Short chamber advantages?

[DLCrocket]

ggshoots, did a little more work on this after re-reading your post a couple times. I removed the firing pin from my 243 AI bolt so that it would "fall" closed. Next I sorted through my old Winchester brass that had been fired and reloaded several times, and found three that the bold would close on but were pretty snug. They measured 1.698" at the ogive. Next I took a new Redding S bushing 243 Win Imp full length sizing die and removed the bushing and rod with expander and decapping pin. I adjusted the die in my press so it was just touching the shell holder. I lubed the case and ran it through the die, pausing a few seconds before removing it. I wiped off the lube and measured with Hornady headspace comparator. The case grew to 1.701 and the shoulder measured 0.458. Next I set up my other Win Imp die that I had taken 0.010 off and ran the case through it. No bump on the shoulder. Then I dug out Redding 243 Win Imp body only sizing die I had bought years ago. Once again no shoulder bump. Then I took a sharpie and blackened the case and closed the bolt on it, very snug. The case showed rubbing only on the shoulder between neck and body. Even though my shoulder was not as small as your example of 0.452 I have to conclude that the Win Imp die is the problem. Until I can find a real Ackley improved die, all I can think to do is have some more metal removed from the die until I can get to 1.698.

Also, was looking at https://www.6mmbr.com/243win.html. They have a diagram of a 243 AI round with all the dimensions. Don't know where they got it since it's not a SAAMI round but looks like they have the shoulder diameter at 0.4589 which is about what I'm getting with the Win Imp dies.

 

[ggshoots]

I just read through all of this again and decided to go pull some 243AI fired brass. Here are the dimensions.



Here is after sizing with 243 Win 40deg Impr dies.


I will have to post again to show 243Ackley Impr die measurements do to pic limit.

 

[ggshoots]

After using 243Ackley Improved sizer dimensions




If you notice 2 things here
1. The shoulder oversized the brass on the 243 Win Imp dies.
2. The case length grew more with the 243 Win Impr dies.

On a side note with doing this I noticed. Now I was able to get both dies to set the shoulder back to the right depth. Difference from when I initially chambered this rifle years ago was that I am using different sizing lube now and stuck cases in the die are no longer an issue. Before I constantly stuck cases in the 243Win Impr dies which led me to the in-depth search and discovery of the shoulder oversizing. I used many of the popular lubes trying to get it to quit sticking cases. Now I use alcohol and Lanolin 10/1 ratio mix and it is amazing. I also anneal every firing. These 2 things make a world of difference. Before I could not size the case enough to bump the shoulder.

By the shoulder dimensions you gave earlier it appears you sizing die is not over sizing the brass like mine did. You said yours is sizing to .4589" which is about the correct reduction for an Ackley shoulder to be sized down. May be a different issue.

 

[DLCrocket]

After using 243Ackley Improved sizer dimensions
View attachment 1613719
View attachment 1613720
View attachment 1613721

If you notice 2 things here
1. The shoulder oversized the brass on the 243 Win Imp dies.
2. The case length grew more with the 243 Win Impr dies.

On a side note with doing this I noticed. Now I was able to get both dies to set the shoulder back to the right depth. Difference from when I initially chambered this rifle years ago was that I am using different sizing lube now and stuck cases in the die are no longer an issue. Before I constantly stuck cases in the 243Win Impr dies which led me to the in-depth search and discovery of the shoulder oversizing. I used many of the popular lubes trying to get it to quit sticking cases. Now I use alcohol and Lanolin 10/1 ratio mix and it is amazing. I also anneal every firing. These 2 things make a world of difference. Before I could not size the case enough to bump the shoulder.

By the shoulder dimensions you gave earlier it appears you sizing die is not over sizing the brass like mine did. You said yours is sizing to .4589" which is about the correct reduction for an Ackley shoulder to be sized down. May be a different issue.

Interesting. My shoulders are coming out .4575 to.458. That website graphic showed .4589. Was wondering why you're using the A3.30 comparator instead of D400. Thanks for all the input. Think I'll have another 0.010 taken off my die and see where that leaves me.

 

[ggshoots]

Just had it on. Its not what I use to record it so doesnt really matter. Just needed a reference point to show difference.

 

[DLCrocket]

Interesting. My shoulders are coming out .4575 to.458. That website graphic showed .4589. Was wondering why you're using the A3.30 comparator instead of D400. Thanks for all the input. Think I'll have another 0.010 taken off my die and see where that leaves me.

Was just reading over at 6mmBR.com. The author is saying the Ackley improved die gives you a 0.460 shoulder and Win Improved die gives you a 0.455 shoulder. With my Win Imp die, after annealing, mine are pretty close to 0.455. I took another 0.010 off my die for a total of 0.020 and now i can shoulder bump. I'm now sold on annealing. Tough cases that I couldn't push the shoulder on pushed back easily after annealing.

From 6mmBR.com:
"One thing that you need to watch for is what version of the .243 Improved that you have. This depends, for the most part, on whose reamer you will be using for the chambering of your barrel. It is easy to determine if your .243 Improved is the .243 Ackley Improved, or the .243 Winchester Improved. If you have the .243 Ackley Improved, the shoulder-body section will measure .460" dia. at this point. If you have the .243 Winchester Improved, the shoulder-body section will measure .455" diameter at this point. Both cartridges have the 40-degree shoulder. I have used both versions and found that you can use any data developed for either version interchangeably."

