What size is my chamber? Measuring shoulders.

[seand]

Scotch tape is about 0.002. A easy check is to add tape to the bottom of the longest case (FL sized with no shoulder bump - it might grow slightly) and see if you get resistance on bolt close. If not, add another layer. Then you can get a headspace measurement, pretty close.

 

[TaperPin]

I’ve been reminded my way of setting the FL die a full turn out doesn’t always work, and that is true. The cases with minimal taper, or situations with fat chambers and minimal die dimensions sometimes need some shoulder setback and/or full length sizing or cases are more likely to stick or have a harder than normal bolt closing force. Generalizing only works until it doesn’t. It seems die making could advance a little more than it has and mass produced dies could have some sort of stated dimensions to allow folks to more closely match them with chambers and not have to resort to expensive custom dies, but that’s a different story.

 

[Castle Rock]

FF = fire form.

I've tried just neck sizing with a collet die once with 6.5 creed after initial firing of brass and wound up with 90% of the rounds tight on bolt close.. I can see how it would work on belted mags that have a lot of stretching to do but I dont know how all the folks do it on standard cartridges that dont have a sloppy brass/chamber fit to start.

How tight?
Do you mean you feel slight resistance, or was it difficult to close the bolt?

 

[wind gypsy]

How tight?
Do you mean you feel slight resistance, or was it difficult to close the bolt?

Hard to quantify. A little more resistance than typical on bolt open when cocking the firing pin I'd say (obviously in the opposite direction).

 

[Harvey_NW]

I've tried just neck sizing with a collet die once with 6.5 creed after initial firing of brass and wound up with 90% of the rounds tight on bolt close.. I can see how it would work on belted mags that have a lot of stretching to do but I dont know how all the folks do it on standard cartridges that dont have a sloppy brass/chamber fit to start.

I've experienced similar, sometimes just from finding pressure with new brass I feel a bit of resistance on close if I try to chamber a fired case. I try to use those for initial die setup. A lot of times the cartridges I see neck sizing working on are older designs with looser tolerances.

 

[Castle Rock]

Wind Gypsy
Sounds like that is normal, I like to feel a slight resistance on bolt close, my brass lasts forever as long as it isn’t hornady.
I probably have way over 30 firings on my Lap 223 stuff, and it has only been FLS 3 or 4 times and trimmed and anealed once

 

[wind gypsy]

Wind Gypsy
Sounds like that is normal, I like to feel a slight resistance on bolt close, my brass lasts forever as long as it isn’t hornady.
I probably have way over 30 firings on my Lap 223 stuff, and it has only been FLS 3 or 4 times and trimmed and anealed once

Interesting. Resistance on close and more resistance on opening isn’t something I want to deal with at all. I feel like it could get worse easy with a little snow/ice/rain or condensation on ammo too?

 

[Castle Rock]

I don’t have any issues opening

 

[wpeach1912]

.300WM
New Nosler brass measured with Hornady E420 headspace bushing 2.261" +/- 0.001" (nice job Nosler).

After firing one time 25 pieces of brass measure:
2.269" up to 2.275" so there is a variance of 0.006" The majority of them 2.271" to 2.272"
I understand that isn't a huge amount but I honestly thought that they would all be fire formed, smashed into that chamber and only vary maybe 0.0005"

I bought the Redding Type S full length bushing die but now I'm wondering what headspace should I resize these cases to?

Goal was 0.002' under the chamber dimensions. But is that under the biggest? The Average? I would assume under the biggest right? Why are they not the same length?

For reference too, the hornady shoulder bump gauge isn’t a great tool for measuring the base to shoulder. It is really only designed for measuring the same point on a shoulder of the same piece of brass before and after sizing for the difference. Like the rest of people said, it probably will take a few firings to fireform all the way to the shoulder junction.

 

[Lawnboi]

On top of it sometimes taking multiple firings for your brass to grow to your chamber, sometimes when you have brass mixed in from pressure ladders, or different times of the year being fired, or fired in moisture you can have more variation in your brass growth. If I have one show pressure say during a powder test, I put that aside for a tester piece.

It’s a good practice to take 10 or so pieces of brass and fire them a few more times than your main lot. It assures that you don’t end up sizing hundreds of pieces of brass not getting a result you want.