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Bazoo
05-07-2019, 07:46 PM
I trim my rifle brass every firing for consistent crimp.

I generally trim to the suggested trim to length in my Lyman manual. But would there be any advantage to trimming to the max length?

I was given some brass that happened to be all trimmed to the max length.

Any thoughts are welcome.

georgerkahn
05-07-2019, 07:53 PM
Great question, Bazoo! The theory is that rifle brass stretches/gets longer with firing. You are most "smart" trimming to all the same length -- I consider this perhaps one of THE most important brass preps, as if you use profile crimp dies, it's the only way to get all the crimps uniform! If you were to trim to maximum length, then -- again theoretically, after firing they'd all need being trimmed again; and again; ...
An interesting note is quite often my (even new!) brass is on the short side, right from the bag/box. I'm jealous that yours is in need of trimming.
I use a L. E. Wilson trimmer to get all the brass to IDENTICAL lengths; and then use a hand tool to chamfer/remove the burrs from both the inside and outside edges.
BEST!
geo

MrHarmless
05-07-2019, 07:56 PM
Same as above. If you trim to max length every firing, as the brass stretches on the shorter cartridges, eventually all of it is going to be trimmed to max length, which means your crimp is going to be consistent between all your cartridges, which is good for consistency.

RED BEAR
05-07-2019, 08:22 PM
I always trim to trim length to but you may be on to something although if you trim every firing anyway may not matter much as all will be same lenght. Not sure if the slight difference in length will matter as long as they are same lenght. Some bench rest shooters may be able to shed more light on what they think is better shorter or longer brass.

243winxb
05-07-2019, 09:35 PM
A crimp is not always needed or best for accuracy. Neck tension should keep bullets from moving.

Running at maximum trim length or longer may reduce carbon fouling and throat erosion.
https://www.sinclairintl.com/reloading-equipment/measuring-tools/case-gauges-headspace-tools/sinclair-chamber-length-gage-prod32925.aspx

The Sinclair Chamber Length Gage is used to find the true length of the chamber.

The chamber area in front of the maximum trim length is what i call the "safety zone" its around .010" long. This extra clearance is just in case the brass didnt get trimmed when its needed.

If a loaded rounds trim length is a lot longer then maximum, the bullet may get crimped in the case by the chamber. Pressure would go up and will be dangerous.

Strange things can happen in a chamber on firing. The trim length of fired brass may get shorter after firing. Measure brass before and after full length sizing.

The firing pin strike may set the shoulder back. This may push the neck deeper into the chamber. The pressure then expands the brass and blows the shoulder forward.

The head to datum measurement on a bottle neck case is something to control when full length sizing.

I maintain the maximum trim length for my target rifle in 243 win, checking length and trimming before each loading. This method requires chamfer and deburring after each trimming.

For most reloaders, just trim back the required amount when brass reaches maximum.

lightman
05-08-2019, 05:04 AM
For general purpose I trim to the suggested trim to length. I'll check a few everytime I reload them and trim again when one of them approaches max length. The time between when they need trimming differs from cartridge to cartridge. For some its 5 loadings and on others I may wear out the brass before it needs trimming the 2nd time. I start all new brass off by resizing and trimming.

I also don't crimp any rifle brass except that being shot in tubular magazines. My limited testing shows that crimping usually hurts accuracy.

Bazoo
05-08-2019, 11:59 AM
Thanks for the replies.

I'm used to loading 30-30 so consistent length and crimps is the name of the game.

Switching to 30-06, I've not loaded any yet so I'll have to experiment to see what it likes. I will feel better crimping, provided accuracy doesn't suffer terribly. The brass I had that was all at max length was 30-06. I trimmed it back to the suggested length. Then I got to thinking about it, why would anyone prefer max length. The brass was trimmed and chamfered and deburred.

Walks
05-08-2019, 01:16 PM
I also trim my .30-30 brass to min. Length every other time. Makes for even uniform crimp. Even though I partial size. Have to, to get a worthwhile/proper crimp.

