I purchased two of the 7/8th plugs from Metrics Unlimited. After a couple alterations, I went to the range today. I shoot triple7 fffg loose and a 250 grain lead bullet I mold myself and a triple 7 primer. I am using the #60 rings from Lowes. Anyway I had been shooting between 90 and 100 grains before I switched plugs. I used the 25 acp plug from precision. The two times I took the gun to try the plug, I shot 100 grains and it sure seemed a lot hotter and harder on the shoullder. Today, I dropped back to 85 grains and gavr it a try. The plug worked flawlessly with great ignition and absolutely no blow back. At 85 grains, the gun sot as accurately as it did at 100. 75 yards it will place them in a 1 inc box on my targets all day. I swab between each shot at the range. Now I am looking forward to deer season. Great product and economic as I am saving powder with every shot. I shot 15 times without removing the pug. When I was done, it spun right out with no problems.
