twist rate for 243

[hedditch]

Opinions wanted: What would be the maximum bullet weight for a 14 twist barrel in a 243? What are the relationships between Ogive, weight and twist? While I am at it, one more question: is there any kind of a powder sensitivity charts to tempurature? It appears to me my BLC-2 loads are effected greatly once the temp get below 20 Degrees in my 222. At 40 degrees and above, I get fantistic 5 shot groups of .3 and many times under that. At 20 degrees and under I am pushing hard to get .750. I can't get any more powder into the case to try to adapt to colder temps. My load is 28.1 grs of BLC-2 with a 40 gr V-max.

 

[jonbearman]

Go to the berger website and they give recommendations on twist rate by caliber and bullet weight.Most .243's are around 10 twist however the 6mmbr is 14 twist for up to 70 grain bullets,but I would go with 8 twist.That way you can shoot bullets from 55-115 dtacs.

 

[CanusLatransSnpr]

I have Berger's quick reference sheet right here in front of me. According to their chart, a 62gr. match bullet would be the heaviest of their's that you could shoot in a 14 twist or faster. Their 65gr. match bullet calls for a 13 twist or faster.

As far as the powder deal goes, you will have to try Hodgdon's exteme line of extruded powders if you want temp. stability. Ball powders meter nice and give great velocity but, are temp. sensitive.

Mike

 

[headhunter1111]

Stability is related more to bullet length than anything. I believe an 80 gr bullet at .900 inches would be the max in a 14 twist. As far as ogive, it does not affect the stability at all other than long ogives typically means a longer bullet which requires a faster twist to stabilize. Higher velocity also will help stabilize the bullet a bit better however, this effect is marginal.

 

[hedditch]

I stand corrected on the 14 twist rate. I just checked my Cooper catalog and the twist rate for the .243 is 10 and looking at the Berger bullets guide I can go up in weight to a 90 gr bullet. I am trying to find a load that will shoot in this Cooper and cannot.

I will have to look up the Hodgen Extreme powders.

 

[Yellow11]

As Headhunter1111 has already mentioned, bullet length must be taken into consideration as well as bullet weight.

I suggest you apply Don Miller's formula to your problem and settle for a gyroscopic stability factor of 1.4 or higher

 

[Kenny474]

If you haven't tried the 88gr flat base Bergers in your .243, they are definitely worth a shot. They were very easy to find an accurate load with in my Savage .243.

The 90gr Berget BT's also shoot well, but I have better results from the flat base in my rifle, though I haven't put a whole bunch of effort into the 90's either.

If you want a good hunting bullet for larger game, the 87gr VLD is designed to be used in the 1-10 twist and may work well also.

Another very easy to tune bullet for the 6mm is the 90gr Nosler BT. They shoot very well in my rifle and are an excellent game bullet.

What are you using for powder in the .243?

 

[hedditch]

I have tired H 414, h 380, AA 4064, H 322, Varget and for bullets, 58 gr & 65 gr V-Max, 70 gr TNT, 70 Gr Blitzking, 70 gr Sierra hpbt match, 55 gr blitzking, 68 Gr Euber, & 65 Gr Gentner.

 

[RonAKA]

The bullets that perform the best for me in my 12 twist 6BR are in this order, with best average of three three shot groups, and velocity.

Berger 68 Target, 0.176, 3420
Bart's 68 Target, .245, 3354
Berger 69 High BC Varmint, .254, 3476
Berger 80 Varmint, .287, 3114

However a 62 grain Berger does not group at all, and gives groups ten times the size of those listed above. So, for sure the bullet counts. Velocity is important too. Have you done a ladder test to see what velocity your barrel likes? Mine seems to do best around 3400.

 

[CanusLatransSnpr]

My 12 twist .243 loves the 70gr TNT on top of 46gr. of H414! As a matter of fact, I shot a 3 shot group, at 354 yds, off of an improvised rest that measured 5.5" today. Almost all of that was do to the fact that I had nothing to reference for how much wind I was holding. That load shoots .25 MOA at 100 consistently for me, off of a rear bag and rest of course. Good luck!

Mike

 

[hedditch]

Mike, I shot two 5 shot groups with your perticular load of 46 grs of H 414 and a 70 gr. TNT: 1.200 & .437. I have some 68 gr Barts Ultras and 68 Gr Nosler I will try next loading both with AA 4064 and some H 414 as soon as the weather warms up. Twelve degrees today. I am using a Bald Eagle front rest and rear bag.

 

[Rustystud]

.243 rate of twist suggestions:

1:14 70 grain bullets or lighter
1:12 85 grain bullets or lighter
1:10 95 grain or lighter
1:8 108 grain or lighter
1:7.8 115 grain nor lighter

This is just a general refrence.

Nat Lambeth

 

[CanusLatransSnpr]

How far are you jumping those 70gr. TNTs David? I am only jumping mine .005", same as what I jump 52gr. Berger Match Varmints in my .22-250, and they shoot lights out. If you are jumping them alot, try not jumping them so much and see how they behave. Just an idea!

Mike

 

[DCRYDER]

I like H4350 behind a 87gr VMAX. Hornady's VMAX shoot really good for me and are pretty cheap. I'm not saying I would shoot competition with them but for informal paper punching and varminting I don't think they can be beat. Any of Hodgdon's EXTREME line of powders are supposed to be the most temp insensitive. They are all stick powders, for this reason I never shoot ball powders.