Author Topic: Case trimming - necessary or optional?  (Read 17396 times)

Offline Stein

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Case trimming - necessary or optional?
« on: March 11, 2009, 11:04:59 AM »
Like several others, I am looking at getting into reloading and trying to buy right the first time.  For now, I am looking only at 9mm.  I have done a ton of research on these boards and the internet and can't figure out if case trimming is necessary or "good to do" for handgun rounds.  I have a bunch of brass that has been shot at least twice as I bough reloads from a police reloader guy in the past but no longer live near him - too bad, last batch cost $100/1,000  plus a free 50 cal can and I got a $10 discount if I turned my brass in.  As you may guess, it was a few years ago.  I don't know how much the shell stretches, but could guess that it would eventually either lead to loading failures or the bullet would be pressed too far down to maintain the correct overall length.

Same thing goes with crimping autoloader cartridges - some do and some don't.  Same thing with tumbling the brass, many don't seem to think it is necessary.

I don't mind saving up for the extra gear and extra steps, but would like to hear opinions on the subject so I can make some informed decisions.

Offline Jack Crabb

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Re: Case trimming - necessary or optional?
« Reply #1 on: March 11, 2009, 02:15:08 PM »
Trimming 9mm and similar straight wall cartridges is not necessary.  I am not sure that it even rates "good to do" because there are so many better things to do in life than trim thousands of pistol brass.  Bottleneck cartridges are a different story.

Crimping is good.  A consistent crimp will lead to consistent head space/feeding, consistent powder ignition, consistent velocities, consistent accuracy, etc.  Watch for head space problems on rimless catridges that are related to insufficient or over crimping.  For rimless cartridges like the 9mm, use a taper crimp die; roll crimp from rimmed, revolver-type rounds.

Do tumble pistol brass.  The brass has likely been on the ground/floor and fairly cruddy.  Shiny brass keeps all the dirt out of your reloading dies and press.


Offline Stein

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Re: Case trimming - necessary or optional?
« Reply #2 on: March 11, 2009, 03:22:47 PM »
Great information, thanks a bunch.

tallfoo

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Re: Case trimming - necessary or optional?
« Reply #3 on: March 13, 2009, 04:51:11 PM »
Good question.  The guy that taught me to reload says case trimming isn't necessary as long as you do light loads.

Offline RipTombstone

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Re: Case trimming - necessary or optional?
« Reply #4 on: April 02, 2009, 07:14:09 PM »
Bottlenecked cartridges do need trimmed to some extent. If you are using it all in the same rifle, you can full length size it, then trim it the first time, then use a NECK sizing die for your reloads. After that, the brass should be pretty much matched to your rifle. All this is assuming the head spacing is on the shoulder of the round ie. a 30-06.
If you are reloading a case with a large rim, like a 303 British, you may need to trim often. These cases are headspaced on the rim, and the brass stretches a little more.

I have never ever ever ever trimmed my 45 Colt brass, and have loaded it many times for competition.

DM

Offline Muddyboots

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Re: Case trimming - necessary or optional?
« Reply #5 on: April 28, 2009, 12:10:21 PM »
I know this has been idle for a while but I have some comments to add.

Weather or not case trimming is needed is a function of several things. Firstly, what are your goals? If you are trying to make a .311 hole with 10 .308 rounds at 200 yards, yes you need to trim. If you are trying to but meat on the table and this is the first reload for the casing then probably not. If your rounds won't chamber due to "brass creep" you need to. If you fire formed your case into an Ackley Improved chamber, You'd better at least Mic everything.

For most casual reloaders, you won't need to trim until you know more about the whole system and can "out shoot" your rifle/pistol.

Reloading is an Art, Science or Religion and to some, all three.

HTH!

Muddyboots

Offline cohutt

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Re: Case trimming - necessary or optional?
« Reply #6 on: May 03, 2009, 05:16:17 PM »


Reloading is an Art, Science or Religion and to some, all three.

HTH!

Muddyboots

+1

Btw I only trim 223; I used a dillon powered trimmer on a 650 with a casefeeder and spend one afternoon every year or two on a large trimming run.  I only trim new to me cases @ 1.75" and don't bother measuring before- if it is under 1:75" then it is sized and decapped but doesn't get trimmed as the blades don't contact the case mouth.)

Haven't ever bothered to measure a straightwalled case before much less trim one.

