When to trim brass?

[BGD]

I am thinking brass should be trimmed after resizing?

How do you determine when the brass needs trimmed? Is there a way to see how long the chamber is in a particular rifle and keep the brass just the right length for that particular rifle or should I just trim the the max length stated in the specs?

I may be over thinking this.

Thanks,

 

[Steel Horse Rider]

I trim to a chart I downloaded from The Reload Bench website. I keep the charts for both rifle and pistol brass along with some of my favorite load information in plastic page protectors in an old three ring binder I keep at my reloading bench. Most necked rifle cartridges require trimming after resizing in my experience but most straight wall cartridges do not.

 

[cfullgraf]

Yes, you trim cases after resizing.

Generally, I only trim cases that are longer than the accepted maximum length. This is usually 25 to 35 percent of the total that I am working on at the time.

I only trim rifle cases including 30 Carbine. I do not bother trimming straight walled pistol cases.

 

[Hungry1]

I trim after after resizing.

I trimmed a couple hundred .357 cases that are on their 5th or 6th use with relatively low pressure cast loads.

I've found that after shooting and resizing, they're right back to where I trimmed them to.

Many people will say that trimming pistol cases is unnecessary, and maybe it is, but I wanted to eliminate as many variables as possible. Trimming to achieve a consistent crimp made sense to me.

I used the "trim to" length length listed in my Speer reloading manual.

 

[murf]

all reloading manuals have the minimum and maximum allowable case length for each cartridge in the manual. it is usually on the intro page to each cartridge.

use a dial caliper as a snap gauge to measure the length of each case. it goes quick once you get the hang of it.

if one case is over-length, i trim all cases in that batch down to the minimum length stated in the reloading manual.

i check case length on all my sized cases. you never know.

murf

 

[GLOOB]

If you only have one rifle for a caliber, you could find out how long you can go by waiting until your reloads start to pinch on chambering, I suppose. You'd have to measure your sized brass on each go around to find the longest cases. Then seat a bullet and see if it still fits. Whenever you nail down the max length for your rifle, I'd subtract a hundredth or two off that length to be safe.

The major problem with that is you might buy a new rifle at some point, and you could have a lot of bad ammo already loaded up.

If I wanted to trim less often, I'd rather trim to less than the minimum than to let my brass get too long.

 

[BGD]

Thanks, I appreciate the advice. Is there anything to gain by having the cases longer than max if they still fit in the rifle without crimping the bullet?

 

[Arkansas Paul]

I measure each with a caliper after sizing. If it's longer than the max length I trim.

http://www.midwayusa.com/product/559802/lyman-e-zee-case-length-gage-ii

Anybody used one of these? I've thought about getting one. How accurate are they?

 

[WNTFW]

If you can trim efficiently it is easier to trim every case after sizing than to measure or gauge each case.

 

[Ehtereon11B]

I run all my cases through a Lee cutter and rod length guide every time. Most of the time very little if any material is removed from the case. Doesn't take up much time if you put the lock stud in a cordless screwdriver.

 

[cfullgraf]

I measure each with a caliper after sizing. If it's longer than the max length I trim.

http://www.midwayusa.com/product/559802/lyman-e-zee-case-length-gage-ii

Anybody used one of these? I've thought about getting one. How accurate are they?

I have not used the Lyman gauge, but I make my own. Here is mine for 223 Remington, 22 Hornet and 221 Remington Fireball. I cut the gauge a couple thousandths less than the max length and trim any case that does not fit the gauge. I trim the cases a couple/few thousandths longer than the "trim to" length so my cases range .005"-.006" or so.

A caliper can do the same but I get butter fingers on occasions so if I drop the gauge, I really do not hurt anything.

I have made gauges for all the rifle cartridges that I shoot for.

 

[dragon813gt]

I will trim all new to me rifle and pistol brass that requires a roll crimp. I will set the trimmer to slightly below max and run all the brass through it. Very rarely is a lot taken off. I find it makes roll crimping 357 brass easy since I don't have to constantly adjust the seat/crimp die.


Brought to you by TapaTalk.

 

[jwrowland77]

I wonder if a case gauge could be made out of wood that's just laying around that would actually hold up? Hmmmm...the wheels are turning.

 

[helotaxi]

all reloading manuals have the minimum and maximum allowable case length for each cartridge in the manual. it is usually on the intro page to each cartridge.

