Hello All. I was just posting to share some of my activities over the last couple weeks.
I recently received a new 45-70 barrel from MGM (15 7/8 bull barrel, 1-20 twist, 8 channel fluting with tactical integrated break and 6 hole scope rail). Due to a mixup caused by me sending them a neck-sized dummy round and the person building it thinking it was getting hung up on the bullet rather then the sidewalls of the case, the throat length is very loooonnnnnggg. I am loading the Barns TAC-TX bullet with a OAL of 3.00 inches with the brass ending at the lowest of the 3 grooves (not much bullet in the brass even) and am still ~>0.1" from the lands. In spite of this mixup I was very happy to shoot three 100 yard 3 shot groups measuring from 0.49-0.65 MOA during the first trip to the range with 3 different RL7 loads all at ~2080fps. With the extra case capacity (~0.3" in length) I'm getting a big boost in powder capacity and velocity with the same quickload derived pressure as I was getting with the same bullet set back to fit the factory barrel where the case nearly wrapped around the ogive. I am happy to say that the muzzle break is working very well, and the setup is more pleasant to shoot then the factory contour barrel with fish gill break of similar length.
I again found that RL7 seems to reach a max velocity that doesn't seem increase with larger powder charges. Being a good bit denser, AA1680 had a lower % case fill and gave me a big advantage when I was volume limited. I never reached compressed loads with this OAL, but it did give me an extra ~120fps in velocity over the RL7 and seemed to be a close match to the accuracy.
One of the questions I have is when I mounted this to my blued encore frame, it is is hard to close and open. It appears that the inside of the frame directly above the pivot pin is too narrow and galling the sides of the barrel. This doesn't happen in my other frame, nor does it happen with other barrels in this frame. Has anyone else seen this? I'm tempted to take a dremel to the frame with a rubber buffing wheel or fine sanding wheel, but when it shoots like this I am likely to leave it alone.
Has anyone else had similar experiences with frame on barrel rubbing?