Redding Competition seating die problem/ question

[CH Luke]

Using a Redding Type S Match Die Set #36155 for a .308 rifle using 200 Hybrid Berger bullets. This has been a continuing problem for me across two different chambers on this rifle since I began using these dies beginning with the second firing of Lapua brass. Here are some applicable measurements.

Sized Lapua Palma brass that seats nicely before a bullet is seated.
Brass mouth/bullet junction: .337"
Halfway from mouth to shoulder: .339"

After bullet is seated (will not chamber).
Brass mouth/bullet junction: .343"
Halfway from mouth to shoulder: .344""

A successfully seated round at the mouth/bullet junction is typically .338-.339" which seems typical for the 308's I've had. So you can see my brass is sized at he moth junction for .001-.002" neck tension.

Seems I am doing something very wrong with the bullet seating that is causing the mouth to spread so much. I've read the instructions repeatedly and searched this site and others for any tips. Seems like this is going to be something really uniquely stupid that I'm doing as I've been unable to find any other posts on this topic here or anywhere.

The problem begins typically with the 2nd or 3rd loading of brass so on new brass no problem.

 

[ireload2]

Do you have another .308 seater die that you can try?
Does your die have a crimp shoulder or other feature that the mouth of the case can hit during seating?

 

[CH Luke]

Do you have another .308 seater die that you can try?
Does your die have a crimp shoulder or other feature that the mouth of the case can hit during seating?

This seater die doesn't crimp. There is a slight bump as the ram comes up.

 

[SheepDog]

Are you chamfering the inside of the neck?
Are the necks clean inside?
Are the bullets a stepped boat tail?

 

[gunsandgunsmithing]

Using a Redding Type S Match Die Set #36155 for a .308 rifle using 200 Hybrid Berger bullets. This has been a continuing problem for me across two different chambers on this rifle since I began using these dies beginning with the second firing of Lapua brass. Here are some applicable measurements.

Sized Lapua Palma brass that seats nicely before a bullet is seated.
Brass mouth/bullet junction: .337"
Halfway from mouth to shoulder: .339"

After bullet is seated (will not chamber).
Brass mouth/bullet junction: .343"
Halfway from mouth to shoulder: .344""

A successfully seated round at the mouth/bullet junction is typically .338-.339" which seems typical for the 308's I've had. So you can see my brass is sized at he moth junction for .001-.002" neck tension.

Seems I am doing something very wrong with the bullet seating that is causing the mouth to spread so much. I've read the instructions repeatedly and searched this site and others for any tips. Seems like this is going to be something really uniquely stupid that I'm doing as I've been unable to find any other posts on this topic here or anywhere.

The problem begins typically with the 2nd or 3rd loading of brass so on new brass no problem.

Not sure what to say, but there's nothing inside of one of those dies that will open the neck..except the bullet.

 

[RonAKA]

Are you using an expander ball in your sizing die, or just a bushing on the OD? I'm wondering if you have a non uniform ID, or the dreaded donut on the ID, and the bullet is pushing the problem to the outside when it is seated?

 

[SheepDog]

Since the neck is expanding at the mouth it has to be the bullet hitting the mouth causing it to expand (roll inward) as the bullet is seated.
camfering the case will also get rid of burrs that might catch on the bullet.

 

[CH Luke]

All brass was clean inside and out (stainless media), chamfered, trimmed. Carbide expander ball on sizing. 200 Hybrids are tapered boat tails.

Now I'm wondering if 90 minutes in the tumbler mis-shaped the mouth again. Wouldn't think so.

Gonna re-size the failed ones and wipe clean. See if that helps. If not then I will try the old standard seater.

 

[Cool Tool]

What is the loaded round after you seat the bullet an are you neck sizing with what bushing.

 

[CH Luke]

.343 loaded as on top post George. Using a .337 bushing to get the .337 reading at the mouth. The brass is spreading .006".

I did go back and pulled three bullets that wouldn't load and re-size those brass which would have seen any out of roundness from the tumbler taken care of by the carbide expander ball. Everything back to original .337 mouth diameter and shoulder height. Seated rounds again got to same .343" mouth and would not chamber. So that should cover Ron AKA's idea.

Pulled them again, resized again and seated with the old standard Redding die. Took a few minutes to get the CBTO adjusted. Same results - .343.

I have one size smaller bushing - .336. I would use that but I can't see that making a difference. The problem is the mouth spreads by .006" from .337 to .343 when a bullet is seated. That seems like a lot more than it should.

