. 243 Win. - flat base better than boat tail?

[EastHumboldt]

I have a Browning X bolt stalker in 243 Winchester with 1/ 10 barrel twist. It’s my practice rifle and I shoot it a lot because it’s a little less expensive to buy bullets and load for. Of all the factory ammo and hand loads that I’ve tried it loves Norma 100 grain whitetail and is giving me 1” 10 shot groups at 100 yards. Best I’ve done with handloads is about 2” groups. The normal factory white tails are flat base, 100 gr, and all my hand loads have been boat tails.

Since it likes these bullets, I’ve been thinking of trying to acquire some from Norma but the damn things are $.50 apiece. So much for economical shooting. I think I might buy a couple boxes of Sierra pro hunters and try loading some of them up.

I read somewhere else on the forum that the standard 1/10 barrel twist of a 243 will stabilize a flat base 100 grain bullet better than a boat tail 100 grain bullet. This seems to be the case with my experience here, but I’m wondering what has been the experience of y’all?

 

[Steve300xcw]

I'd pick up a box of 105gr bthp's and give em a go.

HORNADY 6MM (.243) 105gr BTHP BULLET MATCH 100/BX - Graf & Sons

All Hornady® Match™ bullets feature revolutionary AMP® (Advanced Manufacturing Process) bullet jackets. Developed by Hornady® engineers, these bullet jackets are a technological advancement in design, tooling and manufacturing that combine to produce the most consistently concentric bullet...

www.grafs.com

Factory Second Match 6mm, 243 Cal (243 Diameter) Bullets 105 Grain

MidwayUSA has just made a huge purchase of blemished bullets and we are passing the savings to our customers. Blemished bullets are bulk-packaged,...

www.midwayusa.com

 

[hereinaz]

Match shooters choose flat base for 300 yards if I am not mistaken. They stabilize and the benefits of a boat tail aren’t meaningful until further distances.

Check into that.

 

[EastHumboldt]

They had these on sale for $15/100 so I bought some. They look like factory seconds pro-hunters.

Factory Second 243 Cal, 6mm (243 Diameter) Bullets 100 Grain Spitzer

MidwayUSA has just made a huge purchase of blemished bullets and we are passing the savings to our customers. Blemished bullets are bulk-packaged,...

www.midwayusa.com

 

[Deere_Man]

1:10” twist will like a lighter bullet, not a 105gr.

I’d try a Sierra Pro Hunter Spitzer if you want a 100gr. It’s a flat base. Or better yet, the Speer 90 Hot-Cor spitzer.

 

[EastHumboldt]

even though I bought some bullets which I hope will work, I'm still academicaly interested in educated / experienced replies to the flat vs boattail question. Always trying to learn something. I'll post my results when I have some.

 

[rhagenw1988]

My older savage 110 which is 1/10 barrel twist prefer flat base 100 grains over 100 SBT. But it loves sierra 85 GMK and VK.

 

[Steve300xcw]

I ran pro-hunters outta my tikka until I started shooting canyons. Then switched over to the BTHP's as they are cheap and flew a bit better.

I cannot complain about a $0.20 bullet that lets me kill rocks well past 800yards and also tip over a buck every now and then.

 

[Steve300xcw]

1:10” twist will like a lighter bullet, not a 105gr.

 

[hereinaz]

My older savage 110 which is 1/10 barrel twist prefer flat base 100 grains over 100 SBT. But it loves sierra 85 GMK and VK.

Flat base bullets are shorter by nature than the same weight boat tail bullets. So they are easier to stabilize.

 

[Koda_]

even though I bought some bullets which I hope will work, I'm still academicaly interested in educated / experienced replies to the flat vs boattail question. Always trying to learn something. I'll post my results when I have some.

I have only heard that flat base bullets are more accurate at close ranges, the propulsion behind them is more evenly distributed to the whole bullet mass at ignition. After a certain range boattails become needed to maintain the aerodynamics. Im not certain what the distance is maybe 300yds.

 

[MT-nuffgun]

My dad had a rem 700 adl .243 win that acted the same as you describe. We tried 85gr and 100 gr soft point bt’s with a few different powders. The gun grouped ok but not great. At that time, hornady had just come out with the 95 gr sst bullet which was a flat base. We bought a couple boxes of those and loaded them with max load of imr 4064. The rifle shot amazing and the sst bullet was devastating on whitetails and mule deer.

 

[KenLee]

Hornady custom btsp always shot well for us in old a-bolts. 243, 270, 308, 30-06, 7 mag and 300wm. Never tried them in my x-bolts. Those factory loads are now discontinued.

 

[jaredg]

My Browning X-Bolts and My Sakos / Tikkas in 1:10 243 all prefer the Sako 100gr Gamehead which is a flat base. It's a 500 yrd cartridge for me. At 550 yds that gun shoots a 2 1/4" 3 shot group.

So for me yes, the flat base stabilizes that 100gr bullet in my 1:10 243 out to 550 at 4400 elev.

 

[Stearinlys]

Does it need to be 100gr? Have you tried 95 NBT's?

 

[TaperPin]

That’s interesting. I’ve never paid much attention to flat base vs boat tail in all the 243s I’ve loaded for since they shot so similarly, but some guns are finicky.

Since it seems finicky, I’d be curious to try a lighter bullet. Back when boat tails weren’t the norm, one rifle shot lighter bullets one step down much better than the heaviest the barrel twist was designed for.

I have always wondered why Nosler 6mm Accubonds and Ballistic Tips have such a tiny boat tail - it’s like they didn’t want to, so minimized it to make folks happy.

 

[Kurts86]

It’s not directly the shape but the bullet overall length that is the issue to stabilize 1:10 6mm bullets. At the same weight a flat base will be shorter than a boattail and require fewer rpm to stabilize.

https://bergerbullets.com/twist-rate-calculator/

Most 1:10 .243’s will shoot well with flat base 100 gr bullets or 95 gr boattails on the upper end. You may get a high BC 103 or 105 bullet to stabilize but that will likely take very high velocities and higher elevation. At a minimum it will be finicky and run a lower than published BC. It isn’t an accident 1:8 is becoming the 6mm standard twist rate.