Help with 6mm choice

[Jackmonkey]

I would like some input on which 6mm route to take.

I currently have a Rem 700 SA in 243 that I would like to rebarrel. This rifle will be used for hunting whitetail deer and the occasional groundhog. I would like to use VLD and/or Amax bullets in the 105-115 grain range for deer and the 87 grain Vmax for groundhogs. I want to push the heavier bullets to 3100-3200 fps but keep the barrel length at 24” so it’s easier to carry. A Wyatts mag box will be installed to allow for 2.995” COAL.

I was almost sold on the 6mm CM but have been kicking around the idea of the 6mm Ackley Improved lately due to the case capacity and neck length. I have also considered the 6x284, 6mm Crusader,243 AI and the 6mm CM. Would any of these cartridges accomplish this? I don’t know if I might be asking for the impossible but that’s why I’m posting this question.

What would be the best twist rate for using 105, 115 and 87 gr bullets? Is that even possible? If I can’t get both to shoot well, I will only shoot the heavier bullets.

I don’t mind fire-forming cases as I think that is part of the fun of reloading. Barrel life is not a huge factor as this will be a hunting rifle but I would like 1000+ rounds out of it.

Any positive input is greatly appreciated. I will be sending my rifle off to my smith in January.

 

[6fatrat]

I shoot a .243 win. 7.5 twist in my any rifle, 3080 fps in a long throated 30' barrel. I also hunt with a 22' barreled 243 throated for a SA mag length that allows me to get 2975 to 3000 fps with a 100 grain weight bullet. In a hunting rifle the OAL of your ammunition will be the determining factor.
Steve Bair

 

[Dgd6mm]

You will need a 1-7.5 twist barrel to run the 115, 8 twist is marginal and most 8 twist will not give you satisfactory accuracy. 24" is a stretch for 3200 with a 115, not sure it can be done without your equipment suffering (brass, barrel). The 6AI may get you there. I cannot speak for the 6mm Competition Match for mine are 27, 28, and 30".

 

[Liven The Dream]

I shoot a 6 Rem. 1-7.5 32" 115 D-tack 3040 Vol. Yes it will shoot faster. Remember the barrel life is short.
On my 2nd barrel 1800 to 2000 rounds This is a 1000 yard rig.

Small hole Big Burn = short life.

If you want to shoot 115's you will need case capacity ? If you go 107 105 gr. Smaller case 1-7.5 twist 600 yard Plus.
Go with the longest barrel you can.

 

[Frankr]

Jackmonkey the barrel twist imo is going to depend on your altitude you plan on shooting the rifle. I'm anywhere from 300 to 1,200 FT and I need a 1-7 twist to stabilize a 115 VLD Hunting Bullet. I have been building the same kind of rifle you are. But i'm using a custom action that will allow a 3.2" OAL loaded round. short mag action. I also don't have a Problem with a 26" length Barrel. I went with the 243 improved 30 deg for my build. I feel it was easy to get die's & reamer. I think it will work fine. My current Rifle is a 6XC 26" 1-8 twist barrel on a Rem 700 SA Standard Rem BDL style box mag. I shot it yesterday morning at 25 deg F My load of 40.5Grs RL17 produced 3,152..3,149..3,152 FPS dead on at 200 Yards. 3 shots measured 3/4" at 200 yards. This is with a 105gr VLD Bullet. I really Like the 6XC It's super accurate low recoil,High Velocity,Easy to load. But I can only get this kind of Velocity with RL17. The greatest thing I have found with RL17 Is it is Truly a temp stable powder. From 85 deg F to 25 Deg F I olny lost 30 FPS. And it does shoot better in colder weather. But wanting that kind of speed with different powder's and be able to shoot the 115 lead me to the 243 Improved 30. so i'm in the process of building it hope to have shooting in July.

I may have Forgot to mention it was ca ca COLD..berr... may have been the reason for the 3/4" group and only shot three to check Velocity and zero cause Hunting starts Monday. But My season wont start till next Saturday.The rifle Shoot's 1/2 MOA or Better most of the time.