 

[RonAKA]

Are you annealing the brass? Brass possibly too soft?

 

[CH Luke]

Not sure what to say, but there's nothing inside of one of those dies that will open the neck..except the bullet.

Understood. Bullet OD's are of course .308 while the OD of the sized brass as I've written is .337.

What I don't understand is why the bullet seating is spreading the brass OD by .006"? Particularly by the 3rd loading.

What I'm thinking is the neck is getting thicker with successive firings and the solution is to start trimming necks???

Are you annealing the brass? Brass possibly too soft?

 

[CH Luke]

Are you annealing the brass? Brass possibly too soft?

Yes. Every firing. Trying to keep everything consistent

 

[Cool Tool]

.343 loaded as on top post George. Using a .337 bushing to get the .337 reading at the mouth. The brass is spreading .006".

I did go back and pulled three bullets that wouldn't load and re-size those brass which would have seen any out of roundness from the tumbler taken care of by the carbide expander ball. Everything back to original .337 mouth diameter and shoulder height. Seated rounds again got to same .343" mouth and would not chamber. So that should cover Ron AKA's idea.

Pulled them again, resized again and seated with the old standard Redding die. Took a few minutes to get the CBTO adjusted. Same results - .343.

I have one size smaller bushing - .336. I would use that but I can't see that making a difference. The problem is the mouth spreads by .006" from .337 to .343 when a bullet is seated. That seems like a lot more than it should.

Well what brand brass are you using ,what is loaded diameter of same bullets in the new brass you are at the size of your chamber does the bullets seat hard if they are the right diameter check the case wall thickness on your necks . PS the brass that does not chamber pull bullets an resize an try to put in chamber an close bolt

 

[gunsandgunsmithing]

Maybe too obvious, but how thick is the brass as measured with a tubing mic, if you have one. What are you using to measure with? If calipers...that's a good way to get off on the wrong foot....use a mic for the od and a tubing mic for brass thickness. I know this doesn't explain them not chambering. What is the chamber neck diameter or what does a fired and unsized case neck measure? Honestly, it just sounds like the brass is thick and you're winding up with .006" neck tension...337 before seating and .343 loaded. I just measured some new std Lapua 308 brass. It's about .016" thick. So, 308+.016+.016=.340.

edit...George beat me to it but I think we're asking the same thing. KISS. This has to be an oversight or mis measurement. I can't imagine how it's anything else.

 

[primer popper]

Check brass thickness at neck.

 

[Cool Tool]

Maybe too obvious, but how thick is the brass as measured with a tubing mic, if you have one. What are you using to measure with? Honestly, it just sounds like the brass is thick and you're winding up with .006" neck tension...337 before seating and .343 loaded. I just measured some new std Lapua 308 brass. It's about .016" thick. So, 308+.016+.016=.340.

edit...George beat me to it but I think we're asking the same thing. KISS. This has to be an oversight or mis measurement. I can't imagine how it's anything else.

I went out to my shop after responding a few minutes ago an same measurement you got right at .016 something strange here cant put my lips on it but I think he will figure out .

 

[CH Luke]

Don't have a tubing micrometer but sounds like a late Christmas present for myself. Recommendations?

Using a digital Mitutoyo micrometer.

Just seated a brand new Lapua Palma. OD is .336 before and .338" after bullet seated.

Should mention with previous box from same lot that second time loaded was .338 to .339". A few had to be sized a second time.

Apparently the max of that will chamber is about .339, maybe a tight .340". Doesn't seem like a tight chamber. Gunsmith said it would be a no turn chamber.

 

[SheepDog]

I think you are over annealing the brass and the mouth of the case is rolling under when you seat a bullet. It's either that or you have magic cases that are adding metal to the case neck instead of making it thinner.

 

[CH Luke]

I think you are over annealing the brass and the mouth of the case is rolling under when you seat a bullet. It's either that or you have magic cases that are adding metal to the case neck instead of making it thinner.

It is possible I could be over annealing via slightly too high temperatures. I had not heard of this happening elsewhere but what you say seems to make sense. As usual I researched how I anneal and I have done it consistently. On my next two boxes of brass I can apply a test vs control to settle that.

There is at least one article on this site around neck thickness and neck turning that refer to necks thickness variance increasing as brass "flows" toward the neck. Sounds like you are saying that this flow only results in the increase in length (that we trim) but definitely not in thickness? That would make sense as I would have expected to have come across a lot of content referring to that.

Thanks.