Drop-In Case Gage Substituion Question

[Bayou52]

Hi, Guys -

I load for several rifle cals, including 30-06. I use a drop in headspace and case length gage for each rifle calibler to assure the sizing die sets the shoulder within specs. Like this one:

http://www.midwayusa.com/product/270484/lyman-case-length-headspace-gage-30-06-springfield

I check each and every resized casing with the drop-in gage before charging it.

I do not currently load for 270 Win, but I may start loading for this caliber soon. I will need a drop-in case gage for this caliber before I start loading for it.

Question - will the 30-06 drop in headspace and case length gage work for the 270? I thought I read that the 270 case is a necked down 30-06 casing. I'm not interested in the case length part of the gage since I use calipers to measure each one for trimming. I'm interested in the headspace part of the gage - determing if the shoulder is set correctly.

Any ideas/comments?

Thanks, All -

Bayou52

[mdi]

I'd check the SAAMI drawings of both cartridges and compare the measurements of the datum to case head and compare. If they are the same (shoulder point to case head), then give it a try...

[Bayou52]

I'd check the SAAMI drawings of both cartridges and compare the measurements of the datum to case head and compare. If they are the same (shoulder point to case head), then give it a try...

Thanks -

The SAAMI drawings for both cases/cartridges have the same measurement from the datum to the case head, that is, 2.0526". The datum line also starts where the case shoulder tapers down to 0.375" for SAAMI in both cartridges. So, these measurements appear to be identical for both cases.

So, it may be worth giving it go ahead try-out before buying a 270 case gage that might not be necessary. I'll try the 30-06 drop in gage on a factory 270 cartridge to see how it settles in.

Thanks,

Bayou52

[EDG]

Yes it will work
There are no differences other than the diameter of the neck and length of the neck.

[Bayou52]

Yes it will work
There is are differences other than the diameter of the neck and length of the neck.

Thanks, EDG -

Bayou52

[lead-1]

I was a little skeptical so I had to check for myself, here is a factory loaded Winchester Super-X .270 round in a .30-06 case gauge. It fit just as pretty as Christmas, as flush as if made for it.
Of course the neck/bullet protruded out the other end a tad bit but the shoulder and rim was spot on.

[Bayou52]

Thanks,lead-1 -

Your pic confitms our conclusion that the 30-06 drop in gage will accurately measure shoulder set-back for the 270 Win brass. The SAAMI measurements from shoulder edge to datum are the same for both as well as the distance from datum to case head.

You helped me save $25....for a gage I won't be needing after all.....

Thanks, and good pic!

Bayou52

[jsizemore]

I bought mine when it was still owned by Stoney Point, the Lock-n-Load headspace kit with body in conjunction with SAAMI specs will get you there for about every bottleneck case out there. The plus is you can adjust your dies to "bump" the shoulder a couple thousandths for once fired from a particular gun your loading for. Just add your own calipers. I also use their bullet comparator for seating bullets instead of OAL.

[lead-1]

Not a problem, and I learned something new also.

[hd09]

Never thought of this, good info. I tried it with my 30-06 Moe's gauge and it does work.

[Bayou52]

Never thought of this, good info. I tried it with my 30-06 Moe's gauge and it does work.

I know that I've never seen this info anywhere else. Hope it benefits others, too.

Bayou52