I have noticed that when I coat my Sierra and Hornady bullets with moly I get a windage deflection. I could understand an elevation change but windage deflection defies my understanding. They continue to be very accurate with very tight groups..but the point of impact changes windage wise. Have any of you guys seen this too? Any idea what is going on?

When a rifle shoots, the barrel kind of vibrates/flexes while the bullet is moving down the bore. They seem to vibrate in a kind of oval pattern. Change WHEN the bullets exit, and the difference can be horizontal or vertical.

Chances are, you'll see the same type of difference (horizontal/vertical) when changing loads...or changing bullet weights.


One way to look at making a bullet more slippery is that it has pretty much the same effect on expanding gas as making it lighter.

Appreciate that....I thought I was going cross eyed or something....btw..I do not see that in my bull barrelled 22.250 so your comments make perfect sense to me. Thanks

My .257 Roberts does that, going between different 100gr. bullets. Speer is off about 4 inches; Remington and Nosler are the same at 100 yards. Same brass, powder charge, and primers....

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MikeG

Keep in mind that though you bullets from a 22-250 may be traveling 3700 fps or more they may be spinning at 250,000 rpm or better. That's why the barrel harmonics kdub and MikeG mentioned may cause them to hit in different places.

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Bob from Idaho

I gave up the moly thing after a few experiments. I always saw quite a bit of difference with the two, but never in a predictable way. Different with every rifle and/or bullet.

Mtmrolla,

You didn't say what range you are shooting at or whether there was any side wind coming from the direction the moly bullets seemed to move over toward? Moly-coated bullets generally exhibit slightly better ballistic coefficients than plain bullets of the same type, and that reduces wind drift, causing them to be blown sideways a little less. That will only really show up clearly at long ranges or under a pretty stiff wind at 100 yards.

More commonly missed by people trying out moly bullets is that they change the barrel time for a given powder charge, so they exit the muzzle at a different point in the barrel vibration than their un-coated counterparts. Loads intended for un-coated bullets need to be worked back up for that same bullet with moly coating added. Otherwise you won't achieve best accuracy or have the same vibrational exit point. This usually takes a little more powder. Typically one or two percent more.

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Nick

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"First contemplation of the problems of Interior Ballistics gives the impression that they should yield rather easily to relatively simple methods of analysis. Further study shows the subject to be of almost unbelievable complexity." Homer Powley