Headspacing with a live round

[223Rem]

I know that is what the gauges are for, yet some have used the empty case method.

I have read that some have used a live round (hopefully with the firing pin assembly not installed, or pin protrusion negated).

Hoping to borrow a set of gauges, if not I will attempt the live round method.

Do I still put one piece of tape on the back to act as the go gauge? Seems counterproductive as the ammo is SAAMI spec and does not possess the same crush effect as empty brass.

Your thoughts?

[reynoldsfamily3]

What caliber are you head spacing for?

[dfrosch]

Don't think I would ever be tempted to use a live round. Just too much to worry about.

Have always used headspace gages. Even ordered a set from PTG when delving into wildcat cartridges.

I think the idea is to use a fired case, not a resized or live one(please correct me if I'm wrong). And, the piece of tape simulates a no go gage, not a go.

What gages do you need?

[earl39]

Bad ideal. Now the why. Factory rounds are notorious for being under size. This means if you use such a round and you happen to get a properly sized round the latter will not fit. In other words your head space will be excessively tight and smaller than it needs to be.

[Robinhood]

Most factory ammunition falls somewhere longer than the no go gauge or shorter than the go gauge
If you set it too short, worst case scenario is ammo does not chamber. Frustrating but no one hurt.
If you set it a little too long(<.005), worst case scenario you may have a case head separation. Not good but probably not be a death thing.
If you set it a little too long(>.005), worst case scenario...

Bottom line is if you swapping barrels and you did not get gauges, or you don't have tools to check you case to saami specs in order to use the case as a gauge, you did not plan your project correctly.

If you do decide to use live ammo(no one can stop you), don't rely on the trigger safety. Pull the firing pin out of the bolt. Safety is a religious experience. Practice the highest level at all times.

[Hotolds442]

I personally don't advocate the use of live ammo for any gunsmithing purpose except test firing. Do it right and buy a gauge.

[earl39]

Most factory ammunition falls somewhere longer than the go gauge.
.
Robinhood,

If factory ammo was longer than the go gauge then you would not be able to chamber it.

[223Rem]

The barrel in question is a 6.5 Creedmoor.

I was able to pick up 6 box of Hornady on the cheap (under $15 a box, wish he had more), so cost wise it was a no brainer since new 100 pieces of new brass and bullets would cost more (not including, powder, primers and dies). After the initial firing I will be handloading for this rifle via neck die or slightly bumping the shoulder back with a full length sizer.

If the firing pin is removed, I really do not see a huge problem using live round. Could it possibly be beneficial, since the ammo comes from all the same lot?

As earl39 pointed out, factory ammo is notoriously undersized. With this thinking in mind, using a headspace gauge could inadvertently create excessive headspace with undersized factory ammo.

[Hotolds442]

I guess if you'd be ok with letting a gunsmith set up your rifle for you using brass as a headspacing tool, then you should just do it your way.

[Robinhood]

Robinhood,

If factory ammo was longer than the go gauge then you would not be able to chamber it.
My brain was still booting up. At least I was just prepping brass this morning and not throwing powder. Thanks for pointing that out.

[earl39]

My brain was still booting up. At least I was just prepping brass this morning and not throwing powder. Thanks for pointing that out.

Just one word for that. COFFEE

[RichinVA]

There are those that believe that what you propose is fine. If I was to do this, I would still use a piece of shim on the bolt face, as MOST factory rounds ARE a bit small. Removal of the FP is mandatory, for sure.

FWIW, I don't see anything wrong with either method, IF ​done correctly.

[olddav]

RichinVA defined the problem with your plan with a bold and italic font, IF. I would suggest that you purchase a Go gauge to do the barrel swap IF for no other reason than it will not explode, discharge of create any unpleasant experiences. Good Luck.

[jonbearman]

Listen, a 25.00 gage shouldn't break the bank to install correctly. The problem is even if the case would work, it is so easy to collapse it when tightening the barrel as it always likes to drag tighter as you tighten it. If you use a gage it wont slip. Please don't do it with a case. What caliber is it as I noticed you never said. Maybe one of us has one to rent so to speak.

[clintsrv]

I've headspaced a few with factory cases. All seems to be fine. I removed the projectile and powder to do so though.

Gauges are the best way to headspace and are available for rent thru numerous vendors.