KP1 Accuracy problems

Re: KP1 Accuracy problems

Postby starbuck » February 19th, 2014, 2:41 pm

After a lot of shooting with a variety of different muzzleloaders, Its been my experience that the bullet you shoot is not near as critical to accuracy, to a certain extent, as the sabot you use or the charge of powder you load. I first noticed this phenomenon in a Remington 700ML that I owned for a long time. The XTP Hornady that came prepackaged with a black sabot, which required a tremendous amount of force to load, would have all it could do to keep a 10" group at 100yds; the same exact bullet in the green sabots included with some Hornady offerings, which still required a lot of force to load - but less than the black sabot, yielded 3-5" groups; and when the red EZ load sabots came out, which required about 40 pounds pressure to load, the exact same XTP bullets were near touching.

I've found a lot of variation in the diameter of the sabot included in the prepackaged bullet-sabot combinations I've tested, which might offer some insight into why certain bullets have great accuracy while other brands shot from the same gun aren't consistent at all. Research on the internet confirms that different manufactures are known to have different diameter bores; TC, for example, is known to have tight or smaller bores - my own experience with three TC guns supports this. Further complicating things is the fact that each barrel, even if it is on the same model offered by the same manufacturer, can have slightly different bore diameters. This can be a result of different causatives: For some manufacturers the barrels are outsourced to the lowest bidder, so each run of guns they build might have a different brand of barrel on them. In other cases, as tooling gets older and warn, the tolerances it holds will be different, resulting in variations to the finished bore diameter. According to several different sources I've found, the loading pressure - how much force is required on the ram rod - should be in the 30-50 pound range for best results. As such, the diameter of the sabot needs to closely correlate to the diameter of the barrel it will be used in. Too small and the sabot will not seal the barrel, which will allow some of the ignition gasses to bypass it, and/or the riffling won't impart the correct amount of spin required to stabilize the bullet; too tight and the plastic of the sabot, and even the bullet itself, can become distorted from the tremendous force required to load it, which will result in similar, concentricity sucking results. Either way, accuracy suffers.

The best solution I've found is to buy the sabots separately from the bullets. Several companies sell sabots separately, but I've had the most experience with MMP. They make several different diameter sabots, making it easy to fine tune the sabot to your barrel. They can usually recommend one or two sizes of sabot to try based on the brand and model of gun you own and the bullet you would like to shoot. Sometimes it takes trying several different sizes to get the best accuracy, but the efforts are well worth it. You can then buy most bullets in "bulk" boxes of 50 or 100, which can save some money while giving you a better results in the end. Additionally, they offer different inside diameters, allowing for use of a wide range of rifle and pistol bullets. My favorite load for deer sized game where a scope is legal is the non-magnum Hornady XTP 300 grn .452 in a properly sized MMP. I've recommended this approach to numerous friends and acquaintances, and I've yet to encounter a gun in which this combination does not shoot accurately. Further, we've collectively taken a good many head of game with these bullets and without exception the terminal performance has been outstanding. As a plus it is a very cost effective way to shoot. I've tried Hornady SST, Nosler Partition pistol bullets, and some Barnes original rifle and copper pistol bullets with great accuracy results as well, which adds to my discernments on the sabot having more affect on accuracy than the bullet. This is not to say that some bullets are not more inherently accurate than others, I'm just concluding that a properly sized sabot is the only way to realize the best accuracy from any bullet.

The other solution is to buy a handful of different bullet-sabot combinations and try them all to see which ones will offer the best groups. Then, once you find something that works, just stock up on it. It is more expensive, but more importantly you might be bypassing a great bullet that isn't grouping in your gun because the sabot is not properly sized.
starbuck
 
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