Inconsistent Full Length Resizing

[Fire4Effect]

I have been reloading 308 Win and 6.5mm Creedmoor and now started reloading 223 Rem. I have never loaded 223 Rem before and have encountered inconsistent full length resizing when I was setting up and adjusting the full length resizing die.

EQUIPMENT

• Forester Co-Ax Press
• Redding Type S Bushing Style Full Length Die
• Once Fired Winchester 223 Rem Cases (Note: Fired from my rifles)

[LynnJr]

I'm not familiar with your press.
On a standard single stage press the pivot pin will give you some inconsistency.
Lube the brass well and you should be fine. The type S die doesn't stretch the brass on the downstroke like some dies do.
I only run custom chambers and never set the headspace at zero for this very reason.

[Bastard]

I thought that the Forester press wasn't supposed to cam-over - I also am not sure how cam-over would effect the headspace

[bruce381]

where is guffey when you need him lol

[Dooder]

+1!!

[slamfire1]

I had to look at a you tube video to understand the precision mic.





One of the things I have learned, with my cartridge case headspace gauges, is that there is a lot of variance in the process. Brass differs in composition, thickness, and hardness. As you fire your cases, you are work hardening the brass on each sizing. So you would expect differences in final dimensions as the brass material properties change. I wish a real metallurgist comment on this, but I believe the Young's Modulus changes for brass, as you work harden the material. So brass will react differently, and spring back differently, based on composition, work hardness.

The guy in the second video does not understand that a comparator cannot be used to set up sizing dies for gas guns. Comparator's are relative gauges, not calibrated to a standard, but the first video shows the RCBS mic is calibrated to a standard.

Given all the differences between brass cases, I have found that the best thing to do is have a case gauge on the bench, size a case, see how it is reacting, and adjust the die up or down to maintain 0.003" shoulder clearance in the chamber. I will size in batches (generally), same make, same times fired, etc. When I get mixed brass, base to shoulder distances out of the die vary more, so I just have to make sure that nothing is over length.

Something I have also found, is that the amount of lube on a case shoulder changes the shoulder to base distance of a sized case.

F class shooters will have their own opinions, but for me, I want safe and 100% totally functional ammunition first and foremost. I want my cases to always chamber and extract. My non precision ammunition will hold the ten ring of the decimal NRA target out to 600 yards, and that is fine for me. The NRA ten ring is 2 MOA, huge by modern standards, where shooters rest their bipod rifle on a concrete bench, but 2 MOA is plenty tight for a hand held weapon fired from the shoulder.

As long as the sized cases are smaller than the chamber my cases will feed and extract. My standard is 0.003" clearance between case shoulder and chamber, but that is more or less an average, as brass reacts differently from case to case. Only with my 35 Whelen's do I maintain a zero clearance in the chamber, or a slight crush up. I have found my 35 Whelen's are sensitive to case clearance. The 35 Whelen design has such a slight shoulder that on a couple of rifles, I will get misfires if the case is undersized for the chamber. I think what is happening is the firing pin blow pushes the shoulder back, and given the shallow shoulder, that cushions the firing pin blow to the primer, creating misfires. I did increase firing pin protrusion on a Mauser 35 Whelen by swapping firing pins, and that really helped. None of my other cartridges have this problem.

The importance of sizing a case below the chamber, is that you want your case to extract after firing! (not everyone understands that the case is a gas seal, not some structure that reduces bolt thrust by gripping the chamber) There is a limited amount of springback to a case, and if you start with a crush fit, or interference fit to your case, you will experience extractor problems in the future!

[J-cat]

I have been reloading 308 Win and 6.5mm Creedmoor and now started reloading 223 Rem. I have never loaded 223 Rem before and have encountered inconsistent full length resizing when I was setting up and adjusting the full length resizing die.

EQUIPMENT

• Forester Co-Ax Press
• Redding Type S Bushing Style Full Length Die
• Once Fired Winchester 223 Rem Cases (Note: Fired from my rifles)

[Fire4Effect]

My LMT LM8MRP has a tight chamber that requires me to go to 0 on the RCBS Precision Mic.