 

[std7mag]

Wow...

This thread is all over the place!

First off, a "short chambered" barrel from E.R. Shaw is chambered 0.04" short so that you (or your gunsmith) can finish ream the chamber to set headspace.
It's not left "short".

As far as the Ackley Improved vs Improved 40°.
As far as I know, P.O. Ackley never did any work with the 308 family of cases.
We call them AI, but it's not the correct monniker.
If you order a reamer for say your "243AI" you will get a 243 Improved 40°.
IF indeed 40° is what you want.
There are Improved 30° reamers and dies out there.

OP,
Are you sure you have a full length die and not a neck die?

 

[DLCrocket]

Wow...

This thread is all over the place!

First off, a "short chambered" barrel from E.R. Shaw is chambered 0.04" short so that you (or your gunsmith) can finish ream the chamber to set headspace.
It's not left "short".

As far as the Ackley Improved vs Improved 40°.
As far as I know, P.O. Ackley never did any work with the 308 family of cases.
We call them AI, but it's not the correct monniker.
If you order a reamer for say your "243AI" you will get a 243 Improved 40°.
IF indeed 40° is what you want.
There are Improved 30° reamers and dies out there.

OP,
Are you sure you have a full length die and not a neck die?

First, let me apologize for the rambling nature of this post. I'm new to forums and not versed in all the etiquette. Second, it seems that as more people post to this thread, new questions, suggestions and procedures are introduced, all of which are appreciated and I'm learning from them.

As far as the ER Shaw barrel, this was 15 or so years ago so I'm going by memory, such as it is. This barrel was Shaws Savage heavy barrel profile and was sold as ready to set the headspace, tighten the barrel nut and have at it. No finish reaming required. Yes, I have a Redding Winchester Improved full length sizing die. When I was shooting Prarie dogs I only neck sized, which led to some cases with shoulders that needed to be bumped, which is what started this thread. Finally, after taking 0.020" off the die and annealing the brass to reduce spring back, I'm able to bump the shoulders.
As far as Ackley and the 243 Winchester, the following is on the 6mmBR.com website:

by Bob Blaine, Sinclair International

Parker Ackley reluctantly developed the .243 Ackley Improved ("AI"). Ackley finally gave in to his customers' requests to develop the .243 AI. He had always felt that the .243 Winchester was already an improved configuration, but he did say that the best thing to be gained by improving the .243 Winchester was to substantially reduce the case-stretching problems

 

[dellet]

First thing I would do is to blacken a case and confirm where in the chamber it’s contacting,

Edit to add
Just read your other thread about brass that won’t fire form. If this is the same brass, anneal it, or junk it. Maybe try different brass first, but shoulders that won’t blow out at 50,000 psi, are going to be hard to reset with a die.

It’s tough for new folks to figure out how forums work, even people with experience going to a new one need time to see the personality of a new hang out.

Multiple threads on seemingly different problems can be hard to sort through. Sometimes hearing the same thing differently makes a big difference.

It will be interesting to hear how the fire forming goes after annealing.

 

[DLCrocket]

It’s tough for new folks to figure out how forums work, even people with experience going to a new one need time to see the personality of a new hang out.

Multiple threads on seemingly different problems can be hard to sort through. Sometimes hearing the same thing differently makes a big difference.

It will be interesting to hear how the fire forming goes after annealing.

Fire forming may be a ways off. Weather here is turning cold and nasty. Thought I'd give Hornady's hydro form die a try and save a little wear and tear and components. Unfortunately there's a sixteen week backup on their custom dies.

 

[Sniperhandle]

ggshoots, did a little more work on this after re-reading your post a couple times. I removed the firing pin from my 243 AI bolt so that it would "fall" closed. Next I sorted through my old Winchester brass that had been fired and reloaded several times, and found three that the bold would close on but were pretty snug. They measured 1.698" at the ogive. Next I took a new Redding S bushing 243 Win Imp full length sizing die and removed the bushing and rod with expander and decapping pin. I adjusted the die in my press so it was just touching the shell holder. I lubed the case and ran it through the die, pausing a few seconds before removing it. I wiped off the lube and measured with Hornady headspace comparator. The case grew to 1.701 and the shoulder measured 0.458. Next I set up my other Win Imp die that I had taken 0.010 off and ran the case through it. No bump on the shoulder. Then I dug out Redding 243 Win Imp body only sizing die I had bought years ago. Once again no shoulder bump. Then I took a sharpie and blackened the case and closed the bolt on it, very snug. The case showed rubbing only on the shoulder between neck and body. Even though my shoulder was not as small as your example of 0.452 I have to conclude that the Win Imp die is the problem. Until I can find a real Ackley improved die, all I can think to do is have some more metal removed from the die until I can get to 1.698.

I would not ruin an expensive set of dies getting material removed from them when you can get the material removed from a ten dollar shell holder and accomplish the same task.

 

[DLCrocket]

I would not ruin an expensive set of dies getting material removed from them when you can get the material removed from a ten dollar shell holder and accomplish the same task.

I'm using a Forster Co-ax press so no shell holders. There was a risk in altering the die, but it worked out good.