Properly sizing cases

[markT]

I found this very useful.. I listened to Cortinas speak on how to do it, but this "shows" how to do it. I also like to see that he pulls trigger and closes bolt to un-cock rifle..

 

[Dusty Stevens]

He strikes me as a neck sizing guy in real life. Once the case is formed you can measure it and skip the having the rifle step. Once you write that down you can even see if your cases need bumping at all

 

[markT]

What I liked was he points out that the RCBS instructions are not correct and there is a or better way. Randy shows the simplicity of using the actual rifle and no tools and figures and bla bla bla.

 

[Murray Brook]

For years when I adjusted my bump I done it as he done till I got bump gages. The only thing I didn't do like him was I liked my bolt to close freely on the case with the firing pin removed. I feel his way gives you zero bump or even a neg .0005. JMO

 

[BoydAllen]

For factory chambers and production dies setting by bolt feel is probably fine....but for custom work, you can run into a situation where the die is essentially too big for the fired brass. In that case, by the time you get the bolt close that you want, you have bumped the shoulder back too far. That is my problem with guys who tell others, who may not have the same dies and chamber, how to do it. One of the first things that I do with a new die, while I am setting it up, is to measure the diameter at the shoulder body junction and slightly above the extractor groove, before and after sizing, to make sure that those diameters are reduced by sizing. I prefer to have well formed cases for this, both for diameters, and for before and after shoulder to head dimensions. I think that most of us have either dial or digital calipers and the cost of the attachments needed to measure to set your FL die is reasonable.

 

[Alex Wheeler]

The last thing I want is to feel the case when I close the bolt.

 

[BoydAllen]

The last thing I want is to feel the case when I close the bolt.

Alex. do you set your dies by feel alone? (rhetorical question) My point being that if you really are not measuring at all, once you reach the point of absolutely no feel on close, you really do not know whether you have bumped too much or not. Lots of old school short range shooters (who have done well in competition) have said that they want some feel toward the end of the close, which makes no sense to be because the lugs and their seats should be parallel if everything is correct. Speaking for myself, if I have a carefully established .001 of bump and I don't like the bolt fee, I believe that I need a different die.

 

[Alex Wheeler]

Boyd, I cant speak for all SR BR guys, but many seem to like what you say. However, my advice for a LR BR shooter would be to bump at least another .001". Probably my best shooting 1k rifle, I bumped .0035". I want that bolt to drop like nothings there.

 

[J.d. Popkes]

In my opinion. You should measure, check in your chamber, and then see how consistently your measurements come out.

Also in my opinion, to get dead nuts consistent bump, it comes down to:

Annealing every time
Consistent lube technique
Press stroke consistency
cam over on comp shell holders
No expander ball

There’s surely other methods but this is what I found. I have a recess in my anvil base that goes on my caliper so a fired case with a dimple or high primer doesn’t interfere. The only thing I am certain of is that inconsistent shoulder bump shows up at distance. I went to public school so it took awhile for me to work all this out, I’m sure it’s a given to some. I damn near got admitted into the rubber room before I gotter all fingered out.

 

[Jtate]

I want that bolt to drop like nothings there.

Alex I do not doubt what you say. I just want know the Why? behind the statement.

 

[Dusty Stevens]

Alex I do not doubt what you say. I just want know the Why? behind the statement.

If youve ever shot a BR rifle youve gotten cases that may not size like the others and you get a bit of a tight bolt close. That bullet will not go into the group no matter what. In BR we value gun handling way more than case life. If you get a die set to feel a case and size 50 ill be you money youll feel at least one way more than the others

 

[Alex Wheeler]

Alex I do not doubt what you say. I just want know the Why? behind the statement.

Whys are mostly guesses. I have just done it and I know what successful shooters are doing. I could feed you a reason why. Or better yet, test for yourself. Thats all that matters.

 

[K22]

What the gentlemen is describing is the method used before the advent of bump gauges and measuring actual case head space. This is a qualitative not a quantitative method. It's tedious, outdated and not precise but it's better than just adjusting the FL die per the mfg.'s instructions and sizing without any idea how far you are pushing the shoulder back. However, in my opinion, there is a more efficient and precise way.

While I've found it beneficial to initially spot check my FL sizing adequacy by chambering a sized case in the rifle chamber to verify fit, measuring fired case headspace with a bump gauge and caliper then adjusting the FL die to produce the optimum fit is a more efficient and precise method in my experience rather than the "feel" method. By measuring fired versus size case head space you know exactly how much you are pushing the shoulder back. Making adjustments as cases wear and age becomes much easier.

 

[BoydAllen]

Boyd, I cant speak for all SR BR guys, but many seem to like what you say. However, my advice for a LR BR shooter would be to bump at least another .001". Probably my best shooting 1k rifle, I bumped .0035". I want that bolt to drop like nothings there.

My point was that you measure. Of course you are going to do what shows up best on the target, but you do not do it by feel. I know that short and long range are different, and would never presume to correct you. I was just addressing the idea of setting bump by feel. I measure. You measure. If the die is small enough to reduce the diameter of the body of the brass, you can get away with doing it by feel, and if you adjust for just a little feel you will not over bump, but if you are looking for a free no feel drop, unless you measure, you really don't know what you have done. That was my point, nothing else.

 

[M-61]

If youve ever shot a BR rifle youve gotten cases that may not size like the others and you get a bit of a tight bolt close

What does having a BR rifle have to do with it?
Nothing at all. That case doesn’t know if it’s in a BR rifle or a barn gun.
Maybe it’s an exclusive club thing.

 

[Darwin]

What does having a BR rifle have to do with it?
Nothing at all. That case doesn’t know if it’s in a BR rifle or a barn gun.
Maybe it’s an exclusive club thing.

I’ve heard that will cause that bullet to not go into the group no mater what.

 

[M-61]

In BR we value gun handling way more than case life.

Who is “we” and what is ‘gun handling’?

 

[M-61]

have said that they wand some feel toward the end of the close, which makes no sense to be because the lugs and their seats should be parallel if everything is correct.

?

 

[M-61]

I’ve heard that will cause that bullet to not go into the group no mater what.

Yeah. Actually I enjoy definitive answers. I also enjoyed f guffey’s posts.

 

[rwj]

He strikes me as a neck sizing guy in real life. Once the case is formed you can measure it and skip the having the rifle step. Once you write that down you can even see if your cases need bumping at all

In a fired lot of cases, how many do you typically discover that need the shoulder “bumped”?

I had a barrel from which less than 10% needed the shoulder, and case body, sized each firing. For the life of that barrel, I was largely a neck sizer! At first I didn’t trust my measurements, so they were verified by stripping the bolt, then chambering the cases to determine if the bolt handle fell by gravity… it did!

Shooting the same load in the replacement barrel (same reamer) did not produce the same outcome. In fact the opposite in that all cases require full resizing each firing. Never was able to determine why. The smith that chambered both barrels suspects that the first barrel had a rougher chamber wall finish. Seems like a plausible explanation….?