Normal case growth?

[Paddyd]

Im just wondering whether my experience is average or not. Im shooting a Savage M12 single shot with a Criterion 223R barrel adjusted for the bare minimal head space. Currently between.
.001 and .002". My issue is the cases. After FL sizing, they all seem to be uniformly growing exactly .005" after each firing. Brass is Starline brand, but Sig and LC brass basically do the same thing. My Alpha Munitions brass in 6BR will go 5 or 6 firings before it grows that much. Is it the brass or something all 223s do?

 

[RegionRat]

After FL sizing, they all seem to be uniformly growing exactly .005" after each firing.

Something here isn't clear.

If your rig is set with a SAAMI GoGage and is roughly a +1 or +2 to the gage, then the brass will grow to that level.

If the virgin brass starts at -0.003" and goes 0.005" to a +0.002" , then this is to be expected.

Maybe share the dimension of the virgin brass, then fired brass, when the gages are referenced to your GoGage.

 

[mgunderson]

What you are experiencing is not out of the normal for 223 and 6mm br. Some times you can get an ideal combination of chamber/ sizing die combination and cases like the 223 won't grow as much.

 

[243winxb]

uniformly growing exactly .005" after each firing.

A MUST READ LINK.
Shooting hot loads, like these? Brass will flow. Jam the bullet & add 10,000 more PSI

 

[gdbleb]

The fired brass (in multiple brands) is basically telling you your chamber size. Do you have a set of go / no-go gages to compare the fired brass to these fixed reference point(s)? That would validate (or not) your assertion of "bare minimal head space".
Remember what Speedy said. "Everything is broken until proven otherwise".
I might be somewhat inaccurate on the quote but that's the gist of it.

 

[DShortt]

Im just wondering whether my experience is average or not. Im shooting a Savage M12 single shot with a Criterion 223R barrel adjusted for the bare minimal head space. Currently between.
.001 and .002". My issue is the cases. After FL sizing, they all seem to be uniformly growing exactly .005" after each firing. Brass is Starline brand, but Sig and LC brass basically do the same thing. My Alpha Munitions brass in 6BR will go 5 or 6 firings before it grows that much. Is it the brass or something all 223s do?

What is your definition of brass flow?

Is your base to ogive dimension growing? Or your overall case length?

The first one I mentioned is a sizing problem.

I've not noticed that situation in my pair of .223s. But. They both have barrel nuts and I've set the headspace off a 'go' gauge.

I'm using Starline brass in one, factory Winchester brass in the other. And I don't run either one 'hot'.

Every 10 firings or so, they need a trim off the overall length. Just .003" or there abouts.

 

[charlie b]

I haven't fired anything but Lapua brass in my .223 for many years. They barely grow at all. But, I don't go for max psi loads either, usually the 2nd node.

 

[Paddyd]

What is your definition of brass flow?

Is your base to ogive dimension growing? Or your overall case length?

The first one I mentioned is a sizing problem.

I've not noticed that situation in my pair of .223s. But. They both have barrel nuts and I've set the headspace off a 'go'.gauge.

Every 10 firings or so, they need a trim off the overall length. Just .003" or there abouts.

My definition is after triming to length, 1 firing and f l resizing, calipers say the case is .005" longer.

 

[243winxb]

Brass is Starline brand

Starline website-

The 5.56x45mm NATO is the military version of the .223 Remington, which is one of the most widely used centerfire cartridges today. Starline’s 5.56x45mm brass is identical to Starline’s .223 Remington brass except for a slight change in the metallurgy making it harder at the base of the case.

 

[DShortt]

My definition is after triming to length, 1 firing and f l resizing, calipers say the case is .005" longer.

Oh, wow.

I've not had an issue like that.

Sounds like your chamber and die dimensions are off enough that the case keeps getting 'blown out' to fit the chamber and the sizing die is pushing it back down considerably, causing the length to grow.
Probably need a chamber cast to measure to find out what the issue is.

Your brass probably will live a short life under those conditions.

 

[Webster]

Im just wondering whether my experience is average or not. Im shooting a Savage M12 single shot with a Criterion 223R barrel adjusted for the bare minimal head space. Currently between.
.001 and .002". My issue is the cases. After FL sizing, they all seem to be uniformly growing exactly .005" after each firing. Brass is Starline brand, but Sig and LC brass basically do the same thing. My Alpha Munitions brass in 6BR will go 5 or 6 firings before it grows that much. Is it the brass or something all 223s do?

