My Winchester Palma Trophy Match M70 put 15,000 rounds of 147gr. HB through it's tube and smoothed out close to 8" of the breech of the barrel. At that time in 1989, I entered the World Police & Fire Games with that rifle, 168gr. MKs with 41.5gr. IMR4895, CCIBR2's and was on the winning team for a prone 200 yard match and we placed a record score that stands today (the other guys were good shots-LOL). The barrel was still shooting sub 1" prone with 168's at 100 yards with metallic sights. Later I was able to test 180's and it went 1/2" for 10 shots, prone at our local 100 meter range.

So, good luck wearing out that barrel, tinker.

I cut 5" off the bl., threaded and rechambered it for a shortened (1.6") .303 British, necked to .30 cal.,(thought I'd come up with that wildcat - wrong) and that one also shoots into sub 1/2" at 100 yards but with 130's and 125's.
The rifling is just a memory - swirling dark marks in the steel ahead of the chamber for a couple inches.

Incidentally, the shortened .303 at 1.6" is also called the .303 Pygmy in Ausieland. I used the top 1.5" of a .30/06 reamer, so shortened .35 Rem brass works in a Mauser with standard bolt face. Magnum bolt works with .303 Brit. brass. Ran the reamer in 1 1/2", then with the 1/10" for distance between the bolt face and end of the chamber, gives a 1.6" case, headspacing on the shoulder, which I prefer.

A .30/06 RCBS FL die, shortened 1", is the form die. One pass, done, trim to a .441" length of neck, 1.6" case - outside turn or inside ream and done.

Duplicates the .30BR using cheap .303 brass. 3,000fps with 125's, for gophers or target, AND - 2,465fpr with 165gr. Sierra HP Gamekings. What a terrific deer round for out to 300yards.

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Daryl