Trim to length for 30-06 casing

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Darksith

New member
The max length is 2.494, but none of my books tell me the trim to legnth. Is there a standard or should I just trim to the max length?
 
To make sure commercial cartridges always fit in commercial chambers, SAAMI always gives chamber dimensions as a minimum with the tolerance being no less than those dimensions, plus some number. To ensure cartridge fit, the opposite approach is then taken with cartridges: the maximum not-to-exceed dimension is given in the drawings with a minus tolerance. In the example of rifle cases, the maximum length is given, with a tolerance of -0.020". So the .30-06 can be anywhere from 2.474"-2.494" and be within SAAMI specs. Some shooters ignore that and shorten an additional 0.015" so they never have to trim again during the normal reloading life of the cartridge. Most commercial trimmers that are fixed, though, like the Lee, will trim right at the middle of the SAAMI tolerance: 0.010" less than maximum and more than minimum.
 
thanks, thats a great site. I have the sierra bullet reloading manual and the lyman 45th edition. I now see the trim to length in the lyman book, but still can't find it in the sierra
 
"I now see the trim to length in the lyman book, but still can't find it in the sierra"

That's because it really ain't critical.
 
another thing Ive noticed, is that I have a lee case trimmer. It only trims the casing to max length not to trim to length, has anyone else noticed this?
 
Again, I found this thread via googlefoo concerning trim length for the venerable 30-06 case. I want to resurrect the thread because of the links contained therein.

To the subject at hand, my RP cases are ~2.492. The number already posted in the thread, which is the same as my Speer manual, is 2.494 inches for max length.

Do you guys trim cases that are just below max length, or wait till they exceed max length? Or do you trim to ensure all the cases are the same length?

Also, don't precision shooters trim to the exact point at which the barrel rifling begins? Under the assumption that any bullet "jump" means bullet instability?

I'm trimming for a Ruger #1 30-06 as well as for a Rem 700 KS Mountain rifle. As far as I can determine, they both have 1 in 10 twist.

thanks
 
I trim every firing , I keep my trim length to the middle of the trim scale . When doing it after every firing it's more of a clean up then a trim . Keeps things going smooth .
 
FoghornLeghorn said:
Also, don't precision shooters trim to the exact point at which the barrel rifling begins? Under the assumption that any bullet "jump" means bullet instability?
Click to expand...

Bullet jump is determined by how deeply you seat the bullet in the case neck, not by the length of the neck. The two are independent of one another.

Neck length is not maximized by any shooters I am aware of. If it is too long it bumps against the end of the neck portion of the chamber. This can theoretically cause the brass to upset and jam against the bullet so the case can't release the bullet on firing, thereby raising pressure. In practice, this jamming actually tends to push back on the case, causing it to swell out in the chamber.

I am unaware of actual gun damage attributed to failing to trim brass, but that is far from saying it isn't possible, so I follow the practice. Also, bumping a case shoulder or body back takes the case shoulder out of contact with the chamber shoulder, so it loses the self-centering at the front of the chamber that such contact normally produces, and thus would be unhelpful to group size.
 
Darksith: Here is the Sierra layout. The schemiatic shows the max, but this shows the Trimp to in what I would call the details - firearm, primer etc.

Test Specifications/
Components

Firearm Used: Universal Receiver
Barrel Length: 24”
Twist: 1-9″
Case: Nosler
Trim-to Length: 2.490”’
Click to expand...
Primer: Winchester WLRM

I would put it on top as its probably the most used detail but .....




The op needs to get better reloading manuals as the quality ones all have case specs.....
Click to expand...

The OP found it in the one book, it is in Sierra (I certainly hope you are not saying that is not a quality book?)

Its a bit hard to find sometimes the way laid out,
 
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another thing Ive noticed, is that I have a lee case trimmer. It only trims the casing to max length not to trim to length, has anyone else noticed this?
Click to expand...

If you do enough, the Giraud Tri Trimmer is a very good tool. Chucks up in a drill (you can then clamp it in a vice) and it comes with a trimmed case.

Per Unclenick I now trim them back another -.010 as I have some go over the max before I anneal and I like to process anneal and trim in one go.
 
RC20, sorry, but I resurrected a 2009 thread. The original posters likely aren't watching it anymore.

I googled this subject and this thread was the first link that came up so, I tagged it for future reference.
 
Tracking now. Unclenick answered that part.

I follow what he suggested, not for the same reason it was done but as I run the process through full at 5 shooting (anneal and trim) I find a few cases are longer than they should be.
 
And you are probably not over-trimming. A lot of the M14 shooters that took their cases back an extra 0.015-0.020" below SAAMI minimum were FL resizing and some even small base FL resizing out of fear of getting a feed failure in rapid fire and so got maximum head stretching at every load cycle. That's how they came to toss cases after four reloads. Too much chance of a head coming off and ruining the string in the NMC, where no alibis were allowed.
 
Makes sense. I can alibi all day long with my recreational target shooting (RTS)

Still nice to keep it out of the excess zone as an odd one sometimes does go long for unknown reasons.
 
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