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Old June 10, 2010, 09:49 AM   #18
dksac2
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Join Date: May 17, 2010
Posts: 62
QUOTE from Nnobby45
The RCBS Mic gage is very good, because it measures the difference between a fired case (perfect head space), and your sized cases. I find that .002 sometimes gives me a little too much "feel" when I close the bolt. .003 is about right. Because brass is elastic, not all of it gets sized (or stays sized) the same amount. You need to allow for that when you size. Hunting ammo, little or no feel. Varmint, target, it's up to you. My experience is with bolt action rifles.
Yesterday 04:27 PM

End Quote

I agree with your post on bolt rifles.
For precision target type shooting, you want the headspace on the tighter side, on a hunting rifle, especially when hunting big game, a litle more headspace is a good thing.

Just be sure that you check the FP protrusion when going to a little more headspace.
It's never a bad idea to buy a set of HS guages for the calibers that you have or want to buy, especially when buying a weapon at a gun show or used.
As a retired gunsmith, I've seen too many blown up rifles from excessive headspace, some resulting in some pretty bad injuries.
I know that HS guages are not cheap, but can be sold without too much loss later.
Buy the same brand when getting go and no go.
Check E Bay, sometimes you can find some deals.

If it's just one rifle and you don't plan on ever buying more in that caliber, sometimes it's cheaper to just take it to a gunsmith.
Also, on some calibers, headspace guages work on more than one caliber, so check before buying for a spicific caliber.
Belted magnums take the same size HS guage. Except the .240 Weatherby Mag which is a different case size.
Most belted mags are based on the .375 H&H mag case. If not, it will need the correct guage to get the right reading.

If you can only afford one HS guage, get the NO GO. A new loaded round will close with a NO GO on a new unfired round.
You can always find out the difference in thousanths betwen the GO and NO GO and carry shims that are just a little over the difference in total length between the GO and No GO, put the shim pack on top of the NO GO guage. If the bolt closes on it, the headspace is too tight.
Go very easy on the bolt if trying this and be sure the rifle is pointed in a safe direction so that if it goes off, the round will not hit any one or fly into the air or take out your big screen TV, best to have the rifle pointed at the ground. Strip the bolt of the extractor, FP and ejector.
If the stripped bolt closes on a NO GO go, you know the HS is excessive, don't fire the weapon without geting it checked out by a qualified gunsmith.

I always checked with both guages just to cover my rear end.
When checking HS, always strip the bolt first and make sure that the chamber is clean.
On a weapon like a Mini 14, M1, AR, REM Browning, Win or others with a bolt that is not operated by a bolt handle (usually gas operated bolt), strip the gun and bolt. If the bolt fully closes on a NO GO, it has excessive HS and is unsafe to fire. Put the stripped bolt only into the weapon with the No Go HS guage. If the bolt won't fully close, then it's OK, again, clean the chamber first.

On a weapon like a semi auto Rem, Win or Browning that has a bolt that locks into spireled lugs, check the lugs for wear, you can feel them with your finger, just don't let the bolt snap closed on your finger, it really smarts. Ridges on the lugs in the receiver that are worn away or that you can feel groves in can mean an unsafe weapon or at least one that is starting to get some bad wear on it.

If if the locking ridges are worn away, and I have seen this more than once. Do not fire a weapon in that condition, have it checked by a gunsmith. People will try to unload these at gun shows, they are unafe.
Stripping the bolt or bolt and weapon is a pain in the butt, but it's the only way to get a true reading.

Never push down hard on a bolt when checking headspace. One finger without a lot of pressure should be all that is needed.
The camming action of a bolt gun is really strong, and if you force the bolt closed on a NO GO and the heaspace is ok, you can hurt the weapon.

Older weapons where the bolt almost fully closes tend to indicate that the headspace is getting near the max to for getting good accuracy and I would not fire hot loads in them. This may be OK on a big game rifle, but for most uses, it shows that you may have to re barrel for maximum accuracy. It is safe to fire as long as the bolt does not close.

There are field guages which show the max headspace. I don't like to shoot a weapon that will close on a NO GO, but won't on a field guage, especially if it almost closed on that guage.

On any semi auto that the bolt is hard to get to, so that you can check the headspace, put a mark on the bolt that exactly extends to the receiver and lines up perfect (you don't have to scratch it, just make sure it does not come off easy), then strip the bolt, clean the chamber , put the NO GO headspace guage into the weapon's chamber and re assemble except for the parts taken off the bolt (extractor, ejector and FP).
Re assemble the weapon, being careful not to erase the mark you put on it.
If the mark on the bolt is back to the rear from the mark on the receiver, your head space is ok. If the mark is still even, there is a excessive headspace, take the weaon to a good gunsnith to be checked.

Be sure to check and clean any bores on new, used and especially mil surp weapons before firing.
Sorry for the long post, many of you know this, but the newer shooters may not, and safety was always number 1 with me.

Best Regards, John K

Last edited by dksac2; June 10, 2010 at 10:27 AM.
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