Thought I would share my findings after treating my barrel with GJ. I would like to thank "Phorwath & MontanaRifleman" for their help and insight on this endeaver.
Microlon has come out with a new method for treating a barrel. I modified the procedure a little but the end results were the same. The rifle I treated is a 338 Lapua Improved. Lilja 30" fluted, 1-10 twist with a #8 contour. I broke the barrel in 1st and after 35 rounds down the tube i started the GJ treatment.
I stripped the rifle down to barreled action. I used a rifle cradle to hold the barrel. The barrel was heated to 120-150 degrees using a Snapon heat gun. I used a IR lazer to monitor the heat. Once the barrel reached the desired temp I ran a wet patch of GJ down the bore. I followed up with a wet nylon brush to scrub the GJ into the barrel. I did this two times and kept the heat to it during the entire procedure. Next I started running 1 wet patch through the bore. I waited for each run of the patch to completely dry the GJ in the bore. I repeated this procedure 12 times. GJ instructions called for 8-10 times. I figured a couple more could not hurt.
I also used a Lucas Bore Guide during this entire procedure. Did not want to get any GJ in my chamber. While I was doing the barrel I also treated my Lugs on the bolt and raceways on the Stiller TAC-338 action. I heated the action and the bolt and treated one time.
There was a noticable difference in smoothness when working the bolt with GJ treatment.
Onto the testing. I had chronoed my non-fireformed cases days earlier. At 99gns Retumbo my muzzle velocity averages 2,867 fps over a 5 shot string. It was reccomended by Microlon to back off a little on loads after treating barrel. I loaded 3 rounds at 98gns and noticed a 50fps increase over the last time I had shot at that charge weight.
My next step was to shoot the 15 rounds i had loaded at 99gns. I shot all 15 rounds and let the barrel cool between shots. My Oehler 35P gave me an average increase in velocity of 39fps, velocity was 2,906fps.
Now remember that this was using Virgin 338 Lapua brass that was not fireformed.
Earlier testing with fireformed brass I was getting 2,980fps with 102gns of Retumbo, 300gn Sierra's, .030 off the lands. This was the max load for this rifle before GJ.
I am waiting on Neil Jones custom dies to reload the fireformed brass and see what velocity I can get with the GJ treatment. I think I will be close or a little over 3000fps with max loads. However, I suspect my accuracy load will be under 3000fps. More testing will tell.
I am not very good at all this but hope you guys enjoy