[Fire4Effect]

I thought that the Forester press wasn't supposed to cam-over - I also am not sure how cam-over would effect the headspace

I spoke with the production manager at Forester and the Co-Ax press can cam-over. He said up to a quarter turn of the die past shell plate contact will not harm the press.

[Fire4Effect]

One member over on Snipers Hide responded to me and confirmed he has experienced the same issue with the Forester Co-Ax press. He states it is the auto shell holder, which is what I thought.

I did look for ejector extrusions on the case head and minor dents on the neck that could throw the RCBS Precision Mic off, but could not find any.

As an experiment I looked for unresized cases that measured +5 with the RCBS Precision Mic and set the Redding FL die to just before the die contacted the shell plate holder. This setup resized the cases to +3 on the RCBS Precision Mic and the resized cases were very consistent. This would be sufficient for most of my rifles, but the LMT LM8MRP has a tight chamber that requires me to go to 0 on the RCBS Precision Mic.

It sure seems to me the best course of action is to have Redding remove material from the bottom of the die so I can’t cam-over.

[slamfire1]

I spoke with the production manager at Forester and the Co-Ax press can cam-over. He said up to a quarter turn of the die past shell plate contact will not harm the press.

That is more likely due to the springback of the press materials than anything else. The press stretches.

I have an older Spar T Turret press and it does not use compound leverage. I don't remember when compound leverage was introduced in presses, but it had to be early 1960's. Compound leverage is an asymmetric change in the fulcrum distance, the fulcrum becomes smaller the closer you are to finishing the stroke. There can be one heck of a lot of force just at "Cam down". I think attempting to flex the press past the cam down point is bad for the press, I can't think how it would be good.

Once you get case gauges, you will find how useless is the advice to set the die, one quarter turn past cam down. If you every correctly size the base to shoulder distance following "one quarter turn past cam down", go buy a lottery ticket, as it is your lucky day.

[Fire4Effect]

That is more likely due to the springback of the press materials than anything else. The press stretches.

I have an older Spar T Turret press and it does not use compound leverage. I don't remember when compound leverage was introduced in presses, but it had to be early 1960's. Compound leverage is an asymmetric change in the fulcrum distance, the fulcrum becomes smaller the closer you are to finishing the stroke. There can be one heck of a lot of force just at "Cam down". I think attempting to flex the press past the cam down point is bad for the press, I can't think how it would be good.

Once you get case gauges, you will find how useless is the advice to set the die, one quarter turn past cam down. If you every correctly size the base to shoulder distance following "one quarter turn past cam down", go buy a lottery ticket, as it is your lucky day.

Actually in the case of the Co-Ax press it is the auto shell holder that is flexing. I am not even going much past 1/16 turn after contacting the shell plate. There is a poster over on Snipers Hide who know exactly what the issue is and has recommended a solution.

[J-cat]

My LMT LM8MRP has a tight chamber that requires me to go to 0 on the RCBS Precision Mic.

[Fire4Effect]

You don’t get it. The rifle will bump the shoulder when the bolt slams the case against the chamber.

Test it. Put a sized case in the chamber and drop the bolt on it. Then measure the shoulder length.

My Clymer Go gauge (1.4636”) reads 0 on my RCBS Precision Mic. My tightest chamber is +2 (1.4656”). Obviously I need to resize to 0 (1.4636”) or -1 to fit the tightest chamber.

I use my press for bumping, not my rifle.

[John Galt]

There are a lot of variables here.

One thing that comes to mind is the brass. All brass has a memory of sorts. It wants to return to the last shape it was heated to. You said you fired the brass in different chambers. This will create different memories where it wants to return to. This phenomenon is commonly called "spring back" by a lot of reloaders.

Also assume you have different lot's of brass and likely different manufacturers. This will also induce variance. Different cases have different metallurgy even though they are all brass. They will have different spring back.

For the above reasons a lot of the guys that are interested in very repeatable ammo(f-class and becnhrest) use the same lot of brass and tie it to a specific camber.

One other thing that I have found over the years. For precision ammo I dont use the decaping pin in my sizing die. I full length resize and then use a neck expanding die to set neck tension. It gives me much more consistency.

As a test remove the decaping pin from both and see if you still get the same issues. Ideally you would use the same lot of brass fired from the same rifle when testing.