The .7 dipper that came with the lee loader would be 5.9g of Titegroup or 8.5g of Longshot. Though that is .1 over I remember back before I got my turret and was using Lee dippers that they all tended to be a little low, I'd guess because they decided to err on the side of caution to be safe.
If you have a *reliable* scale, you can easily make a dipper sized to throw exactly the charge you want. Lots of good ideas for those here:
http://castboolits.gunloads.com/showthread.php?297242-Homemade-dippers
Dipper technique is important: press base-first, don't scoop. If you're not already familiar with that, better ask for more clarification.
As ArchA says, science is real, and the numbers in loading data can't be compared unless they are actually shot from the same barrel (and preferably a real revolver, which most published data is *not*...cylinder gap do take a bite). Longshot *might* get you a little more velocity than Unique, but not what you'll get with H110 or AA9. Even 2400 will lag behind those a little.
Of course, get out past 50 yards and the difference will be less than at the muzzle. FP and HP bullets are terrible shapes for supersonic aerodynamics, and the faster they start, the faster they lose speed. But still, faster is faster
OTOH, dead is dead, and if you have the sort of impudent deer that stand there staring at you from 30 yards, I'll bet an XTP 158 will help them along.
But as they say in auto racing, "to finish first, first you must finish." Or "hit" in this case. Shoot up all those 125s at semi-realistic targets scattered around your property and see if you can RELIABLY land the bullet where it needs to be, then adjust your sights for the 158s. You *do* have adjustable sights, right? If not, I would say don't do it!
The other option would be ordering some 180g online and see what loads I can find for those.
I've read people claiming 180 grain XTPs don't expand reliably at handgun velocities. Can't attest to that myself, but I'd say research it first!
If you want a bargain on a slightly heavier bullet, the true Keith 173 grain SWC mold 358429 bullet (plain base, long nose, less lead below the crimp groove; not the completely different deep-seating bevel-base SWC imposter that lots of casters call "Keith") can be ordered from Western Bullet at a lower price than anywhere else, that I've seen. Shipping time is erratic: I've waited anywhere from 1 to 12 weeks to see my bullets, so order early (one order last fall took so long I thought he'd dropped dead!) A full dose of slow powder will get those moving real fast, and no worry about expansion. He claims his alloy is BHN 12, which is softer than some "hardcast" alloys. Hard enough? I don't know.
Darn, he used to sell an NOE 180 gr GCHP, IIRC, but it's gone. Must have sold the mold due to lack of demand.
http://westernbullet.com/3535738caliber.html
Sorry for the drift, but this *is* the handloading section, not "Rifles," so I don't feel too guilty