Boat tail bullets vs Flat base

Deerdr

CGN frequent flyer
Rating - 100%
161   0   0
Location
North Bay ON
For many years I have used mostly very pointy boat tail bullets for reloading because "THEY" say they are superior, and I have had excellent results. I bought a new Cooper (to me) and called a ballistic technician at COOPER Firearms to inquire what ammo would shoot best out of my rifle.For factory he recommended Federal Gold Medal Match 165 or 168 whatever. For home loading he recommended SIERRA Match Kings and IMR 4064 powder.HOWEVER he also stated that flat based bullets shoot VERY well. He attributes the accuracy to the base of the bullet, mushrooming or expanding to fit rifling tighter. He stated its kinda like shooting a hollow base muzzle loader bullet that flares the base to engage rifling better. When I asked about Hunting Ammo he suggested Sierra Game Kings but STRONGLY advised to try some FLAT BASE. Don't beat me up on Bullet choice guys and gals, I know you all have your favorites. I'm quoting a Ballistition from a very prestigious Rifle Company. Respectfully Jim
 
I have owned rifles that didn't like boattails. My general go to hunting bullet has been a Barnes TSX, but my regular range bullet is a hornady spirepoint, but are accurate.
 
I sorta remember reading an article that concluded that FB bullets were as or more accurate than boat tails, but because of their
lower BCs they would suck at long range (paraphrasing).
 
I'll second those flat based bullets!! I have loaded both 140 gr sierra pro-hunters in a 7 mag and 150 gr hornady interlocks in a 30-06 and they are without question very accurate, and interstingly enough both loads were with 4064. In the 7 mag it really didn't matter what powder I used they all shot very well. On the other hand I tried some 160 gr gamekings with a few different powders and they struggled to stay at an inch. And the 165 gr sst's in my 30-06...forget it, was like a shot gun. I recall reading something about flat based bullets as well and I think the article suggested it was easier for the manufacturers to keep the bullets more symmetrical with a flat base design, there was something about the boattail design that made it more difficult for them to manufacture them as consistantly....in the cheaper hunting bullets anyway. Also seem to recall reading that IMR 4064 is popular with target shooters. Like I said I just read these things somewhere so take it for what it's worth. This is an interesting subject hopefully some more members who have done some extensive experimentation with both bullet styles will chime in.
 
The .303 Enfield rifle is a good example of your question, the Mk.7 cordite cartridge used a flat base bullet which would obturate or expand and fill the bore when fired. This is very useful on worn bores in the throat area to ensure the bullet seals the bore. If a boat tail bullet was used, the construction of the base of the bullet prevents the boat tail bullet from sealing the bore.

A boat tail bullet works well in a bore that matches the bullet diameter, but can perform badly in a worn or over sized bore. Wartime production military barrels can vary greatly in bore diameter and cordite powder was a early type double base powder that burned hot and eroded the bore quickly. The Mk.8z .303 machine gun ammunition used single base powders only to extend barrel life and cordite ammunition was forbidden from machine gun use.

The British compromised with their Mk.8z boat tail bullets used in machine guns using a single base powder and a rebated boat tail bullet that would fill the bore on a worn or over sized bore. One other problem boat tail bullets have is if fired in a rifle with a worn crown or muzzle the unequal gas pressure can cause the bullet to become unstable as it is just leaving the bore.

Below, Mk.7 flat base bullet, cordite powder, rifle use only, and Mk.8z rebated boat tail, single base powder, maching gun use only.

303ammo.jpg


Mk8z.jpg


boattail-a1.jpg


Bottom line, you will not see a difference between the two type bullets under 300 yards, and you need good tight bore tolerances and a perfect crown to get the best from a standard boat tail bullet.
 
Last edited:
Tagged for interest. Are not most "match" bullets of the BT design? And, if one were truly about distance, you would have to be just as concerned that more accuracy is required in order to achieve more distance. You can't witness 1000 yard shots if you don't hit what you are aiming at. And, what you are aiming at deserves your attention as well. A well constructed bullet is required for hunting big game, while any projectile will kill paper. I'm using SGK's and Interlocks for hunting, they are tried and true, maybe not the best, but what is the guaranteed best for taking game at 100-500+ yards. Using SMK's in my .223.
 
Last edited:
Long range accuracy winners use custom made barrels held to "tight tolerances" and boat tail bullets.

Below a custom made hand lapped barrel. (and a perfect crown)

custom.jpg


Below a standard factory button rifled barrel at the throat.

Throat-1-C-RS.jpg


Below, same barrel two inches from the muzzle.

6inchesfrommuzzle-2.jpg


Button rifled barrel before and after fire lapping.

beforeandafter.jpg
 
My Sako L61R doesn't like BT bullets at all.