Offline FreeSpirit

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Re: Case trimming - necessary or optional?
« Reply #7 on: May 13, 2009, 10:34:22 AM »
I see no need to trim straight walled rimmed pistol cases.
I think there is some benefit in trimming rimless pistol cases that headspace on the mouth.
Bottlenecked cartridges get checked and watched for length, trimmed when needed.


Quote
Reloading is an Art, Science or Religion and to some, all three.
;) +1

Offline xxdabroxx

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Case trimming - necessary and optional.
« Reply #8 on: July 05, 2009, 02:51:06 PM »
i am going to trim my 45 ACP brass next go around,  i am looking for more consistency though.  I am trying to work up a very consistent load, and want to start with a good base. 

Offline CountryRootsCityJob

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Re: Case trimming - necessary or optional?
« Reply #9 on: December 07, 2009, 09:28:36 AM »
my understanding is that if you were going to crimp, you should trim your brass... that way the crimp would be uniform on all your rds... ex. if you have one piece of brass longer than the rest, the crimp would be more severe or even end up distorted... can any one confirm that, or am I crazy?  (aside from the obvious of course! :) )

Offline Greywolf27

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Re: Case trimming - necessary or optional?
« Reply #10 on: December 07, 2009, 09:40:04 AM »
I have found that 45 ACP actually get shorter, not longer with each firing...

Offline cohutt

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Re: Case trimming - necessary or optional?
« Reply #11 on: December 07, 2009, 05:10:45 PM »
my understanding is that if you were going to crimp, you should trim your brass... that way the crimp would be uniform on all your rds... ex. if you have one piece of brass longer than the rest, the crimp would be more severe or even end up distorted... can any one confirm that, or am I crazy?  (aside from the obvious of course! :) )

In theory, yes, when it comes to rifle rounds. In practice, for semi auto not worth the trouble, with bolt maybe.

Offline Duc1

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Re: Case trimming - necessary or optional?
« Reply #12 on: December 19, 2009, 10:58:05 PM »
I trim all calibers of my rifles, 308, 243, 223 and none of my pistols, 45 acp, 40 s&w, 10 mm. 

Offline r1kk1

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Re: Case trimming - necessary or optional?
« Reply #13 on: August 04, 2010, 08:18:35 AM »
A case needs to be within a certain spec for a certain chamber. With that said, I use a Sinclair chamber length plug and Cerrosafe. When I do a chamber cast I'm looking for case length, diameter of case, leade, and neck diameter. The Sinclair gauge requires me to sacrifice one case in which I trim down 0.100". I full length size the newly trimmed case and if need be, expand the neck. Using a bullet seater or just my fingers (if tension is not too tight), I load the cartridge into firearm as carefully as I can and close the action. This works on semis, bolts, single shots, and levers. If I cannot use the Sinclair gauge, I will use Cerrosafe.

Reamers do wear. I have a .45-70 that I shoot blackpowder loads in it. It would require case trimming every time I shot it. I found the answer doing a chamber cast. I was trimming to SAAMI standards and the brass was too short. The brass lengthening was not caused by high pressure. This is a low pressure load. Once I found the new trim length, I called Lee and had a custom case trimmer sent to me for that particular rifle. The brass has "settled down" and trimming has not been needed on the last few reloads.

I have a 7.62X54R Mosin Nagant that I have yet to trim base in. Using Norma cases that have been annealed and reloaded 10Xs so far. I have bought certain brands of brass and needed to trim a few pieces that must have been produced on a Monday. My experience is that I rarely trim pistol cases only to retire the magnum cases to the light target practice realm and then I will trim them.

I have found that Machinist's die or smoking the case allows me to set up bottleneck cartridges. Full length sizers now work the brass where I need it most - bumping the shoulder back. I do shoot subcalibers and depending on who cuts the chamber and the tolerance of the dies used will dictate if and how often I need to trim.

In summary,
I need to know why the case needs to be trimmed, full length sized, different neck bushing, etc. if a pattern seems to emerge.

take care,
r1kk1

Offline jbm555

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Re: Case trimming - necessary or optional?
« Reply #14 on: August 11, 2010, 01:18:51 PM »
I don't own or reload for 9mm but the .45 ACP is a similar type case and I never trim.  On a new batch of brass I will select a few for trimming but have never found trimming to be necessary.  It's been my experience that .45 acp brass (with many reloadings) will start to split at the case mouth but this happens very, very rarely since most cases are lost long before this ever happens.

