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case length - how critical?Discussion regarding the reloading of ammunition and tuning of loads for accuracy
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chambered221 Super Member
Joined: Aug 17, 2007 Posts: 3455 Location: Lost for good !!!
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Posted: Thu Feb 14, 2008 5:48 pm Post subject: Re: case length - how critical? |
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Bushy
Didn't say anything about not having calipers!!!!!!!!!!!!!!!!!!!!Got 2 sets of those and a 1inch micrometer also.
What I do not have is a ball micrometer. Thats what you use to measure case wall thickness. You can also use a dial indicator and neck pilot.
_________________ Ask as many people needed, sooner or later your question will be answered the way you want it answered !!!
A free people ought not only to be armed and disciplined, but they should have sufficient arms and ammunition to maintain a status of independence from any who might attempt to abuse them, which would include their own government.
~George Washington |
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Vince Site Admin
Joined: May 25, 2005 Posts: 15912 Location: Brisbane AUSTRALIA
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Posted: Thu Feb 14, 2008 10:32 pm Post subject: Re: case length - how critical? |
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Punkin wrote: |
Thanks Vince. I assume that the inner piece moves up and down with the case and is squeezed in as it comes up? |
Yes mate, that is correct.
In the first pic I have takin the crimping insert out of the die...the second pic shows a bit more detail of the crimping insert and the third pic is looking down into the top of the die with the insert put back in and ready to do its job.
Bushy...you say the FCD puts a taper crimp on the pistol case...so it doesn't crimp it as does the rifle collet die?
Cheers, Vince
_________________ Cheers, Vince
Illegitimi non carborundum
(Never let the bastards grind you down)
Live simply. Love generously. Care deeply. Speak kindly. Leave the rest to God.
"Nulla Si Fa Senza Volonta."
(Without Commitment, Nothing Gets Done) |
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Pumpkinslinger Super Member
Joined: Sep 22, 2007 Posts: 5050 Location: NC foothills
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Posted: Thu Feb 14, 2008 11:41 pm Post subject: Re: case length - how critical? |
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Thanks again Vince. I can see why the case/trim length would be less critical for that type of crimping die.
That said however (and back to the original question), I still think that you need to trim cases correctly to have consistent loads, not to mention the safety aspects that have already been discussed.
_________________ Mike
"I ain't no better than anybody else, and there ain't nobody better than me!" Ma Kettle |
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twofifty Member
Joined: Feb 07, 2007 Posts: 158 Location: BC Rockies
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Posted: Fri Feb 15, 2008 12:36 am Post subject: Re: case length - how critical? |
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An interesting discussion and insights thus far.
I believe that as is usual in this sport, what we have here is another perplexity that must be solved by throwing money at it. :-)
OR, to put it another way, a failure to spend enough money.
The Hornady (formerly Stoney Point) OAL gauge, bullet comparator and headspace gauges look like a well-integrated measuring system that will work with my digital caliper.
Bonus, I will be able to more systematically develop my loads, and my note-keeping will contain more useful information.
I will likely purchase these, find my optimal case length, then borrow a friend's case trimmer.
Crimping is not my goal here for obvious reasons. However, inadvertently crimping a too-long case neck by camming it into the chamber's narrowing throat is something that I must avoid at all costs.
Thank you all for your input.
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Vince Site Admin
Joined: May 25, 2005 Posts: 15912 Location: Brisbane AUSTRALIA
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Posted: Fri Feb 15, 2008 5:14 am Post subject: Re: case length - how critical? |
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Punkin wrote: |
That said however (and back to the original question), I still think that you need to trim cases correctly to have consistent loads, not to mention the safety aspects that have already been discussed. |
Totally correct mate. Nothing beats consistency and having the correct specs.
twofifty' wrote: |
I believe that as is usual in this sport, what we have here is another perplexity that must be solved by throwing money at it. :-)
OR, to put it another way, a failure to spend enough money.
The Hornady (formerly Stoney Point) OAL gauge, bullet comparator and headspace gauges look like a well-integrated measuring system that will work with my digital caliper.
Bonus, I will be able to more systematically develop my loads, and my note-keeping will contain more useful information.
I will likely purchase these, find my optimal case length, then borrow a friend's case trimmer.
