How do you measure Trim Length from the shoulder?

[Lovesbeer99]

OK, I just got my WFT trimmer and tried it just a bit. Before I post my feedback I have a question. If the trimmer, like the Possum Hollow and Giraurd and Gracey, index off the sholder won't that affect COL?

I'm trimming .223 and some are 1.750, 1.748, 1.752. I'm not sure if I have a problem with the timmer or if this is normal becuase the shoulder of each case my be different.

Thanks in advance.

 

[dmazur]

From the Giraud manual -

Next, check your overall length of the
trimmed case with a caliper. I will set
the length fairly close, but it will really
depend on how you size your brass.
Since the case trimmer locates each
case by the case shoulder, if your
headspace dimensions on the resized
brass are not consistent, then the
case can't be trimmed to a uniform
dimension. I suggest the use of some
type of headspace measuring device
to monitor your resizing operation.

For those who want to read the entire manual, it is here -

http://www.giraudtool.com/Giraud%20Trimmer%20Inc.pdf

While I have no experience with the WFT, I imagine the instructions for it would be similar.

If your question is, will varying case length affect COL, I believe the answer is no. COL is determined by the distance between the seater die and the shell holder (for a given bullet).

If your question is, if case length varies, will the distance from the case mouth to the lands vary, I believe the answer is also no. The shoulder to trimmed case mouth will be consistent.

The only dimension that will vary is shoulder to case head, if you trimmed before resizing.

However, as the resizing operation tends to make case length "grow", the general practice is to resize before trimming.

Hope this helps.

 

[Walkalong]

I use the Possum Hollow, which works the same way, and I get very consistent case lengths.

I can only assume it is inconsistent sizing, in other words, the shouder position is inconsistent.

That could be from mixed brass where some is soft and some is hard, where the soft stuff ends up with the shoulder farther down than the springy hard stuff.

It could be from the same thing and press flex. Who knows, but that is m guess.

 

[dbarnhart]

The key I think is consistent setup of the sizing die. I have mine mounted in a Hornady LnL bushing so that the depth of the die is consistent from reloading session to session. I use a Dillon case gauge to check the head-to-shoulder dimension.

 

[cfullgraf]

A Sinclair Bump Gauge or an RCBS Precision Mic will measure the base to shoulder distance on your cases and you can see how consistent your sizing die and process is. These tools can help you set up your sizing die to get the desired amount of shoulder set back on resizing. The numbers measured are a relative number and do not relate directly to drawing datum lines.

A case gauge as offered be Wilson or Dillon will tell you if your shoulder position and case length are with in spec, but they will not tell you by exactly how much. (Note, most bottle neck cartridge case gauges are not chamber gauges. A round can fit the gauge yet still not fit your chamber. Read the manufacturer's fine print).

Generally, once I set up a sizing die for the shoulder position I want, i rarely measure it again unless something has changed. I measure the length of all cases after sizing and trim the ones that are too long. I use Lee trimmers, an L E Wilson trimmer and a Possum Hollow trimmer. All give the same consistent results with trim lengths plus/minus 0.001".

But, when you are starting out, measure, measure, and measure some more until you get a felling how stable the various process are.

 

[fguffey]

Possum Hollow and Giraurd and Gracey:


Loves beer, good question, I have covered this before, I have a M1917 Eddystone chambered in 30/06, lucky for the rifle, if not for me the rifle would have fallen in to that black hole of reloaders misunderstanding. My Eddystone has .016 thousands head space, again, not a problem, I determine head space first, that is I determine the length of the chamber from the bolt face to the shoulder of the chamber.

This is possible because I did not start out as a “FIRE FORMER”, I started out as a case former. All I need to form cases to fit is to find cases that are too long, for the 30/06 family of chambers there is the 280 Remington, the 280 Remington is .051 thousands longer than the 30/06 from the head of the case to it shoulder, that information is not even nice to know to a fire former/reloader but to a case former the extra length from the head of the case to the shoulder is a ‘CAN NOT MISS’ when forming cases for long chambers.

When determining the length of the chamber before firing I adjust the die off the shell holder with feeler gages, a good number would be .010 thousands, after forming the case should chamber but with my M1917 the case chamber, the bolt closed without effort, so, I went the other direction, I increased the gap and formed another case, I adjusted the gap to .015 thousands and still the bolt closed, and then I went to .016 thousands, the bolt closed with slight resistance, this number gave me the length of the chamber from the bolt face to the shoulder, meaning I used (NEW) 280 Remington cases formed to 30/06 with an additional .014 thousands added to the length of the case between the head of the case and shoulder. (keeping up with two thoughts at the same time) I want my case to cover the chamber, if I mindlessly trim my cases to book specification my cases would not cover the chamber, so when trimming I add the .014 to the length of the case when trimming from the shoulder to the mouth of the case.

For most on the Internet the Wilson case gage is a second class drop in gage, the ability of the Wilson case gage is limited by the reloader using it and their lack of reading comprehension skills. The Wilson case gage measures the case from the shoulder back to the head of the case AND from the shoulder forward to the mouth of the case, when measuring cases formed to chamber in my M1917 with a Wilson case gage I have .014 thousands protruding from one and and nothing from the other, and that answers your question, it is not the failure of the Wilson case gage or the Gracey etc. trimmer, the reloader can become a reloader by purchasing a press, die and shell holder with a few related tools to become a reloader, after that they can chamber a round, fire and then eject the fired case to become a fire former, I choose to form first then fire, the difference? I do not get immediate gratification, fire formers get fire formed case, Me? I get once fired cases, because I determine the length of the chamber first.

