Boat tail or no boat tail

mick b

Well-Known Member
just had interesting conversation with local gun shop and he told me that if i am using a MOD then best go for flat base heads as with the boat tail they tend to cause to much disruption as they pass through the baffles.

what are your views on this????
(im sure MUIR will give us the verdict)
 
The theory of a boat tail is that it causes less air resistance by reducing turbulence in the wake of the bullet.

If the bloke in the gun shop thinks for one minute that making the last few mm of your bullet slightly sloped is going to create significantly and measurably more turbulence and "disruption" in the moderator than lighting up a column of powder and expelling extremely high temperature gas at velocities approaching 6000fps followed by a 150 grain (say) lead and alloy bullet at 3000fps then I personally think he needs his bumps felt.

I might be wrong, I usually am, but I'd not put a lot of store by his advice in the future :)
 
You beat me to it with this one Mick. I have just worked up a load using Sierra gamekings with a boat tail and a mate suggested to try a pro hunter as he thought a flat base would be better (he had some science to back this up). I might buy a box of pro hunters at the CLA to try.

Ezzy
 
I had been on nosler patitons BT 100g through my .243, got some pro hunters FB because I was told there are very good with little meat damge etc. Grouping was very good indeed with the prohunters but so are the Nosler in the loads I put together. And I can say they goruped just the same.

Smithy
 
"" The theory of a boat tail is that it causes less air resistance by reducing turbulence in the wake of the bullet. ""

Actually it's been a proven fact for over 100 years. However the boat tail does really show any benefits under 300 yards. if you can get a look in the Vhit 1st Edition reloading manual it has all the science about bullet shapes including the drage and turbulance photos in it. Very interesting.
 
welllll thats a new one, these RFD's, some of them anyway, very, very, very clever blokes, probably never fired a rifle but knows whats happening with the gases from a fired cartridge, Hey Ho!!! you haven't been to bloxwich have you?
 
There was a study done here in the US on boat-tails and it was found that the ballistic benefits really don't show up til about 600 yards from a 30 caliber in 308. Shoot'em if you like 'em but I won't pay extra for them.~Muir
 
For those sad enough to care or suffering from insomnia (i'm the former), can i suggest the book, Applied Ballistics for Long Range Shooting.
http://www.appliedballisticsllc.com/index_files/Products.htm

Muir is correct in that studies have shown that the ballistic benefits for larger calibres doesn't really become apparent until longer ranges, however the shortcomings of flat based bullets becomes more of an issue at quite short ranges. For some of the smaller calibres as little as 150-200yds. I have never seen nor heard of any evidence to show that flat based bullets are better/more accurate when using a moderator.
 
For those sad enough to care or suffering from insomnia (i'm the former), can i suggest the book, Applied Ballistics for Long Range Shooting.
http://www.appliedballisticsllc.com/index_files/Products.htm

Muir is correct in that studies have shown that the ballistic benefits for larger calibres doesn't really become apparent until longer ranges, however the shortcomings of flat based bullets becomes more of an issue at quite short ranges. For some of the smaller calibres as little as 150-200yds. I have never seen nor heard of any evidence to show that flat based bullets are better/more accurate when using a moderator.

I'm not sure if is true but I read somewhere ( an old edition of target gun I think) that flat base bullets are often preferred at shorter ranges as the increased turbulence at the base of the bullet can stabilise the bullet more quickly than with a boat tail. The article went on to suggest that longer boattails were possibly more suitable for the extreme ranges than the shorter boat tails. No data of my own to back this up but I will try to find the artiucle some time.

S
 
... flat base bullets are often preferred at shorter ranges as the increased turbulence at the base of the bullet can stabilise the bullet more quickly than with a boat tail.
S

Correct but the period in which stability deteriorates is also very short. Read a report some time ago where the writer shot flat based bullets of varying calibres and weights into balistic gel. In some 20cals the bullet had already begun to tumble by 200yds over certain velocities.

Flat based bullets are popular amongst very short range target shooters and some pistol shooters (as in pistol hunters).
 
I like `boat tails` as their pointed arses make them easier to stuff into the case neck when re-loading !

HWH.

I'd like to think my choosing boat tails had some sort of scientific basis, but it didn't.... same reason as above! :D
 
Educate me please ! Is there any truth in the scuttlebutt that a boat tail bullet can create more erosion in the initial rifling forward of the leed, because the hot gasses are trying to squeeze past the taper against the chamber wall ?

Second question. Is there a calibre and weight of bullet which gains top velocity BEFORE exiting the case neck ?
I can imagine this with a very fast burning pistol powder acting on a wide diameter bullet, but then it usualy has a heavier inertia to overcome.

I'm no dabbler in the more 'grey' issues of powder and shot, but I've often wondered - - - - - -
 
If I remember my physics correctly, gasses push equally in all directions. I don't know if gasses at the edge of a bullet are pushing harder there than on the tapered base: tho it is the nature of gasses to seek the easiest way out and that may well be the edge of the bullet where is meets the rifling.

As to the bullet reaching max velocity before leaving the neck; I couldn't say. The new gasses of ignition blow the case neck away from the bullet and the gasses rush past the bullet for a bit until the bullet seals the bore. Since all powder is usually burned completely within a several inches of the barrel, and the expanding gasses travel down the barrel pushing the bullet, it might be tough to reach maximum velocity unless it is, as you suggest, very fast burning powder and I might suggest, a very short barrel. Or maybe no barrel at all? Just a chamber that ends at the case mouth? That way, the maximum velocity would possibly be achieved just as the bullet leaves the case/chamber. ~Muir
 
Intresting thoughts. I must say boat tails are easier to load and in that respect the bullet is more likely to be centered centrally. Must say 60grn V max in .223 are a pig CF say a nosler ballistic tip which are boat tail.

Muir, I am not sure you are correct re powder burn, In my quick load programme it details the % of powder burnt for the load and for sure in some loads full burn is not achieved by the time the bullet exits the barrel.
D
 
I don't have quickload but if the powder is is not burned by the time the bullet leaves the barrel the load has a problem. I have loaded ammunition that will not burn the powder completely (H-5010 in a 30-06) but it is not an optimal load. What should leave the barrel is just expanding gasses. With factory ammo this is almost certainly the case. (But I may be behind the times...) ~Muir
 
There is a 30.o6 in our clubs inventory, & when fired prone at the ranges it can produce a flame about 2 / 3 inches in length, after a few rounds the grass lights up under the muzzle.
 
Gasses or powder?? I wouldn't want to grab a handful of flame to find out!!:eek: My Uncle Willie loaded some black powder 12 ga loads for my Dad's old, rickety 12 ga when I was a kid. A rabbit ran and the hay field got set aflame!~Muir
 
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