Do Individual Firearms Prefer Specific Ammo?

[Pathfinder Ops]

I'll just add this and it isn't a scientific study and not an AR specific observation but:

My Ruger 10/22 that I have had for friggin ever and is a stone cold tack driver does not run anything as well as it does the standard issue, over the counter Federal JHP's. The stuff you buy in a brick from Walmart.

Any other manufacturer or better quality stuff and suddenly I'm getting everything from failure to feed to failure to eject to a decrease in accuracy under the same shooting conditions.

I don't know why and I am no armorer or ballistics expert. That's just my street (range) experience.

That being said i can say the I have shot 3 different manufacturer's .223 through my AR and I do not sense any difference in the performance of the gun or my accuracy.

I'm inclined to think that there are ideal loads for certain guns... why? I don't know. Magic maybe..........

[CarlosDJackal]

I know "a whole host of different factors" was intentionally broad, and the real answer might be horrifyingly complex, but why?

I accept that this is true because I've heard it from a lot of people whom I believe know what they're talking about. But at the same time, it strikes me as a little bit of black magic.

I'm with you that two identical rifles will fire the same exact loads differently (perhaps one more accurate than the other) but I'm struggling with how those identical rifles might 'prefer' significantly different loads. Someone walk me (slowly) from here to there, if possible.

It's pretty simple, really. It's all about the Physics. Harmonics are very unpredictable. Why do you think that musical instruments that are made by the same person using the same materials and techniques from the same source at the same time can still end up being different?

No black magic involved. Even when made from the same batch of steel at virtually the same time two barrels may have enough of a difference at the molecular level to have different harmonics once they are used.

One of the factors that define the accuracy of a rifle/ammo combination is where the muzzle is in when the bullet exits. A barrel will "whip" when hit with a hammer or when a cartridge is ignited. If a projectile leaves that barrel at the close to the same point of its "whipping" action, the you may very well have an accurate match.

There is also the possibility that the barrels' twist is not exact. Some 1:9-inch twist ARs loves 75-grain bullets because they are closer to a 1:8.5-inch twist. While some, even from the same lot, may only prefer a maximum bullet weight of 69-grains.

One of these factors is how sharp a cutting tools stays between barrels. There is bound to be some loss of sharpness with each use and this may be enough to make the difference.

Of course, I could be full of crap and someone will eventually come along to correct me (it wouldn't be the first time).

[Complication]

It's pretty simple, really. It's all about the Physics. Harmonics are very unpredictable. Why do you think that musical instruments that are made by the same person using the same materials and techniques from the same source at the same time can still end up being different?

No black magic involved. Even when made from the same batch of steel at virtually the same time two barrels may have enough of a difference at the molecular level to have different harmonics once they are used.

One of the factors that define the accuracy of a rifle/ammo combination is where the muzzle is in when the bullet exits. A barrel will "whip" when hit with a hammer or when a cartridge is ignited. If a projectile leaves that barrel at the close to the same point of its "whipping" action, the you may very well have an accurate match.

There is also the possibility that the barrels' twist is not exact. Some 1:9-inch twist ARs loves 75-grain bullets because they are closer to a 1:8.5-inch twist. While some, even from the same lot, may only prefer a maximum bullet weight of 69-grains.

One of these factors is how sharp a cutting tools stays between barrels. There is bound to be some loss of sharpness with each use and this may be enough to make the difference.

Of course, I could be full of crap and someone will eventually come along to correct me (it wouldn't be the first time).

Aha! I had forgotten to consider harmonics. Sounds perfectly reasonable now. Thanks.