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Case lenghth measurements? THAT important???

 
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  #1  
Old 01-19-2010, 10:33 PM
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Case lenghth measurements? THAT important???

Guys I was just wondering... I'm about to start working up some 30-06 loads w/ some 4831 and some 180 bergers... and I'm seeing a good bit of case length differences. ALMOST all of my once fired 7mm RUMs are 2.850, with a few @ 2.845s. These 30-06 cases are ranging from 2.490-2.509. All sized with the same dies, now not all were fired from the same gun though.

I never even purchased a case trimmer, b/c of the consistency of the once fired 7mmRUM brass. Now to me just looking @ the case trimmers it looks like its going to be hard to get every single case the same lenght without repeatedly checking, and IF you do slip up and cut one a little too much it looks like your gunna start BACK over... IF you have racked up about 50-60 brass, I guess you can set that case out... BUT I like to work in even numbers! lol

I'm gunna order myself a case trimmer this week anyway.
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Old 01-20-2010, 03:35 AM
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Re: Case lenghth measurements? THAT important???

Quote:
Originally Posted by joshua99ta View Post
Guys I was just wondering... I'm about to start working up some 30-06 loads w/ some 4831 and some 180 bergers... and I'm seeing a good bit of case length differences. ALMOST all of my once fired 7mm RUMs are 2.850, with a few @ 2.845s. These 30-06 cases are ranging from 2.490-2.509. All sized with the same dies, now not all were fired from the same gun though.

I never even purchased a case trimmer, b/c of the consistency of the once fired 7mmRUM brass. Now to me just looking @ the case trimmers it looks like its going to be hard to get every single case the same lenght without repeatedly checking, and IF you do slip up and cut one a little too much it looks like your gunna start BACK over... IF you have racked up about 50-60 brass, I guess you can set that case out... BUT I like to work in even numbers! lol

I'm gunna order myself a case trimmer this week anyway.
It IS important that you keep your brass trimmed to below MAX length, it is a safety feature of the brass.
Now, you probably won't run into trouble until your brass grows to around .020" over max length, but not always!
I have a couple of rifles that show 'crimping' when they're only .005" past max length!
This is why it's recommended to trim your brass .010" BELOW max case length.
30-06 brass tends to stretch/grow quite a bit on each firing, so it's wise to check them often, you can trim ALL your brass to min spec when you get it, no matter what the initial source.
I normally fire new brass first to iron out any shortcomings such as growing longer on one side and the like, then trim to MIN spec (.010" below MAX.).
2.490" for 30-06 brass is MAX, you really need to trim them back to 2.480" to be on the safe side, the brass you have that measures 2.509" is way over max and needs to be trimmed!
If you do not understand the reasons for this, get yourself a modern reloading manual, they will explain why it's necessary in detail!
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Old 01-20-2010, 05:48 PM
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Location: Mountians of SW NC, near Asheville
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Re: Case lenghth measurements? THAT important???

[QUOTE=joshua99ta; I'm gunna order myself a case trimmer this week anyway.[/QUOTE]

Get the Lee case trimmer tools. They are quite simple but work fine. Cutting length is fixed, you won't have to be concerned about trimming too much. And cutting too much IS a concern with all adjustable length trimmer types.

Cases don't really grow much during firing, they mostly get longer during normal FL sizing. If we only FL size the absolute minimum needed to chamber the cartridges (or neck size) cases will grow quite slowly if at all.

Last edited by boomtube; 01-20-2010 at 05:53 PM.
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  #4  
Old 01-20-2010, 06:55 PM
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Location: Salmon, Idaho
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Re: Case lenghth measurements? THAT important???

I don't buy factory ammo for my center fire rifles but generally I treat virgin brass and once fired the same. Size and trim then fire and reload until it approaches or exceeds max length and then trim again. Yes, it is important for safety plus it is one more variable that is under your control. Remember consistency=accuracy.
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Old 01-20-2010, 07:22 PM
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Location: Memphis, TN. Soon to be Casper, WY.
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Re: Case lenghth measurements? THAT important???

Or you can buy the RCBS X Die and trim only once. I've not had any cases grow since I got the X Die.
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  #6  
Old 01-20-2010, 09:20 PM
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Re: Case lenghth measurements? THAT important???

Check out the Sinclair/Wilson Ultimate Micrometer Trimmer w/ Shark Fin here's the link: Case Trimmers - Sinclair/Wilson Ultimate Micrometer Trimmer w/ Shark Fin

It works very nice and very repeatable. I use it in conjunction with the Wilson Case Holders hold the case square to the cutter face...about 9 bucks, here's the link: Wilson Trimmer Holder
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  #7  
Old 01-22-2010, 07:02 PM
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Re: Case lenghth measurements? THAT important???

thanks fellas.

I was just wondering. I know the manuals state to trim. I was just wondering if it was such a big deal to have them all within .001 or .002 of each other. I'm not just really worried about the accuracy with this rifle, its more of a b/s rifle that I'll take for under 300 yard stuff. It shoots pretty good for a semi auto(browning bar)
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