sub-inch groups at 25 yards is considered "match grade". That doesn't count the human factor, which can enlarge the groups notably, especially in my case. Back in the late 70s while at my peak, I shot bullseye matches and actually won a few. I used a S&W Mod 17 for the 22 Class and later went to a S&W Mod 41 pistol. My centerfire revolver was a S&W Mod 14, and my centerfire pistol was a Colt Series 70 MK IV. I still own all of these but today if I tried to compete, I would be laughed off the range.

Wearing my gunsmith hat, the challenge from my customers was often to see just how accurate I could get their gun to shoot. More times than not, it had more to do with the ammo than the gun. In general, customers were more concerned with braggin' rights on their guns than with their own scores. This is where I started learning tricks that helped shrink groups .... a quarter inch here, a quarter inch there and pretty soon you had a pistol or revolver that met match grade standards. There were very few revolvers that couldn't get match grade accuracy .... pistols were a totally different story.

Some things that surprise you .... even though I trickled up each charge for match grade loads, I found if I was within a couple tenths of a grain I could still achieve match grade status. Turned out case neck tension had more affect on accuracy that any other single thing. By using brass that had been fired less than 4 times, trimming the cases to a uniform length, and applying a proper crimp, I could get very consistent results over a chronograph. Slight variations in lead bullet weight didn't seem to matter much but lead bullet hardness sure did. Different brands of primers didn't seem to matter. Uniform bullet seating depth made a big difference.

During my gunsmith career, I built a good many 1911s. Bullseye guns had to shoot under an inch at 25 yards but tactical grade could get by with 2" groups at 25 yards. I don't think most people understand how precision a 1911 must be to shoot match grade .... let alone something like Les Baer's guns. It wasn't until much later in life when I bought the Les Baer .... I just couldn't imagine a 1911 that would shoot under a 1/2" at 50 yards. It had a National Match barrel, a National Match bushing, and every tolerance was machined to perfection .... so much so that about every 30~40 rounds, I had to field strip it and wipe down the rails or it would fail to go to battery from just a slight carbon buildup.

You are absolutely right ... a half inch at 50 yards is way beyond practical. For my current 45 ACP loads, I use 5.9gr of Unique under a 230gr FMJ. These get cranked out on my Dillon 550 and more than meet my needs. The combination of my guns and ammo still make me the weak link for accuracy.
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