Crimping is not my goal here for obvious reasons. However, inadvertently crimping a too-long case neck by camming it into the chamber's narrowing throat is something that I must avoid at all costs. |
Mate, I do not own any of these tools OAL gauge, bullet comparator and headspace gauges. Not to say that they do not have a place on the reloading bench, but I have just never considered purchasing them. My reloads are shooting sub MOA at 100m and realistically all I need is "minute of deer or minute of fox" because I don't shoot Bench Rest or hunt prairie dogs at 400m (no PD's out here in Australia). I do however have a Vernier Caliper and a Case Trimmer.
Having said that, do not let me stop you from purchasing these fine tools as they can only benefit your reloading, and shooting, in the long run. I do suggest strongly that you crimp your loads as an aid to consistency and accuracy.
Don't you just love this reloading game....so many variables and things to get your head around to produce a load that does exactly what you want it to do...it a lot of fun.
Cheers, Vince
_________________ Cheers, Vince
Illegitimi non carborundum
(Never let the bastards grind you down)
Live simply. Love generously. Care deeply. Speak kindly. Leave the rest to God.
"Nulla Si Fa Senza Volonta."
(Without Commitment, Nothing Gets Done) |
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Bushmaster Super Member
Joined: Jun 12, 2005 Posts: 11445 Location: Ava, Missouri
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Posted: Fri Feb 15, 2008 7:38 am Post subject: Re: case length - how critical? |
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Vince,
My Lee FCD for .38/.357 is not a collet crimp die like the Lee Rifle FCD. The leading edge of the crimp collar turns the case mouth in and with further movement into the collar completes the taper crimp.
_________________ I have one nerve left and yer standin' on it...
DEMOCRACY Two wolves and one sheep voting on what to have for lunch...
LIBERTY A well armed sheep contesting the outcome of the vote... |
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chambered221 Super Member
Joined: Aug 17, 2007 Posts: 3455 Location: Lost for good !!!
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Posted: Fri Feb 15, 2008 5:29 pm Post subject: Re: case length - how critical? |
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twofifty
Vince has made some very good points about the use of this tool or that tool!!!!!!!!!!!!!!!!!!!
Some specialty tools are good, and some are like gimics. I have paid good money for some tools I've only used a couple of times.
For example, a headspace gauge aids in setting up a resizing die, but after you get the die set what good is it?????
Its not something you use evry time you reload.
_________________ Ask as many people needed, sooner or later your question will be answered the way you want it answered !!!
A free people ought not only to be armed and disciplined, but they should have sufficient arms and ammunition to maintain a status of independence from any who might attempt to abuse them, which would include their own government.
~George Washington |
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twofifty Member
Joined: Feb 07, 2007 Posts: 158 Location: BC Rockies
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Posted: Fri Feb 15, 2008 6:19 pm Post subject: Re: case length - how critical? |
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chambered221 and vince, I hear what you are saying and am letting it sink in - mulling it over.
Truth is that with regard to my comfort level, having fired this brass three times and seeing how it was longer than SAAMI after the initial firing of the factory load, and it has since grown, I feel like I'm walking on thin ice...
I will do some simple experiments like placing a bullet into empty brass at various seating depths to see where the lands leave a mark on the jacket. Also, will soot up shoulder and neck on some brass and see where the soot is removed on the neck, or if the throat crimps the neck. Will try and extrapolate from there where the throat of this damn chamber is in relation to the case neck.
But then my cases are not all the same length - they've never been trimmed. I also hear that Remington throats are quite long...and this rifle has had a thousand rounds so the throat may be even further out.... It still shoots just as good though.
So you can see why I am drawn to the certainty and exact numbers that the instruments provide.
To an experienced reloader, this is not a problem. To me, starting out and having only reloaded these 120 once-fired cases twice, the next reloading holds too much uncertainty.
Guess I can always put this off by reloading the other 180 once-fired cases that I have in reserve, perhaps starting by trimming them all to the same trim-to length of 1.902" as per manual. Put the first 120 aside and deal with them later when I have gained some experience.
Edit: All this hand-wringing on my part wrt instrumenting the chamber is safety related, not accuracy related. I am not trying to emulate BR shooters, nor do I have a rig capable of that level of accuracy. What I am looking for is to develop a few loads that give me a consistent .7 to .8" at 100, off sandbags. Most of my shooting is positional, onto paper and steel.
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Vince Site Admin
Joined: May 25, 2005 Posts: 15912 Location: Brisbane AUSTRALIA
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Posted: Fri Feb 15, 2008 8:19 pm Post subject: Re: case length - how critical? |
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A well thought out reply twofifty.
