Shoulder Bump Inconsistency on Co-Ax

[gmr4]

The die has been set to a .002 shoulder bump. This in my custom rifle I built that I am normally running single digit ES and SD on reloads. I had worked a ladder up with some N565,H1000, and N570 in an attempt to find the best powder combo in my 6.5 PRC. Have settled on N565 at a mid level as it offers the best accuracy at less than .3 MOA groups on most 5 shot groups. I probably should just remove the pressure sign brass and move on as the other all size appropriately. On these pressure sign brass the distance from the .200 line to case base is larger than the non-pressure brass. I can size all the non-pressure brass and the bump is exactly on with a .002 bump. These pressure signed brass will not size down with the same die setting in the Co-Ax. I hypothesize that is is something to do with the the way the jaws grip the case. I am getting a Co-Ax shell plate holder to try out to see if that is part of why this occurs. These brass on on their 4th reloads. Just something interesting I have found and was curious if anyone else had seen this happening.

I doubt it is the jaws on the CO-AX. You could try to let those cases dwell in the die maybe 6-8 seconds and see what you get…
I segregate over-pressured brass and use it for sighters / fowlers as I believe it will shoot different than the other… I’m shooting 1000 yards. We’ve tinkered with over-pressured brass quite a bit.. if you measure the .200 line and any other locations on the fired over pressured brass you will find it is different from the other non pressured brass. Maybe this is folklore.. but I know many guys that sort it out… there is also fire sorting.. aanother topic.
Lastly, in the 6.5 PRC that pressured brass will give you clickers soon.

 

[SDDasher]

If you’re willing to spend the $$ on a roll sizer, then spend the $$ on a Zero press and solve the issue. .JMHO

 

[SSchnd]

I too run 1 Curved (Inline Fab) and 1 Original Forster straight link arm on the Forster Co-Ax, no issues.

 

[JFrank]

Alex does a good job of explains some die issues guys might want to check out.

Videos | wheeleraccuracy

www.wheeleraccuracy.com

 

[LRPV]

If you’re willing to spend the $$ on a roll sizer, then spend the $$ on a Zero press and solve the issue. .JMHO

This will NOT fix all sizing problems.

 

[SDDasher]

This will NOT fix all sizing problems.

No one implied it did.

 

[Webster]

This will NOT fix all sizing problems.

Thanks for the input- that roll die is pretty slick. Don't know anyone with one, but looks like a new reloading bench accessory in my future

I think a roller die just gets an oversize body smaller than a traditional FL or small base die. I doesn't address the problem that caused it. Save your money for something else. Anyone know what they cost. They look complicated.

 

[marchboom]

I am getting a Co-Ax shell plate holder to try out to see if that is part of why this occurs

Okay since you are doing this, order the Redding comp shell holders too. Anneal every time, lube correctly, and watch the trouble disappear

Please let us know what your results are regarding the shell plate holder. I've considered getting one but the guy at Forester said this defeats the concept of the factory shell holder. I.E. the floating shell holder.

 

[marchboom]

As to the press I ONLY use Forster die rings for the Coax. If I use another die lock rings it is no bueno.

Have you have poor results using non-Forester lock rings? I have used Hornady rings (and Forester) and they seem OK but I haven't done any comparative tests on them.

 

[LRPV]

No one implied it did.

It was my understanding that you were implying that a zero press or a roll sizer would fix the sizing problem. I have no experience with a roll sizer so I was commenting on the zero. Teachers used to tell me I had a reading comprehension problem. I guess they were right. My apologies.

 

[J.d. Popkes]

Please let us know what your results are regarding the shell plate holder. I've considered getting one but the guy at Forester said this defeats the concept of the factory shell holder. I.E. the floating shell holder.

I was quoting him in the beginning of my post.

 

[RabbitSlayer]

I measured bump on 400 pieces of 1x fired starline 556 sized on my coax. I made three piles. Most were in the middle of my target. A about 30 percent over and 30 percent under. I tried to resize a few of the longest with several more passes through the die and it didn't move them.

All were annealed and all were same bullet and fired with a below book max load.

