Curious ?

[rmist]

I'm looking at a 308 Win chamber reamer print...overall case measurement is 2.0250"...So, would you let your cases grow to 2.0150" and use that as your trim length? Or use the standard of 2.005 ? Just seems like a lot of brass being removed. Currently I trim mine to 2.010" for this particular chamber.
Thanks again

 

[ab_bentley]

Measure your chamber oal first. The print isn't always correct.

But yes about .010" is all you want to trim back and keep it there.

Adam

 

[ireload2]

Your chamber is not necessarily a perfect match to the drawing - in fact it is almost guaranteed to not match exactly.
Just measure your chamber length, it is easy to do.

Find a similar but longer case and form it with a really long neck. Then trim the neck until it is about .030 longer than the drawing.
trim .005 off at a time until the bolt almost closes. If it does close, form another case and trim it to .005 longer than the case that the bolt closed on. Once you are very close to the bolt closing trim your cases .001 at a time until the bolt closes. Repeat 3 or 4 times until you get an exact feel for the length of the chamber. Write the number down. If you load a round .001 shorter than your chamber and fire it you will find it is shorter after firing. If you resize the case it will grow and it may be too long. Check it before loading it again. You can use these extra long cases as long as they are shorter than the chamber and you must check the length after each resizing to verify they are not too long. This may result in trimming some brass at each loading. I prefer that the cases are at least .003 to .005 shorter than the chamber so trimming is not required every time.

for a .308 a longer case to measure the chamber with might be an 8X57 case or 30-06 case. A .270 case will work ok too.

I'm looking at a 308 Win chamber reamer print...overall case measurement is 2.0250"...So, would you let your cases grow to 2.0150" and use that as your trim length? Or use the standard of 2.005 ? Just seems like a lot of brass being removed. Currently I trim mine to 2.010" for this particular chamber.
Thanks again

 

[Dusty Stevens]

You can also drill the back of a case and look in there with a borescope to see how much room you have

 

[rmist]

Thanks again...I'll check and see what the actual length is.

 

[4xforfun]

Sinclair chamber length gauge. $6.00.

http://www.sinclairintl.com/reloadi...r-chamber-length-gage-prod32925.aspx?psize=96

 

[fguffey]

I'm looking at a 308 Win chamber reamer print...overall case measurement is 2.0250"...So, would you let your cases grow to 2.0150" and use that as your trim length? Or use the standard of 2.005 ? Just seems like a lot of brass being removed. Currently I trim mine to 2.010" for this particular chamber.
Thanks again

I will assume you are not a case forming reloader, I am, my favorite forming die is the 308 W forming die. I can form 30/06 cases to 308 W. I know, there are too many 308 W cases available for a reloader to find it necessary to form the cases.


Point; I form cases, I have no problem forming 308 W cases out of 30/06 cases because before I can use the case after forming I am forced to trim .479” from the formed case neck. I am not obligated to fire theses cases but when trimming the neck I can leave them long when determining the length of the chamber.


The one thing I must keep up with is the length of the case from the shoulder to the case head. No one knows if the case neck is seated into the throat or the shoulder of the case is contacting the shoulder of the chamber.


So I start with sizing the case for a short chamber first.


F. Guffey

 

[Brians356]

I like the Sinclair chamber length gages, and have quite a few dummy rounds with those, for permanent reference. But if you happen to have a set of pin gages, you can use one which is slightly smaller diameter than your chamber neck, and a cleaning rod, to find the chamber length to a close tolerance.

[Edited: "leade" to "freebore"]

Another way to get a ballpark measurement is to seat a flat-base bullet backwards in a sized case, then chamber it. Obviously a long enough bullet, seated shallow enough, to allow it to run into the end of the freebore. Just enough neck tension to grip the bullet so you can't dislodge it by hand. You'll have to guesstimate how much to subtract for the freebore length, however, so this is far from a useful method unless you have the reamer print as you do. And the rounded heel of the bullet will "jam" a minute distance into the lands as well.