"Trim-to" is not the same as "minimum" The SAAMI minimum case length is usually 0.010" shorter than the published trim length. The trim length is set in the middle of the allowable length to permit some wiggle room when trimming. I'm pretty meticulous and use a very good lathe type trimmer and still get variance of about 0.001" on a batch of trimmed cases.

Personally, if I trim one case in the batch, I trim them all. Once I'm in the groove, I can manually trim more than 100 cases in a half hour and around 400 using the power trimmer. I have a 3-way cutter on the power trimmer as well that makes it all go that much quicker.

 

[cfullgraf]

I wonder if a case gauge could be made out of wood that's just laying around that would actually hold up? Hmmmm...the wheels are turning.

Soft woods, probably not dimensionally stable enough.

Hard woods, maybe.

Line the measuring places with some thin 16 ga or so metal to protect the wood, seal the wood against moisture and see how much the gap changes over time and humidity.

 

[Clark]

A great book on the dimensional stability of wood, is Understanding Wood by Hoadley
http://www.amazon.com/Understanding-Wood-Craftsmans-Guide-Technology/dp/1561583588

There are three dimensions wood changes with moisture, longitudinal [~0.1%], radial [~4.0%], and tangential [~7.0%]. The difference between radial and tangential is why cracks form in wood as it dries.

I have done an experiment, and old dried wood changes in weight and dimensions in a sinusoid throughout the year. There is a phase lag in wood following the relative humidity of air.

 

[gamestalker]

It is important to keep bottle neck cases trimmed to within max SAAMI specification to prevent pinching in the throat, thus avoiding excessive pressure issues.

As for straight walled brass, auto loading cases that head space off the case mouth can in some instances grow longer than what will allow the round to chamber deep enough and create issues related to battery.

Rimmed cases, or those that are commonly operated through a revolver need to be trimmed to same lengths to assure consistent crimping. But this can also be true when working with auto loading type cases, if some are excessively longer than what the crimp die is set up for, an issue of over crimping could result in loss of neck tension, buckling of the case, and deformed bullets. I often see posts in which reloaders are struggling with problems that I think are obvious indications that inconsistencies in brass length is the major contributor.

Many who reload don't feel it is necessary to trim straight walled brass. I do not agree with this and maintain all my brass to within SAAMI spec and to same lengths. As a result, I've never had problems with excessive crimps or lack of necessary crimp, battery issues, FTF's, and so on. There are very good reasons why all brass should be maintained accordingly, and if it is supported by a SAAMI specification, then it is necessary in my opinion.

GS

 

[murf]

helotaxi,

be careful. sammi specs do allow .020" variance (negative only) on all rimmed and a few rimless cartridges. but, most all semi auto cartridges are only allowed a .010" variance (probably has something to do with headspacing on the case mouth).

i would strongly suggest you stick with the reloading manual suggestion.

murf

 

[RustyFN]

I measure each with a caliper after sizing. If it's longer than the max length I trim.

http://www.midwayusa.com/product/559...length-gage-ii

Anybody used one of these? I've thought about getting one. How accurate are they?

I have seem them but not used one. I lock my caliper open at max case length and any case that won't pass through gets trimmed.

 

[kelbro]

I used to waste a lot of time and effort trimming brass. Then I got a set of chamber length gauges from Sinclair ($6 ea) http://www.sinclairintl.com/reloadi...s/sinclair-chamber-length-gage-prod32925.aspx

Found out that my primer pockets get too big long before my brass lengthened enough to need trimming. Your chambers may vary.

 

[helotaxi]

be careful. sammi specs do allow .020" variance (negative only) on all rimmed and a few rimless cartridges. but, most all semi auto cartridges are only allowed a .010" variance (probably has something to do with headspacing on the case mouth).

I'll assume that you're talking about straight-walled handgun cartridges which I don't bother to trim at all. If what you say is true though, what happens when you're set up to trim to "trim-to" which is set at 0.010" shorter than max and your variance takes you 0.011" short?

Don't take my statement to mean that you should trim shorter than the "trim-to" in the manual, I was simply stating that it isn't the SAAMI min length in any cartridge that I've bothered checking. Mind you the ones I've checked were all rifle cartridges because I simply don't trim handgun brass, especially semi-auto that I'm not crimping.

Final note, the .223 Rem actually has a tolerance of -0.030" instead of the standard 0.020".