Mate, far be it from me to even remotely suggest that the methods I use are the only "correct" way to approach your reloading experience.
What you have said is all good. The only counsel I can add is "don't get all wrapped around the axles on the nitty gritty", and consider the points each and evey one of us has bought up as there is a wealth of knowledge and experience in HuntingNut. Once you have considered it all, extract what is good for your purposes or fits your situation. As you said:
All this hand-wringing on my part wrt instrumenting the chamber is safety related, not accuracy related. I am not trying to emulate BR shooters, nor do I have a rig capable of that level of accuracy. What I am looking for is to develop a few loads that give me a consistent .7 to .8" at 100, off sandbags. Most of my shooting is positional, onto paper and steel.
Once you have attained your goal of a safe load that delivers consistent .7 - .8 MOA then you can relax a little to enjoy your shooting. By all means continue with your load development cause thats the name of the game, and its a lot of fun too, but don't loose any sleep over it get all tangled up in details that really just don't make a difference.
Good luck with your load development mate....I reckon you are gonna enjoy the hell outa it.
Cheers, Vince
_________________ Cheers, Vince
Illegitimi non carborundum
(Never let the bastards grind you down)
Live simply. Love generously. Care deeply. Speak kindly. Leave the rest to God.
"Nulla Si Fa Senza Volonta."
(Without Commitment, Nothing Gets Done) |
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woods Member
Joined: Oct 15, 2005 Posts: 89
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Posted: Fri Feb 15, 2008 8:22 pm Post subject: Re: case length - how critical? |
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I too use the Lee Factory Crimp Die. In each caliber I reload for I try to have 4 dies
Lee Collet Neck Sizer
Redding Body Die
RCBS Competition Seater
Lee Factory Crimp Die
In tests in my rifles I have found the LFCD to increase velocity an average of 10 fps or so and decrease the group size by 1/8", so why not?
As far as trimming, I use the Lee Case Length Gauge trimming system so it is easy to stick the trimmer in and it trims if it needs to and doesn't if the case is below the trim length.
Quote:: |
But then my cases are not all the same length - they've never been trimmed. I also hear that Remington throats are quite long...and this rifle has had a thousand rounds so the throat may be even further out.... It still shoots just as good though. |
I do not think I would continue to shoot if the cases are over the recommended trim-to length in the manuals. Throat wear, even excessive throat wear will have no bearing on the trim-to length because that part of the chamber does not wear and get longer.
Quote:: |
Some specialty tools are good, and some are like gimics. I have paid good money for some tools I've only used a couple of times.
For example, a headspace gauge aids in setting up a resizing die, but after you get the die set what good is it?????
Its not something you use evry time you reload. |
I do use the headspace gauge every time. This is the Gauge I use www.midwayusa.com/epro...t=11082005 .
[img]http://www.midwayusa.com/mediasvr.dll/image?saleitemid=479704[/img]
Some would not call it a headspace gauge, especially on belted cases but the information it yields can be used as a headspace value on non-belted slanted shoulder cases like the 30-06. After a belted case has been fire formed so that it will begin to headspace on the shoulder rather than the belt then this gauge can be used to measure the excess headspace on those also.
On new cases I take the measurement in order to measure how much my case shoulder will move forward after the first firing.
The first thing I do when I hit the reloading bench with some cases that have been fired is to chamber them in the rifle to see how easily they chamber. If they chamber easily then I am good to neck size only. With some rifles that have a tight lug fit a crush fit with a case is hard to determine. The gauge is essential then.
It's true that you don't need to measure every time if you have your die set up already but I find it useful to set the die to push the shoulder back to the exact same place everytime.
Quote:: |
The Hornady (formerly Stoney Point) OAL gauge, bullet comparator and headspace gauges look like a well-integrated measuring system that will work with my digital caliper.
Bonus, I will be able to more systematically develop my loads, and my note-keeping will contain more useful information. |
I agree 100%
_________________ Guns only have 2 enemies, rust and politicians |
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twofifty Member
Joined: Feb 07, 2007 Posts: 158 Location: BC Rockies
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Posted: Sat Feb 16, 2008 2:14 am Post subject: Re: case length - how critical? |
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Thanks for staying with this little drama!
OK, so now I've checked 60 once-fired cases from another lot of Win commercial brass. These were first fired out of the box through my rifle.
