BRA die question.

[MDM]

Same here... you need the D3 6 dasher sizing dies from Harrels....I had mine trimmed 90 thou and it it is perfect. But the trimmed Forstner seater works great
You best talk to your gunsmith about the reamer he used
2950 here with both 30.6 of h4895 or 31.5 of re15

I have the reamer, print and lathe in my basement It's basically the same reamer Mr. Wheeler uses with a .272 neck. Harrells sent me the #2 die.

Fired brass - .4605 at the shoulder, .4712 at the .200 line.

Forster dies - shoulder .457 and .200 line to .4695

Harrells - shoulder .460 and the .200 line .4704

The problem I had with the Forster was too much sizing at the shoulder. I'll say this, the Forster was pretty rough sizing, almost like I could feel ribs on the body when sizing. Polishing it up with 320 then 600 helped it quite a bit to smooth that out, but didn't really change the dimensions much at all. Must have just been a little undersized or possibly the reamer was on its way out.

 

[Gilbert Garza]

Running brass that's at about 6 firings I get 0.0006 to 0.0007 at the .200 line. Fired brass is .4715 and sized brass comes out at .4708 to .4709 with my Forster dies. What base sizing are you getting with your Wilson dies?

I cut .080” off my Wilson die. It chambers fine in my AI, but on bolt lift it is a slight firm. I can’t see any pressure in the primers and webbing isn’t growing more then the initial measurement.

 

[MDM]

Well this is not what I expected. I got the Harrells dies and bushing just came today. Much less perceived pressure on the bolt lift when running the same exact load, with the same exact neck tension when using the Harrels dies over the Forster dies. Same shoulder bump as well. Literally just loading up the same everything, just different FL die. Load is 30.4 H4895. Even went up to 30.75 and didn't get the stiff bolt lift I'd get at times with 30.4 and the Forster dies. Not sure I understand all I know about that.

 

[#40Fan]

I have the reamer, print and lathe in my basement It's basically the same reamer Mr. Wheeler uses with a .272 neck. Harrells sent me the #2 die.

Fired brass - .4605 at the shoulder, .4712 at the .200 line.

Forster dies - shoulder .457 and .200 line to .4695

Harrells - shoulder .460 and the .200 line .4704

The problem I had with the Forster was too much sizing at the shoulder. I'll say this, the Forster was pretty rough sizing, almost like I could feel ribs on the body when sizing. Polishing it up with 320 then 600 helped it quite a bit to smooth that out, but didn't really change the dimensions much at all. Must have just been a little undersized or possibly the reamer was on its way out.

@Sheldon N

 

[Sheldon N]

@Sheldon N

Just saw that... doh!

Wonder why it would give that result, I would think that more sizing would ease bolt lift rather than less sizing.

 

[MDM]

Just saw that... doh!

Wonder why it would give that result, I would think that more sizing would ease bolt lift rather than less sizing.

I don’t get it either. I’ll do some more testing during load work up over the weekend.

 

[Gilbert Garza]

This is just a thought and could be a wrong one. But maybe with the correct die is sizing less and created less bolt thrust when forming.

When you size the shoulders to much or have excessive headspace it’ll create higher pressures and usually you’ll have flow into the ejector hole.

Just a thought

 

[Sheldon N]

This is just a thought and could be a wrong one. But maybe with the correct die is sizing less and created less bolt thrust when forming.

Interesting... now you've got me thinking. Here's the hypothetical scenario that I'm imagining.

Case #1
Dimensions along the wall of the case and shoulder of the case very closely match the angle of the chamber. When the case is fired it grips the wall of the chamber quickly, creates less bolt thrust, and also leaves less room for the brass to stretch forward against the shoulder of the chamber. As a result bolt lift is easier.

Case #2
Dimensions at the shoulder diameter are smaller than at the base diameter (clearance in chamber). When the case is fired it is more prone to move backwards against the bolt face, creating bolt thrust and slightly more space for the shoulder to expand in the chamber, or at least allows it to expand under a higher stress situation. When the firing of the case is complete, that tension between bolt and chamber shoulder is higher and as a result bolt lift effort is higher.


Any thoughts on whether this is viable theory?

 

[MDM]

That's kind of what I was getting at in my first post. I shot some more today, round robin identical loads and cases sized with each die. Same results as yesterday. Here is another head-scratcher...Same load in excessively sized Forster brass is 2870 with more pressure on bolt lift. Harrells sized brass yields 2890. ES of 4 over five shots, ES of 5 over five respectively.

I just think the my Forster dies where sizing the body excessively, particularly at the shoulder body junction and the case was not gripping the same as it does with the Harrells. Also, I get some soot on the shoulder of the Forster sized stuff and that has not happened with the Harrells sized stuff.

 

[Sheldon N]

Thanks man, this is really good info. I think I'm going to be looking for new dies too.

I wish Harrells made a FL non-bushing die. Might have to look into Whidden and Redding FL non-bushing dies.

 

[MDM]

Thanks man, this is really good info. I think I'm going to be looking for new dies too.

I wish Harrells made a FL non-bushing die. Might have to look into Whidden and Redding FL non-bushing dies.

This is my first venture into bushing dies. Not much to it now that I took the plunge. FYI, I’m using a .265 bushing and the stem/decapper/expander out of the forester die. Yields the same neck tension as the Forster. .002

 

[MDM]

I think my load work is done. Much easier the second go around now that I’ve got some experience with the round. This was testing seating from .014/.017/.020 jump. My other one likes .018 and I’ll just run this one there as well. Same charge too. Prone and rear bag and too much mirage to probably see a difference. I’ll shoot it at 500 but unless I see something I don’t like, I’ll stay where I’m at. Makes it easy when both barrels like the same load. FYI I dialed up .2 after that first group.

 

[Edward Manning]

I don't think it's your velocity issue but I agree that your die is sizing excessively compared to your chamber/fired brass. I like about half of that...about .0015 @shoulder/body junction and about .0005-.0006"@ the .200 line.

As for the bolt thrust...I doubt it seriously. Now, if you bump the shoulders excessively, different story, IMHO.

Can I ask a stupid question? What’s the .200 line

 

[JFrank]

Can I ask a stupid question? What’s the .200 line

A datum located right about here ... Although I find it easier to measure in line the fat part of the case as in the second picture, it just seems to work well with what is important to me.

 

[Edward Manning]

A datum located right about here ... Although I find it easier to measure in line the fat part of the case as in the second picture, it just seems to work well with what is important to me.

Thank you very much