243 1:10 Heaviest Bullet?
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~87 grains.
115 DTACs take a 7.75 I believe.
115 DTACs take a 7.75 I believe.
Gunpoor
Well-Known Member
A 1/10" twist 6mm barrel will stabilize cup and core bullets up to and including 100 grain weight. I had a 243Win that would shoot 100 Rem. Corelokts into a group too small to measure. On the lighter side of this barrel, it wouldn't stabilize bullets under 58 grains.
Mikecr
Well-Known Member
+1 jfseaman
Please explain the logic behind it.
WRONG.. Where did you get this notion?
Please explain the logic behind it.
Gunpoor
Well-Known Member
I just stated that my 243 would not stabilize bullets lighter than 58 grains. Now I only tried one bullet under 58, and that was a 55 grain Hornady and they began to shoot better the harder I pushed them but ran into excessive pressure at 1.5 or 2 grains over max load, when the group tightened up to 1.5 MOA. I think these light for caliber bullets were jumping the rifling and when I pushed them harder it made them obturate the barrel grooves a little better. If your hands on experience differs from mine please feel free to expound on your findings.
BTW,Mike C.R., do you even shoot a 243Win?
BTW,Mike C.R., do you even shoot a 243Win?
Mikecr
Well-Known Member
I've shot & loaded for 7wsm, 6.5wssm imp, 243AI, 6XC, 6br, and bunch of 223s.
243win I've shot(my father's) and killed a few deer with growing up. But I didn't reload for it.
Group sizing with different bullets & loads means little to nothing about bullet stability. If there was any group at all, and bullets were not whacking paper sideways at 10ft, then the bullets were stable.
Your 55 Hornady was stable, but shooting poorly. That's all.
It doesn't mean light bullets were not stable, or wouldn't be.
243win I've shot(my father's) and killed a few deer with growing up. But I didn't reload for it.
Group sizing with different bullets & loads means little to nothing about bullet stability. If there was any group at all, and bullets were not whacking paper sideways at 10ft, then the bullets were stable.
Your 55 Hornady was stable, but shooting poorly. That's all.
It doesn't mean light bullets were not stable, or wouldn't be.
Bullet bumper
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It is not the bullet weight that determines barrel twist it's the bullet length .
So a long boat tail lighter bullet will need more twist rate than a shorter heavier one . Weight is only used as a rough rule of thumb guide and was more suitable back before boat tail , long ogive bullets were around .
I have been using the .243 for about 45 years now so I have some experience with this cartridge . I remember when it first appeared on the market .
There is no real advantage to using a bullet heavier than about 87 to 90 grains in a 243 at range . The loss of velocity and powder room using the heavier and longer bullets just losses kinetic energy and at longer range has less hitting power than the lighter bullet going faster to start with . If you do want a 100 grain bullet in .243 keep it for close range and or thick bush use in a 1 in 10 twist barrel then choose a flat base bullet . This shortens the bullet compared to a boat tail of same weight and at short range a boat tail is of little to no ballistic advantage anyway .
The longer bearing area of the flat base also gives better gas seal , better rifling grip and resists in bore yaw better when being driven hard .
Some very light for the caliber bullets can require more twist rate even though they may be shorter than another bullet that is fine in said twist rate. The reason is that inside the bullet the core may be made very short and the ogive is basically hollow inside . This moves the center of gravity way back and creates an unstable design example is Barnes varmint grenade . Extra twist rate compensates for that bad design work.
So a long boat tail lighter bullet will need more twist rate than a shorter heavier one . Weight is only used as a rough rule of thumb guide and was more suitable back before boat tail , long ogive bullets were around .
I have been using the .243 for about 45 years now so I have some experience with this cartridge . I remember when it first appeared on the market .
There is no real advantage to using a bullet heavier than about 87 to 90 grains in a 243 at range . The loss of velocity and powder room using the heavier and longer bullets just losses kinetic energy and at longer range has less hitting power than the lighter bullet going faster to start with . If you do want a 100 grain bullet in .243 keep it for close range and or thick bush use in a 1 in 10 twist barrel then choose a flat base bullet . This shortens the bullet compared to a boat tail of same weight and at short range a boat tail is of little to no ballistic advantage anyway .
The longer bearing area of the flat base also gives better gas seal , better rifling grip and resists in bore yaw better when being driven hard .
Some very light for the caliber bullets can require more twist rate even though they may be shorter than another bullet that is fine in said twist rate. The reason is that inside the bullet the core may be made very short and the ogive is basically hollow inside . This moves the center of gravity way back and creates an unstable design example is Barnes varmint grenade . Extra twist rate compensates for that bad design work.
D
Deleted member 46119
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While they are fighting about other useless things.
Some of the old old design short nose, soft point flat base bullets will stabilized up to 100 grains. That part is true. I live at sea level and even these usually shoot like.. Well you know.
You will not stabilize any Berger boat tail and I had my number wrong it's 88 grains. All Bullets | Berger Bullets
Bullet bumper
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What do you mean " that part is true " . You knock what you don't understand that is why people don't learn anything new .
I make bullets so I know what is happening inside and outside . Bullets can be made wrong on the inside but look ok on the outside . This can effect the twist rate needed irrespective of overall length .
I make bullets so I know what is happening inside and outside . Bullets can be made wrong on the inside but look ok on the outside . This can effect the twist rate needed irrespective of overall length .
I have 243 with Kreiger barrel @ 24"long, 1/10 twist also 243AI @ 27" long, 1/10 twist.
I'm shooting Berger 95 gr Classic in both using H-4350 in 243 and IMR-7828ssc in 243AI and data from Berger manual.
You can use this with Berger bullets Twist Rate Stability Calculator | Berger Bullets
I live Co and shoot from 5000ft up to appr 9500ft and some my bullets may not stabilize low elevation. I'm able to shoot some like 100gr Hornady interlock.
Good Luck.
