.Are the powder though ptx dies just a flare like lee dies or a expander like the Lyman m or my hornady dies seem to be?
The only one I have seen that is like the M-die profile is 9mm.
If you look at the pictures of them on the net you will see that most of them are a flare profile. Not an M-die profile.
Thought I should add using flat seating stem so not seating off ogive
Are you using round nose bullets with a flat seating profile stem. If you are that's why your OAL's are all over the place.
Something else to. If you are using mixed brass, some like PPU's are really stiff to resize and some like Fed or Win once fired resize like butter. So sorting your brass by headstamp will make a big difference in OAL variances.
I sort my brass per head stamp and if my press starts seating bullets with more than .005" as a max OAL, I start looking for the problem. It hardly ever goes over .005".
A lot of the time it hangs around .002-.003" which I'm very happy with.
If your using mixed brass where some is once fired and some have had been shot many times, your OAL will vary around .005" or more because the brass that has been shot several time has hardened up and is harder to resize.
Make sure the seating stem in the seating die has a profile that matches the bullet your shooting. Round nose or flat nose. Your variance sounds to me like you may be using the wrong seating stem for the bullet your seating.
Also,
If you look at the side of the case where the base of the bullet is seated to you should be able to see a shadow the whole way around the case and see where the base of the bullet stopped.
If the shadow disappears part ways around the case, then the bullets are seated crooked and that also effects the OAL.
I use an M-die on my LNL-AP press exclusively, that really helps with seating round nose bullets straight, with the correct nose profile seating stem. and with flat nose bullets, it's just effortless.
I have the Hornady M-die type profile, PTX for 9mm, and it sticks in my cases so I quit using it unless I'm using my bullet feed die with tubes. With the bullet feeder die I have to use the PTX or leave my powder checking die out and that is one thing I will not do. I think it's NOS that makes PTX inserts for Hornady powder measures and they are supposed to not stick in the case at all. I've not tried to polish my PTX to improve it. That may work, I just don't use the bullet feeder die and Horandy PTX often enough to do it.