[Arctic_Eddie]

I've had several 243 rifles in the past with 1:10 twist. They all shot 100 gr bullets quite accurately. Those guns are gone now and I'm about to get another with a 1:9 twist. I'd like to try some of the heavier bullets in the range of 105 gr to 115 gr. What are the opinions on stability with this twist factor and is there a particular brand to either use or avoid?

Thanks

 

[mattsbox99]

These are my favorites, http://www.nosler.com/Bullets/Custom-Competition.aspx

I thought they made one heavier than 105 but I don't see it now.

Berger recommends a 1-8 twist for their 100-108s and a 1-7 twist for their 115.
http://bergerbullets.com/Products/Target%20Bullets.html

 

[Arctic_Eddie]

The Berger seems to be the heaviest but I'm surprised that they recommend a 1:7 twist. I know the 1:10 is good for 100 gr and was hoping the 1:9 would get me to 105-108. If I knew the length of the Bergers I could use the stability program to see how close it might be to going unstable. When I order the rifle tomorrow I was going to get a box of Sierra 107 gr SMK.

 

[Cheezywan]

I lost interest in my 6mm Rem at 100 grains (1 turn in 10). Seemed to run bullets 80 grains and lighter better. The 100 grain pointy ones work fine though.

My view is that above 100 grains, is time to go "up a caliber" for the task.

I hope you prove me wrong!

Cheezywan

 

[Arctic_Eddie]

I had not intended to shoot anything heavier than 100 gr since I have some ammo left over from the old days and thousands of bullets. When I saw that the rifle will be 1:9 I decided to try some heavier ones. I guess it's just a question of how heavy I can go. This rifle will be used almost entirely for target. If I do anymore hunting I would use my M77 Hawkeye in 308. When I get some results for the Sierra 107 gr, I'll post again with the targets.

 

[mattsbox99]

Sierra even recommends a 1-7 or 1-8 twist for their 107 Matchking.

http://www.sierrabullets.com/index.cfm?section=bullets&page=bc&stock_num=1570&bullettype=0

 

[Arctic_Eddie]

That's surprising since most 243 rifles, and all my previous, are 1:10. It's going to be interesting to see how the new gun performs with 100 gr and 107 gr.

 

[arkypete]

The most accurate bullet that I used in my 243 Browning Safari was the Speer 105 grain. The, now discontinued, 105 grain round nose was far and away the most accurate. Both were deadly on deer.

Jim

 

[Cheezywan]

Because "you" are a handloader Eddie, you will find a good load. I've never worked a 243 that hard. I use my 6mm. up to about 80 grain bullets, then switch to a 30 caliber.

I can shoot 100 grainers purdy good. Just choose NOT to buy them because other rifles do "better" for me there.

I wish you well.

Cheezywan

 

[oneoldsap]

I find the 105 Gr. Speer to shoot very well from my Mod 7 Rem. They are good Deer medicine , I use W-760 .

 

[arkypete]

The 105 Speers are deadly. I used 39.5 grains of IMR 4350, CCI mag primers, for both the round nose and the spitzer. They had different points of impact, but very tight groups.

Jim

 

[broom_jm]

The 6mm Remington was originally introduced with a 1:12 twist, but quickly fell behind the 243 in sales because the Winchester offering had the 1:10 twist, which would stabilize both the lighter varmint bullets and the 100 grain big game bullets. After realizing their mistake, Remington reintroduced their gun (with a weird name, for a time) and changed the rate of twist to 1:9 inches.

If your barrel is being sent to you with the 1:9 twist but the chamber is not finished, you might consider going up slightly in power by having it finished as a 6mm Remington. This would be a better combination, all told, for the heavier bullets.

 

[Arctic_Eddie]

This rifle is coming complete and is a Ruger tactical model 17140. I already have a Hawkeye SS in 308 and wanted something smaller. I was going to have a local gunsmith build a 260 on an FN SPR action but the stock delivery was 5 months. Since I've got thousands of 243 bullets left over from the old days I thought the Ruger would be nice for some target shooting. Next year, I may still have the 260 built.

I checked Midway and Speer and they have nothing heavier than the 100 gr. I already have a sack of Sierra 100 gr SP flat base with a good load, 39 gr IMR4350. The only heavier bullets are 115 gr Berger, 107 gr Sierra SMK, and 105 gr Hornady SPBT. If someone could give me the bullet length for the last two, I could run the numbers through the JDM stability calculator and see if I'm close to trouble. I have a box of the Sierras on the truck now to arrive on Thursday. I think the best groups ever shot with my older 243s were using IMR4895 and 87 gr Hornady SP flat base(0.5 MOA). The 100 gr Sierras were not far behind at about 0.75 MOA. This was in a Rem 760 with a Bushnell 2-8x32 Scopechief.

 

[broom_jm]

The Hornady 105gr A-Max is 1.229" and the Berger 115 VLD is 1.325" long.

 

[Arctic_Eddie]

I found a photo of various 243 bullets on 0.1" grid paper. From there, you can estimate the bullet lengths. However, your numbers are more accurate.

http://www.6mmbr.com/243Win.html

The Hornady 105 gr A-Max at 2800 fps has a stability factor of 1.213. Pushing it to 2900 fps improves only to 1.227.

The Berger 115 VLD at 2700 fps has a stability factor of 1.053.

Based on a discussion by "unclenick" elsewhere in the forum, the Hornady appears marginal and the Berger may be out of the question.

http://shootersforum.com/showthread.htm?t=65775&highlight=stability+calculator

The old 105 gr Speer in round nose version would work as others have found. There's a reloading shop near me so I'll give them a call.

I notice also that most bullets heavier than 100 gr are boat tail. This probably aggravates the stability factor by requiring more length for a given weight.

 

[broom_jm]

Well, in all fairness, as a projectile of a given diameter increases in weight, it can only get longer, more cylindrical or more dense. In other words, there's a pretty good reason most .243" bullets don't weigh more than 100 grains.

 

[243dave]

Berger now makes a 95gr VLD made for the 1-9 twist. The BC on that bullet is .486(I believe). Also Sierra has a 95gr hpbt but I can't remember the BC on it but I believe its made to handle in the 1-9 twist also. Check out their websites for the info. These two bullets would make awesome long range bullets while cruising at a easy 3000fps. Dave

 

[Arctic_Eddie]

Found them at Midway. The Sierra BC is 0.480 and they still recommend a 1:7 or 1:8 twist. The Berger BC is 0.486 as you stated with a recommended twist of 1:9. Since the bullets are the same weight and form factor it's surprising the different recommended twists. I've got a box of Sierra 107 gr SPBT coming and some leftover ammo using Sierra 100 gr SPFB. Will try to shoot the 100's next week at the range.