brass trimming question

hound2013

hound2013

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ive been reloading for about 2 years now just a question about trimming , im shooting my own guns so the ammo is for my guns only is it necessary to trim the brass all the time ????? or ckeck it after each use too see if it has stretched . I use a guage that I bought all I do is slide it in if its not tight I leave it alone ... what do you guys do??????? thanks..hound2013
 
For pistol brass like 38 special, case length is only an issue with respect to uniform crimping. Sort by head stamp and/or number of times fired and check your crimp for each "batch".
 
Why are we assuming that the OP is only referring to pistol cartridges? I check all of my brass after each firing, and I only trim when the length exceeds the standard length for the cartridge.
 
I believe that rifle brass gets longer after firing and resizing, so I check all of mine after the resizing stage. Depending on the firearm (AR vs. Bolt gun) I get at least 2-3 firings out of a piece of brass before the case rim peeks up above gauge. Then I trim the entire batch down to minimum trim length as a batch for consistency.

I don't find that pistol brass "stretches" much, in fact it seems to shrink a bit. Trimming a pistol case at least for semi autos seems rare, though for consistency of crimp I do check lengths and keep brass in batches by manufacturer and number of firings.

Hope this helps!
 
With centre fire rifle cases, why do we trim? The chamber has clearance for a case which is a bit over standard length. When the case grows to exceed the chamber length designed for it, the case mouth will pinch the bullet in the taper where the chamber is narrowing. This tends to drastically raise pressures---very quickly and very much, depending on how much the bullet is pinched. Thus, they must be trimmed so as never to exceed the length to where they start to squeeze the bullet.
Most of us who use bolt action rifles never crimp the cases, so pinching the bullet is the only thing we have to worry about as cases lengthen. Cases a little shorter than the figure given in modern loading books is of no concern, whatsoever, if one is not crimping them. Oh,oh, I hear the accuracy guys getting up steam, but until someone can prove to me that a case .050" shorter will effect accuracy, I stick to my guns.
We have sized down lots of 30-06 brass to make 270 brass. These sized cases end up about 100 thousands, like a tenth of an inch, shorter than standard 270 cases. I have fired many of these in a very accurate 270 rifle over the bench rest, at ranges to 500 yards and could detect no difference at all in accuracy (or anything else) over brass at the length specified for a 270.
There is a great deal of difference in various calibres, regarding the amount of "growth," when the cases are fired. For example, a 270W will "grow" about twice the speed of a 30-06. A 243W will expand with firing faster than will a 270W, while a 30-30 has very little expansion with shooting. The very little taper of a 45-70 means they will wear the case out before one has to worry about an expanded case of enough to effect crimping.
For cases that are crimped, probably each shooter will set a difference of what he/she considers maximum difference between the shortest and the longest they will be crimping.
For me, if the difference between the shortest and the longest case to be trimmed is no more than about the thickness of a piece of writing paper, about .010", I am good to go.
 
Yep. Trimming is not required every time, but you do need to check. And a case length gauge will do nicely(you could have just bought a Vernier, set it to the max case length and used it.). When you trim you'll have to chamfer and deburr bottle necked cases too.
 
When I start a new bunch of brass I fully inspect/size/trim/process them all. After that check if they need trimmimg every 2-3 reload's.
 
H4831 said:
With centre fire rifle cases, why do we trim? The chamber has clearance for a case which is a bit over standard length. When the case grows to exceed the chamber length designed for it, the case mouth will pinch the bullet in the taper where the chamber is narrowing. This tends to drastically raise pressures---very quickly and very much, depending on how much the bullet is pinched. Thus, they must be trimmed so as never to exceed the length to where they start to squeeze the bullet.
Most of us who use bolt action rifles never crimp the cases, so pinching the bullet is the only thing we have to worry about as cases lengthen. Cases a little shorter than the figure given in modern loading books is of no concern, whatsoever, if one is not crimping them. Oh,oh, I hear the accuracy guys getting up steam, but until someone can prove to me that a case .050" shorter will effect accuracy, I stick to my guns.
We have sized down lots of 30-06 brass to make 270 brass. These sized cases end up about 100 thousands, like a tenth of an inch, shorter than standard 270 cases. I have fired many of these in a very accurate 270 rifle over the bench rest, at ranges to 500 yards and could detect no difference at all in accuracy (or anything else) over brass at the length specified for a 270.
There is a great deal of difference in various calibres, regarding the amount of "growth," when the cases are fired. For example, a 270W will "grow" about twice the speed of a 30-06. A 243W will expand with firing faster than will a 270W, while a 30-30 has very little expansion with shooting. The very little taper of a 45-70 means they will wear the case out before one has to worry about an expanded case of enough to effect crimping.
For cases that are crimped, probably each shooter will set a difference of what he/she considers maximum difference between the shortest and the longest they will be crimping.
For me, if the difference between the shortest and the longest case to be trimmed is no more than about the thickness of a piece of writing paper, about .010", I am good to go.
Click to expand...

Pegged it as usual H4831 ^.

I, .. ~once~ .. let a way too long stretched out 6.5x55 case slip through inspection. It chambered normally, and there was no sign whatsoever of anything amiss on closing the bolt.
Result?. Blown primer disappeared without a trace, blackened pocket expanded oblong to a fare thee well, case head all mangled with headstamp lettering pretty much erased, massive brass flow into the ejector slot(mauser), a 2x4 needed to open bolt.

