I posted this in Gunsmithing but it may be that the reloaders have some experience in what to expect with reloading for this rifle, as is.

Background: I have a particular 338 WM, new this year, producing some once-fired cases that hold 87.8 to 88 grains of water. (measured without primers, using masking tape on primer pocket).
The 338 WM is typically rated at 86 grains of water and some new WW cases hold 85-85.6.
Also, the area immediately in front of the belt of the once fired cases mics at .5156-.5164" after firing, which is big in my opinion.
Current 'new' WW cases mic .508, while the SAAMI spec at that point is .513.

So is a chamber that produces once-fired cases with 87.8--88 grains water capacity, and .516" diameter on the body shaft at the belt, too large?

Should I consider sending it back to its factory/importer (Tikka/Beretta), or just load for it as a 'wildcat', with a slightly larger capacity than 338WM?

Fortunately, the chamber is fairly concentric and the once-fired cases give variance like .5156-.5163 or .5157-.5164 for a case. Rifle seems accurate, sub-MOA capable, though we're still in the load development stage and yet to reach 100 rounds.

It's easy enough to limit this gun to neck-sizing and special loads that may use 2-3 of grains of powder more than expected or than my other 338s.

In confirmation of the above, most of the loads with various bullet weights chronograph about 100 fps slower than expected and slower than other 338s I own. This would seem to support the idea that the chamber is a bit larger than typical.

As an example, I need 71.5 grains of Rel-17 to reach 2800 fps with a 225 grain TTSX. that's 2.5 grains more than what I use in a different rifle (same manufacturer).

A range of 3grs across a brand or even a lot of brass isn't that much. I've had twin rifles that had differences as much as you quote. If it were mine I would either neck size or set up my FL die to headspace off the shoulder. Then simply work up a load.

If you want loads that will give the same accuracy and velocity across two different rifles I wish you luck. I've had it a few times. But if I bet against it everytime I would be ahead.

quote:

Should I consider sending it back to its factory/importer (Tikka/Beretta), or just load for it as a 'wildcat', with a slightly larger capacity than 338WM?

I see no reason to return the gun. Load it as an individual. This is no different than any rifle. They are all individuals.

I think your concerns are over nothing. Just set your resizing die correctly so the cases will just chamber and then work up the best load you can.

A few things to consider and no flame or diss intended or implied...

WHO sez 86 gr H2O is average for a 338 WM, and WHO sez a 1.5 gr H2O variation is excessive?

I've gotten 4 gr H20 variation in 25 rounds picked out of a box of 100 Rem or WW in large belted magnum cases. You can get that much variation in a digital weight scale and unless you happen to use an analytical scale or balance beam your just whizzing in the wind.

I guarantee that...I have 3 digital and 3 balance beam weigh scales and I can get 6 different weights with ONE case...I've done it several times to show people when they don't believe what I say...but ALL the balance beam scales are accurate using a set of scale check weights. And ALL the digital scales tell you the accuracy range in the fine print if you bother to look.

Plus...not to mention the fact that measuring 0.0001 of an inch is iffy at best unless you are in a climate controlled environment using perfectly adjusted instruments.

Talk about splitting hairs!!!!!

10 gr H2O variation might be considered a bit excessive in large cases and 1.5 H2O variation in a 223 size case will cause a BUNCH of trouble with top end loads.

There is ALWAYS some variation in reamers so chambers will have the same variability.

You're splitting hairs without needing to.

Just follow what everyone has already posited and you won't have any problems.

I have several rifles with slight to "WAY too damed much" oversized chambers...my 338-06 chamber is long and the throat is longer and I need 6 grains of 4320 powder OVER what has been posted in magazine articles over the years to just equal those posted velocities with the same 26" barrel length...and a touch more to get the best accuracy.

You're not even close to "wildcat" in that rifle, just within normal tolerance variation statistically speaking.

Set your sizer die to just push the shoulder back about 0.001-0.002" and polish it out to give about the same amount of base sizing. Reload for the bullet you expect to use at the OAL and with the powder that gives the highest velocity and accuracy and call it good...and go hunting...don't waste the best part of a barrels life on the bench chasing a tail wag.

Luck

quote:

Originally posted by 416Tanzan:
I have a particular 338 WM, ..the area immediately in front of the belt of the once fired cases mics at .5156-.5164" after firing, which is big in my opinion.
Current 'new' WW cases mic .508, while the SAAMI spec at that point is .513. ...

Hey 416, I'd recommend you buy one box of Factory Cartridges, probably the Superperformance Federals, and use them to establish your Pressure Ring Expansion(PRE) Benchmark. Shoot 5-6 of them and take the Average. Then I'd consider whatever PRE they expand to(Averaged) to be the SAFE Max.

Then you can pull 5-6 of the Bullets in the unfired Factory Cases, dump the Powder in the garden and Reload those Cases with the Load you want to use. When you compare the PRE of your Reloads(in the same Lot Factory Cases) to the Factory Average, you will know if you are at a SAFE Pressure or not.

CHE will not work, since they are "new" Cases and they need to have at least one firing on them.

This tells you more about the Pressure of your Loads than all the non-calibrated Haphazard SGSs ever made.
-----

Just checked and one of my Belted Mags is running 0.5156"-0.5157" at a SAFE MAX. But, that only applies to this specific rifle. The others are different, some larger and some smaller.

Best of luck to you.

Full reply over on the Medium Bore forum.

Short version: PFLS, or, potentially have custom sizer made matching your chamber.

Your chamber size is not a particular worry, but using a small(-ish) FL die, you may be forced to trim your cases with every sizing. PFLS *may* cure this, a custom die will definitely cure this...

- mike

Looks like you are getting the same response here.
You might try Snipers Hide, 6BR.com, Benchrest Central,24hr Campfire, or whatever. You might find a different opinion if you check around enough.
Butch