I always find these types of threads interesting. Everyone looks at things differently, myself I look at the components instead of the loaded rounds.
Leading:
This word shouldn't even be in the conversation. Something a simple as lee liquid lube or my favorite john's paste wax will eliminate leading. I like the jp paste wax, goes on with a cloth/fingers/etc, dries hard & bullets lubed with it can easily be driven 2600fps+ in rifles. You can't drive a bullets lubed in jp paste wax hard enough/fast enough in revolvers/pistols to get leading.
Bullet coatings/jacket
Typically when using the same powder charge/load plated bullets are the slowest, then jacketed. Lead bullets/coated (pc'd) bullets tend to be the fastest. Of the jacketed bullets brass jackets tend to be faster than their copper jacket counterparts. In longer bbl'd firearms bullet make-up/material doesn't matter as much as snub nosed/short bbl'd firearms. +/- 50fps is huge when it comes to a snub nosed 38spl by simply choosing 1 bullet over another.
Bullet design
Most people worry about the nose/shape/hp of the front of the bullet & never give any thought to the base of the bullet. Long bodied bullets like wc's ,bullets with thick/long bottom drive bands & gas checked bullets have higher velocities than their small bottom drive band counterparts. I tested 10 different 150gr to 160gr bullets in a 2" bbl'd snub nosed revolver and there was as much as 70fps difference between bullet's velocity wise using the same loads.
My own testing
A couple years ago I decided to take a hard look at sd loads for a snub nosed 38spl.I decided to do a test to get an idea of the performance of different bullets designs and a general idea/ballpark idea of of the average performance to expect from 150gr to 160gr bullets. I used these 8 bullets in the test along with 2 hollow based bullets (swc & rfn) not shown.
I used 5 powders in the testing, I used 1 load for each powder and those loads were
HOT pushing the limits of top end data
bullseye
be-86
unique
power pistol
2400
I loaded up 5 rounds of each bullet/powder combo. While 5 rounds by itself doesn't prove much, the 250 round test was supposed to give me a general idea of what the snub nosed 38spl can do. At the end of the day these 4 bullets consistently outperformed the other 6 velocity wise. When you see as much as 70fps difference in velocities just by changing bullet's. It a real eye opener!!! These are the 4 bullets that had the highest velocities with every powder.
At the end of the day the fast powder/short bbl thing didn't fly. (bullseye) Never does but I already new this from years of testing loads in a snub nosed 44spl. The unique loads and the be-86 loads were pretty much identical velocity wise averaging 830fps (unique) & 845fps (be-86) over the 10 bullet test. The 2400 load was impressive averaging 880fps and the slower powder gave a push instead of the sharp crack/slap the faster powders produced for recoil. Power pistol averaged just over 900fps and clearly/easily outperformed the bullseye/unique/be-86.
In feb-march 2012 handloader magazine (Brian Pearce) did an article on short bbl'd loads for the 38spl. The handloader article in #276 was trying to duplicate the buffalo bore A20 38spl p+ load that's 1000fps rated in 2" bbl's using the same 158gr rimrock lead gas checked hp bullet. Pearce was able to duplicate the bb load using 6.3gr of power pistol and that rimrock 158gr lead gas checked hp bullet.
What I found interesting in that article was the 5.9gr of power pistol/lyman 358429 bullet load that was getting 946fps. I ended up using that 5.9gr of power pistol load for my snub nosed 38spl P= sd load and paired it with these bullets. I also use the same 170gr bullet for my 357/l-comp sd loads.
On a side note
I use/shoot a lot of these "target bullets" in the 38spl's and 9mm's. Left is a modern version of the himmelwright bullet (130gr) and right is a old cramer "indoor gallery bullet" 115gr. I was plating around with that cramer bullet and p+ loads of unique 1 day at the range. Never pushed that bullet hard before and ended up with 1100fps in a 2" bbl'd snub nosed 38spl using that cramer bullet/unique p+ load combo. That 115gr bullet is well worth testing with 6 or 7 different powders to see what it can really do.