Case length question

[Tonmarchelli]

I have a question regarding case length. Im getting into reloading for the first time and am getting measurements for Case length, OAL and ogive for the round im developing. I bought a sinclair chamber length gauge
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Im loading for a brand new never fired Remington 700 sendero II in 300 WM. when using the gauge i get an overall chamber length of 2.665". that is what i was going to trim all my brass down to to get a uniform custom case length for the rifle. BUT.... the longest piece of brass i have (new unfired Remington brass) is 2.614" SO ive got roughly 50 thousands shorter brass than my chamber.

Should i not worry about this now as the brass will lengthen as i shoot and re size then trim down from there? at this point should i not really worry about case length until i have to bring it back?

I also bought the hornady OAL length gauge and will be seating the bullet just off the lands (.010" right?) which will give consistent shots.

thanks for the input. going to crank out some rounds tomorrow and take my gun to the range for the first time.

 

[mdesign]

Re: Case length question

Your brass is and should be shorter than your chamber. It is good to know the length of your chambers as it give you one more piece if info as you work to tailor your load to your gun.

I usually start by firing my brass before I prep it with the exception of turning my necks if I am going to do that. Once my brass is fired, I trim them to the same length, just to be consistent. After that, I watch the cartridge OAL and let them lengthen as they are fired until they get within .010 of the length of the chamber.

Once they reach that point, I keep them trimmed to .010/.012 short of my chamber length. I have found that running them that close to chamber length minimizes the build up of the carbon ring in the throat.

This method works for me but BE CAREFUL not to let them get too long as they will jam against the length of the chamber and significantly raise chamber pressure during firing. Not a good thing to have happen.

FWIW - the chamber on my 7mag is almost the same length as yours. I have a batch of 7RM brass that was so short out of the bag that even after 10 firings, it is no way close to the length of the chamber. In that case I have just kept them trimmed to the same length and my groups are great.

 

[MALLARD]

Re: Case length question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Tonmarchelli</div><div class="ubbcode-body">
1 SO ive got roughly 50 thousands shorter brass than my chamber.

2Should i not worry about this now as the brass will lengthen as i shoot and re size then trim down from there? at this point should i not really worry about case length until i have to bring it back?

3I also bought the hornady OAL length gauge and will be seating the bullet just off the lands (.010" right?) which will give consistent shots.

</div></div>

1 unfortuantly that is somewhat normal
2 yes but its ideal to keep your case necks square , especially if you use a flashhole tool.
3 you shoud do a seating depth test to determine what your bullet jump should be.

 

[Hookturnr]

Re: Case length question

To further clarify, at least the way I go about it, I start at the lands, find the powder charge range that looks most promising, then run the seating depth test as outlined by berger. This seems to consistently get me onto a good load in less than 60 rounds. I usually tinker and refine from there but you have to start somewhere..

 

[Tonmarchelli]

Re: Case length question

thanks for the replies. sounds like i should let the brass lengthen as I shoot and size them. at one point though, the brass will be touching the end of the chamber. Is there an optimal distance to trim the brass away from the chamber. Im assuming right on the chamber can cause high pressures.