Are you bumping the shoulder 0.002"? Is the case getting the shoulder pushed forward because of excess shoulder bump? I shoot a 6BR and only trim a few thou off after a few firings. Case overall length is the total case and no info as to where the growth occurs. Is the shoulder getting pushed forward and you removed metal from the neck when it's the shoulder moving forward???

 

[243winxb]

Savage axis 223 , As it came from factory.-

The firing pin strike on a dead primer will set the shoulder back .006"
The 2nd strike makes the head to datum measurement,, even more shorter.

My Savage extractor allows the case to be driven forward by the pin strike.

But does the head to datum get shorter from the firing pin strike, under normal conditions? Maybe? Firing of primer alone, no powder, produces 23,000 PSI in the pocket.
All this may add to the working of the brass?

Bottom line, reduce pressure, less trimming.

 

[Paddyd]

Savage axis 223 , As it came from factory.-

The firing pin strike on a dead primer will set the shoulder back .006"
The 2nd strike makes the head to datum measurement,, even more shorter.

My Savage extractor allows the case to be driven forward by the pin strike.

But does the head to datum get shorter from the firing pin strike, under normal conditions? Maybe? Firing of primer alone, no powder, produces 23,000 PSI in the pocket.
All this may add to the working of the brass?

Bottom line, reduce pressure, less trimming.

These are not anywhere near max loads. I never get good accuracy pushing velocity so most are in the lower half of the charge tables. Im leaning towards crappy alloy in the Starline cases vs the Alpha brass. I bump shoulders .001" and theres a very slight resistance when closing the bolt so there isnt much if any case movement when struck by the pin.
I also jam bullets during fireforming new cases to keep the case head in contact with the bolt face during the first firings to avoid stretch in front of the web.
Im seriously considering getting one of those RCBS Xdies to see if it helps.

 

[Iowa Fox]

When you pull the expander back through the neck on most dies it stretches the case. I don't care how much you polish it or what lube you use it stretches them. I proved that to myself a long time ago and quit using them.

 

[243winxb]

The donut on some brass, make it near inpossable to pull an expander out of a lubed neck.
The fix-
1 Neck turn
2 Bushing die
3 Modify fl die.

PHoto from AMP.

 

[243winxb]

m seriously considering getting one of those RCBS Xdies to see if it helps

Requires .020" shorter then maximum trim length, to start. (Instructions)

From case mouth to end of chamber, can be as much as .030" or more.
I think, not good for accuracy?

No sure what is causing the problem, but its a strange one.
Good luck.

 

[Paddyd]

When you pull the expander back through the neck on most dies it stretches the case. I don't care how much you polish it or what lube you use it stretches them. I proved that to myself a long time ago and quit using them.

Then there's some reason why the Redding 6BR die doesnt do that? It too has an expander ball. I have long wondered whether that actually pulled the shoulder bump back out. I will try FL sizing without it in the die to see if there's any difference when I get back from the range.
Like I say, I notice this only in my 223R, but will surely try this this morning and see what happens.

 

[358WCF]

See post #3. Pretty sure it's a chamber/die dimension discrepancy. Measure your fired cases at the (imaginary) .200 line... the fattest portion of the case above the extractor groove. Size & remeasure at the same place. How much difference is there? Oversize/sloppy chambers/brass & minimum dies dont play real well together. Betting your 6BR chamber/brass interaction is less than the 223.

 

[Paddyd]

When you pull the expander back through the neck on most dies it stretches the case. I don't care how much you polish it or what lube you use it stretches them. I proved that to myself a long time ago and quit using them.

OK. Just fired 30cases. De capped on a Lee decapping die.
Removed the expander from the Hornady die and same thing. FL resize and case is again now .005" longer than it was prior to firing so it isnt pulling the shoulder out. Using a go guage with a piece of scotch tape on the end, the bolt won't even begin to close so headspace is confirmed to be less than .002". I'm stumped.

 

[DShortt]

I've been using Starline brass in a .223Rem. 23.5 grains of 8208XBR. 69 grain SMK. 1 in 8 twist. Shoots accurately and I've not noticed case growth like you mentioned. About .001" for every couple of firings and FLS.
Again, I'd check your chamber diameter and make sure it's not oversize.
You can do this rather easily. FLS a case and insert it in the chamber. If you can wobble it around, your die or your chamber is out of spec.
Trim the neck back to correct base to case mouth length after FLS.