These 60 once-fired never resized cases form a bell curve with a dip in the middle. As stated before, SAAMI specs 1.912" as the max case length; my manual states 1.902" is the trim-to length.
The 60 case average length is 1.911". Here's the data:
1x are 1.903" (longer than trim-to of 1.902")
1x are 1.904"
1x are 1.906"
1x are 1.907"
2x are 1.908"
10x are 1.909"
4x are 1.910"
12x are 1.911"
10x are 1.912" (this is the SAAMI max)
9x are 1.913"
4x are 1.914"
1x are 1.915"
3x are 1.916"
1x are 1.917"
So now I'm starting to really wonder how long this chamber is head-spaced to.
Other than these long cases, there are no visible signs of failure near the case web, or primer problems, or crimping at the case mouth. The inside and outside are smooth throughout.
Soot head-space tests:
- A long 1.919" sooted/resized brass shows soot removed just forward of the shoulder, in the area where the case is supposed to headspace. The lands left light marks on the bullet, pushing it back to a COAL of 2.539" (without jump allowance).
- A shorter 1.903" sooted/resized brass shows soot removed as above except not all the way around the shoulder, and the COAL is 2.515" (without jump allow.).
- In either case the bolt was not hard to close, just the normal camming force. Is these good signs?
Other question:
Every one of these cases that I subsequently full-length resized grew by .002" to .003" - and I'd brushed the neck and lubed the case. The die's expander seems a little rough though (RCBS). This case growth seems counter-intuitive, but apparently always happens when resizing?
Anyhow, I should trim these suckers to 1.902", then shoot the heck out of them. :-)
Thanks.
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SingleShotLover Super Member
Joined: Dec 26, 2007 Posts: 1006 Location: Illinois
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Posted: Sat Feb 16, 2008 5:56 am Post subject: Re: case length - how critical? |
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Twofifty,
Don't get caught up heading down the wrong road. Headspace and case length aren't the same thing.
Headspace is measured from the shoulder of the chamber (bottle-neck cartridges) to the bolt-face. Excessive headspace is a major chamber issue that will soon show itself by case head separation but is generally preceded by a shiny bright line just forward of the case web.
You are concerned about over-all case length...a different matter that pertains more to case-neck lengthening. The safety issue with case-neck growth is to keep cases short enough to prevent the necks from being pinched in the throat area of your chamber causing pressures to skyrocket.
Even factory new brass will vary in length from case to case. Sizing also will cause case-necks to lengthen though several studies seem to prove that the expander ball isn't the culprit. What causes the lengthening is simply the act of squeezing the brass back to "spec".
I know it gets confusing, but hang in there...and stay safe!
_________________ If you can't hit it with one, you probably can't with two either!
The biggest problem with a closed mind is that it never seems to come with a closed mouth.
SSL |
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Pumpkinslinger Super Member
Joined: Sep 22, 2007 Posts: 5050 Location: NC foothills
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Posted: Sat Feb 16, 2008 10:47 am Post subject: Re: case length - how critical? |
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Ummm... I hate to seem abrupt but just trim the cases! Then you will KNOW that they are safe. Trim 20 to the "trim to" length, load them and check to see if you see any difference in accuracy. I'm betting that you won't see any difference or that it actually improves a hair. Either way you will now KNOW that you have SAFE loads.
_________________ Mike
"I ain't no better than anybody else, and there ain't nobody better than me!" Ma Kettle |
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Bushmaster Super Member
Joined: Jun 12, 2005 Posts: 11445 Location: Ava, Missouri
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woods Member
Joined: Oct 15, 2005 Posts: 89
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Posted: Sat Feb 16, 2008 11:44 am Post subject: Re: case length - how critical? |
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Hey 250
Perhaps a set of pics will help. You are talking about 3 different measurements which have no direct relationship.
Case length for your 22-250 is the 1.912" shown here from the case head to the end of the neck
Headspace is the distance from the case head to the point in the chamber that stops forward movement of the case, in your case from the case head to the datum line on the shoulder
Seating depth of the bullet is measured from the case head to the point on the bullet that first reaches caliber diameter (ogive)
They are different measurements.
On the last picture of the chamber notice that the chamber decreases in diameter just forward of the case neck. If your cases get so long that they pass that point then when you cam the bolt down you could force the end of the neck into a severe crimp which could astronomically increase pressure.
Trim them all below the 1.912" recommended length!
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