Case length trimming

[dustyboots911]

Help. At what length do you start trimming case necks? I shoot 308 and only neck size. The Berger Reloading Manual calls for 2.015 case length. I have 2 new bags of Winchester brass and they all measure an even 2.0 inches. Some others that I have fired measure 2.015 up to 2.022. My COL is 3.028 with 175 gr Berger VLD's. So I know with the variation in case length that is not helping my groups. Thanks for any and all answers

 

[IndispensableDestiny]

Maximum length is 2.015 inches. Trim to 2.005.

You should full length resize new brass and fire it once before starting neck sizing only. That first trip through the FL die and firing will bounce up the length to over 2.005.

If you are seeking consistency, trim every time. Or sort the brass by case length.

 

[byf43]

Maximum length is 2.015 inches. Trim to 2.005.

You should full length resize new brass and fire it once before starting neck sizing only. That first trip through the FL die and firing will bounce up the length to over 2.005.

If you are seeking consistency, trim every time. Or sort the brass by case length.

^^^^This!!!!!!!

 

[Nanook]

LEE manual says length of brass should be 2.015. SAAMI minimum length is 2.000. I trim my stuff to 2.005 (+/- .003) and it works just fine. Whatever you choose to do, be consistent with it but there is really no need to be 'super-anal' with it.

 

[John from MD]

Unless you are a bench rest shooter, I suggest you look into using a RCBS X die rather than trimming cases. If you only shoot the brass in one chamber, the X die will save you alot of work and your cases will last longer as they get less stretch.

I have a Gracey trimmer that I no longer use as I use X dies for .223, .308 and 30-30. I would use them for 8x57 and 7.62x54 if they made them.

Regards,

John

 

[dustyboots911]

Thank you all for your replies. Now let me ask this. My COL jam length is 3.068. I backed off .040 as Berger suggested and my rifle loves this length. If I am loading into a new sized case that is 2.0 inches and I have others that are 2.015 in length will this difference in seating depth affect my groups? I shoot at AGC from the bench and so far I am getting 1/2 inch groups with 5 rounds. Thanks again.

 

[John from MD]

The real difference is in the case neck tension. The reloaded and fired cases have harder necks than the new brass. I would keep them separate until the new cases have the same amount of reloadings as the old ones.

If you are shooting at 100 yards, it won't be a significant difference. I would not use different lots of brass or bullets if shooting over the course as it would make a difference.

Regards,

John

 

[dustyboots911]

John from MD: Thanks

 

[John from MD]

Anytime. I enjoy passing on stuff I have learned to others.

John

 

[Pinecone]

The real difference is in the case neck tension. The reloaded and fired cases have harder necks than the new brass. I would keep them separate until the new cases have the same amount of reloadings as the old ones.

If you are shooting at 100 yards, it won't be a significant difference. I would not use different lots of brass or bullets if shooting over the course as it would make a difference.

Regards,

John

Just anneal the older cases.

Some benchrest shooters anneal every loading.

There is a guy on Snipers Hide that will deprime, SS tumble, and anneal your cases.

 

[John from MD]

Annealing works but is usually best left to the experienced reloaders. Since the OP started out with a basic case trimming question, I didn't want to get into the complexities of annealing correctly.

Does the fellow on snipers hide tell what process he uses to anneal the brass?

John

 

[Pinecone]

He uses one of the annealing machines. I forget which one.

I may have to pick one of them up, then offer annealing services to help pay for it.

 

[John from MD]

I was going to buy one of those that had a rotating holder and a couple of propane torches some years ago. I found that using a melting crayon was alot cheaper.

John

 

[Pinecone]

There is one that you can load several hundred cases into and you let it run. Of course, you need to keep and eye on it, as flames are involved.

This one:

http://www.giraudtool.com/annealer1.htm

 

[Pinecone]

There is one that you can load several hundred cases into and you let it run. Of course, you need to keep and eye on it, as flames are involved.

This one:

http://www.giraudtool.com/annealer1.htm

 

[John from MD]

The one I saw some years ago, had two burners so that the neck was heated more evenly.

Considering the days of cheap CMP ammo are gone, anyone interested in serious competition may want to look into one of these. In the sixties and seventies, everyone I shot with reloaded and really took care of their brass. Seems like those times are back.

John

 

[Bang]

There is one that you can load several hundred cases into and you let it run. Of course, you need to keep and eye on it, as flames are involved.

This one:

http://www.giraudtool.com/annealer1.htm

Funny you post that, I bought one of those a month ago. Unfortunately there is a 12 week wait. Will post a review when it comes in.

from an undisclosed location

 

[E.Shell]

Help. At what length do you start trimming case necks? I shoot 308 and only neck size. The Berger Reloading Manual calls for 2.015 case length. I have 2 new bags of Winchester brass and they all measure an even 2.0 inches. Some others that I have fired measure 2.015 up to 2.022. My COL is 3.028 with 175 gr Berger VLD's. So I know with the variation in case length that is not helping my groups. Thanks for any and all answers

Maximum length is 2.015 inches. Trim to 2.005.

