Home Forums Hunting & Shooting Ask The Gunwriters Tight chamber?

Also, the fact that the fit was "less tight" as I screwed the sizing die in farther...does that not mean it is a tight headspace issue?

I recently acquired a 338-06 and started working on running some Nosler 30-06 brass through my Lee 338-06 sizing die. I adjusted the die down until it made contact with the shell holder and ran a piece of brass through. Loaded the empty brass into the chamber, and the bolt had to be forced closed. Hmm, need more shoulder setback. I ended up adjusting the die down until it cammed over pretty hard. Sized the same piece of brass and tried chambering again. Better, but I can still feel a bit of resistance when I close the bolt. Tried switching from my RCBS shell holder to the Lee. Same thing. Is there any reason not to shoot as it is? I am sure it won't stick in the chamber so hard I can't open the bolt, nowhere near that tight.

Will I run into pressure quicker if I shoot as sized now? Or would you just shoot it as is? I wonder if the chamber was cut on the tight side, and if so, makes me curious to whether it was on purpose. It is a BRNO Mauser with an aftermarket barrel, my gunsmith said if he had to guess he would guess a Douglas barrel.

My understanding is I could solve the problem by getting a machinist to grind .008-.010 off the surface of my shell holder, and I am not opposed to going that route. There is a good machinist just down the road from my place, I am sure he would do it for me.

Sounds like a go / no go gauge set might be in order.

I am trying to angle Hornady one shot inside the mouths, but apparently not enough! So what about the 95 pcs Nosler brass I sized already? They will prob have way to much headspace?!

For FL sizing dies that have an expander ball I lube inside necks. I use an appropriate size bore mop with lube applied to mop. Since I'm an old fud I still use RCBS lube. You could apply your One Shot to bore mop.

When inserting mop into case neck I try to ensure I get a good dose of lube at inside shoulder/case neck junction. This is where expander ball engages neck first, so most important imo.

Some brass will develop a doughnut for lack of a better description at the shoulder/neck junction due to brass flowing here during the case firing. This brass flow is why cases need to be trimmed as needed due to aol increases.

Your cases may not have this doughnut. Probably not, dunno. However, doughnuts do add additional resistance when retracting, pulling expander ball out of case potentially moving shoulder/neck junction to where case seems to have headspace changed. Result might be the shiny ring displayed as on case in your photo.

If you have a fired case that bolt closes ok on, remove the expander ball from your FL die and size case. Then see if sized case <that expander ball has not been pulled through neck> chambers and bolt closes ok.

Please post results if you do this.

It appears to also have a contact line about 2/3rds the way down the shoulder? Tough to tell from the pic but there may be some taper above the neck/shoulder contact point. Could be a bit of upper shoulder, could be a thickened lower case neck (since the lower is what was once shoulder prior to being necked up)...hard to say. It might just need she shoulder pushed back a couple thou., too. At this point, it's hard to phone in the answer.

Remove the primer and with a caliper and and a head space gauge, measure it. Then tweak the die adjustment a small bit and remeasure. It might get longer before the case shoulder firmly contacts the shoulder area of the die and gets shorter. Go slow, and measure each you adjust the die.

Good shootin' -Al