Measuring Headspace for 338 Win Mag

[stevelsd]

Hi Reloader Gurus,
Has anyone got suggestions on how to inexpensively measure (not cheap to sacrifice safety) headspace for a 338 Win Mag. In the past I used a specific FF case that was correctly measured for headspace spec and that worked okay but I am looking for something a lil better perhaps. I have comparators but I do not have "Go, No Go, Field" gauges. I saw some gauges but $100.00+ I just feel those prices are too exorbitant at least for my wallet.
If someone believes a pre-measured headspace spec for a 338 Win Mag is enough to do the "bump job" from FF brass, i am open to that measurement as well.

Thank you
Stevelsd

 

[RiverRider]

So, are you really just looking for a method to set up a sizing die for optimum should bump during resizing?

 

[stevelsd]

So, are you really just looking for a method to set up a sizing die for optimum should bump during resizing?

Yes. Apologize for not stating this. Currently using Redding Body sizing die and for FL using an RCBS full sizing die.


Geesh if I had looked just a little harder before submitting I would have found this. Anyone believe this would assist in headspace measuring?

E. Arthur Brown Company

Shop for accurate rifle barrels and shooting accessories to fit your AR-15, Ruger 1022, Savage Remington, Thompson Center Encore, Contender and other popular gun models.

eabco.com

 

[TackDriver284]

I use this. Simple and quick. There are others on the market, more expensive, but the Hornady works for me.

Lock‑N‑Load® Headspace Comparator & Anvil Base Kit - Hornady Manufacturing, Inc

Lock‑N‑Load® Headspace Comparator & Anvil Base Kit Lock-N-Load® Headspace Comparator The Lock-N-Load® Headspace Comparator extends brass life, improves accuracy, and enhances safety. The gauge measures...

www.hornady.com

 

[stevelsd]

I use this. Simple and quick. There are others on the market, more expensive, but the Hornady works for me.

Lock‑N‑Load® Headspace Comparator & Anvil Base Kit - Hornady Manufacturing, Inc

Lock‑N‑Load® Headspace Comparator & Anvil Base Kit Lock-N-Load® Headspace Comparator The Lock-N-Load® Headspace Comparator extends brass life, improves accuracy, and enhances safety. The gauge measures...

www.hornady.com

Super thanks Mark!
I do have the Hornady set but my understanding is this would work for bottle neck cases but not for magnum belted cases since one should be measuring headspace off the belt and not from the head? Am I incorrect?

 

[Joec7651]

The Hornady comparator is what I use for headspace on all rounds I load for. It will give you your chambers exact dimensions after measuring a fired case. It will also tell you how much your brass stretches during firing by comparing new and fired brass.
If you want general headspace readings the Go, and NO-GO gauges for 264 WM, 7mm RM, 300 WM, 338 WM, 458 WM and the like are interchangeable as they headspace on the belt. You can have a properly headspaced magnum that still has a loose chamber if the smith is heavy handed with the reamer.

 

[stevelsd]

The Hornady comparator is what I use for headspace on all rounds I load for. It will give you your chambers exact dimensions after measuring a fired case. It will also tell you how much your brass stretches during firing by comparing new and fired brass.
If you want general headspace readings the Go, and NO-GO gauges for 264 WM, 7mm RM, 300 WM, 338 WM, 458 WM and the like are interchangeable as they headspace on the belt. You can have a properly headspaced magnum that still has a loose chamber if the smith is heavy handed with the reamer.

Thanks to you Joe and Mark. So it appears I do not necessarily need the "Go, No Go, Field gauges"
I was thinking I was missing some very critical. Currently I use the Hornady tool and comparator with both inserts and bushings.

Again thank you both for saving me money and concern

 

[Joec7651]

I meant to mention this but didn’t. Ideally I want my belted cartridges to headspace on the shoulder, not the belt. Headspacing on the shoulder lengthens brass life dramatically.

 

[stevelsd]

I meant to mention this but didn’t. Ideally I want my belted cartridges to headspace on the shoulder, not the belt. Headspacing on the shoulder lengthens brass life dramatically.

I absolutely concur.
Thanks again Joe!

 

[SJB358]

I’d use a piece of fired brass in your gun then size until you’re .002” under the fired dimension. Forget about the belt. Pretend it doesn’t exist.

 

[stevelsd]

I’d use a piece of fired brass in your gun then size until you’re .002” under the fired dimension. Forget about the belt. Pretend it doesn’t exist.

Scott that is what I have done in the past years ago, but been away from this for a bit long time so I wanted to make sure on that.

Scotty! Is this you from the Adirondacks?
I am still the same Steve you sent some free cases to me when I first joined 10-11 years ago and you stood up for me a number of times when some were not so kind . Alot has happened since then so have not hunted or reloaded in almost 6+ years including a "minor heart attack" lolol. I see JD338 is still here too. Great to see you are still around!!!

 

[SJB358]

That’s me buddy! Great to see you around! Glad you’re still kicking Steve!

 

[jimbires]

the new belted brass is usually short somewhere in the .015" - .020" range . I've found it takes 2, or 3 , sometimes 4 firings to get it fully expanded . so what I do is fire 3 or 4 pieces of brass with only neck sizing , until it starts to get tight to chamber . when it gets tight to chamber the brass is fully expanded . now you can set up your sizing die to bump the shoulder back about .002" .

if you want to extend your brass life you can form a false shoulder before the first fire and eliminate a lot of the case stretch .

