A Shout Out for the Check Gauge

[Gus]

Hello Everyone,

Just wanted to take a few minutes and pass on my thoughts on check gauges for your reloads/handloads.

Last spring, I was out at Birchwood shooting the Garand and began having trouble with rounds not chambering.  In 2020 I had no such trouble and had always kept my trim lengths in tolerance. But, I was using 'regular' .30-06 dies and even though I was full-length resizing the brass, it wasn't enough. So I did two things: 1, I bought a small base resizing die and 2, I bought a .30-06 check gauge.

For those who may not know, a check gauge is a small device (see the picture) that looks somewhat like the chamber of your rifle. To use a check gauge simply drop your round in.  the round should drop in easily, but not too far. If it drops in below flush, you have an issue with excess headspace.  If it doesn't drop in all the way, you have an issue with oversized brass (like mine were).

Enter my check gauge. Once I switched over to the small base resizing die, my reloading issues with resizing went away by the tune of 95%.

With my previously loaded ammo, I ran them all through the check gauge.  I found I had a good 10% failure rate!  I pulled all the bullets, ran the brass through the small base die, and reassembled loads.  For what it's worth, pulled bullets shoot just fine.

Once reassembled, I ran the cartridges through the check gauge again and had only three failures out of 57. 

So, I solved my problems with the Garand.

Then last week, running a .308 bolt action, I was shooting a KD in Talkeetna.  Some of the rounds were a bit snug when chambering.  With the leverage of the bolt action I was able to cam the bolt down and chamber the round, but it cost me time and a few shots not fired in stages 2 and 3.  Then I really ran out of time during a rapid fire AQT. My running out of time cannot be blamed on be fully blamed on the ammo, but, it was a factor.

I see more check gauges in my future!

In Liberty,

Gus

[ItsanSKS]

While a Case Gauge may be great for ensuring that your hand loaded ammunition will fit any chamber that meets SAAMI specification, if you are loading for one specific rifle, I recommend the use of the RCBS Precision Micrometer. 

The RCBS Precision Micrometer can provide you with an exact measurement (to the .001") of the headspace of a fired cartridge.  This information can then be used to ensure that your sized brass will fit in the chamber.  Typically, one will size the case so that the shoulder has been 'bumped' .002" back from its once-fired state. 

I have also found that the neck sizing ball on most sizing dies will actually deform the case shoulder during the sizing process; unless the inside of the case neck has been lubricated, the resistance of the sizing ball being pulled through the case neck will tend to stretch the case shoulder, leading to insufficient headspace.

To determine if this issue is present in your loading process, set your sizing die without the neck expander, and determine if the case will easily chamber; if it will easily chamber before the case neck has been expanded, but will not chamber afterward, there is a strong likelihood that the case neck needs to be lubricated prior to the expander ball being drawn through the case neck.

[TOMINCT]

 +1 on what ItsanSKS said. I've been using an MCS headspace guage for a long time, in setting up dies for sizing.

https://www.fulton-armory.com/headspacegaugeforcartridge308.aspx

It used to be made from a Wilson guage as shown above, with the RCBS mic installed. Not sure if they're made the same any longer.

Also concur on removing the expander from the FL sizer. I use a Lyman M die to expand and bell the case neck instead. An extra step but worth it to me. Especially if you use flat base bullets.

Size, de prime, expand in M die, then continue the procedure. Easy peasy once you get the hang of it. Your brass may last longer also.

[malabar]

+1 on what ItsanSKS said. I've been using an MCS headspace guage for a long time, in setting up dies for sizing.

https://www.fulton-armory.com/headspacegaugeforcartridge308.aspx

It used to be made from a Wilson guage as shown above, with the RCBS mic installed. Not sure if they're made the same any longer.

Also concur on removing the expander from the FL sizer. I use a Lyman M die to expand and bell the case neck instead. An extra step but worth it to me. Especially if you use flat base bullets.

Size, de prime, expand in M die, then continue the procedure. Easy peasy once you get the hang of it. Your brass may last longer also.

An adjustable headspace gauge?  Now that's slick....

tk

[TOMINCT]

An adjustable headspace gauge?  Now that's slick....

tk

Not really adjustable, maybe variable? It measures from the datum line on the case shoulder to the base of the case.

Cases stretch upon firing depending on size of chamber. Not sized enough they don't fit or need extra effort to close, which is what Gus experienced. Sized too much and your cases stretch a lot after every firing and fail sooner than they should.

Gas guns tend to have large chambers, radially and in length for adverse conditions. Out of my 308 semi it comes out at .012" longer than 0 on the guage. So, size enough to re chamber at say .009 or .010" for easy chambering/functioning and good case life.

>002" for gas guns, .001" for bolts was what i was told the Hi Power guys did for the reloads. Chamber cleaning essential with gas guns as they do get a lot of stuff  building up in there.