Go guages

[Paddyd]

Hi,
Please forgive this if a dumb idea.
Got a friend with CNC lathes and mills who says I can come play and learn. I figure an easy project would be a set of guages for when I swap prefit barrels on my Savage.
Question I have is can I use the SAMMI drawing of the cartridge case as a blueprint for my go guage? I never use a no go and just put a piece of scotch tape on the back of the go .
Thanks.

 

[Jonnyofalltrades]

This depends a lot on what type of cartridge you are working with. Headspace gauges for rimmed and belted cases are easy to make, and easy to measure/verify.
Rimless cartridges usually use a measurement to a certain diameter on the shoulder. I believe the 30-06 family uses a .375" diameter.
For the price of a gauge, I wouldn't do it, and I'm usually game for just about any time wasting project you can imagine.
Having said that, many a rifle has been headspaced with a fresh case or cartridge.

 

[DaveTooley]

Use the dimensions for the go/no go HS numbers on the reamer print. That's usually -0.000" to +0.006"
No reason you shouldn't be able to do it.

 

[Paddyd]

This depends a lot on what type of cartridge you are working with. Headspace gauges for rimmed and belted cases are easy to make, and easy to measure/verify.
Rimless cartridges usually use a measurement to a certain diameter on the shoulder. I believe the 30-06 family uses a .375" diameter.
For the price of a gauge, I wouldn't do it, and I'm usually game for just about any time wasting project you can imagine.
Having said that, many a rifle has been headspaced with a fresh case or cartridge.

Only one I need right now is 204 Ruger

 

[SKWERLZ]

I’ve made a few gauges, pretty simple.

 

[Walt Krafft]

For your own use, go ahead and make one if you want. If you are using them on firearms for other people, spend the money and buy one.

 

[NorCalMikie]

Having said that, many a rifle has been headspaced with a fresh case or cartridge.

MANY!!
If you plan on using factory loaded ammo, keep in mind that not ALL loaded ammo is the same.
If you roll your own, set the headspace to where YOU want it.
None of my Savage rigs will chamber "factory loaded ammo". I've tried.
All my headspaces are set on the snug side. The less you move your brass when resizing, the longer it will last. Havn't used gauges in YEARS and no plans to start now.

 

[Paddyd]

For your own use, go ahead and make one if you want. If you are using them on firearms for other people, spend the money and buy one.

Only for me

 

[Paddyd]

MANY!!
If you plan on using factory loaded ammo, keep in mind that not ALL loaded ammo is the same.
If you roll your own, set the headspace to where YOU want it.
None of my Savage rigs will chamber "factory loaded ammo". I've tried.
All my headspaces are set on the snug side. The less you move your brass when resizing, the longer it will last. Havn't used gauges in YEARS and no plans to start now.

So what do you use to set it, a cartridge case? I once heard of a guy taking a case and filling it with bedding epoxy and using that, but To me that might prove not hard enough for my comfort.

 

[gunsandgunsmithing]

So what do you use to set it, a cartridge case? I once heard of a guy taking a case and filling it with bedding epoxy and using that, but To me that might prove not hard enough for my comfort.

It's very hard once filled. That's your easy button.

Getting the datum point and angle perfect will be the hardest part and an optical comparator is likely about the best option there. Once that's right, establishing length from that point should be pretty straightforward.
Something to keep in mind is that reamer angles have tolerances and I wouldn't make the angle exactly say, 30° for example. I'd probably to it at 29 instead, then establish the datum point on that. If the chamber has an actual 29.9° and your gage is 30...you see the issue, I hope.