case length

[Wavslave91]

I pick up a batch of once fired Lake City 308 brass. The book states that the case should be trimed to 2.015. I have a Lyman universal trimmer and after dinking with it, my cases are ranging from 2.0135 to 2.0155. My question is just how close do you have to be to get a consistency in accuracy? Do you have to be dead on or am I being to picky? Dennis.

[steveno]

get you calipers or micrometer out and set it for .002 and you can see how really small that it is. you can decide how picky you are. to me .002 is nothing to worry about

[F. Guffey]

I pick up a batch of once fired Lake City 308 brass. The book states that the case should be trimmed to 2.015. I have a Lyman universal trimmer and after dinking with it, my cases are ranging from 2.0135 to 2.0155. My question is just how close do you have to be to get a consistency in accuracy? Do you have to be dead on or am I being to picky? Dennis”

Dennis, I will assume you are not looking for an answer that can be covered in 10 words or less. Trimming? and exact length, with the 308 W bottle neck type neck it is necessary to be exact of the reloader has plans on crimping. Crimping can cause shoulder collapse and bulges if the cases are not trimmed to the same length. then there is the length of the chamber, reloaders have SAAMI, I have not figured that one out, seems most are loading for something they do not have, I determine the length of the chamber from the mouth of the chamber back to the bolt face, knowing the length of the chamber allows me to decide if a case requires trimming,

For example, I built a 30 Gibbs, I started with a 30/06 chamber, the 30 Gibbs chamber is shorter than the 30/06 chamber, meaning? My 30 Gibbs chamber is .040” longer, that helps when one considers the neck on the 30 Gibbs is .217” long, my neck lengths are .257” long.

There are methods and techniques that could allow a reloader to determine the length of their chamber.

“I being to picky?” I do not care if you are picky, I do believe it is important you know why you are picky. A reloader does not want the mouth of the case extending past the chamber mouth, the long case can cause high pressure if the neck of the case is not allowed to open/expand.

F. Guffey

[higgite]

What book do you have that says trim to 2.015" for .308? My reloading manuals say 2.015" is maximum case length, trim to 2.005".

I wouldn't worry about .002" variation in case length, but maybe some benchrest shooters might, I dunno.

[Dave P]

"my cases are ranging from 2.0135 to 2.0155."

Anything from 2.005 to 2.015 should be fine. And you don't need 4 decimal places of accuracy.

[steve4102]

Originally Posted by higgite

What book do you have that says trim to 2.015" for .308? My reloading manuals say 2.015" is maximum case length, trim to 2.005".

Good Catch higgy, your are indeed correct.

[cw308]

Once fired lake city brass, I would first full size, trim back to proper length, as higgite & steve 4102 state 2.005- 2.015 max. and fired in your rifle then your brass is fire formed to your chamber, if using a bolt action you can try neck sizing, full sizing & even partial neck sizing to see what works best in your rifle. If your not loading hot loads your brass isn't going to stretch so fast. I guess for accuracy everything should be exact,but I haven't seen much of a difference between 2.005-2.015 case lenght. Hope I helped and double check your numbers.Be Safe Chris

[jepp2]

You are running your neck inside and outside chamfer tool around the case neck to remove the burr before measuring, right?

If you are using calipers to measure, you can probably rotate the case between the jaws and get slightly different length measurements.

[Bart B.]

I've always trimmed my .308 Win. cases to an even 2.000" then back to that when they reached about 2.010". Never had any accuracy issues shooting the short ones with the long ones.

Well, maybe a 1/100th MOA difference at most but I cannot remember which ones shot the best .

[Wavslave91]

First off, thanks for the replies guys. As all have good points. I dident think of deburring the case before measuring it. I am getting into long distance precision shooting, but I'm just learning both the shooting and the custom reloading aspect of the game. So for right now I am just trying to get some rounds down the pipe without having my investment "rifle" blow up in my face. Am glad I got a little wiggle room for now. F Guffey, thanks for the insite. Higgite, the book I'm using is Lymans 49 edition and you are right that 2.015 is max length. So, my next question is, if I trim the cases down to say 2.005 and shoot them thru my bolt action sniper rifle, will it expand to fit the chamber so when I reload it again, I wont have to re size it or trim it again?. CW 308, I will take your input to heart. After I put a few reloaded rounds down the pipe, I will remeassur the cases and see how it goes accuracy wise. Thank you all for the input. This is why I joind this forum. Dennis.

[steve4102]

Originally Posted by Wavslave91

So, my next question is, if I trim the cases down to say 2.005 and shoot them thru my bolt action sniper rifle, will it expand to fit the chamber so when I reload it again, I wont have to re size it or trim it again?. CW 308, I will take your input to heart. After I put a few reloaded rounds down the pipe, I will remeassur the cases and see how it goes accuracy wise.

You will always have to "size" your fired cases. You can either Full length size them or you can just size the neck (neck sizing), but you have to size.

You do not have to trim every time as long as the case "After Sizing" is 2.015 or less. Always check case length after sizing.

[Bart B.]

Wavslave91, check out the info in these links on loading for best accuracy at long range for the .308 Win. round:

http://riflemansjournal.blogspot.com...ation-and.html

http://riflemansjournal.blogspot.com...for-palma.html

http://riflemansjournal.blogspot.com...-308-load.html