Runout with FL sizing 30BR (little update.)

[Kevin1990]

So I recieved my harrells die and set it up. Put my Wilson .326 bushing in and put 2 thou bump on the shoulders. Everything was perfect.

Then I went to check runout while I was trimming the brass and I have .003-.004. some are .0015-.002. I'm using a RCBS rockchucker supreme to size.

I'm updating this: I tried my ressing 6br die as well and I'm still getting about the same amount of run out of 10 cases. What the hell is going on?

Any suggestions?

 

[gunsandgunsmithing]

Have they been fired yet? They typically get straight after ya hit em good

 

[Kevin1990]

Have they been fired yet? They typically get straight after ya hit em good

They have been fired once. I checked runout on a fired case and it was almost non existent. So I re-sized with the Harrels and I'm getting 3-4thou runout. Wondering if the die isn't centered or something simple I'm missing?

 

[TonyinKY]

Since you’re trimming I’m going to assume the brass has been fired at least twice. If so you may want to try another batch of that high dollar brass. It’s not all created equal.

 

[SeabeeKen]

Check the variation in the body where your case rolls. I've found variation there that showed as runout. I'd eliminate that possibility first thing

 

[Kevin1990]

Check the variation in the body where your case rolls. I've found variation there that showed as runout. I'd eliminate that possibility first thing

Just checked a few cases. Seeing virtually no run out there.

 

[Kevin1990]

Updating this: I tried some 6br brass with my Redding die and still getting the same amount of run out on those cases as well. So I think I'm narrowing it down to the press perhaps? But what in the press is causing it? Or rather what am I doing/ I introducing into the press to make this happen?

 

[Bill Norris]

Updating this: I tried some 6br brass with my Redding die and still getting the same amount of run out on those cases as well. So I think I'm narrowing it down to the press perhaps? But what in the press is causing it? Or rather what am I doing/ I producing into the press to make this happen?

Have you removed the metal clip from the ram that holds the shell holder in place and replaced it with an O-ring? This seems to help with some Rockchucker presses.

Pausing at the bottom of the press stroke momentarily helps.

Some reports placing an O-ring under the insert in the top of the press works as well.

 

[Kevin1990]

Have you removed the metal clip from the ram that holds the shell holder in place and replaced it with an O-ring? This seems to help with some Rockchucker presses.

Pausing at the bottom of the press stroke momentarily helps.

Some reports placing an O-ring under the insert in the top of the press works as well.

Nope! Didn't know about that, however you may be on to something and probably correct, OR it's the shell holder itself?

I just resized some 6.5 Grendel brass (different shell holder) and I am getting about .001-.0015 runout. The other 2 BR cases were using the same shell holder that was giving me quite a bit of run out.

I'm still new and learning, but would bad a shell holder still give proper shoulder bump and crappy run out on the neck?

 

[Bill Norris]

Nope! Didn't know about that, however you may be on to something and probably correct, OR it's the shell holder itself?

I just resized some 6.5 Grendel brass (different shell holder) and I am getting about .001-.0015 runout. The other 2 BR cases were using the same shell holder that was giving me quite a bit of run out.

I'm still new and learning, but would bad a shell holder still give proper shoulder bump and crappy run out on the neck?

I guess it could. Nothing is chiseled in stone with this stuff.

 

[Kevin1990]

I guess it could. Nothing is chiseled in stone with this stuff.

Tried another shell holder for my .223 (no expander ball) and that is also giving me .001 run out. I will be getting an oring and some Redding comp shell holders I think.

 

[Shooter13]

What brand of neck bushing are you using? I've gone from the RCBS to the SAC and seen a reduction in runout, it's real.

 

[Kevin1990]

What brand of neck bushing are you using? I've gone from the RCBS to the SAC and seen a reduction in runout, it's real.

I bought 2 le Wilson's. Both gave the same run out. Perhaps I could try a SAC bushing as well.

 

[Link]

I didn't see where you did twice fired. ?

 

[Kevin1990]

I fired it once. With a stout load and jammed. It measures the same on everything as the brass I fired 3 times, so I figured that was enough. Also when checking the run out of a fired case it was about .001 or less and then when I sized it, it became .004-.005

 

[Webster]

So I recieved my harrells die and set it up. Put my Wilson .326 bushing in and put 2 thou bump on the shoulders. Everything was perfect.

