I am by no means an expert in bullet design or ML's. However I have shot at least 2000 0.451" all copper Barnes ML-bullets both the 290 grain boat tailed TMZ's, 245 grain boat tailed Spitfires and newer 290 and 250 grain flat based based T-MZ's out of my savage 10ML-II alone, and at least 500 Barnes 0.458" Original semi-spitzer cup and core bullets, an additional 200-250 Hornady 325 grain 0.458" FTX bullets. Add another 100+ Hornady .0458" 250 grain all copper Monoflex and a 100-110 mixed Remington and Hornady SJHP 0.458" bullets. I used both Harvester smooth black sabots and Harvester Black crushed Rib sabots. I achieved my best results with Harvester Black Crush Rib sabots with all 0.458" bullets.
Add in how many bullets and sabots my sons and I have shot out of our three Knight Elites and T/C Encore and that number go's up considerably
What I learned was without exception if you are using sub caliber bullets and sabots the larger 0.458" bullets shoot measurably more consistently and accurately than the 0.451/.452" bullets due to all having flat bases and longer bearing surfaces. I found by varying my sabot thickness (I use Harvester and only harvester sabots) along with knurling my bullets between two files to enlarge their OD, to get as tight a fit as I could achieve while loading, by tight I mean needing both hands to run the sabot/bullet combination down the bore and seat it on the powder charge I got excellent and consistent results.
I also learned the longer the bearing surface of a bullet has more accurate but especially more consistent it will be. My flat based Barnes all copper ML bullets definitely shoot better than my BT ones because the the flat based bullets have more bearing surface. Harvester does produce sabots specifically designed for and only to be used exclusively with Barnes all copper boat tail ML bullets' and they did improve both accuracy and consistency, but especially consistency. The sabots Barnes supplies with their all copper ML bullets are not quite a thick as the ones Harvester sell at least not per what my ML's bores tell me when I load them.
This fact becomes even more vital the faster you push the bullet. My 10ML-II pushes a 290/300/325 grain bullet at 2350-2400 FPS/MV and a 245/250 grain bullet at 2550-2650 FPS/MV depending on how much H4198 or RL10x I use.
My advice is if your .50 caliber inline ML is having difficulty achieving and maintaining consistent shot to shot accuracy try some 0.458" bullets and Harvester Black Crush Ribbed sabots. If you can find them Hornady 0.458" cup and core 325 grain FTX or 300 grain Interlock, or their all copper 250 grain tipped Monoflex bullets. I own and have shot all three all shot very well out of my 10ML-II and my Encore.
It is also worth mentioning the Barnes Expander MZ standard NON-tipped exposed hallow point all copper ML bullet has a very long bearing surface and a well earned reputation of opening reliably at slower non-smokeless ML speeds.
As far as knurling bullets go's it can ONLY be done if you are using sabots that completely encapsulate the bullets as if any of the knurling contacts your barrels riffling it will ruin your bore.
I have shot close to 2000 knurled bullets out of my 10ML-II alone and many many out of my other non-smokeless inlines and never had a single issue so for me it has been 100% safe, but to use knurled bullets in your sabots one must be made aware of the potential hazards all be it extraordinary small they pose to your bore. Knurling also insures 100% your bullet will "lock contact" with the sabot and spin at the same RPM along with the sabot as sometimes a sabot will not have sufficient grip on a bullet and it will not spin with or spin more slowly than the sabot as it travels down your bore.
In my experiences unless shooting a inline that was designed for and can safely use smokeless powder that can push all copper bullets' fast enough to open reliably, I would stick with standard lead core and copper ML bullets.
Just my 0.2c worth.
hammerbullets.com
