chamber length measurement

[TackDriver284]

I did the chamber length measurement on the .308 and its 2.043" and I checked my recommended trim length and its 2.005". I do trim the brass batch to 2.005 and leave the shorter ones alone. Will extending trim length have any effect since there is a .038" gap?

 

[kraky1]

What you have is a very typical Factory chamber.....Here's my guns.....
Rem factory vtr.....2.040 actual trim
Sons Browning 2.047
My Savage Le 308 2.042
My 308 bar Browning 2.040
I have not had any problems starting with Factory virgin brass that would be close to trim length or by trimming down to Sammi recommended trim length..... and because I have quite a few dies for my 308 including a forestor Bump fie, redding body die, several FL dies and Lee collet die..... I can pretty well control my case stretch and get one heck of a lot of reloading before having to worry about trimming in any of my guns. This is what makes having those inserts quite an eye opener.... and a big Big Time Saver.

 

[kraky1]

Just for curiosity I just spend some time looking in some guns that have been fired a quite a bit that have generous trim lengths with my lyman borescope.... I was curious if I would see some excessive carbon buildup in the Gap area....the answer is NO.
My normal cleaning regimen is Wipeout bore foam with a plastic Delrin bore guide with an O ring so I'm guessing the foam is getting things cleaned up there just fine.... or maybe there's another reason but there is no problem.

 

[TackDriver284]

kraky, can you control case stretch by die adjustment? If so, how do you do it, if I may ask?

 

[kraky1]

I feel you can do it a couple of ways. First of all by doing the minimum shoulder bump when you resize....I shoot for. 002.
And.... I think it helps not pulling in expander ball up through the case neck when you are done sizing. With the lee collet die I can often skip A FL resizing every other time I load and that helps too. The redding body dies also seem to work the Brass a little less than a lot of my FL dies. Bottom line..... the less you squeeze and pull on your brass the less likely it is to move a lot.

 

[TackDriver284]

There is also a Redding carbide button kit to replace the expander ball, makes pull on necks a little easier I assume. Just never tried it.

Most of the time new brass stretches on the first two firings or so, after that it stretches less. I really dislike trimming brass, even with my drill on a RCBS Pro Trimmer.

 

[longrangehunter]

There is also a Redding carbide button kit to replace the expander ball, makes pull on necks a little easier I assume. Just never tried it.

Most of the time new brass stretches on the first two firings or so, after that it stretches less. I really dislike trimming brass, even with my drill on a RCBS Pro Trimmer.

I've used the carbide sizing buttons on everyone of my dies for the last 17 years, or in some cases if the mouth of the case is perfectly good on my fired brass I won't even use a button at all and I run them through just a neck Bushing die. Less stress on the brass IMO, and I can quickly run them through my die with less runout.

The button also helps with the stem and button line up inside with the centerline of the case better.

 

[kraky1]

Well tackdriver now that you know you're real trim length you wont have to be trimming a whole lot!!....lol.
Your mission done been accomplished........ and you can keep reusing that insert on a whole bunch of other cases..... I think my 30 caliber insert does duty on about 10 different cases. I don't think there was any investment in the reloading game that can save more time per dollar than those cheap little inserts......jmho!

 

[waveslayer]

The only thing you will want to do is keep the brass at the same length because the necks will impact how much neck tension is on the bullet. That is big for accuracy.

My wife thinks I only have 3 guns