Local Knoxville area shooting buddy and I sent some 7mm barrels to be nitrided (Melonite process)….his cut-back, rechambered and thoroughly cleaned 7RM (approx 1500 shots) and my 2 new 7RSAUMs (thoroughly cleaned after 25 shots to establish speed/accuracy baselines).
With 4831sc and 180 Berger hybrids, our before treatment loads were in the 2970 fps range.
After treatment, we really, really cleaned the bores before shooting the first time. I started out following Frank Green’s (owner/manager of Bartlein Barrels) suggestion to stroke the bore 100 times with steel wool but chickened out after 60 strokes and switched to many strokes of Iosso paste and JB. The bore did not look like I had touched it. I loaded a nylon bristle brush with steel wool and Iosso, chucked it into my electric drill and honed the chamber full speed for about a minute… with result that chamber was still black, but more shiney.
Early last month we both loaded up our base-line charges and went to the range. Expecting similar speeds as baseline, our first shots were a huge surprise... way over pressure. Had to hammer our bolts open. Cases were trash. My speed was 3108 fps! His was in very high 3000’s. With subsequent shots the first day our speeds dropped about 25 fps, and bolt lift eased somewhat, but we both still trashed about a dozen cases.
After several trips to range and over 300 fire-forming shots, I have now reduced my charge by 3.5 grains to get back to baseline speed. 57.5 grains vs baseline 61.0. My bore is still black but now shows some signs of getting polished by bullet passage and at least 200 more strokes with Iosso and JB paste during several cleanings. Buddy’s results were similar…..and his 1/4 moa accuracy is still there (still working on mine...new brass).
Another area shooter told me last week his new, treated barrel had increased speeds 70 fps after treatment and turned his slow shooter into a fast shooter. His was treated by a different company, so the results do not seem to be related to where the work is done. All our barrels were from different manufacturers.
After thinking about it, the speed increase makes some sense. The melonite process turns the barrel surface into a matte black finish, even on the highly pre-polished barrel exterior. We think the “roughened†finish has, in effect, reduced bore diameter.
The finish is incredibly tough. You can work up a sweat trying to polish the matte surface by hand, and get nowhere. In other words, trying to re-polish the exterior to a shiney black by hand might take many days….I won’t try….matte looks good.
Frank B
With 4831sc and 180 Berger hybrids, our before treatment loads were in the 2970 fps range.
After treatment, we really, really cleaned the bores before shooting the first time. I started out following Frank Green’s (owner/manager of Bartlein Barrels) suggestion to stroke the bore 100 times with steel wool but chickened out after 60 strokes and switched to many strokes of Iosso paste and JB. The bore did not look like I had touched it. I loaded a nylon bristle brush with steel wool and Iosso, chucked it into my electric drill and honed the chamber full speed for about a minute… with result that chamber was still black, but more shiney.
Early last month we both loaded up our base-line charges and went to the range. Expecting similar speeds as baseline, our first shots were a huge surprise... way over pressure. Had to hammer our bolts open. Cases were trash. My speed was 3108 fps! His was in very high 3000’s. With subsequent shots the first day our speeds dropped about 25 fps, and bolt lift eased somewhat, but we both still trashed about a dozen cases.
After several trips to range and over 300 fire-forming shots, I have now reduced my charge by 3.5 grains to get back to baseline speed. 57.5 grains vs baseline 61.0. My bore is still black but now shows some signs of getting polished by bullet passage and at least 200 more strokes with Iosso and JB paste during several cleanings. Buddy’s results were similar…..and his 1/4 moa accuracy is still there (still working on mine...new brass).
Another area shooter told me last week his new, treated barrel had increased speeds 70 fps after treatment and turned his slow shooter into a fast shooter. His was treated by a different company, so the results do not seem to be related to where the work is done. All our barrels were from different manufacturers.
After thinking about it, the speed increase makes some sense. The melonite process turns the barrel surface into a matte black finish, even on the highly pre-polished barrel exterior. We think the “roughened†finish has, in effect, reduced bore diameter.
The finish is incredibly tough. You can work up a sweat trying to polish the matte surface by hand, and get nowhere. In other words, trying to re-polish the exterior to a shiney black by hand might take many days….I won’t try….matte looks good.
Frank B
