Here's the S.A.A.M.I. derived "math" as a "word problem" (followed closely by the math):
Min. "Trim To" Case Length plus Bullet Length equals Unseated Component Length minus Max. Case Length equals S.A.A.M.I. Bullet Seated Depth (embed) in Case.
Take for example my 270 ('cause the data is easy for me to find):
2.530" Min. "Trim To" Case Length
+1.250" Nosler Partition 150 gr. bullet length (+/-)
3.780" Total unseated component length
-3.340" Max. Case Length
0.440" S.A.A.M.I. Bullet Seated Depth (embed) in Case (> 0.277" [one caliber])
You should measure the chamber (face of receiver to lands) by hack sawing a fire formed, neck sized, deburred, chamfered, and unprimed case longitudinally (~1/2"), insert your bullet choice in the chamber - by hand - ahead of this sawn case, and slowly close the rifle on the two. Then carefully extract this "dummy round". DO NOT disturb the two components, now together as one. Measure the COL of this "dummy round" and write that down for posterity. This is your chamber's Specific Max. Cartridge Overall Length (SMCOL and it could be pretty long).
You can't load rounds in your chamber that are longer than your SMCOL. Trying to do so will cause the the bullet to be jammed backward into the case as you close the receiver - making the receiver "difficult" to close and if fired, potentially increasing chamber pressure to an unanticipated extreme.
The bullet is the only component that can move longitudinally between the receiver face, chambered case, and the lands. You don't want to jamb a round in the chamber. That's not advised. You should and most likely will make rounds shorter than SMCOL by seating bullets deeper.
If you substitute your SMCOL in place of Max. Case Length, you will derive the specific minimum bullet seated depth (embed) such that your SMCOL round will touch the lands when chambered. This is your rifle's ZERO JUMP to lands for that specific bullet in your chamber (this may vary for different bullets).
Your minimum bullet seated depth should be "close to" one caliber of embedment. For the (0.308") 30-30 (say not more than minus 10% or 0.030" thirty thousandth) and this is my opinion, a MIMIMUM of 0.278" calculated embedment.
For the single shot rifle shooter trying to find the barrel's "Sweet Spot", after accurizing with a suitable powder (you know the drill), consider modifying the bullet's jump to lands (by increasing bullet embedment) to improve barrel harmonics. Increase bullet embedment increments similar to powder trial increments (say 0.003" at first, then tighten up when a relative minimum is noted) until accuracy is satisfactory.