04-26-2018, 02:59 PM
Stone, I have 2 McGowen 6mm Grendel barrels both 20", 1 mid wt and the other is a heavy barrel .875 at the gas block. I ordered the heavy last fall when the ran the Halloween special, I've ran enough rounds through it for break in using the 105 RDF with good results so far. I'm assuming they used the same reamer for my barrel as yours which I'm finding was designed to work well with mag length rounds.
I get 2.275 Oal touching the lands 105 RDF. I'm using a Sinclair seating depth gauge to measure.
So far I've tried with this barrel XBR, CFE and RL15, all velocities around 2,500 fps for break in. RL15 showing the best results. I have Quick Load which says this bullet wt in a 20" barrel starts to max out around or blw 2,700 fps. I tend to trust QL as you can customize the BA to match the velocities you are actually getting and double check the results.
Today I'm starting serious load development using the 105 RDF and RL15 as I have half a box left. I have charges all the way up to 28.5 with a .015" jump, Hornady brass 7 1/2 primer.
I get 2.275 Oal touching the lands 105 RDF. I'm using a Sinclair seating depth gauge to measure.
So far I've tried with this barrel XBR, CFE and RL15, all velocities around 2,500 fps for break in. RL15 showing the best results. I have Quick Load which says this bullet wt in a 20" barrel starts to max out around or blw 2,700 fps. I tend to trust QL as you can customize the BA to match the velocities you are actually getting and double check the results.
Today I'm starting serious load development using the 105 RDF and RL15 as I have half a box left. I have charges all the way up to 28.5 with a .015" jump, Hornady brass 7 1/2 primer.