Re: Vanguard VGX Deluxe ?
It's pretty easy to find your barrel twist. Use a 30cal jag and a good patch (so it will spin with the rifling as you push it through. Put some masking tape on the cleaning rod near the handle, and set things up in a cradle or on a table where the gun won't move. Then Mark (with tape and marker) where the masking taped part of the rod is over the table/cleaning area. Also, place a mark at top-dead-center of the tape on the cleaning rod. Push the rod into the barrel and when the mark comes back to TDC, measure the distance the taped mark on the rod moved versus the marked place on the table/bench. Do this five or six times and see how consistent it is. It might help to use two patches on the jag if it's loose. Once you have a few fairly consistent measurements, you should know what your twist is.
As for the copper barnes bullets, I've shot them and they are good shooters, but they do foul more than gilding metal in every gun I've shot them in. The amount of fouling is variable from one gun to the next, but it's always more than gilding metal jackets. You'll just have to try them and see if you like them. Regarding the MRX hitting like a heavier bullet, that seems to defy the laws of physics a bit. Consider there are two primary measurements that matter with regard to how a bullet "hits" an animal. First, you can take your pick between momentum (mass x velocity) and kinetic energy (mass x velocity squared). I prefer momentum as it gives equal emphasis to mass, and I believe, based on my experiences in the bowhunting realm, that momentum is more important that KE in terms of penetration. Either way, as long as you compare the same value across the board, you'll get a valid comparison. So, if you look at a 180gr bullet, it will have the same energy and momentum at the muzzle, launched at any given velocity. A 210gr bullet will have a higher energy and momentum, if launched at the same velocity. The trick is, one can usually launch a 180gr bullet significantly faster than a 210gr, but that doesn't make a 180 with a silvex core (which is basically a tungsten alloy, if I remember correctly) and different in comparison to the 210 than a traditional lead core or solid copper/gilding metal 180gr bullet.
Taking a different approach to the thought process, I consider the 180gr bullet the ideal weight for the 300Wby, across the board. Use something like an Accubond, E-Tip, GMX, Interbond, Scirocco, Partition, TSX/TTSX/MRX, or the like, and you'll have more than satisfactory results in everything from white-tails to elk, moose, and the like. Is it a little heavy for white-tails? Sure, but it will knock them down with authority, so no worries there. It will also take the larger stuff with excellent results. All this is, of course, pending good shot placement. I recently worked with a 300Wby and my ultimate goal was to find an accurate 180gr bullet/powder combination that was running something like 3200fps at the muzzle. That result was accomplished, and now it's down to pretty much shooting the loads that worked well to see which makes the long-term cut. The fact that my buddy said I can hold on to the rifle until he needs it is just gravy for me...
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