 

[Joec7651]

Scott that is what I have done in the past years ago, but been away from this for a bit long time so I wanted to make sure on that.

Scotty! Is this you from the Adirondacks?
I am still the same Steve you sent some free cases to me when I first joined 10-11 years ago and you stood up for me a number of times when some were not so kind . Alot has happened since then so have not hunted or reloaded in almost 6+ years including a "minor heart attack" lolol. I see JD338 is still here too. Great to see you are still around!!!

Welcome to our group Steve. I’m glad your health has returned. There are a lot of great people here. Many friends. Scotty is one of the best without doubt.

 

[Joec7651]

the new belted brass is usually short somewhere in the .015" - .020" range . I've found it takes 2, or 3 , sometimes 4 firings to get it fully expanded . so what I do is fire 3 or 4 pieces of brass with only neck sizing , until it starts to get tight to chamber . when it gets tight to chamber the brass is fully expanded . now you can set up your sizing die to bump the shoulder back about .002" .

if you want to extend your brass life you can form a false shoulder before the first fire and eliminate a lot of the case stretch .

The two 7mm RM’s I have aren’t too bad. One has an X-Caliber barrel and pushes the shoulder forward .007-.008” when firing new brass, and a stock model 700 pushes it forward .012” respectively. The X-Caliber barrel also has a somewhat short throat. 175 grain ELD-X’s touch the lands at 3.350”. Great accuracy and velocity with RL-25 though.

 

[RL338]

I've found it takes 2, or 3 , sometimes 4 firings to get it fully expanded . so what I do is fire 3 or 4 pieces of brass with only neck sizing , until it starts to get tight to chamber . when it gets tight to chamber the brass is fully expanded . now you can set up your sizing die to bump the shoulder back about .002" .

This is the key to extending brass life. If you start bumping the shoulder back at the first firing the brass never fully reach the chamber length. You will see casehead separation in just a few firings.

 

[salmonchaser]

This is the key to extending brass life. If you start bumping the shoulder back at the first firing the brass never fully reach the chamber length. You will see casehead separation in just a few firings.

I experienced the case head separation after about 4 firings with my 338 Jarrett. started neck sizing after that. Haven’t had a separation in quite a few years but I still buy a new box of 8mm Remington brass every other year. Fireform it and then it goes hunting. I think I’ve got 400 rounds of twice fired brass for that damn thing now.
My 300 HH is another that benefits from neck sizing only. While it doesn’t headspace on the shoulder as well as an other belted, except 375 HH, it still gains some support as well as improving accuracy.

 

[TackDriver284]

For my magnum cartridges I full size off the shoulder, I never bother with the belt.

Another option if you don't have tools to measure your bump, ( I recommend using tools ) chamber three fired cases to check if its snug / tight after closing the bolt
( like to average by using 3 cases ), if chamber closes snug / tight,,,,,screw in your die with the ram in highest position until the die contacts the shellholder, lower the ram, and screw in the die about eighth of a turn in / tighten the ring, and size a case. Chamber the sized case in the rifle, if its still snug / tight, then screw in your die another eighth of turn in and tighten the ring, then size the case again. Chamber the sized case until you feel no resistance after closing the bolt. After no resistance is felt when closing the bolt, I would use some scotch tape, and put a layer of tape on the head of the brass, and trim off excess tape overhanging the head of the case, you want just one smooth layer, no wrinkles or folds on the tape. Next chamber the taped case in the rifle and close the bolt, if its still snug, then screw in the die a tiny bit more, an eighth of a turn is fine or less, remove the tape off the head of the case, and size the case again. Reapply a new layer of tape on the head of the case, and chamber the sized case, if no resistance is felt then you should be around .002"- .003" bump. Do not be afraid of a cam over, its normal to cam over to get a good bump. Remove the tape and lock your die at this point, won't hurt to redo to tape check the next two fired / sized cases to make sure all three cases are not having resistance in your chamber. This method is if you don't have any tools to measure your bump, but i recommend spending a little money to get the proper tools.

Side note: I just ordered a headspace kit from Short Action Customs for my 6 Dasher when I ordered their full size bushing die and seater. They got some good stuff.

Headspace Comparators / Bullet Inserts Archives - Short Action Customs, LLC.

Your Foundation For Precision

shortactioncustoms.com

 

[RiverRider]

Like the other guys said, forget the belt is even there.

Try a little experiment...instead of screwing your sizing die all the way down so that it contacts your shell holder, raise the ram and adjust the die so that it does not quite touch the shell holder at all---say, by 10 thousandths or so. Use feeler guages if you have them. Chamber one of your fired (but not yet resized) cases in your rifle, noting the feel of resistance to bolt closure. Then take that same case and run it up into your sizing die, adjusted as described above. Chamber it in your rifle again. If you notice bolt closure being a little stiffer than it was before you ran the case up into the die, then stop and ponder what this is telling you.

 

[stevelsd]

Wow good people and experts. I sure am glad I thought to get back on this forum. Every single expert advice is well taken and hopefully will be remembered going forward.
I have one other concern, but I am going to open a new thread even though it is semi related.
Thank you, every single suggestion\recommendation big time!