Weird issue with .223 reloading

[AnotherNewbie]

Ok,
When I load .308 and 6.5 creedmore I get about a 10 to 15 fps difference in shots but when I shoot .223 I get anywhere from 10 to 75 FPS difference and having a problem figuring it out.
Used my Magneto speed and loaded from bottom of the load to top of the load every .02 tenths of a grain and found with Varget at 23.0 to 23.2 got the same 2680 and still got ranging speeds afterwards when I loaded 50 up.
I load Varget, CCI #400 primer, Lapua brass, Sierra 77 HPBT and about 20 thousands off lands and seems like theirs alot of variance in the speeds ranging in the 2600's compared to the other rifle hand loads.
Got some IMR4895,H4895 and H335 that I'm testing with it now.
I do use a beam scale to verify all charges what am I'm missing or is this a problem with .223 I'm unaware of ?

 

[Milo 2.5]

Gas or bolt gun?

 

[AnotherNewbie]

Its bolt gun that AO set up.
My bad for leaving that out.

 

[Milo 2.5]

Haha, non issue, I'd mess with the charge weight some, try tighten the numbers, neck tension and a seat depth tweak can help, but it will be a better tune if you close the gap with your charge first.

 

[AnotherNewbie]

Found this from Hornaday

 

[918v]

It’s tough to find the optimum load when constrained by case volume. I suggest you abandon Varget and try a powder with higher bulk density where you’ll be able to play with oal to your heart’s content.