Possum Hollow and Giraurd and Gracey: I have the Dillon and Gracey, not a problem but the case holders for each case get’s expensive.

http://www.dillonprecision.com/#/co.../23636/Dillon_s_Rapid_Trim_1200B_Case_Trimmer

http://www.matchprep.com/trimmer.htm

F. Guffey

 

[fguffey]

Loves beer, then there is the fire firm, neck size 5 times then start over by full length sizing to start over, I can not do that, that is beyond my ability, skills, methods and techniques, after firing a case once and neck sizing that same case 5 times the case becomes a 6 time fired case, meaning I do not talk about reloading, I reload but on the outside chance you question the answers determine, in the perfect world, the best case for firing, forming and fire forming, for me? It is the new/unfired case. I had a chance to purchase 1,000 new unfired LC Match cases from PAT’S of OHIO for the sole purpose of forming. At the time the cases were less than .10 cents each.

There is memory, recovery, jump back, snap back and spring back, none of which hang me up, I measure before and after and know the length of the chamber before firing, and, I know/understand time is a factor, time as a factor influence my methods and techniques, a reloader, in my opinion should not go straight to fire forming/neck sizing without understand the effect time has on each.

F. Guffey

 

[gamestalker]

The only element of the finished round that will be effected by this variance your seeing after trimming, is the length of the neck. "Casing over all length" also refrenced as COAL, COL, OAL is only effected by the seating die. In no way shape or form is OAL changed or effected by brass length, shoulder position, head dimension, or any other aspect of the brass.

There are other aspects of OAL that can be considered when seating bullets, but for all practical purposes, case head to the tip of the bullet is the most typical form of determining OAL.

 

[TonyAngel]

Lovesbeer, I didn't see the answer to this, so I'll ask. Are you trimming before or after resizing? It should be after resizing. I do all of my trimming with the Possum Hollow trimmer after resizing and most are spot on, those that aren't only vary by a thousandth or so, give or take.

 

[Walkalong]

In no way shape or form is OAL changed or effected by brass length, shoulder position, head dimension, or any other aspect of the brass.

When the trimmer is using the shoulder as a stop, as in the WFT, it most certainly can.

 

[rcmodel]

+1

if you have .004" shoulder variation AFTER SIZING?

You have a much bigger problem to figure out then neck length.

rc

 

[Walkalong]

Are you trimming before or after resizing?

Naturally it should be after sizing, and then deburring and chamfering after trimming as well, unless it is a trimmer that does it at the same time.

 

[bigedp51]

The object of trimming your cases is to make sure the cases are shorter than the chamber and the neck doesn't end up in the throat of the chamber. If you look at the case manufacturing limits for case length, the case when made can be anywhere from 1.760 to 1.740 in length.

The chamber length can be 1.7720 to 1.7870

Trim your cases to the minimum length in the manuals using a vernier caliper and just make sure all your cases are the same length. Trimming to minimum length makes sure you are below all the possibly variations of chamber length.

Your shoulder position depends on headspace and how you set up your full length resizing dies. If you notice on a new case the shoulder location can vary greatly when new. The case shoulder will not know where it wants to be until it is fired in your chamber.






Remember this, if we have a Apocalyptic Zombie invasion simpler is always better when reloading on the run.

 

[Funshooter45]

I use the Possum Hollow a lot for trimming. I also have a Wilson trimmer for calibers not available for the Possum Hollow. Obviously, if your shoulder is not consistent, then the OAL of your brass will not be consistent when using a trimmer that indexes off the shoulder. The solution is to make sure your shoulder height is consistent. If you are FL sizing, that shouldn't be a problem. If you are neck sizing, it will still be consistent as long as it was fired in your rifle. Mostly that is. If you are neck sizing brass from other rifles or if your sizing isn't consistent, then you will have inconsistent trimming.

 

[fguffey]

“The only element of the finished round that will be effected by this variance your seeing after trimming, is the length of the neck. "Casing over all length" also referenced as COAL, COL, OAL is only effected by the seating die. In no way shape or form is OAL changed or effected by brass length, shoulder position, head dimension, or any other aspect of the brass.

There are other aspects of OAL that can be considered when seating bullets, but for all practical purposes, case head to the tip of the bullet is the most typical form of determining OAL”

CASE LENGTH, TRIM TO LENGTH: without the ability to keep up with more than one thought at a time a reloader is stuck with information provided by reloading data, reloading data does not hang me up. I reload for the 30 Gibbs, my 30 Gibbs was reamed from a 30/06 chamber meaning the length of the chamber did not change, The 30 Gibbs is .040 shorter than the 30/06 chamber, again the length of the chamber did not change. This allows me to take advantage of longer cases when forming, I add .034 thousands to the length of the neck, if bullet hold is important adding .034 thousands to the neck length has it’s advantage.

And I said I want my cases to cover the chamber, as I said I am a big fan of the forming die, I form cases to determine the length of the chamber from the bolt face to the mouth of the chamber, means nothing to most but for me, when trimming cases for case length it helps to know the length of the chamber.

F. Guffey

 

[Lovesbeer99]

Ok I played with this a little. With once fired range cases I got from a friend, and not fired in my gun, the cases varied a lot. But I took some of cases fired in my gun and the results were more consistent.

I need to play with this a little more.

 

[popper]

A case gauge and hornady lock rings have been my best reloading investment. Set up all my tools with the case gauge and check frequently. Use a wrench to tighten your die in the press. FL size everything NOT fired in once your gun. Case gauge will tell you when to FL size or trim.

 

[Lovesbeer99]

I'm shooting an AR. I always full length size my brass.