Pressure issue (HeadSpace? )

[fguffey]

And then we go back to the OPs opening statement; if the case was short from the shoulder to the case head why didn’t that reduce pressure?

F. Guffey

 

[7Saum]

...And thus no apparent swipe mark, either.

HI,
So this is what I did!!!,took my firing pin out,put a fire brass in closed the bolt and there was resistance,so then I started bumping the shoulder back little bits at a time until the bolt closed with no resistance,so basically it is just formed to my chamber,neck sized and loaded them up with known under pressure load,went out this morning,shot 3 and STILL THE SAME MARK ON CASE!!!,so now once I get the tools to take out the ejector,I'm going to,and take some carbide paper and try and clean up around the ejector bore,if that doesn't work it's going to a Smith!!!...Thanx to everyone who has tried to help me figure this out....
Thanx Terry

 

[/VH]

Have you checked neck clearance? Does a bullet drop freely into the neck of a fired case? Measurement of the neck OD of a fired case vs a loaded case?

Terry,

Early in your thread, Sheldon N raised the issue of adequate neck clearance. I might have missed it but I don't see where you have verified whether you have enough neck clearance. Have you done that? Do you know if you have a tight necked chamber?

 

[7Saum]

Terry,

Early in your thread, Sheldon N raised the issue of adequate neck clearance. I might have missed it but I don't see where you have verified whether you have enough neck clearance. Have you done that? Do you know if you have a tight

Terry,

Early in your thread, Sheldon N raised the issue of adequate neck clearance. I might have missed it but I don't see where you have verified whether you have enough neck clearance. Have you done that? Do you know if you have a tight necked chamber?

Terry,

Early in your thread, Sheldon N raised the issue of adequate neck clearance. I might have missed it but I don't see where you have verified whether you have enough neck clearance. Have you done that? Do you know if you have a tight necked chamber?

K,I just went down to check and when I put a bullet into a fired case it goes in but not drop in,I don't have any loads loaded right now because I have been loading as I go to try and figure this out,so is there something I can measure without a loaded shell. .(correction 1 does drop in 2 don't)..

Thanx Terry

 

[7Saum]

Terry,

Early in your thread, Sheldon N raised the issue of adequate neck clearance. I might have missed it but I don't see where you have verified whether you have enough neck clearance. Have you done that? Do you know if you have a tight necked chamber?

Hi,
I neck sized and made a dummy round the
O.D of the loaded round neck is 0.316inch,the
O.D of the fired round neck is 0.326inch,
Please let me know what u think...(I used the shell that the bullet fell in easy)
Thanx Terry

 

[/VH]

.010" difference is way plenty clearance but with that much, I am quite curious as to why the 2 don't drop in. Have those 2 case mouths been flattened or dented? Are all 3 cases of the same brand ?

 

[7Saum]

.010" difference is way plenty clearance but with that much, I am quite curious as to why the 2 don't drop in. Have those 2 case mouths been flattened or dented? Are all 3 cases of the same brand ?

They r all the same brand,not flattened or dented,all Norma brass less than.5 grain of weight difference between..I am going to buy some redding competition shellholders so I can bump the shoulder accurate and consistent ...for next time...I thought it was strange that 2 of them were tighter..
Thanx Terry

 

[/VH]

I don't know if I'm headed down the right road to be of any help cuz I'm kinda just guessing. From prior posts, I got the impression that you've got a handle on adjusting your die for shoulder setback and with that in mind, I'd recommend acquiring a shoulder setback comparator, ahead of the shell holders. With that, you can get a good measurement of how much you have set the shoulder back. Whereas with the tape layer method that you used, it is not very likely but it is possible that you may have pushed the shoulder back excessively while what actually was causing the resistance to the bolt closing was the case body diameter. This can occur in situations where the sizing die and chamber are not well matched to each other and it's possible to adjust the die too far down, in regard to the shoulder, till it finally sizes the body enough to eliminate the resistance.

 

[/VH]

Terry,
I don't know if you've made any progress figuring out your issue. If the pressures were high, I would expect to see those ejector hole marks appear to be smeared to one side but I just thought of another possibility. Do you have any lube in your chamber or on your cases when you fire them? If so and pressure is high, the case may be rotating with the bolt upon extraction. I suppose they might be doing that anyway even if lube is not present. It is hard to tell from the pictures but does the area of those circles on the case heads project out from the case head, or is it just a ring that is either stamped into or protruding from the case head?

 

[7Saum]

Terry,
I don't know if you've made any progress figuring out your issue. If the pressures were high, I would expect to see those ejector hole marks appear to be smeared to one side but I just thought of another possibility. Do you have any lube in your chamber or on your cases when you fire them? If so and pressure is high, the case may be rotating with the bolt upon extraction. I suppose they might be doing that anyway even if lube is not present. It is hard to tell from the pictures but does the area of those circles on the case heads project out from the case head, or is it just a ring that is either stamped into or protruding from the case head?

I took a magnifying glass to try and see the marks on the brass head,no lube in the chamber,last night I took out the ejector out,and took some silicone carbide paper and cleaned up around the hole...Haven't had a chance to shoot yet,but I will let u know the results,I checked out the pressure signs article and it sort of looks like false positive for high pressure,hopefully cleaning that up does the trick...
Thanx Terry

 

[/VH]

Was there a visible ridge or burr around the hole? Whenever you do get it sorted out, I'd be interested in knowing what you find.

Thanks

 

[7Saum]

Was there a visible ridge or burr around the hole? Whenever you do get it sorted out, I'd be interested in knowing what you find.

Thanks

Well I did everthing I can think of,I looked through a magnifiying glass couldnt really tell if it had a rise or burr around the ejector hole,polished it anyway,even dropped another .5 grain off my load which wasnt over pressure already according to buddy's QL Program, still making a mark on case head...so I will be finding a smith I can send to and trust....I will post when I find out what the problem was...
Thanx Terry