True chamber size vs fired brass.

[Mtstalker]

Yep sometimes time gets away when im working 10+ hrs a day and family is here and a new baby and studying for a state apprenticeship. My bad for not being on top of my game.

 

[Someoldguy]

I understand. It seems your schedule has left you in an unfortunate position of 'guesstimation'.
I wish you good luck.

 

[Mtstalker]

Thanks.

 

[Webster]

I still do not understand what is wrong with making a chamber cast or pound cast and THEN measuring the fireformed brass/loaded round?

Am I obtuse? I don't understand the problem?

Nothing wrong with making a chamber cast if there is a problem. I think he has an imagined problem that gets more confusing with all the various replies. The OP thought he had a problem because some experienced shooter he trust said .001" spring back is normal. Looks like we now have several experienced competitive shooters and myself saying they see .003" spring back.

 

[Mtstalker]

I will when i have time. It wasnt imagined when hot gasses were blown back in my face. This is why im done with this forum too many smart ass answers and too many guys trying to prove that there right.

 

[Mtstalker]

It never pierced primers untill i shot lapua brass. It wasnt untill i measured the brass. I opened this thread before trying lapua because of the measurements. I wanted to make sure it would be ok. Then i shot lapua and it pierced and the fired brass was .001" bigger than loaded with .002" neck tension. Its a savage SA model 10. I just tried the lapua brass on friday i have neen shooting it for a while. Right before i shot the pierced primers i shot 3 of the same load with hornady brass and same primers with no issues.

 

[Alex Wheeler]

It never pierced primers untill i shot lapua brass. It wasnt untill i measured the brass. I opened this thread before trying lapua because of the measurements. I wanted to make sure it would be ok. Then i shot lapua and it pierced and the fired brass was .001" bigger than loaded with .002" neck tension.

Lapua brass tends to be thicker, less internal volume. You would need to reduce your powder charge.

 

[Mtstalker]

I did lol. Hornay charge was 43 i started lapua at 41 and it pierced. I follow the 11gr case diffence reduce by .2grs. And i did a bit more just to be safe.

 

[Alex Wheeler]

Well, looks like you need to keep going. If you give me an h20 difference on each case I can give you an idea of how much it will take to get equal pressure

 

[Mtstalker]

Will do tommorow when im there. Thanks.

 

[Mtstalker]

H20 capacity of hornady case 54.5grs.
H20 capacity of lapua case 53.8grs.
Hornady case weight 164grs.
Lapua case weight 177.2grs.
I have a hunch that the sellier and bellot primers im trying might be a little soft too.

 

[Richard Coody]

A perfect example of why when you change anything in your load development you should back off a bit and work up.

I learned long ago that i don't want to work on the ragged edge of max load. Back off a bit and save you brass and you will probably find an even more accurate load.

 

[Mtstalker]

I did back it down 2 full grains.

 

[Alex Wheeler]

If thats all the difference, you would have only gained a few thousand psi.

 

[fguffey]

Pardon me for being Captain Obvious, but you started this thread on the 9th, and I suggested a chamber cast on the 9th, and today is the 16th.

There is no one that cast chambers like I do so I avoid chamber casting questions. The last time I got involved members of another forum treated the original poster in a manner rather rude, I apologized on their behalf and then they approached me in a manner rude. When it comes to casting a chamber the OP (now) is so far ahead of other casters he is pleased with him self.

F. Guffey

 

[Mtstalker]

Shot lapua brass again some neck turned to .0135" thick and some the factory .0155" with cci br2 primers. And everything was good. The ones i neck turned after firing measured .2965" im thinking the pierced primers had to do with brand of primer.

 

[Someoldguy]

There is no one that case chambers like I do so I avoid chamber casting questions. The last time I got involved members of another forum treated the original poster in a manner rather rude, I apologized on their behalf and then they approached me in a manner rude. When it comes to casting a chamber the OP (now) is so far ahead of other casters he is pleased with him self.

F. Guffey

Ummm . . . . WHAT did you just say?

I've never seen such uninhibited perversion of the English language such as American citizens know it in my life.

 

[fguffey]

Ummm . . . . WHAT did you just say?

Forgive, I went back and changed case to cast. A shooter/reloader/collector wanted help casting chambers. No one on the forum had a clue so rather than say nothing they started in on each other. I contacted the OP off line and got him started I was impressed because he was a fast learner. He had no ideal how desperate members on reloading forums were for attention; he had no ideal how socially dysfunctional they could be when hiding behind a keyboard.

Pardon me for being Captain Obvious,

F. Guffey

 

[243winxb]

Shot lapua brass again some neck turned to .0135" thick and some the factory .0155" with cci br2 primers. And everything was good. The ones i neck turned after firing measured .2965" im thinking the pierced primers had to do with brand of primer.

Brass makes a big difference in pressure, (higher) when the brass is heavier than whats used in the loading data. Or when the load was worked up with different brass (lighter).

Just changing to a different bullet of the same weight may increase pressure. Difference in construction, like- Thicker jacket, longer bearing surface, or all copper.

There are many reasons for a pierced primer, but wont go into that, as you changed brands.

The chamber seems fine from your measurements. I found out when using a bushing die, the unsized part of the neck doesn't fully expand to the chamber diameter, till after a minimum of 3 firing. Some times more. After 15/18 loadings, my 243 win. fired brass has no spring back. This gave me the neck chamber dimensions. I dont anneal brass.

 

[Someoldguy]

Forgive, I went back and changed case to cast. A shooter/reloader/collector wanted help casting chambers. No one on the forum had a clue so rather than say nothing they started in on each other. I contacted the OP off line and got him started I was impressed because he was a fast learner. He had no ideal how desperate members on reloading forums were for attention; he had no ideal how socially dysfunctional they could be when hiding behind a keyboard.



F. Guffey