The concept you've touched on is not a new subject. I've shot a number of deer as well with the 125-130gr reduced loads in a .30/06. Within the parameters of your topic, there is essentially no difference in the .30/06 and .308.
I've used the Sierra 125gr Soft Pt. and the Nosler 125gr B.T. in the last 15yrs or so, and they are even better than you've hoped for.
If sighted in 3" high at 100yds, at a m.v. of 2,700fps, you are zero'd at about 250yds and down only 5" or so at 300yds. So, you're actually good to around 300yds, not just 200yds. More than adequate for putting down whitetails with lung shots.
I have not actually recovered a .30cal bullet launched at this speed from a deer as penetration and expansion closely matches that of the 150-165gr bullets launched at this approximate speed so, bullet performance shouldn't be a consideration.
I shot a lot of the Speer 130gr HP's from a Rem 788 in .30/30 at about 2,500-2,600fps back in the early 70's while still in high school. I got very good results with it too.
A side benefit of the loading you've discussed is that they are usually EXCEPTIONALLY ACCURATE !!!
My older brother has shot a good bit of NRA Highpower, along with considerable long range rifle competition in the Airforce, specifically with the M-16. Back about 1991-92, he shot the Montana state championship NRA highpower match. He used his M-1 Nat. Match with the Sierra 125gr Soft Pt. over the same charge of IMR4064 that he used with the 168gr BTSP. He used the 125gr for the rapid fire stage. He won the rapid fire stage and took 3rd overall. Not bad for a "Marksman" class shooter!!! (Got booted up to "expert" for his performance).
He comments that the 125gr load from his M-1 shot/shoots just like the M855 ball from the M-16's that he shot on the Airforce teams. Soft kicking and quite accurate !!!
For the .308, (I had one that I traded the m788 mentioned above for!), I used IMR4064 as well, 44.0gr if my memory serves me well, with the Sierra 125gr s.pt. at ~2,700fps. It was wonderfully accurate (about the same as with 168gr bt match). According to my ancient Sierra loading manual, this should net you about 2,700fps from a 22" bbl. The "book" says 43.6gr will give 2,800fps from a 26" bbl.
Now days, I would probably use the Remington 125gr Cor-lokt, which are about 65% of the cost of the Sierra's, and are more than accurate enough for shooting Whitetails. I saw them from MidwayUSA.com for about $8.50/100 recently. They are even cheaper by larger quantities. (ie: 500 or 1,000)
BTW; Remington is using that bullet to load their "Managed Recoil" loads for .308 and .30/06.
Exactly what you were thinking about !!!
Power isn't actually absent at this level. My younger brother uses a .308 (pre-64 M-70 featherweight) with the Nosler 150gr Part. loaded to a chronographed 2,900fps. He has shot 4 elk to date, and not yet recovered a bullet.
If this works for a 400-600lb elk, the 125gr at 2,700 is still way,way, more than enough for "Bambi".