 

[rcw3]

Jackmonkey the barrel twist imo is going to depend on your altitude you plan on shooting the rifle. I'm anywhere from 300 to 1,200 FT and I need a 1-7 twist to stabilize a 115 VLD Hunting Bullet. . . . . .

I have never had issues with true 7.5" twist 6mm barrels with the 115 VLD's, so I am curious why you indicate you "need" a 7" twist. Did you have a true 7.5" twist that did not stabilize the 115 VLD's? A while back I worked with two different 7" twist 6mm barrels and both the barrels had excess pressure issues with loads that otherwise would be fine in 7.5" twist barrels. A friend of mine also purchased a 6mm 7" twist barrel and had pressure issues with it too. Those personal experiences, and my friend's report spooked me as to using 7" twist barrels in a 6mm anymore.

I guess I am curious if the 7" twist 6mm's have shown any issues for you or anyone else?

Robert Whitley

 

[Frankr]

Jackmonkey the barrel twist imo is going to depend on your altitude you plan on shooting the rifle. I'm anywhere from 300 to 1,200 FT and I need a 1-7 twist to stabilize a 115 VLD Hunting Bullet. . . . . .

I have never had issues with true 7.5" twist 6mm barrels with the 115 VLD's, so I am curious why you indicate you "need" a 7" twist. Did you have a true 7.5" twist that did not stabilize the 115 VLD's? A while back I worked with two different 7" twist 6mm barrels and both the barrels had excess pressure issues with loads that otherwise would be fine in 7.5" twist barrels. A friend of mine also purchased a 6mm 7" twist barrel and had pressure issues with it too. Those personal experiences, and my friend's report spooked me as to using 7" twist barrels in a 6mm anymore.

I guess I am curious if the 7" twist 6mm's have shown any issues for you or anyone else?

Robert Whitley

Thanks for the info on the 7 Twist barrel's. I have never shot one. Im going with the Berger Twist Calculator Berger says you need a 1-7 Twist for the 115 VLD. I have one on order and will chamber it in the 243 IMP 30
from your site. I have asked about the 7 twist my self several times and all I get is 7.5 or 8 twist story's. Im going with Berger's Recommended twist and I will have to try it for my self. I don't have a problem chambering a few barrel's But I hope to see this 7 shoot.

Thanks for having Die's,Reamer prints.Load data, ready to go. Just makes it easy to get one set up.I ordered my dies. called JGS and have a reamer coming. no fuss. answered my e-mails,phone calls. 6mmAR.com Great site.

 

[Phil]

The 6.5 SAUM with the Barnes 127 LRX will do it......

3250+ hits them hard.

 

[Frankr]

yea phil so does the 6.5 creedmoor with a 140 VLD at 2,950 FPS from a 24" barrel BUT they just are not as fun as a good shoot n six bore.

I know you want to ask how do you get a 140 VLD at 2,950 FPS from a 6.5 Creedmoor. the secret is in the brass case. hey if they did not want it to go that fast they should not have made a case holds that much powder.

 

[Jackmonkey]

I already have a 6.5x284 running 140 VLDs at 2950fps and it's shooting bugholes.

This 243 is pushing 95 VLDs at 2935 and I know I have more room to go but it's very accurate at that velocity. I just want something different.

 

[Phil]

I know you want to ask how do you get a 140 VLD at 2,950 FPS from a 6.5 Creedmoor. the secret is in the brass case. hey if they did not want it to go that fast they should not have made a case holds that much powder.

Not particularly..... ;D

I`m getting 3100-3150 with the 140 Berger in the 6.5 SAUM.

I looked STRONGLY at the 6 Creedmoor though....

I will be eagerly waiting your results with the 243 30* imp. I think this is what I`m going to do also.

Actually I`m thinking about doing a switch barrel .243 30* imp and a .22-243 30* imp, as I do more calling than anything else I think this will fit the bill...

The 6.5 will be for hog hunting or longer range yotes.

Keep us posted on your progress.

Phil.

