Quickload computer program has some data on the temperature that powders burn at and that is the most important part of barrel wear. Second
, coated bullets, I use hexagonal boron nitride (HBN), but Tungsten disulfide and molybdenum disulfide (moly) are in wide use. The Norma site shows a reduction in barrel wear from reduced friction of molybdenum disulfide treated bullets.
Compiled by John Valentine and posted at Benchrest.com on 13 January 2005.
The following text was part of a statement made by Norma on tests carried out on Moly coated bullets. Test was in May 1995.
Firing Norma's standard match ammo ( uncoated) under controlled laboratory conditions, in the 6.5x55 Swedish Mauser accuracy invariably began to fail before 3500 rounds. Direct Quote of Norma technician ," Our experience has shown that accuracy life of these barrels consistently falls within the range of 3000 to 3500 shots". Loss of accuracy always results SOLELY from EROSION in the BORE-THROAT and at the beginning of the rifling.
"Norma has contracted an experienced independent shooter who is also a gunsmith, to conduct a barrel life test using their Moly treated 6.5x55 Match ammo. Test barrel was a Sauer 740mm (29inch). This barrel was a run of the mill sample and was not hand picked. To date ( as of May 1995 that is) this test has exceeded 5000 rounds of Diamond Line Reg. ammunition.
(the projectiles in this Black Diamond ammunition were coated by the NECO reg. system supplied to Norma for the test around 1992). see ref. Precision Shooter . August 1995 page 19. Story by Dave Brennan) There is no target evidence of accuracy loss. Further bore scope inspections performed after each 500 shots by Norma's product development technician Christer Larsson, show MINIMAL EROSION in the throat of the bore and at the start of the rifling.
According to Norma, " Several independent experts examined the barrel ( moly test barrel) after the 5000 shot threshold was reached. Without knowing the barrel's firing history. All estimated ( wrongly) that the barrel had been fired approx 2000 times. The test shooter believes that the barrel still has 20 to 25% capacity remaining. Ref. Precision Shooter December 1995 page 12. Written by M.L. McPherson.
The sole remaining US plant producing any kind of powder is St Marks in Florida. They will make any kind of ball powder you wish to purchase. They recently hosted some folks from Swizerland (NITROCHEMIE
Aschau GmbH has been a part of Rheinmetall since 1998 together with NITROCHEMIE
Wimmis AG under the joint NITROCHEMIE
AG) and made a run of ball powder for Blount (Alliant, Federal, Speer, CCI, Weaver, RCBS) that is 4000MR, 2000MR and some other canister grades. Why did Blount go to Nitrochemie? Because Blount was impressed with the stick powder produced by them and their formula for smokeless powder. Blount imports one canister grade stick powder, Reloader 17, from Switzerland. I commend Blount for pushing the envelope bringing new formulas and products and manufacturing in USA. My point is that there are several formulas for smokeless powder, the oldest is guncotton with the IMR series being the representative. The formulas have more to do with the temperature stability, how hot they burn, than the shape (ball or stick). The Magnum you like is produced in Belgium and imported by Western Powders. I find that Retumbo is more accurate than Magnum with 130 gr Accubonds in the 6.5 WSM (2 soon to be 3 Rifles). I like Vihtavuori N-560 with 130 Accubonds and 120 Ballsitic tips in my 6.5X284. I regularly amaze others in my group with the same velocity with N-560 from the smaller case compared to Retumbo (or Magnum) from the larger case with the same bullets. The VV N-500 series powders burn at a higher temperature and are more damaging than other powders but it will make bullets go faster.
I have sent all of my new barrels in for nitrocarburizing treatment to extend their life and protect.