OAL for .30-06. How short is too short?

Hello folks,
Years back I bought a used RCBS "rock crusher". It sat in a box until I went to buy .30-06, and they wanted $50 a box for it!
I'm now geared up to reload .30-06. I cast and gas checked some Lee 170gr flat points. They are sized. A friend sold me a couple hundred primed, once fired cases. I'm using an RCBS die and shell holder. My Lyman manual says, for a very similar projectile (same weight/shape but lyman rather than lee) 2.968" is listed as the overall length.

I made 20 rounds, starting with a dummy round. Unfortunately, I didn't check after I tightened the locking screw, and just went ahead. I don't know how short my rounds are ran out of time before I could measure them, but I would guess about 0.5mm. I'm using a decent caliper, my rounds are all consistent, but just short. I tried them, and they appear to chamber in the rifle just fine (as I would have expected--they are too short, not too long).

Is there a safety issue with firing slightly too short ammo? The case isn't even close to full (21gr 2400 powder), so there is no compression going on. I'm at 21gr 2400--Lyman lists it from 20-27gr. So I am way on the bottom of the pressure scale.

I just don't want to mess up the chamber in my rifle, or do anything that could be potentially dangerous.
It was a dumb, newbie mistake. I made the dummy that was up to the correct length, but tightening the locking ring must have dropped the die just a hair more than intended. Won't make that mistake again!
Thanks for any info.

Your fine. As you know reducing case volume does increase pressure but in your case you are so low pressure you are well under max pressure.

Couldn’t tell you how long mine are, but I seat to the crimp groove with that boolit in 30-06. 21 grains of 2400 shoots very well with that combo, near MOA, sometimes under, and has put a lot of deer meat in the freezer. But, don’t be afraid to drop down a few grains if needed if you don’t find accuracy. I wouldn’t go any higher, assuming a 1-10” twist.

There has been debate on whether or not it was a good idea to seat gas checked boolits, with the GC below the neck of bottle neck cases. Are you getting into that territory? If not, you should be fine.