In general, .30 cal bullets don't seem to have nearly the issue with jacket failures that their smaller diameter .224" cousins experience. That doesn't mean it can't happen, but the rifling twist rates we use with .30 cal bullets are typically nowhere near as fast as in .224" caliber rifles, and the commonly-used .300" diameter .30 cal bore is slightly less tight relative to bullet diameter than is the 0.218" bore often found in .224" barrels. Because both rifling twist rate and friction in the bore are contributing factors to jacket failures, these differences are likely part of the reason why jacket failures seem to be less common with the .30 cal setups.
I'm not exactly clear on what you mean stating that these 125 SMKs have an excellent BC for their weight. Sierra lists the banded G1 BCs for this bullet at .349 @ 2650 fps and above .338 between 2000 and 2650 fps .330 between 1600 and 2000 .310 @ 1600 fps and below. The average G7 BC for the 125 SMK is ~0.179, which is almost 8% lower than a 77 gr SMK 0.224" bullet. I wouldn't really call that an "excellent BC", regardless of its weight.
In this context, it's important to note that it is only rarely possible to ever push a lighter, lower BC bullet fast enough to overcome the BC deficit as compared to a heavier, higher BC bullet. The heavier, higher BC bullet will almost always enjoy lesser wind deflection at realistic load velocities, because you can't normally attain sufficient velocity with the lighter bullet without experiencing over-pressure issues. The one exception to this generalization I have some experience with is the Berger 168 Hybrid bullet, which truly has an exceptionally high BC for its weight class. In that case, it is possible to push the 168 Hybrid fast enough with the right rifle setup to equal or even slightly surpass the wind deflection of the next higher weight class of bullets, i.e. the 185 Juggernaut. The 168 Hybrid is the only bullet I have ever personally loaded that is able to do that.
The conclusion of all this is that if you wish to use the lighter 125 SMK bullet solely to lessen recoil, it should work admirably. However, if the idea is push the 125 SMKs fast enough that they offer wind resistance comparable to bullets in the 155 gr or 168 gr range, I think you will be disappointed. A bullet such as the #2156 155 gr Matchking with a muzzle velocity of only 2650 fps would give very close to half a minute less windage at 400 yd. In addition to the obvious BC deficit as compared to the 155/168 weight class of .30 cal bullets, which are largely boat tail designs, the much lighter 125s have a flat base bullets also shed velocity faster, which also lessens their performance at distances over 300-400 yd. The point I'm trying to get here at is that within distances of only 300 yd or so, the BC of the bullet really shouldn't be the main selling point, anyhow. The bottom line is that if you're wanting to shoot past 300-400 yd, the 155 gr or 168 gr weight class of bullets will do a much better job than the 125s. If recoil mitigation is the primary goal and you only intend to shoot relatively short distances, the 125s should work well for that purpose.