I don't even bother to separate .45 acp by brand any more (with the exception of Amerc head stamped cases, pure junk).  For me it all seems to shoot the same at  25 yards or so. 

Offline The Sage of Monticello

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Re: Case trimming - necessary or optional?
« Reply #15 on: August 18, 2010, 11:17:55 PM »
What case trimmer do you recommend?


Offline ben

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Re: Case trimming - necessary or optional?
« Reply #16 on: August 21, 2010, 08:27:32 PM »
hey man if you go through the trouble to reload do your best job dont skip all the steps and do the very best you can your hardwork will pay off with accuracy and consistency no ftf and pride DO THE BEST JOB YOU CAN

Offline The Sage of Monticello

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Re: Case trimming - necessary or optional?
« Reply #17 on: August 22, 2010, 02:50:58 PM »
With my .45 Colt I loaded light and never ever had to trim the cases. At the very least I would inspect my brass and use a caliper just to make sure there are no problems.

With my rifle, I have brass set aside that indeed needs trimming. I found hours and hours of videos on youtube on reloading quite helpful, and the videos on Lee Precision website helpful. Moreover, when I bought my Lee dies they have instructions with diagram how to reload folded up on the top of the die box. This always helped me out to remind me not to forget any steps or improperly perform a stage.

I reload with Lee hand press and rarely reload more than 100 rounds. I suspect if you don't trim brass you could have problems feeding.

I had a rifle case once that was stuck, had to gently use a hammer to get the brass out. I suspect it was the brass length over specs, or improper head space.


Offline dicko

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Re: Case trimming - necessary or optional?
« Reply #18 on: September 07, 2010, 12:37:27 PM »
Somebody said that you don't need to trim for hunting loads.   WRONG!!    It has to do with safety, not what kind of shooting you do.   But I will return to that later.    There is a fundamental difference between handgun and rifle brass.    Or, to be more precise, there is a difference between straight wall cases and bottleneck.   I mention that because some rifle brass is straight, eg 45-70.   Straight cases (eg 38 Spl ) and tapered ( eg 9mm ) usually don't need trimming for two reasons.   First, they are usually shorter than nominal when new.   Second, they tend to get shorter with use.    I have loaded tens of thousands of various handgun cartridges, and have never found one that needed trimming when new, or after some use.   

What you will find, however, is variance in length.  It won't be much, but it is there, and it is true that unequal length = unequal crimping.   That's because the crimp shoulder in the die is in a fixed position.   If you set the die to give a particular degree of crimp to your ongest case, all other cases will get less crimp, and vice versa.   This is more noticeable with revolver cases because most dies are made with a roll crimp shoulder.   It is much less noticeable with pistol brass because most dies apply a taper crimp.   A roll crimp is a sharp bencing inward of the case neck, which is why you get a noticeable difference of crimp in cases of different length.    A taper crimp is just that, it crimps the bullet by reducing the diameter of the case very slightly over a long distance ie a very slow taper.   A few thousandths variance in case length therefore causes minimal difference in crimping.

A firm roll crimp is often desirable or hard recoilling revolver calibres like the 44 Mag to prevent bullet set back in the case.  But I recommend a taper crimp for lighter loads and lighter recoiling revolver calibres like the 38 Spl.

A roll crimp cannot be applied to pistol cartridges because they headspace on the case mouth.  That is, the slight step formed by the case mouth is what stops the cartridge in the right position in the chamber.   That is, the mouth of the case comes to a stop against the  corresponding shoulder in the chamber.   A roll crimp that turns the case mouth into the side of the bullet will remove that step and prevent that positive stop in the chamber.  But it is worse than that.  As a serving range officer, I have opened several pistols to that had jammed because the mouth of a roll crimped cartridge had been forced part way into the chamber throat and tied up the gun.

Most modern pistol dies have a taper crimp, but some older dies like my old RCBS 9mm dies apply what looks like a cross between a taper crimp and a roll crimp.  If not carefully adjusted they can apply a crimp that ties up a gun as described above.   So I don't crimp 9mm cartridges with the seating die.   I use taper crimp die as the fourth die.  Gets a much better result.

You might think that variance in case lenth might cause problems in pistol cases that headspace on the case mouth.   Not really.   Most pistols have enough firing pin protrusion that they reach the primer of a short case easily.  Nor does it seem to materially affect accuracy, as far as I can tell.  In any case, service pistols are not built for close accuracy, they are built to do a job.  My Sig Sauer shoots into 4" at 25 yards off the bench.   How much better do you need it to be ?

