What .45 ACP powder to look for ???

[da gimp]

if you're using Bullseye...... be very, very careful that you do not double or triple charge your cases...........you can reach the maximum load of Bullseye with very high pressures, using just the slightest amount of Bullseye.........you can easily double charge your cases & with some calibres, even triple charge a case & not have the powder overflow the cases.......we only loaded Bullseye when using a single stage press, & charged the cases with our old RCBS powder thrower.....then using the Mark 1 eyeball to insure every case in the RCBS plastic loading block had the same amount of powder in it.....I'd be too afraid to use Bullseye powder when we're using our Dillon 550 to reload.

[Former Cav]

that is also true when loading 45 ACP with Win 231 or Unique, or Tightgroup.
buy this light and then you can use your dillon 550
https://www.storesonline.com/site/696296/product/T1429
I've been using a piano light and I finally bought one of these. (haven't got it yet)
but I LOOK at each round in station 2 for powder level before I index.
you can NEVER be "too safe"

[da gimp]

with our loads of Unique. it is impossible to double or triple charge a .45ACP,.38spec, .357mag, 9mmpara.......... you can easily do so with bullseye....... I've never used/bought Tightgroup.........and still have yet to open a jug of Win 231.........might as well use up the opened Unique & other opened powders first. Like you. we depend on the Mark I Eyeball sensor to check every case's powder level at station III of our Dillon 550.........before the bullet gets put on the case...... We always use 2 people to reload on the 550.......... safety first........... & a third refills primer tubes...........one person putting in the case at station 1 & pulling the handle..... and indexing the plate, the 2nd eyeballs powder level & puts on the bullet.......... you can turn out a very large quantity of premium reloads in an hour doing it this way..............

[Rick the Librarian]

I admit, at the gunshop I've started to frequent, I did see IMR4895, which I haven't seen for some time.

[Former Cav]

Natchez had a bunch of IMR 4895 at a good rate last week.

[bdm]

I have always used 231 purchased a fair amount years ago still using it