I spent over an hour writing a lengthy piece on this, a couple days ago, and lost it somehow when trying to post! Will be a bit more brief this time.
First of importance, the concept doesn't work in rifles and isn't practical in autoloaders. Both need to have bullets seated close to the rifling.
The concept works well in revolvers if the bullet being used can be seated deeper without bulging the cases so much they won't chamber, and if a suitable crimp can be applied to prevent bullets from pulling. Normally over the ogive, or SWC shoulder works fine.
Use the slowest powders or bullet jump at high velocity will cause stripping on the rifling which can degrade accuracy before the desired velocity is reached. Also, start loading with greatly reduced loads, because pressures climb quick when bullets are seated deeper, which is what gives the ecomomy. More pressure with a given charge, higher effeciency, velocity wise.
Gas checked bullets will allow higher velocities than PB, and heavy bearing bullets will perform best. No bullet design made will give as high an increase in velocity as our WFN's, because their bearing length is longer than any other bullets of similar weights. Also, they tend to have very heavy drive bands up front, which helps minimize stripping when the bullet hits riflig.
If you are understanding what I've written above, the two important factors to watch out for are. 1. Reaching max pressure far sooner, ie with lower powder charge weight. and 2. Accuracy loss from bullets stripping the rifling engagement at lower velocities than when bullets are seated out.
You will find that LBT bullet lubes will allow higher velocities and produce better accuracy than any other lube because our lubes control friction better.
Some brands of primers are the same price, whether magnum or standard, while some are listed for both magnum and standard uses. Magnum primers will tend to ignight powders a bit quicker, which increases efficiency, or velocity per grain of powder. If you have a selection of primers, try them all to see what gives you the most speed per $$$.
Heavier bullets work better than light ones, due to their long bearing length, which holds the rifling best, and when using bullets designed for gas checks, heavy bullets are much more likely to perform well without checks applied. Leaving checks off can save more money than the powder savings.
Fire any questions you have on this issue. I've probably done more experimenting with the concept than anyone else on earth, because the most delightful advantage of this concept is a dramatic reduction in muzzle blast, which I really like for hunting loads. This because I am NOT going to wear ear protection when in the woods. Therefore most of my experimenting with deep seating has been with gas checked bullets and relitively fast powders worked at maximum pressure. Cost of the loads not being of any concern, but noise reduction only. I'd gladly pay 4 times the cost for a load that has enough power to kill what I'm hunting without hurting my ears than to save some money and damage my hearing. If you ever talk to me on the phone you'll understand why I cherish what hearing I have left!
My two most successful revolver loads were. 10 grains of Unique behind a 240 gr WLN, plainbase, in 38 brass, for 357 mag use. Very quiet, and deadly. Pressures are at mag level, velocity 1100 fps, and accuracy good enough for chipmunks out to 50 yards. The second and favorite is 10 gr of Universal behind a 170 gr XS, in 38 special brass. Again velocity is 1100 fps, the kill punch is awsome considering the low velocity, due to the large meplat, accuracy good enough to hit motor oil bottles regularly at 100 yards, shooting offhand, and the report very mild, with no ear misery after a cylinderful without muffs. A bright spot with this load is no fire when shooting in very low light. Just a few sparks visable, which don't dim eyssight at all. This last trait is a Universal powder attribute. It's the cleanest burning, lowest smoke and flash powder I've ever used.
Fire any questions you have on this issue. I've probably done more experimenting with the concept than anyone else on earth, because the most delightful advantage of this concept is a dramatic reduction in muzzle blast, which I really like for hunting loads. This because I am NOT going to wear ear protection when in the woods. Therefore most of my experimenting with deep seating has been with gas checked bullets and relitively fast powders worked at maximum pressure. Cost of the loads not being of any concern, but noise reduction only. I'd gladly pay 4 times the cost for a load that has enough power to kill what I'm hunting without hurting my ears than to save some money and damage my hearing. If you ever talk to me on the phone you'll understand why I cherish what hearing I have left!