Flat based vs boattails, what distance

[Koda]

Ive read that flat base bullets are more accurate at close ranges but what is the distance and cause at distance?
Is the cause when the bullet goes transonic?

I have a good understanding of why they are more accurate at close distances, but Im interested in learning what they do at longer distances and if there is a way to accurately estimate a flat based bullets max accuracy range?

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[Ben B.]

I don't know the answer, but I discovered that the flat based 50 gr VMAX and Varmageddon shoot lights out in .223/5.56 out to 300 yards, compared to any boat tail I've tried yet. 60 gr VMAX is almost as good for me.

Yep, I discovered it…and then later read that was a known thing.

Here's one I kept for awhile, 20 shots at 200 yds, 50 gr VMAX thru an 18" AR.

 

[aaron_l]

Ive read that flat base bullets are more accurate at close ranges but what is the distance and cause at distance?
Is the cause when the bullet goes transonic?

I have a good understanding of why they are more accurate at close distances, but Im interested in learning what they do at longer distances and if there is a way to accurately estimate a flat based bullets max accuracy range?

This video from little crow has really good info on bullet type.

View: https://youtu.be/VoHhntDc6qk?si=DikWo4ZZpBQplJwE

 

[Koda]

I don't know the answer, but I discovered that the flat based 50 gr VMAX and Varmageddon shoot lights out in .223/5.56 out to 300 yards, compared to any boat tail I've tried yet. 60 gr VMAX is almost as good for me.

Ive read and heard that most shoot better out to 300yds, but this seems too short to me. The flight time is just still too quick at 300 for wind and the lesser areodynamics of the flat base to "suddenly" take effect at 300. I could see 600 being more realistic... but dont know, as for some reason Ive only picked boat tails to handload for my rifles.

 

[Ben B.]

I don't know either, because I haven't had a chance to shoot past 300 yds.

 

[aboveandbeyond]

Short range benchrest competitors(100-300yards) use flat base bullets. There is your answer

 

[Pepe-lepew]

I take it as a ballistic coefficient problem. At long distance the flat base bullet will slow down more and be more influenced by external factors, mostly wind. They tend to be lighter bullets and that hurts them with lighter mass to resist wind and drag and aerodynamically as they don't have length for a boat tail.

 

[TTSX]

Ive read and heard that most shoot better out to 300yds, but this seems too short to me. The flight time is just still too quick at 300 for wind and the lesser areodynamics of the flat base to "suddenly" take effect at 300. I could see 600 being more realistic... but dont know, as for some reason Ive only picked boat tails to handload for my rifles.

I'm not sure where I stand on that. I've tested higher BC, heavier bullets and their lighter counterparts up to 1400 yards and I have yet to find the distance where I truly feel the extreme high BC bullets give me an advantage. They drop faster because they're heavier and they don't seem to buck the wind any better for me, either. I'd think the actual distance where you'd find a noticeable and measurable difference in accuracy for flat base vs boat tail is a lot further than the Internet might have you believe....

 

[osprey]

My understanding is more propellant gasses get by a boattail bullet in the barrel causing more disruption of the bullet muzzle to the first 6" of flight. This affects the time it takes the bullet to go to "sleep" and why flatbase bullets have a reputation to be more accurate at shorter ranges. Exact distances are probably dependent on many different factors and vary widely with rifle and bullet design. I have had a couple rifles that shot boattail bullets to a lower moa at say 300 yds than at 100yds. Both of these rifles were what I would consider overbore. I assume the effect may be pronounced with more volume and speed of the gasses?

 

[Steel Head]

I'm not sure where I stand on that. I've tested higher BC, heavier bullets and their lighter counterparts up to 1400 yards and I have yet to find the distance where I truly feel the extreme high BC bullets give me an advantage. They drop faster because they're heavier and they don't seem to buck the wind any better for me, either. I'd think the actual distance where you'd find a noticeable and measurable difference in accuracy for flat base vs boat tail is a lot further than the Internet might have you believe....

Past a mile and especially past 3000 yards that high bc really helps it get there faster so less time for wind to affect it.
Plus more wind resistant anyways.

Almost a whole mil difference for a 168 Berger classic hunter (3000fps) vs a Berger 190LRHT (2880) for a full value 10MPH wind at 1800 yards.

The BR guys use flat base because the gasses leaving the barrel upsets them less than a boat tail is what done BR old timers say.

