New Brass Case Length

[bobbyrum]

Since I royally screwed up this question yesterday , with your indulgance, I will ask it again. I have 50 new (Rem.) 7mm RUM cases to load. I ran them through the RCBS resize die. My Lyman Manual (& others) say my "Trim To" length is 2.840". Some of the cases trimmed to this length while others were too short to be touched by the trimming blades. Some lengths turned out to be as short as 2.837", without trimming :?. My questions are, does this cause a problem & should I trim to the shortest length :?:

There, now I feel better. Sorry for the confusion & above all, thanks for your help :grin:

 

[Richracer1]

Your previous post was accurate. 2.85"/2.84" (depending on which manual you're usng) is the SAMMI max case length. Like everyone mentioned in your previous post, trim your brass to 2.83", so all are of equal length to start.

 

[bobbyrum]

Thanks Rich. Makes me feel better. I kind of figured trimming to same length for all would be the answer but its always best to get a second opinion. I was reading about your 7mmRUM. I hope you enjoy it :grin:.

 

[C.Smith]

Speaking of neck trimming for you guys that neck size only, do you still find you have to trim your cases?

Corey

 

[jtoews80]

Not as much, usually I get 3-4 firings out of my 264 between triming. I found that out when I first had it and not very much brass. I had a 22-250 that I used to neck size and I used to trim when I full sized(every fifth firing) because I always do. Usually it was 4-5 thou longer. My 30-378 usually doesn't require trimming every FL sizing, it only grows 1-2 thou per sizing.

I think it has alot to do with brass quality and how hard you push your load performance. I will be watching my Nosler brass in my 264 to see if it hold it's length well.

CC.

 

[jtoews80]

I assume you're refering to the BR guys, that isn't me. my mistake. I just neck size to reduce lock time and save my brass from being over worked. I got used to the way the brass chambers and it was trial and error to get to where I knew they needed FL sizing. I have gotten a piece of brass stuck when I tried to get one more neck sized load out of a lot of brass. Best solution is to size a few of the lot, wipe'em down with a paper towel to avoid lubing your chamber up, and run them thro your gun. If the bolt closes without force thy're good. It may give a little tighter fit on the bolt, but shouldn't take any real force to close it. If it does you'll get a case stuck on firing or even just loading. Better a unprimed case tho.

CC.

 

[C.Smith]

I'm doing this for my hunting rifle. I had been neck sizing with no problems but had some rounds that were tuff to chamber, and I was thinking I needed to trim all my brass. I was in the process of doing that but the garage is too cold right now.

Corey

 

[YoteSmoker]

C.Smith, most likely the neck is not the issue but the shoulder headspace it too tight now to your chamber after a few firings. I would full length your brass every 2-3 firings and check trim length every firing to be on the safe side. Is this a varmint or big game gun you are loading for? For varmint/bench shooting, necking brass is not as important whereas big game hunting you may get one shot or need two and run the risk of getting a stuck case ruining your season in a hurry.

 

[C.Smith]

This is my big game rifle. I never thought about the shoulder. Would I be better off using the full length die to partially full length resize than using the neck sizer? I think the ones I was having issues with were fired twice to three times. (My system for keeping track does not work very well).

Corey

 

[old #7]

You won't be able to bump the shoulder back if you don't run your brass all the way into the die.
You can control how much you push the shoulder back by adjusting your die in or out of the press.
Typically speaking you would run your press up to the top of the stroke, screw the die into the press untill it contacts the shell holder, lower the ram and screw the die in 1/2 a turn more. That method will insure the round will chamber in almost all guns of that chambering. Try sneaking up on it. Leave your die 1/2 turn away (or more in some cases) from the shell holder, run a piece of brass into the die, wipe off any size lube and chamber it into your gun. Keep screwing the die into the press until your bolt closes with a slight crush fit or easilly. You will only need to push the shoulder back a couple of thousandths for an easy fit. I would check the lenght of your brass after you bump the shoulder back.
Most of the time brass will flow into the neck when full length resizing and the neck will have to be trimmed.

 

[YoteSmoker]

+1 to what Old #7 said.

 

[C.Smith]

I will have to try that. Thank you for the advise.

Corey