Virgin vs fired shoulder measurement

[mike a]

6.5 creed Lapua. At the shoulder datum my comparator shows virgin at 1.519 and once fired at 1.527. .008 increase. Is this over stretching my brass? Seems excessive! Just screwed this barrel in. It's a Bighorn TL3 an has the floating bolt head and I struggled to get that "just right feel". Used Manson h/s gauges. I wonder if I should screw barrel in a touch more. BARREL NUT. Mike

 

[mikeinct]

Before you go any further...Check the Gauge vs the fired brass...It is possible the new brass comes up short..Mike in Ct

 

[ballison]

You're seeing what I typically do with virgin brass. My guess is that it's undersized to make sure it fits in any chamber to start.

 

[JFrank]

6.5 creed Lapua. At the shoulder datum my comparator shows virgin at 1.519 and once fired at 1.527. .008 increase. Is this over stretching my brass? Seems excessive! Just screwed this barrel in. It's a Bighorn TL3 an has the floating bolt head and I struggled to get that "just right feel". Used Manson h/s gauges. I wonder if I should screw barrel in a touch more. BARREL NUT. Mike

Do you have the reamer print?

 

[mike a]

Before you go any further...Check the Gauge vs the fired brass...It is possible the new brass comes up short..Mike in Ct

So there it is. The difference between the gauge and virgin is .008! I knew virgin brass was short but didn't expect that much. Thanx

 

[MikeMcCasland]

I'd leave it as is, but in the past I've tried a few settings on aftermarket savage barrels. I have one setup where I used a piece of new Lapua brass to headspace it. Close the bolt on a new piece of brass with the barrel loosely fitted. Then screw the barrel down until tight. Then back it off 1/5-1/8th a turn; I'd have to go back and check but I believe the brass only grows .002-.003. I didn't really see any accuracy benefits from setting it up with tight headspace like this; if anything it just made it more of a pain to use other brands of brass, and you're more susceptible to spring-back issues if you're not annealing.

I'd leave as is, and just bump size your brass .002 from the fired reading.

 

[fguffey]

6.5 creed Lapua. At the shoulder datum my comparator shows virgin at 1.519 and once fired at 1.527. .008 increase. Is this over stretching my brass?

Good, you measured before and again after. There is another method and or technique: Measure the length of the chamber from the shoulder/datum to the bolt face. And there are go-gage length chambers and no go-gage length chambers and field length size chambers; and for me there is ever chamber from minimum length to field reject length in thousandths.

Based on your measurements you chambered a minimum length/full length sized case in a no go-gage length chamber. You could go for the 'magic .002'. I would adjust the die to shorten the case .002" from the shoulder to the case head.

And then there is the 'fix'. Move the barrel back .005", that would leave you going for the 'magic .003', or you could go for moving the barrel back .006".

F. Guffey

 

[243winxb]

Will the fired brass chamber after fl sizing? An overly tight chamber may not allow the bolt to close on a fl sized case.

.008" on 1 firing, not a problem..

 

[fguffey]

.008" on 1 firing, not a problem..

"Not a problem?" Only if a reloader could be taught to determine where the case stretched. When it comes to a case increasing in length between the shoulder and case head reloaders only have one answer; 'it stretched', stretching cases is a bad habit. And then there is that crowd that insist the firing pin drives the shoulder of the case to the shoulder of the chamber: when that happens there is no option, the case stretches between the case head and case body. That crowd insist the firing pin strike shortens the case as much as .005".

For those that can keep up if the case has .004" clearance and the firing pin shortened the case .005" the case has .009" clearance before the bang. THE SCARY PART: If the shoulder of the case is against the shoulder of the chamber the case has no choice but to stretch between the case head and case body.

F. Guffey

 

[mike a]

Will the fired brass chamber after fl sizing? An overly tight chamber may not allow the bolt to close on a fl sized case.

.008" on 1 firing, not a problem..

Yes. I stripped the bolt and closed the bolt on a fired piece. It chambered with light force applied. I sized to achieve .002 bump and it chambers freely.

 

[mike a]

"Not a problem?" Only if a reloader could be taught to determine where the case stretched. When it comes to a case increasing in length between the shoulder and case head reloaders only have one answer; 'it stretched', stretching cases is a bad habit. And then there is that crowd that insist the firing pin drives the shoulder of the case to the shoulder of the chamber: when that happens there is no option, the case stretches between the case head and case body. That crowd insist the firing pin strike shortens the case as much as .005".

For those that can keep up if the case has .004" clearance and the firing pin shortened the case .005" the case has .009" clearance before the bang. THE SCARY PART: If the shoulder of the case is against the shoulder of the chamber the case has no choice but to stretch between the case head and case body.

F. Guffey

Come on guffey. I don't have my secret decoder ring with me. Reading your post sounds like you don't actually know where it stretches either. This bolt has control feed and mechanical eject. So no ejector plunger pushing forward and the extractor holds the case fairly well against the face. .008 just seems like a lot in relation to case longevity. Even just stretching once. No riddles please. Mike

 

[fguffey]

Come on guffey. I don't have my secret decoder ring with me. Reading your post sounds like you don't actually know where it stretches either.

Decoder ring? That is silly.

Reading your post sounds like you don't actually know where it stretches either

You have to make your own mind up, if the firing pin drives the case of the shoulder of the case to the shoulder of the chamber and the case locks to the chamber when fired the clearance is between the bolt face and case head. And then there is the claims department, they claim the case shortens with the impact of the firing pin. I do not know how much sillier than the 'decoder ring' thing you can get but that leaves 'stretch' between the case head and case body.

And then there is the Wilson case gage, as I have said the Wilson case gage has been with us for over 70 years and during that time reloaders have gotten sillier not smarter.

As I have said before: There has to be something that reloaders do not understand about the events/sequences that happen between pulling the trigger and the bullet leaving the case. I'm thinking you are trying to hard to be silly.

F. Guffey

 

[flintcreek6412]

I like tight headspace but that's just me. I set mine at basically zero so I actually bump size new brass ever so slightly. This way I have competed(local fun ones) with brand new cases. It always seemed like such a waste of time, barrel, bullets, primer, powder and case life to fireform. I seem to get very good case life this way because not much is stretching. Plus, no one can be tempted to put their own reloads in my chamber.

I had a factory .308 Remington 700 that must have been maxed out specs because those cases grew a ton and I had to fireform. I hated that gun simply because I had to fireform. I think fired vs new were .006 different. Some people like the increased case capacity for more velocity. I could care less. I guess it depends on your shooting application too. Hunting where MOA is good enough and speed helps unknown distance or F class where you must have .25 or better MOA.