Normal case growth?

[jsn]

I've read every post but I must have missed this--how far are you bumping the shoulders during FL sizing?

Edit: Yeah, I missed it.

 

[DShortt]

I've read every post but I must have missed this--how far are you bumping the shoulders during FL sizing?

See post #13.

 

[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?

I never liked expander balls or mandrels getting pulled or pushed thru the neck. Been using Redding FL -S bushing dies for many years with minimal neck trimming. I think most serious competitors have dies made from dimensions of 3 fired cases. Bushing dies are good enough to get my varmint rifles under 1/2" groups.

Are some 223 dies made assuming your shooting a semi-auto with a big sloopy chamber?

 

[DShortt]

Are some 223 dies made assuming your shooting a semi-auto with a big sloopy chamber?

If that was the case, the die would size the brass less, resulting in an oversized case that wouldn't fit a 'standard' chamber.

Would make -0- sense to manufacture a below-spec die for a chamber that's large.

 

[dellet]

You keep referencing .005” longer after firing then sizing. What is the length difference after firing, before sizing?

Are you 100% certain that the resistance you are feeling to bolt closure on sized brass is due to length and not diameter?

 

[Doom]

If you make length and diameter measurements, what you will likely see is the case expanding in diameter pulling the shoulder back on firing or actually going longer and the overall length gets shorter. Different cartridges behave somewhat differently depending on the case to bore ratio but this can happen with lower powered loads. When resizing the brass in the body will move the existing fired shoulder towards the neck end of the case. Depending on the pressure the case shoulder may have actually moved forward some on firing. If it moves far enough forward then when resized a new shoulder will be formed with brass from the body and existing shoulder and a new neck with brass from the shoulder and existing neck. In this case the OAL of the case will grow.

 

[Texas Solo]

My 6Dasher with Alpha brass seldom needs trimming. I set my caliper to 1.545. That's the max length before needing trimmed.
Then I test each sized case to the caliper. If it fits, it's good...no trim.
I just FL sized 50 cases and had to trim 5. Headspace is at .001 - .002.
I shoulder bump .002.

 

[Paddyd]

You keep referencing .005” longer after firing then sizing. What is the length difference after firing, before sizing?

Are you 100% certain that the resistance you are feeling to bolt closure on sized brass is due to length and not diameter?

Yes. Ive been measuring the base of the case near the web and it doesnt seem to grow around that area. I see cases grow about 1 to 2 thou before sizing, but 3 or 4 thou more after a fl size. The die seems to be squishing the brass towards the neck. I only bump shoulders 1 to 1.5 thousands. I need to add that it seems to be related to these Starline cases as it didn't happen with the LC brass. Maybe I'll try some Lapua, but they're so damned expensive.

 

[dellet]

Yes. Ive been measuring the base of the case near the web and it doesnt seem to grow around that area. I see cases grow about 1 to 2 thou before sizing, but 3 or 4 thou more after a fl size. The die seems to be squishing the brass towards the neck. I only bump shoulders 1 to 1.5 thousands. I need to add that it seems to be related to these Starline cases as it didn't happen with the LC brass. Maybe I'll try some Lapua, but they're so damned expensive.

.001-.002” after firing is not all that uncommon on first firing. Growing .003-.004” after sizing is a clear indication the doe does not match the chamber, or is set incorrectly.

You need to check diameters more places than at the web. Then you will know how much the brass is expanding.

Does fired brass chamber easily, or the same as sized?

Honestly it seems that you are oversizing the brass, the brass will conform to the chamber, it has to. The die needs to match the chamber, not some drawing. The chamber needs to match the drawing.

If you have a neck only sizing die, I would try that and see what happens to the brass, check iif growth stops. If you don’t have one, the same thing can be accomplished using a crimp die. All you need to do is close the neck enough to hold a bullet. Last choice is back the sizing die off until it only sizes a small portion of the neck. Generally this also touches the diameter.

One thing to make certain of is that the necks are not too long and being pinched in the chamber. It is entirely possible to have too long of a neck, and still have correct overall length.

Something else to be careful of is correct information when asking for help. In your first post, you stated having the same problem with both Sig and LC brass. Above you stated no problem with LC brass. It seems simple, but can change opinions of the case. Having strange problem, and the only difference is brand or lot of brass. Points more to the brass. So it’s an important piece of the puzzle.