When I used to run Hot/Max Loads in cases like the .300H&H, they had to be trimmed every time. As did all the other cases I loaded Hot/Max.

For .30-06 I run G.I. Brass with a medium Garand Load, I FL size all cases every time and Taper Crimp.
I'm very fortunate in that 3 out of 4 of My Service Rifles all have very similar chambers. And can share ammo.

Tom W.
05-08-2019, 01:20 PM
I'm blessed that the 30-06 a.i. hasn't stretched in a coon's age, and the 30/30 a.i. hasn't yet, either. Handgun brass just doesn't get trimmed.....

Larry Gibson
05-09-2019, 10:33 AM
I prefer to trim cases to fit the OAL of the chamber instead of some arbitrary length. With cast bullets in the 30-06 I neck size the cases so the cases don't stretch. Even with '06 cases that are full length sized I use a RCBS X die so once trimmed they don't stretch. Most case stretching or lengthening occurs during partial or full length sizing with regular FL dies.

If you are going to neck size those '06 cases and they fit your chamber neck I would suggest leaving them as they are.

David2011
05-09-2019, 06:22 PM
Thanks for the replies.

I'm used to loading 30-30 so consistent length and crimps is the name of the game.

Switching to 30-06, I've not loaded any yet so I'll have to experiment to see what it likes. I will feel better crimping, provided accuracy doesn't suffer terribly. The brass I had that was all at max length was 30-06. I trimmed it back to the suggested length. Then I got to thinking about it, why would anyone prefer max length. The brass was trimmed and chamfered and deburred.

Keeping brass at max length for a target rifle increases the length of support for both the bullet and the cartridge within the chamber.

I don’t crimp the .30-‘06 for my Garland which loads fairly violently and I don’t get bullet setback. The surplus Garland ammunition I’ve bought wasn’t crimped either.

gwpercle
05-09-2019, 06:44 PM
It doesn't really matter . Since you are trimming at each firing what you want is Consistent Case Lengths...as long as they are consistent ...you are good.
Maximum is just as good as minimum.
I usually split the difference between max. and min. and fire them until a few streach to max. and then trim them back to middle of the road again .
Minimum always seemed so drastically short .
Gary

fredj338
05-10-2019, 02:06 PM
Even if you do not crimp, rifle brass should be trimmed to a uniform length that is short of max. If you have a minimum cut chamber, the brass can be forced into the lands & pressures go crazy.

country gent
05-10-2019, 10:28 PM
Some have claimed brass fit to the chamber including over all length shoots smaller groups. I don't think actual dead nuts length is as important as all cases being the same length.
I cant see the normal .010 from min to max on case length making a big difference, but cases varying from min to max over the batch will make good consistent crimps hard to achieve, along with the different tensions produced by the varying lengths.

On a 2.010 max case min is usually 2.000. On 100 cases all 2.000, 0r 2.005 or 2.009 ( remember 2.010 is max and hence should be the trim point) is fine but the 100 case lot varying from 2.000 - 2.010 randomly may cause problems with crimp and such

Winger Ed.
05-10-2019, 10:40 PM
I trim my rifle brass every firing for consistent crimp.

Wow. Hey bro, don't make extra work for yourself. Plenty of other people are more than glad do that for ya.


What I've done, and works for me is taper crimp handgun ammo due to the lengths being less critical.
Rifles- I've never had a problem with 'setback' from recoil, so I don't roll crimp.
For cast, after seating, I take out the stem, and adjust the die just enough to take out the flare enough to smoothly chamber.

When I get in new rifle brass, I'll trim it .01 shorter than the length in the book.
When resizing, I lube inside the neck to minimize any stretch.

After several reloadings, it's usually still under a max. length.
I only load common cals. .308, .30-06, 5.56 etc. and when any get back to needing a trim,
they're about ready to retire anyway.