Conclusion, there is variation in brass that causes them to size differently be it hardness, thickness, case volume that changed pressure during firing. I dunno why, but there will always be some variation in bump. Probably should cull outliers if you care that much.

 

[SDDasher]

I think a roller die just gets an oversize body smaller than a traditional FL or small base die. I doesn't address the problem that caused it. Save your money for something else. Anyone know what they cost. They look complicated.

Close to a thousand dollars and they are a manual crank.

 

[Fire Dog]

Have you have poor results using non-Forester lock rings? I have used Hornady rings (and Forester) and they seem OK but I haven't done any comparative tests on them.

Foster rings are just a tad thicker and that means a tighter fit in the slot that holds the die ring meaning there is less movement of the die upwards as the case enters the die…

 

[SDDasher]

My implication was that the $$ spent on a Roll Sizer would be better spent on a quality press like the Zero. I prefer stopping the problem before it happens rather than after which would require a Roll sizer. The Zero doesn’t stop all issues you can encounter with sizing brass, but in my experience in using one it produces more consistency in shoulder bump and neck run out than any other press I have owned including Lyman, Frankford Arsenal, RCBS Rock Chucker and Dillion. Like I said it’s just my personal opinion.

 

[Fire Dog]

Close to a thousand dollars and they are a manual crank.

A Rollsizer sizes the case in the area that dies cannot touch, even small base dies.
From the top of the extractor groove to just above the “200” line, it will help prevent or cure “Clickers”, also some indication that if done from the first firing, that it prolongs the life of the primer pocket…
It will Not repair a primer pocket that has already stretched.
They are quick to use and now have a motor option if you are doing a lot of cases, the motor drives the roller instead of having to turn a crank.
Even turning the crank is a quick and easy job and requires way less force/energy to do than full length sizing.
You still need to size the case, this machine just addresses the very lower base area that cannot be sized by a die and has swollen enough that the case is tight enough in the chamber that the force necessary to open the bolt produces the resistance that makes the clicking sound when the bolt finally opens.

 

[SDDasher]

A Rollsizer sizes the case in the area that dies cannot touch, even small base dies.
From the top of the extractor groove to just above the “200” line, it will help prevent or cure “Clickers”, also some indication that if done from the first firing, that it prolongs the life of the primer pocket…
It will Not repair a primer pocket that has already stretched.
They are quick to use and now have a motor option if you are doing a lot of cases, the motor drives the roller instead of having to turn a crank.
Even turning the crank is a quick and easy job and requires way less force/energy to do than full length sizing.
You still need to size the case, this machine just addresses the very lower base area that cannot be sized by a die and has swollen enough that the case is tight enough in the chamber that the force necessary to open the bolt produces the resistance that makes the clicking sound when the bolt finally opens.

I’ve used a Roll Sizer borrowed from a fellow shooter on some “clickers” caused by over pressure and my failure to insure the shoulder bump was correct for the action I was loading for. Not convinced it will prevent over expansion of the head if over pressured. Mitigate yes, prevention not convinced. To me it’s like using a condom with a hole in it; very expensive if it goes south on the prevention part. I just keep my loads within pressure perimeters to avoid the issue in the first place if possible. BTW the Roll sizer did reform the expanded brass “almost” to normal expansion of non pressure loads, but I tossed them any way.

 

[gdbleb]

A zero cost hack I learned here is to do 1 resize stroke with a dwell in the die. Lower the ram, turn case 180 degrees and resize again with a dwell. Takes time but it does improve setback consistency when I am looking to achieve it.

 

[243winxb]

my cases were coming out varying case lengths after trimming

Flipping the trimmer vertical allows you to let the brass shavings naturally drop
away from the cutter and shell holder. If you use the trimmer horizontally,
eventually you will get shavings inside the case holder. With shavings in the
case holder, the index for the case shoulder is no longer true. Your cases will
come out longer by the same length the shavings prevent the case from entering
the case holder.

 

[243winxb]

varying shoulder bumps

Use Custom shell holders made by Redding. Shell holders for complete control of shoulder bump.