Better believe .. every one gets checked every time, ever since.
 
X2, very important to check, as different brass for the same caliber can stretch differently. And for some pistol brass, they space off the mouth of the case so you should check !

stubblejumper said:
Why are we assuming that the OP is only referring to pistol cartridges? I check all of my brass after each firing, and I only trim when the length exceeds the standard length for the cartridge.
Click to expand...
 
vviking said:
Pegged it as usual H4831 ^.

I, .. ~once~ .. let a way too long stretched out 6.5x55 case slip through inspection. It chambered normally, and there was no sign whatsoever of anything amiss on closing the bolt.
Result?. Blown primer disappeared without a trace, blackened pocket expanded oblong to a fare thee well, case head all mangled with headstamp lettering pretty much erased, massive brass flow into the ejector slot(mauser), a 2x4 needed to open bolt.

Better believe .. every one gets checked every time, ever since.
Click to expand...

My lesson was learned with a 270, but I could find the pieces of extractor and got it back together!
The 6.5x55, being sort of under bore, probably "grows" pretty fast and snuck up on you.
But for sure, one such event is enough!
 
I trimmed every session since I pick up or use range brass, faster than measuring the overall length of every case, I'm using Giraurd Power Trimmer, will only take 2 secs per case,
 
H4831 said:
My lesson was learned with a 270, but I could find the pieces of extractor and got it back together!
The 6.5x55, being sort of under bore, probably "grows" pretty fast and snuck up on you.
But for sure, one such event is enough!
Click to expand...

Ahh. The exuberance of youth back in those halcyon days of experimentation. lol! 'Tis a wonder, we, or the bloke standing to the right of us, survived long enough to find a modicum of wisdom, eh?.

I had a first gen Dillon "D-terminator" electronic scale back then .. sooo hy-tec it was, but POS was tossing wonky overcharges due to proximity with the flourescent lite's ballast.
Took a while(pre-internet remember) to suss out why cases would stretch from zero to 15+ thou. per firing within the same batch.
Not to mention the vert that plagued my groups.
All was well when I switched back to the 10/10 balance beam for powder charges.
That dillon gathers dust ever since.

The dial caliper is my most used reloading tool.
No antichrist evil wires in that tool either.
In fact, the only powered equip at my bench is a drill/driver to speed trimming and primer pocket uniforming.
 
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I don't worry about pistol but if you have trouble chambering you better take notice. For rifle it's important to know where your throat is. I have a LNL oal gauge and I trimmed a neck very short and turned a brass insert to fit the case and od size on the part outside the neck. Stick this in and then measure so you actually know what the oal is to the end of the neck in the chamber. On factory guns you will probably find it way out but at least you really know where it is. My JGS Palma reamer print says this is distance is 2.020 and with a trim to length of 2.005 it allows only 15 thou for growth, not very much. This is a match chamber.
 
H4831 said:
With centre fire rifle cases, why do we trim? The chamber has clearance for a case which is a bit over standard length. When the case grows to exceed the chamber length designed for it, the case mouth will pinch the bullet in the taper where the chamber is narrowing. This tends to drastically raise pressures---very quickly and very much, depending on how much the bullet is pinched. Thus, they must be trimmed so as never to exceed the length to where they start to squeeze the bullet.
Most of us who use bolt action rifles never crimp the cases, so pinching the bullet is the only thing we have to worry about as cases lengthen. Cases a little shorter than the figure given in modern loading books is of no concern, whatsoever, if one is not crimping them. Oh,oh, I hear the accuracy guys getting up steam, but until someone can prove to me that a case .050" shorter will effect accuracy, I stick to my guns.
We have sized down lots of 30-06 brass to make 270 brass. These sized cases end up about 100 thousands, like a tenth of an inch, shorter than standard 270 cases. I have fired many of these in a very accurate 270 rifle over the bench rest, at ranges to 500 yards and could detect no difference at all in accuracy (or anything else) over brass at the length specified for a 270.
There is a great deal of difference in various calibres, regarding the amount of "growth," when the cases are fired. For example, a 270W will "grow" about twice the speed of a 30-06. A 243W will expand with firing faster than will a 270W, while a 30-30 has very little expansion with shooting. The very little taper of a 45-70 means they will wear the case out before one has to worry about an expanded case of enough to effect crimping.
For cases that are crimped, probably each shooter will set a difference of what he/she considers maximum difference between the shortest and the longest they will be crimping.
For me, if the difference between the shortest and the longest case to be trimmed is no more than about the thickness of a piece of writing paper, about .010", I am good to go.
Click to expand...
Thanks, Bruce. Now no need to waste time typing that all in.

ted
 
Now that the OP has his question answered I am going to completely hijack this thread.

I have run several .308 cases through my Lee case trimmer without the lock stud installed and they came to within 0.001 of being the recommended trimmed length of 2.005 when the sizing pin gets held in the flash hole. Why do you need the lock stud? I have ordered a differant trimmer but it seems to me I can put the cutter instead of the lock stud in a drill and just hold cases in my fingers and do them way faster.

I have never seen anyone do this and I have looked all over the Internet so there must be a problem. Is the flash hole not a good reference point for sizing?
 
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