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Military Guns and Ammunition

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This is intended for people interested in the subject of military guns and their ammunition, with emphasis on automatic weapons.

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How much easier is it to design a decent projectile that has lead versus ...   General Military Discussion

Started 18-Apr by 17thfabn; 661 views.
In reply toRe: msg 3
Mr. T (MrT4)

From: Mr. T (MrT4)

24-Apr

In practice, we have seen low drag solids take off mostly in long-range calibers larger than .338 , and nearly all as single feed, even though some were advertised as compatible with conventional barrel twists and chambers, things quickly spiraled into much faster and possibly progressive twist rates and special chambers for solids and it remains the case today.

Indeed solids have to use 'under caliber' diameters, wasp waists or driving bands to engage the rifling and seal the bore and have in practice proven to be less accurate or at least harder to get the same accuracy. In meantime lead bullets also gained a bunch of new heavier weight options and narrower meats or sharper aluminum or plastic tips.

Its always hard to separate hype from reality but many lathe turned bullets are far from the consistency they advertise i have to find it but i have doppler measurements from an ELR competition where they measured 35 or so competitors and their shoots and i was quite surprised than many solids had considerable BC variation shot to shot Werner Bullets being the worst Cutting edge bullets being the best but lead cored Hornady was among the top performers

nincomp

From: nincomp

24-Apr

As mentioned above, when materials less dense than lead are used, the mass of a bullet particular shaped bullet goes down.  The ballistic coefficient is sectional density divided by form factor.   The only way reduce the drag of a less dense bullet is to improve its form factor.  This leads to attempts at highly optimized bullet profiles.   

That is more difficult than it appears because as a bullet travels, it is not pointed directly into the oncoming air.  Even a fully stabilized bullet travels at a slight angle to the oncoming air.  Before it "goes to sleep" or becomes fully stabilized, things are worse.  The bullets angle of attack to the oncoming airstream can vary widely as it goes through various oscillations.   The drag for many bullet profiles is increased significantly at the larger angles-of-attack that occur during these oscillations.   If I recall correctly, Emeric once stated that he has seen doppler radar numbers that indicate some bullets are still oscillating at 600m.  In other words, the drag measured from the flight paths of real bullets can be much higher than expected.  

Mr. T (MrT4)

From: Mr. T (MrT4)

24-Apr

When talking beter form factors in practice much of it is in the bullet tip. Note how many solids have extremely sharp tips.

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