Then I went to check runout while I was trimming the brass and I have .003-.004. some are .0015-.002. I'm using a RCBS rockchucker supreme to size.

I'm updating this: I tried my ressing 6br die as well and I'm still getting about the same amount of run out of 10 cases. What the hell is going on?

Any suggestions?

I assume the cases were neck turned? I never measured runout. From pictures I have seen the case is put on some kind of support and rotated. The runout is measured on the neck or the bullet. The case body wall should have some variation in thickness which would cause an error in bullet runout? If there are a few thou variation in chamber roundness from reaming, this dimension should be transfered to the fired case body. It would be interesting to rotate the case on its support and see what the body runout variation is.

Check the case neck runout after firing and compare to seated bullet runout. Post the data if you have it. This could tell you if the runout is from the die? It would be a learning experience. A few thou are only the thickness of a human hair. Sounds like many things may contribute to runout? Are you really measuring runout since the case is not being rotated on a true absolute center line. It's being rotated on the case body external surface.

ADDED LATER:
The sized case is smaller than the chamber. This means it's not centered in the chamber. It's laying on the bottom of the chamber. The forcing cone isn't much bigger than the bullet. Does it straighten out the bullet with the bore? Does it whack the bullet and cause a very small amount of damage?

 

[Kevin1990]

Hey Webster,

Good info and valid points. So I had them neck turned for me, by a guy on the forum. I have a Sinclair concentricity gauge. I am measuring the run out on the neck after using a Harrels FL sizing die with a .326 bushing and a .327 bushing.

I checked the run out on a few fired cases and it was at or under .001. after re-sizing it in the sizing die I was getting .003-.005.

I checked the case body run out by flipping the case and checking the case body. The run out was at or under .001

So, I tried a different die and some 6 BR brass and was still getting .003-.004 on 10 cases. So then I tried a different shell holder for my 6.5 Grendel and a 6.5G case and resized it and had about .001-.0015 run out.

Then, I tried another shell holder for my .223 rem and sized some fired cases, and again had about .001-.0015 run out.

So I think the culprit is the shell holder, because on my other two shell holders and cartridges everything checks out normal. So I'm going to take bills advice and try the oring and get some better shell holders.

I think I found the reason for what's happening. Hopefully I'm not wrong, because if I am, I have absolutely 0 idea. Haha!

 

[gunsandgunsmithing]

What brand of neck bushing are you using? I've gone from the RCBS to the SAC and seen a reduction in runout, it's real.

Was gonna say, just remove the bushing completely, check runout, then step down a bushing at a time if you can. Most all runout issues are somewhere in the sizing op. Rarely in the seating step with good prep to that point. I didn't see neck diameter mentioned but the more you move the brass, the more runout becomes a noticeable issue and most people use a pretty fair amount of neck tension in a 30 BR. So try no tension and work up(or down??). It will help isolate where it's happening. Also, annealing can help or make it worse.

 

[Kevin1990]

Was gonna say, just remove the bushing completely, check runout, then step down a bushing at a time if you can. Most all runout issues are somewhere in the sizing op. Rarely in the seating step with good prep to that point. I didn't see neck diameter mentioned but the more you move the brass, the more runout becomes a noticeable issue and most people use a pretty fair amount of neck tension in a 30 BR. So try no tension and work up(or down??). It will help isolate where it's happening. Also, annealing can help or make it worse.

Good to know. I have a few unfired cases. I'm going to get a different shell holder at my LGS on Tuesday, but tonight I will try no bushing and then a .327 and see what happens and report back. Hopefully this is an easy fix. Also I opted for a .332 neck in my 30BR over the usual .330 I'm getting .330 under a loaded round, so with the bushings I have the highest I can go is .327.

 

[gunsandgunsmithing]

Good to know. I have a few unfired cases. I'm going to get a different shell holder at my LGS on Tuesday, but tonight I will try no bushing and then a .327 and see what happens and report back. Hopefully this is an easy fix. Also I opted for a .332 neck in my 30BR over the usual .330 I'm getting .330 under a loaded round, so with the bushings I have the highest I can go is .327.

I wondered if that was the case. I suspect it'll get better with a bit less neck tension or even doing it in two steps just to further isolate it down. Ultimately, I'd judge it on the target though and not let it worry me if it shoots small.