In the early 80's, we hiked around hay fields up in Idaho, my hiking rifle was a Rem 788 in 222. I shot the sierra 50g Blitz with a hot load of H335, crawlers were rare, we killed untold hundreds. My longer range rifles were a 22/250 where I shot a 55g Sierra lead tipped blitz with Win 760 using a Shilen Match barrel with zero freebore. This rifle was good for DRT kills out to 400 in the very least and that was due mainly to the power scope(6.5x20 leupold). Then I went to a custom 6mm Rem with a zero freebore chamber shooting 85g Bbhp and was good to 550, which was about as far as I had to shoot on those farms.
Crawlers are usually due to hits behind the diaphragm.
Our favorite shot was a shoulder shot on a broadside shot.
The standard for a "hunt ready" rifle back in those days was 1" group at 200 using the 222 and 1/2" on all other guns.
Most crawlers are due to bullets that don't expand well or bad hits of course. Today the Sierra Blitz kings are the most explosive bullet on the market and Sierra uses a match quality jacket on this bullet which is explains the slightly higher price. The V max bullets are second in explosiveness. Nosler ballistic tips are very close to a match grade bullet also in 22 and 6mm calibers that I have shot, I have NEVER doubted the ballistic tips ability to shoot .250" groups in many rifles.
I can not stress enough the quality of the sierra blitz king in all weights and sizes, and their explosiveness is unbelievable. I wish that Sierra made a 80g Blitz king and 95g Blitz king in 6mm.
The OP wanted to know about ft/lbs of energy to kill reliably. I think that shot placement is first, bullet expansion qualities is second, ft/lbs a distant third. Many long range heavy for caliber bullets do not expand well at all on chucks.
I tried shooting a custom 17 Mach 4 somewhere around 1986, immediately noticed a lot of crawlers with 25g Bergers going 3800, and the gun shot bug holes at 100 yards. Extremely precise hits were necessary with this case and I limited it's use for shooting in Cattle feed lots where the chucks were eating an enormous amount of cattle feed.
Due to the few crawlers we had with the 6mm 85g BTHP, we went to the Sierra 80g Single shot pistol bullet as soon as it hit the market, holy cow what an accurate bullet and explosive. At 3600 fps, the 80g Sierra would make a full grown rock chuck fly 30 feet at times at 400 yards, 6 Remington.
We are talking about minimal ft/lbs of energy in this thread. To that I would say, always use enough gun. There are guys that hunt in the East that are very concerned about shooting in an area with surrounding neighbors, and NOISE. These guys would be very well served by shooting a 222 with a 40g/50g Blitz king or a 221 Fire ball shooting the 40g blitz king. Know your gun, and know YOUR limitations. Laying on the ground with your neck, back, shoulders hurting does not make for accurate shots. I took a short leg Beach chair to the field when we hiked, spotted while sitting in the chair, then went to the gun to eliminate the neck/shoulder strain, not to mention staying up off the ground where there are all kinds of critters biting on you, briars, thorns, etc.
If you are having a lot of crawlers at yardage, then go to a faster lighter bullet. A 243 Ai using the 70g Nosler at 3850 fps is no slouch load (28" bbl), then the 6 AI with the 70g at 4000(26" 14" twist) has been my experience and 600 was as far as I had to shoot. For shots further than that, I would try for a 22/250 AI, Swift AI, 22/243 Ai, 22/6 AI with the 75g A max and pray for a good lot# of bullets.
I have no experience with the 105g a max on chucks, I hear of success and failure and I would bet that a 243 Size case with this bullet may produce great results depending on the range. Personally, I would want as much speed as I could get with a bullet in this weight with extreme accuracy(6mm Rem AI).
There is a relationship in how far a chuck flies after he has been hit, and how far he is able to crawl afterwards. If you focus on the flying part, the crawling is greatly diminished. Flying chucks does not equal crawling chucks, keep things simple.