Here is an easy answer, your barrel is wearing out.
I bought a L61R new in 270 Winchester calibre and it shot boattail bullets very accurately. But after a time boattails of any weight first started to make oval holes and shortly after that they completely tumbled at 100 yards, while flat base still shot with good accuracy. Yes, the barrel was thoroughly clean.
The barrel started doing this sooner than I thought it should, like maybe a doubtful 1,500 rounds, but most of these were boattail.
 
All things equal, for under 300 yards I see no benefit whatsoever to using boattail bullets, under 400 really. In fact, for 200 yards or less ill put my money on the flat base IRT accuracy.
 
Here is an easy answer, your barrel is wearing out.
I bought a L61R new in 270 Winchester calibre and it shot boattail bullets very accurately. But after a time boattails of any weight first started to make oval holes and shortly after that they completely tumbled at 100 yards, while flat base still shot with good accuracy. Yes, the barrel was thoroughly clean.
The barrel started doing this sooner than I thought it should, like maybe a doubtful 1,500 rounds, but most of these were boattail.


no oval holes or tumbling here...just won't group under 1" with BT...the 130gr I had anyway.
Consistently under 1" with FB bullets of the same weight.

might be a moot point as I'm considering a 9.3x62 or 338-06 rebarrel...

now...back to the original topic :)

bigedp51...good info
 
In the mid 1970s I bought a new Remington 788 in 6mm Remington and what I couldn't see with the naked eye was a very small defect in the crown. I was at the range shooting work up loads and I switched from a Sierra flat base bullets to a Sierra boat tail bullet of the same weight. I was getting around 1 1/2 inch groups at 100 yards with the flat base bullets and the rifle was zeroed with this load. When I switched over to the boat tail bullets using the same cases and powder the boat tail bullets were not even hitting the target. The boat tail bullets were hitting 2 feet to the right of aim. When I got home I looked at the muzzle with a jewelers eye loop because the powder blast marks on the muzzle looked uneven. Sure enough the crown had a small defect that was enough to push and deflect the boat tail bullet to the right when fired.

After having the barrel recrowned the flat base and boat tail bullets would hit to the same point of aim.
 
I use FB bullets now. I find they tend to be more accurate than comparable BT bullets in the same rifles, cheaper too. For shots less than 300m, there is no difference. For shots to 400m, no practical difference.
 
I sorta remember reading an article that concluded that FB bullets were as or more accurate than boat tails, but because of their
lower BCs they would suck at long range (paraphrasing).
what do you call long range? With a reasonably flat shooting cartridge lik a 270 you have to be either 400 + yards before it makes much difference, and lots of guys shoot well enough to take deer sized animals at that range with flat based bullets.
 
I have shot a number of big game animals at 400+ yards, using Nosler Partitions.
I never noticed any issues with the flat based design at any normal hunting distance.
As has been stated, often FB bullets shoot better than BT designs.
Regards, Eagleye.
 
Pretty sure most / all benchrest shooters use flat based bullets for short range, they are just plain more accurate. The BT's shine at long range where the improved ballistic coefficient actually means something, 300 yards plus.
 
In the line of what tomamyhobbies wrote above, I read (can't remember where) that boat tail design bullets were for more accurate long distance flights. With the excellent information provided by bigedp51, it highlights the extreme importance of having a barrel in a condition that allows the proper launch of BT bullets in order to achieve long distance accuracy.

Personnally, no BT bullets for me since all my shooting is within 300 yards.
 
Last edited:
There are three grades of barrels out there. Custom match quality barrels. Good factory barrels. Worn factory barrels (milsurp).

A high quality barrels will shoot any bullet to the limit of the bullet's potential.

ordinary factory barrels and worn barrels will do better with a flat base.

If the barrel is in poor shape, a round nose flat base is your best bet for decent results.

Also, note that a soft point will usually be a better bullet than a FMJ.

If you want good results from a cheap bullet, a 150 gr soft point is a better choice than a 150 gr FMJ. This was all explained to me a long time ago by Joyce Hornady, who knew a thing or two about bullets.
 
There are three grades of barrels out there. Custom match quality barrels. Good factory barrels. Worn factory barrels (milsurp).

A high quality barrels will shoot any bullet to the limit of the bullet's potential.

ordinary factory barrels and worn barrels will do better with a flat base.

If the barrel is in poor shape, a round nose flat base is your best bet for decent results.

Also, note that a soft point will usually be a better bullet than a FMJ.

If you want good results from a cheap bullet, a 150 gr soft point is a better choice than a 150 gr FMJ. This was all explained to me a long time ago by Joyce Hornady, who knew a thing or two about bullets.

I'll take his word for it!
 
Back
Top Bottom