You should full length resize new brass and fire it once before starting neck sizing only. That first trip through the FL die and firing will bounce up the length to over 2.005.

If you are seeking consistency, trim every time. Or sort the brass by case length.

LEE manual says length of brass should be 2.015. SAAMI minimum length is 2.000. I trim my stuff to 2.005 (+/- .003) and it works just fine. Whatever you choose to do, be consistent with it but there is really no need to be 'super-anal' with it.

Trimming cases is merely a safety measure and as Nanook says, there is no need to be obsessive about it.

If cases get too long, the act of chambering a round forces the end of the case into the end of the chamber, which can act as a crimping mechanism by turning the case mouth into the bullet. This forms a mechanical lock and raises pressures substantially.

As long as we are even .001" below the maximum length of 2.015", this will never be a problem. However, if we only reduce the case length to just under the maximum length, we would probably have to trim every time we load the case.

The "Trim To" length given in manuals is not some magical number, but simply a reasonable place to trim to, because it allows us at least a few firings between trimmings. By reducing the case length by .010", we allow room to grow and thus reduce trimming frequency.

The SAAMI minimum of 2.000" is simply an arbitrary standard that mainly guides manufacturers. Other than eroding the end of the chamber a little further back, there is no real harm in having them shorter. Consider the .38 Special vs .357 Mag, .44 Spc vs .44 Mag, etc... Further, even at less than 2.000", the .308 case neck is still a lot longer than a .300 WinMag case neck, so we're not on thin ice in any way at all.

Unless you are a bench rest shooter, I suggest you look into using a RCBS X die rather than trimming cases. If you only shoot the brass in one chamber, the X die will save you alot of work and your cases will last longer as they get less stretch.

I have a Gracey trimmer that I no longer use as I use X dies for .223, .308 and 30-30. I would use them for 8x57 and 7.62x54 if they made them.

Regards,

John

Some die designs do reduce the trimming interval, but some trimming will always be necessary.

Trimming is necessitated by case stretch. Case stretch is a product of headspace. Headspace is a result of die adjustment. Setting the die to the manufacturer's suggested setting will create lots of clearance in most rifle chambers, and thus lots of stretch.

Proper die adjustment will reduce headspace to minimum working levels (.002" is a good number), but some clearance is necessary, and thus some stretch is introduced, and thus some trimming will always be involved.

Thank you all for your replies. Now let me ask this. My COL jam length is 3.068. I backed off .040 as Berger suggested and my rifle loves this length. If I am loading into a new sized case that is 2.0 inches and I have others that are 2.015 in length will this difference in seating depth affect my groups? I shoot at AGC from the bench and so far I am getting 1/2 inch groups with 5 rounds. Thanks again.

The real difference is in the case neck tension. The reloaded and fired cases have harder necks than the new brass. I would keep them separate until the new cases have the same amount of reloadings as the old ones.

If you are shooting at 100 yards, it won't be a significant difference. I would not use different lots of brass or bullets if shooting over the course as it would make a difference.

Regards,

John

Agreed. I would be MUCH more concerned with neck tension variations arising from varying degrees of work hardening than I would over a few thousandths of an inch in case length. Those concerned with this (trim length) can do the math and see exactly how much interior surface area we give up when we take a few thousandths off the neck. They will see an insignificant difference when compared to almost any other parameter.

Annealing works but is usually best left to the experienced reloaders. Since the OP started out with a basic case trimming question, I didn't want to get into the complexities of annealing correctly.

Does the fellow on snipers hide tell what process he uses to anneal the brass?

John

I'd disagree on the "too complex" perception. Annealing is no more difficult than any other aspect of loading and is actually quite simple. I anneal after every 4-5 loadings, and also when I wish to "equalize" brass of different ages/firing cycles.

IMO, annealing machines are overkill unless you're doing thousands of cases, and even at that, some machines are more for high production for the sake of automation and may not do as good a job as doing it "by hand". I use a pencil flame propane torch, a Lee shellholder and battery powder drill/screw gun, a bowl of icewater and I achieve fine results.

 

[Pinecone]

Funny you post that, I bought one of those a month ago. Unfortunately there is a 12 week wait. Will post a review when it comes in.

from an undisclosed location

Cool, can I come over and use it?

I will bring the beer and propane.

 

[Pinecone]

The one I saw some years ago, had two burners so that the neck was heated more evenly.

Considering the days of cheap CMP ammo are gone, anyone interested in serious competition may want to look into one of these. In the sixties and seventies, everyone I shot with reloaded and really took care of their brass. Seems like those times are back.

John

The Giraud can up upgraded with a second torch. There are other ones with two and even 3 torches.

It looks like the Giraud spins the case enough to only need a single torch.