Please tell me what I'm doing wrong?

[Arkyvarminter]

I've been loading for a long time and understand the process of making good loads but I'm here to learn so here goes. I found a piece of fired brass that bolts fairly hard in my rifle. I used this case as my measurement and bumped back .002. Now, after I fire this brass shouldn't it need bumping again? I mean, after firing and resizing, my brass is too short. I think I started off with too short of a length to start with. Info Appreciated...

 

[LHSmith]

If the load was mild, it may not need a shoulder bump....remember neck sizers only size the neck. Not sure what you mean by short? case length, or bump length (base to datum)? I'm thinking you may have set the shoulder back too far in an effort to reduce the web diameter. Don't use "found" brass for this exercise-ever!

 

[Arkyvarminter]

If the load was mild, it may not need a shoulder bump....remember neck sizers only size the neck. Not sure what you mean by short? case length, or bump length (base to datum)? I'm thinking you may have set the shoulder back too far in an effort to reduce the web diameter. Don't use "found" brass for this exercise-ever!

I'm using full length. I started off with brass fired from my rifle. I used it as a reference and bumped .002 and then FL resize. I think I may have discovered my problem. Some of my brass is not fully formed yet and i'm having trouble getting it there...

 

[gotcha]

Before you sized the case that you "found" was it making contact at the shoulder or at the base when you chambered it? Find a similar size case, polish it at the base then chamber it. Look for scrubbing at the base. ......If found, you may need a small base die................. Did you take a before and after sizing reading of cartridge head space?

 

[Arkyvarminter]

Before you sized the case that you "found" was it making contact at the shoulder or at the base when you chambered it? Find a similar size case, polish it at the base then chamber it. Look for scrubbing at the base. ......If found, you may need a small base die................. Did you take a before and after sizing reading of cartridge head space?

I shouldn't have used the word "found". I "selected" a piece of brass that had been fired in my rifle that was fairly hard to bolt and it was making shoulder contact. I measured from the shoulder, resized and bumped back .002. I did measure before and after.

 

[gotcha]

I shouldn't have used the word "found". I "selected" a piece of brass that had been fired in my rifle that was fairly hard to bolt and it was making shoulder contact. I measured from the shoulder, resized and bumped back .002. I did measure before and after.

O.K., understood ................ Your assessment may be correct the cartridge may have been making contact at the neck/shoulder junction but, if it isn't yet fully formed on the shoulder the datum to base measurement may be a bit short yet. .............. Not unusual to need two fire-formings to fully expand case shoulder for accurate bump measure. ...... With Lapua brass (harder alloy) this is a must. A stout load is helpful also.

 

[Tim Singleton]

What do you mean by bumped .002 then FL sized?

What dies are you using?

 

[Arkyvarminter]

What do you mean by bumped .002 then FL sized?

What dies are you using?

I meant I FL sized while bumping shoulder back...sorry..i need to proofread more. I"m using redding bushing dies..

 

[Shynloco]

I'm curious, did you happen to measure the shoulders and the OAL of the test piece of brass before and after firing it? I do comparison firing and measuring from time to time (but do not fire the known casing) because I EXPECT that brass will stretch in most instances when fired). BTW, when you say your test piece was "hard" to close the bolt, I was always taught, that with your test piece you should feel more resistance than not, but "hard" means you are decreasing (pushing the shoulders back further) than the desired .002 bump and thereby shortening the length of your brass.

Alex

 

[K22]

I base my shoulder bump back measurements off a fired case in the rifle that I'm reloading - over time this measurement sometimes changes with increased firings and sizing so I verify each time I load a group of cases. I don't think you can produce a reliable "standard" case to serve this purpose. You have to use a fired case and measure set back.

 

[Shynloco]

.... I don't think you can produce a reliable "standard" case to serve this purpose. You have to use a fired case and measure set back.

K22,
You apparently don't understand what I wrote. Yes bumping your shoulders .002 and using a just fired casing is good practice. BUT, I wrote I check for any change "from time to time" from a casing I started out with and you can see how much change (caused by throat erosion) as that change will contribute to how much your brass has changed and trimming (or the lack thereof) and what was once a tight bolt closing has become easier with little to no resistance.

Alex