trimming straight wall cases??

PaulS · Posted: Tue Jan 28, 2020 2:12 pm Post subject: trimming straight wall cases??

I have found in my shooting that all cases grow in length. My supposition is that as the brass expands to fill the chamber it never fully relaxes back to its prior size. When the brass is resized it flows in the direction of least resistance which is the mouth as the rest of the case is being squeezed by the die.
I have found, since I started reloading 9mm that 53% of the new, once fired, brass trimms in the reloading process and on the second firing it goes up to 73%. (working with the same lot of 200 cases)
I haven't kept track of my 40 caliber or my 357 but I always trim cases in my reloading process. I use the Lyman Universal Trimmer and have it permanently adjusted for 9mm cases at maximum SAAMI length and have spools that are used to set the trimmer for other cases. The spools stop the trimming shaft from going beyond the length they are cut for (I made them myself on my lathe). It is faster to slip the sized cases in the trimmer than it is to check them with my caliper. If the cases trim at all I consider them "needing" to be trimmed. Admittedly sometimes the cases trim on one side of the mouth just squaring it up and other cases trim the entire mouth.Since I do trim them each time they are reloaded I can adjust the case length for the gun(s) the guns that shoot them. The 357 is the only caliber I use in two guns and the case length works for both.

I keep hearing that some people never trim straight wall cases and knowing that the cases grow each time they are fired (even 38 wadcutter loads) I woner how they get away without trimming. Any answers?

dhc4ever

My pistol club used to reload thousands of 9mm rounds over a 2 week cycle, shoots were every 2 weeks.
From memory we didnt trim them, just visually inspected and culled the cracked cases and those badly deformed. Usual club setup, most of the work done by the minimum of willing members, there simply wasnt time.
Almost no feeding, firing or accuracy problems, if you could call shooting a flogged out military Browning hi power accurate.
Still these days I agree with you Paul, trimming is part of the reloading process, although I dont reload for straight walled or pistol calibers these days.
Cheers

Vince

I learnt about trimming my .357 cases about 2 or 3 years into shooting pistol (I only had a rimfire rifle at that time). I couldn’t believe how much I had to actually trim the cases to bring them back into spec.

I wonder if it was really necessary now because a revolver doesn’t headspace off the case mouth, so a few thousands of an inch in length shouldn’t create a problem. Biggest problem I had was split case mouths caused, I believe, by the application of a roll crimp. I didn’t have any real guidance in reloading so I didn’t know any better, I just used the features of the dies.

These days I only shoot rifle, .223 .243 30.30 and .303 and I check the cases for length after every third reload and trim as necessary. I also as a matter of course anneal the cases after trimming at this time.

English Mike

Some of my .357 mag brass is on it's 10th firing & chambers just fine. Not that it's been used for any really heavy loads though. Same goes for .38spl but seeing as it's all shot in a GP100, it'll have to stretch a ways to get to magnum length. Very Happy

Having said that, I ought to check the brass I'm using in the .45 ACP cylinder in the Blackhawk, as it might be that, rather than needing post-sizing that causes the occasional "sticky" insertion.

Pumpkinslinger

If I'm loading plinking loads I don't worry about it too much. I check a few to make sure they aren't way too long. For target or hunting loads I trim to make sure I get a consistent crimp.

Gil Martin · Posted: Wed Jan 29, 2020 6:17 am Post subject: Trimming straight wall cases?

It depends what you prefer. My preference is to trim all cases as part of the reloading process and use a Lee case trimmer. It only takes a few minutes to check and trim cases and chamfer and deburr the case mouths. All the best...
Gil

Bushmaster

Revolver cases require trimming because I want the crimp to be even on all cases. Never trimmed 9mm or .380 cases, but I have been known to trim .45 ACP cases. My Colt 1911 Series 80 with a match barrel seems to be more accurate with cases trimmed to .90...

I trim all rifle cases (.30-30, .30-06 and .308).

RCBS Case Trimmer 2

RePete

I've never trimed pistol cases.

I have 38 Special cases that I've loaded and shot over 35 years. I have only discarded cracked cases.

Vince

Same here RePete...I have .357 revolver cases that are 40 years old and still in good useable condition. Those cases were only ever used for target shooting, and as there was no minimum power factor other than the need to penetrate a piece of Masonite (about 3mm thick) at 50 metres, they only ever suffered a loading of 2.8 - 3.5gr of Bullseye. The only problem I ever had with them was cracked case mouths cause by work hardening from roll crimping.

English Mike

Vince wrote:

Same here RePete...I have .357 revolver cases that are 40 years old and still in good useable condition. Those cases were only ever used for target shooting, and as there was no minimum power factor other than the need to penetrate a piece of Masonite (about 3mm thick) at 50 metres, they only ever suffered a loading of 2.8 - 3.5gr of Bullseye. The only problem I ever had with them was cracked case mouths cause by work hardening from roll crimping.

I was having occasional examples of necks cracking (not a big problem with .357, as I just trimmed 'em to .38spl length...), so I invested in one o' those rotary motorised annealers & run cases every 4th reload. Haven't had a neck crack since.
OK, so I've 2,700 .38spl cases & about half that in .357 mag(ain't brass ratting great)... Very Happy

Bushmaster

Now that's great. I am always glad to run across another "Brass Rat".

I've been known to have people trip over me at the range as I , on my hands and knees, collect brass.

PaulS

I use range brass too but it is rare to find any revolver cases. Most of my 9mm is now range brass and about half of my 40. Back when I was trying to get over a flinch with my 357 I was shooting light wad cutter loads with it but the cases still grew. It might be the difference in the chamber size that adds to the problem. My 03A3 has a chamber that is big enough around to handle bullets from machine guns. The chamber lenth is OK but when I tried full length sizing that brass I was trimming with every reload and at about the third or fourth load the body of the case would split vertically. Since I started neck sizing only I haven't had any splits.
Like I said, my cases are trimmed at the maximum case length or close to it so especially with the semi autos it becomes necessary to do.
I'm also with Bushy on the equal crimp rule with all the cases I crimp. It doesn't matter whether it is a taper or roll crimp, if they aren't the same results will show it. I do shoot my handguns a bit farther than most but I got used to shooting at 100 yards when I was shooting silhouette and it stuck. Accuracy is real important at 100 yards with a pistol.

RePete

The O3A3's had oversized chambers for easy extraction with no regard for reloading.

English Mike

Bushmaster wrote:

Now that's great. I am always glad to run across another "Brass Rat".

I've been known to have people trip over me at the range as I , on my hands and knees, collect brass.

Me & my mate in Albuquerque have been known to head out to the club for a late afternoon shooting session mostly with gleaning brass in mind.
One kind person once threw 4x50 boxes of factory .38spl brass in the trash can, having put all the cases back in the boxes first.
We had a count up (or rather a weigh & guesstimate) when I was over in November & we worked out we have 14,000 .45 ACP cases, with half of them sized & steel pin tumbled & about 8,000 rounds loaded with 200gr LSWC.
There's a couple of sacks full of once fired 5.56 brass waiting it's turn - mebbe 200lbs, which we reckon is about 8,000 cases...

All loading's done using an RCBS Junior (heck, I do better here in the UK as I have a Rockchucker). Very Happy

PaulS

Mike do you use a cement mixer to clean all that brass with steel pins?
Doing it a batch at a time in a Frankfort Arsenal tumbler would take weeks.