I got out to test Olde Eynsford 1F powder in my second Bridger Hawken copy I made. Shot from bench at 50 yards. Bottom target was with 80 grains of OE 1F and a .530 Hornady ball. Velocity averaged 1410 fps with 48 fps spread. Compared to Goex 2F with 80 grains (weight-corrected measures for all), five different rifles for 29 shots averaged 1544 fps. Top left target was with 100 grains of OE 1F, but I didn't get any more velocities. Right target was with 100 grains of OE 1 1/2F. 40 shots of OE 1 1/2F in 7 groups averaged 1759 in previous testing. In comparison, 40 shots of Goex 2F averaged 1730 fps in 9 tests.
I thought these groups were large until I took a closer look. The sun was on the right, and I didn't have sight shaders. There was some right wind. Four of the OE 1F went into a 2.2 inch spread, and four of the OE 1 1/2F went into a 2.5 inch spread. Still, half of the shots, 7 of14, would have cut a string at 50 yards. I'll repeat this test to get velocities.
In this month's Muzzle Blast Magazine ( September 2022), the Bevel Brothers wrote an article "FG Ballistics". They used an adjustable measure set at the same charge for all powders. In a .50 caliber, 80 grains of Goex 1F gave 1487 fps, and 80 grains of Goex 2F gave 1702 fps. In .45 caliber, 80 grains of Goex 1F gave 1590 fps and 80 grains of Goex 2F gave 1861 fps. In .32 caliber, 30 grains of Goex 1F gave 1328 fps and 30 grains of Goex 2F gave 1676 fps. In a .36 caliber Remington1858 revolver, 22 grains of Goex 1F gave 825 fps and 22 grains of Goex 2F gave 978 fps. They also had an article about Goex 1F powder in the August 2005 copy of MuzzleBlasts Magazine.
Olde Eynsford 1F has very large Kernels, but it is not bulky. It measures very close to OE 1 1/2F, within a grain or two. You can trust your adjustable measure with it.