Boat tail vs Flat base bullets

W

Whistler

New member
Will boat tail bullets erode your chamber and barrel quicker than flat based bullets. An old gun smith told a friend this is true. His logic being that the gases and pressures are forced into the angle between the boat tail bullet and the barrel. If this has been discussed before...Sorry. What do you think? Regardless of the situation they are used in and how many rounds it might take do you think this is a fact?:confused:
 
Whistler said:
do you think this is a fact?:confused:
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No I don' t believe it. Throat erosion results from roughly one millisecond bursts of propellant gas heating, softening, and dislodgin very thin amounts of the inside surface of the throat. Ti takes place in the throat because it's there thats where pressures are highest, , the temperture is highest, the molecular velocity is greatest, and the duration of exposure is longest. At 50,000 psi the molecules of propellant gas are moving very much faster than the the bullet moves down the barrel. They will fill all spaces limted by the case, the part of the barrel behind the moving bullet, and bullet whether the space is tapered or not, and at nearly the the same pressure, and temperature. The amount of exposure time is much greater near the throat.

It seem to me that the only way two bullets of the same weight could cause much difference in throat erosion is if one is undersized and allows significant blowby.

In my rifles the boattails do accompany most of the throat erosion. That's because they're what I mostly shoot.
 
This was tested extensively by the US Gov't without finding any substance to it. Sorry, your old gun smith was just parroting a rumor started on a slow news day.
 
It may be that the tiny bit of extra gas passed by boat-tailed bullets not jam seated might possibly lead a BR shooter who considers the useful life of a barrel to be over after 600 rounds to prefer a flat based bullet for that reason and the fact that pressures are better controlled and less bumping around in the throat occurs with the FBs........................
 
No truth to the old wives tale. If you are looking for info, check out the book Rifle Accuracy Facts, by Harrold R Vaughn, who worked for NASA and specialized in ballistics. A must read for any serious shooter.
 
Flat Base Verses Boat Tail.

Some rifles show their preferences, I have a .303 British that will give "Faries in the bottom of the garden" accuracy with 125g sierra .308 flat bases. In fact it will shoot most flat base bullets well wether they are .308" or .311"and I have yet to find a boat tail that it likes, so maybe the question to ask is not one of throat erosion but wether rifles have a preference for a particular configeration.:confused:
 
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