Bottlenecked rifle cases ( rimmed or rimless ) sure do need to be trimmed.   Regularly.   Unlike straight wall handgun cases, they lengthen with each firing.   The high chamber pressure cause the brass to flow forward at the shoulder and neck.   That lengthens the neck so quickly that the rule of thumb is to trim to length every fifth firing.   Somtimes it can be necessary more often.  I check mine with a vernier caliper after every firing and trim them all when the longest is a bit shorter than max.   It has to dowith safety.   If a case gets too long, the chamber shoulder ahead of the neck will crimp the case into the bullet.   But, unlike a normally applied crimp, this has the effect of sandwiching the case neck between the chamber and the bullet.   The case will therefore not let go of the bullet and pressure will go through the roof.

But there is another equally dangerous phenomenon.  The forward brass flow also thickens the neck wall.   If it gets thick enough, it will chamber tightly, with the same situation of the neck being tightly sandwiched between the chamber and the bullet.    With the same increase of pressure.   I pass all my loaded cartridges through a micrometer set slightly less than max neck diameter.

I hope that answers the question about trimming to length.  I will comment about case cleaning another time.


Offline dicko

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Re: Case trimming - necessary or optional?
« Reply #19 on: September 09, 2010, 12:42:16 PM »
Tumbling is the easiest and least labour intensive method of cleaning and polishing cases.  In fact there is no labour, because the tumbler does the work unattended.   And, of course, you get beautifully polished cases.   So it is the preferred method for good reason.   But do cases need to be polished ?   No, they just need to be clean, and there are various ways of doing that.   The military armouries pickle them in a warm 5% sulfuric acid solution.    Unfortunately that is problematic for us because of storage difficulties.   The best chemicals I have found are the proprietary liquid case cleaners from RG and other companies.   One hour pickle in RG cleans cases very nicely, but they are clean and dull, not polished or bright.   RG has an almost unlimited life and can be used several times.   I store mine in a glass jar with screw top that once contained fruit.   A 10% citric acid solution is almost as good and costs next to nothing.   The crystals can be bought at most pharmacies (drug stores ?).    After rinsing, drying can be speeded up by putting in the kitchen oven at no more than 150F.   Needs be switched on for only 15 minutes.   It will get hot enough to completely dry the cases if left in all night.   Don't forget that too much heat will anneal the brass and weaken it.

Remember also that some cases need more cleaning than others.   Pistol cases that are ejected to the ground get dirty fastest.   Rifle cases dont get dirty, they just get darker with each firing.   I clean mine about every tenth firing.   As they don't last much longer than 20 firings without annealing, that means no more than cleaning twice in their service life.   Moreover, rifle cases being bigger, they can easily be polished bright by hand with fine steel wool of the sort that can be bought in most supermarkets.   It can be speeded up by pushing the case on to a piece of wood dowel and chucked in a drill press or in an electric drill held in a bench vise.  Cleaning with wire wool does not remove a measurable amount of brass.

Offline Nacinator

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Re: Case trimming - necessary or optional?
« Reply #20 on: October 23, 2010, 03:21:05 PM »
Everyone that has posted on this topic is spot on. I don’t trim pistol cases. I do swage and trim all my .223, .308 and 30-06 brass. When I load for accuracy in the .308 and 30-06 I ensure the following are done.

Trim each case to a specific length

Clean and trim the primer pocket to a uniform size for all the cases.

Clean and trim the flash hole to a uniform diameter for all the cases.

Using a digital scale I weigh each case and break it down into lots by case weight and then store by weight. I also do the same with the bullets I use.

Anneal the head of each case.

And finally I take a group of the cases I store by weight and I load them. With the bullets I have stored by weight. I know .1 gr weight differences in the bullet probably won’t make that much of a difference down range but it all ads up when you start shooting past 500 yds.     

When I am finished I have 50 to 100 rounds that are almost as close to perfect as I can get them. Consistency and uniformity are the hallmarks of accuracy. 

Nacinator Out

Offline Stein

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Re: Case trimming - necessary or optional?
« Reply #21 on: October 24, 2010, 02:23:56 AM »
After 4,000 pistol reloads I am quite confident agreeing that it isn't necessary.