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Flat base bullets verse Boattails
txhunter469
Member Posts: 22 ✭✭
whats yalls opinion on useing flat base bullets for long range shooting verses boattails..
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Thier was a good article on this very subject not long ago in Handloader magazine. Sadly I don't remember the issue and couldn't find it when I look for it.
It was a pretty major piece and , if memory serves correctly, the boattails had a better than slight edge in both drop and wind drift over the flat base bullets.
A quick visit to thier web site might get a copy headed your way?
www.riflemagazine.com [8D]
Not much flat looking in that picture... Seriously, Flat base bullets have better efficiency in the barrel. The gases want to push directly and straight forward on the flat base. The gases want to push at 90 deg to the base of the bullet. Well as you can see that isn't very efficient for the boat-tail while in the barrel. So, the flat base leaves the barrel with as much as a 15% advantage. This is one of the reasons why boat-tails burn out barrels faster than flat base bullets. Of strong note here this is why you see all the short range bench rest shooters shooting flat base bullets. High BC doesn't really even start coming into play until around 300 yds.
Now, after leaving the barrel the aerodynamics of the boat-tail reverse the above trend. This is extremely evident after the bullets go subsonic. But it still happens while each are super-sonic. The flow around the boat-tail doesn't let the vacuum at the back of the bullet drag it even more. Like the flat base. The vacuum created at the back creates a lot of drag. So where is the change-up point? Well it varies with different bullets of different weights and styles but 300 yds in a high velocity bullet is an approximate range for a lot of bullets with these issues.
So, out to 300 yds. I would go with flat base. After 300 yds I would go to the boat-tail.
However, what I'm shooting right now(not exclusively, that's for sure)are rebated boat tail bullets. Where the boat tail meets the body of the bullet the diameter is decreased from the full bullet diameter. You lose a little bit of BC by doing that but you gain back the efficiency almost entirely of the flat base bullet whilst in the gun. Combine that with super long ogives and you have very efficient bullets both in the rifle and beyond.
Actually it was nononsense who pointed me in the direction of a Canadian, Richard Graves, who is making his Wildcat(copyright) bullets with the rebated boat tail. I've shot up two boxes so far and need more. but I am extremely impressed with them.
The rest I just came to the conclusion finally that at 300 yds., at my home range here, it may come to a 1/4 or 1/2MOA adjustment and that's it for about all styles. I've never had more than one MOA adjustment for equal velocity bullets in the same caliber. And, I've shot a lot of round nose .311 and .323 bullets at 300 yds.
If not, why have the picture he posted as your sig pic? Not that it isn't a good pic.[;)]
My cousin shoots Berger's High BC Flat Bases in his 6mms and gets them to out shoot every other bullet(boattail and flat base)out to 600yds.
Hmmm, someone else I've shoved around. (688 boat, eh)
USN 1991-2001 / USS San Juan SSN-751
Hmmm, someone else I've shoved around. (688 boat, eh)
Is there any other type?[;)]
Yes Handgunhunter, there are....BOOMERS! (shoved all of them around too)
Boomers aren't real boats, just like boomer sailors aren't real submariners.
Now there's stupid if I ever saw it.
"Boomers aren't real boats, just like boomer sailors aren't real submariners."
Now there's stupid if I ever saw it.
Of course you seen it, you have mirrors in your house don't you?