Ran it in my solver that's trued up for one of my 7mm barrels
1800yards
10MPH full value wind
3000DA

190 @2880 17.56 up 2.56 right
168 @3050 24.56 up 4.67 right

Kinda a big difference as far as I'm concerned

 

[Steel Head]

My understanding is more propellant gasses get by a boattail bullet in the barrel causing more disruption of the bullet muzzle to the first 6" of flight. This affects the time it takes the bullet to go to "sleep" and why flatbase bullets have a reputation to be more accurate at shorter ranges. Exact distances are probably dependent on many different factors and vary widely with rifle and bullet design. I have had a couple rifles that shot boattail bullets to a lower moa at say 300 yds than at 100yds. Both of these rifles were what I would consider overbore. I assume the effect may be pronounced with more volume and speed of the gasses?

There's a video of a flat base vs a boat tail that's pretty clear how gasses affect the bullet

View: https://youtu.be/ZDUL_1vrABI?si=YGUR1H4OsC_ol9Ej

 

[Koda]

I'd think the actual distance where you'd find a noticeable and measurable difference in accuracy for flat base vs boat tail is a lot further than the Internet might have you believe....

This is my suspicion.

My guess is BTs are more consistent in their precision till their end, a tolerance zone like a tube.
FB stert out more precise but get less consistent till their end, a tolerance zone like a cone.
But i just dont see how 300yds is the cutoff where suddently FB bullets precision suddenly drops off.
My guess it it depends a lot on the caliber, MV, the bullet itself... with the right combination can go much farther staying very precise.

 

[thorborg]

I use boat tail for hunting because of the bullet that has always been good for me I started with in the 70's and used till the end came with it..
However, I've always been under the understanding the major advantage of the boat tail is in its friendliness to the loading process, but if I wanted to get presnickety the flat base was supposed to be better. This is from technology from 30 or 40 years ago or earlier.
Notwithstanding any miniscule technical advantage data generated by todays pro or conners, I agree with the reload advantage and leave the science to those wanting to hit the moon in his eye.

 

[Spitpatch]

The issue for "accuracy" is not only the bullet type, but the barrel crown's relationship to it.

Benchresters indeed favor flat base bullets. Benchrest rifles have significantly different barrels and crowns than most other guns, especially hunting rifles.

A machined bottail base CAN be more consistent than some swaged/formed cup ones. Either style may "agree" more with the barrel/crown type on a given sporting gun.

When a boattail is of benefit at long range is dependent on THAT bullet's specs as designed, and its relationship to THAT gun. "Benefit" needs to be defined. Velocity? Accuracy? At what practical range of usage? A general conclusion may be gleaned from drop tables. Only field testing is hard science.

If we limit ourselves to shots 400 yards or less on big game (as everyone I hope learns eventually), most boattail bullets deliver very little measurable ballistic improvement over an otherwise-identical flat base bullet.

My allowance for personal hypocrisy permits me to hunt with a whole lot of racier-lookin' boattail bullets, but when a certain gun "just won't group" with 'em, I can't get to a flat-base problem solver fast enough.

 

[Spitpatch]

There's a video of a flat base vs a boat tail that's pretty clear how gasses affect the bullet

View: https://youtu.be/ZDUL_1vrABI?si=YGUR1H4OsC_ol9Ej

In THAT gun, with THOSE bullets.

 

[Steel Head]

True but I've seen hall of fame BR shooters describe exactly what's on that video.
I tend to believe them.

 

[Spitpatch]

True but I've seen hall of fame BR shooters describe exactly what's on that video.
I tend to believe them.

The video illustrates that theory that may be quite valid. It proves absolutely nothing conclusive about boattail vs flat base bullets.

Where it fails is that it promotes a sweeping conclusion based on testing two bullets not even of the same weight or brand, and only in one rifle (one barrel, one crown).

Jim Carmichael's theory (devoted benchrester) was that a boattail's interaction with the crown cannot be as perfect concentric a gas seal as a flat base, and therefore the possibility can be increased of a little "English" being put on the base of the bullet by expanding gasses escaping unevenly there at departure from the crown.

I'd give both theories the credit they deserve, and ignore an entirely anecdotal video as any evidence of a sole root cause.

 

[Andy54Hawken]

No matter what some gun writer says...or what some competition shooter uses....
Shoot your rifle....let your rifle tell you what it likes best for how you shoot with it...then stick with that.
Andy

 

[User 1234]

My HiPoint Yeet Cannon prefers boat tail projectiles.

 

[Spitpatch]

The danger in hastily orchestrated, haphazard, unscientific and entirely anecdotal videos like this is that they promulgate an "axiom" that "flat base bullets are always more accurate than boattail bullets".

Absolutely NOT true in many, many sporting rifles. Not a few of which reside in my stable: fat barreled varminters and big game guns that thrive on boattails and shun flat base bullets.

The "vortex" or "uneven escape of gasses as the base" (or both at play) sometimes have no detectable effect at all.