Thread: 303 headspace gauge

A simpler way is to just shoot it, and if you don't get a case head separation, then its fine. I could count the .303's that have matching bolts I have seen on one hand.
Once you've shot all your ammo, then just neck size that brass after that.

thanks carlsen highway, getting my mitts on some gauges seems to be difficult, workshop inovation are waiting for new stock to arrive so got a blank there.
the rifle is a as issued long branch no 4 mk1* matching numbers on all parts and I had to clean the cosmoline off it, so as you say it should be fine to shoot it.
cheers everyone
Ray

Originally Posted by Carlsen Highway

A simpler way is to just shoot it, and if you don't get a case head separation, then its fine. I could count the .303's that have matching bolts I have seen on one hand.
Once you've shot all your ammo, then just neck size that brass after that.

You have just stated a classic about the 303's. Most worry about headspace but its nowhere near as big an issue as it seems to be.
I thought I had the dimensions written down or saved somewhere as I was going to make some coin style ones but forgot about it. Not on a lathe in the new job so that aint gonna happen.
This has some info in there and the dimensions seem to pop up frequently so I would suggest are right although 70" seems to pop up as a field gauge dimension also. better descriptions in the link below
https://www.enfield-rifles.com/deter...topic8001.html

GO = 0.064" NO-GO = 0.067" FIELD = 0.074".

Originally Posted by Carlsen Highway

A simpler way is to just shoot it, and if you don't get a case head separation, then its fine. I could count the .303's that have matching bolts I have seen on one hand.
Once you've shot all your ammo, then just neck size that brass after that.

Yes, and if I may add, if you don't have a neck sizer, you can just partially size / shoulder bump.

The .303 has quite sloping/forgiving shoulders due to the old way of making them, a bundle of Cordite (cf my avatar picture) inserted in a straight walled case, and only after that given the bottleneck crimping. Shoulder bumping has most of the advantages of neck sizing, but additionally ensures they feed well (both for if out in the woods and a bit of dirt gets in, but also if you have different rifles). Bump it back just far enough so it will chamber nicely in any of your LE's. Being rimmed cartridges, they headspace on the rim and not on the shoulders anyway, a useful feature for a battle rifle as it allows generous chamber tolerances.

If just for the range and for a single rifle, neck size only.