 

[Frankr]

Ok back to jackmonkey's question. It can be a tough choice. with so many fine cartridges to choose from.
I know for sure I wanted a 6XC. love it. I have got the velocity out of mine that was claimed. with no case or loose primer pocket issues. but Im shooting a 1-8 twist for the 105's which is what I wanted, can stay inside the short action mag with no problems. but in my experience shooting it from say 3,000 to 3150 FPS I can say I think it would be hard to get a 115 to that speed out of the 6XC. so I looked at other 6mm that are nothing more than a longer 6XC to be able to drive the 115's to 105 velocity. I went with the 243 imp 30 because it fit the bill,die's ,reamer, load data readily available and easy to get. Truthfully there may be no need at all to shoot the 115's over the 105's. but I wanted to build something so I know how you feel. I do not think any of the 6mm are a bad choice, 243,6 rem,6cm,243 I30, 243 AI 40, 6mm AI 40. gee 6SLR 6/284.6/06 ect. just a few I can think of.
but when it comes time to pick one, if you don't have die's. if your smith does not have a reamer or not the right reamer you want. if you cant find cases. ect some times that can eliminate a few from your list. I also think you need to throat it right to either fit your mag length or personal preference. I like to throat them long I like the bullet out of the powder space just at or slightly above the neck shoulder junction. it works for me. I don't like the bullet high in the neck or half way in the case. I looked at all the prints and made some measurements from cases and bullets I have and chose a .130 free bore for mine. it maybe shorter than I would like but I may have to shoot 105's if 115's dry up and I cant get any. so I hope you now know what to chamber.lol....

 

[Phil]

Ok back to jackmonkey's question. It can be a tough choice. with so many fine cartridges to choose from.
I know for sure I wanted a 6XC. love it. I have got the velocity out of mine that was claimed. with no case or loose primer pocket issues. but Im shooting a 1-8 twist for the 105's which is what I wanted, can stay inside the short action mag with no problems. but in my experience shooting it from say 3,000 to 3150 FPS I can say I think it would be hard to get a 115 to that speed out of the 6XC. so I looked at other 6mm that are nothing more than a longer 6XC to be able to drive the 115's to 105 velocity. I went with the 243 imp 30 because it fit the bill,die's ,reamer, load data readily available and easy to get. Truthfully there may be no need at all to shoot the 115's over the 105's. but I wanted to build something so I know how you feel. I do not think any of the 6mm are a bad choice, 243,6 rem,6cm,243 I30, 243 AI 40, 6mm AI 40. gee 6SLR 6/284.6/06 ect. just a few I can think of.
but when it comes time to pick one, if you don't have die's. if your smith does not have a reamer or not the right reamer you want. if you cant find cases. ect some times that can eliminate a few from your list. I also think you need to throat it right to either fit your mag length or personal preference. I like to throat them long I like the bullet out of the powder space just at or slightly above the neck shoulder junction. it works for me. I don't like the bullet high in the neck or half way in the case. I looked at all the prints and made some measurements from cases and bullets I have and chose a .130 free bore for mine. it maybe shorter than I would like but I may have to shoot 105's if 115's dry up and I cant get any. so I hope you now know what to chamber.lol....

True^^^^^

There are a lot of good choices for the 6mm, brass and die availability are among your bigger concerns as well as the correct reamer.

Speed is GREAT, I love velocity, but accuracy kills.

Your goal of 3100-3200 is a lofty one, I understand it completely, but I don`t think it will be easily achieved in a short action.

Pick the one best suited to your application and have a ball.

Good luck in your quest.

Phil.

 

[Dgd6mm]

I was running 3225 fps in my 27" with a 115 Dtac. I settled at 3153 fps, quite a bit less vertical at 1000 yards. The powder is H1000.

 

[Jackmonkey]

I was running 3225 fps in my 27" with a 115 Dtac. I settled at 3153 fps, quite a bit less vertical at 1000 yards. The powder is H1000.

Which cartridge is that with?

 

[Liven The Dream]

More 2 cents Why a 243 Ackley ?? The cost of Dies the Brass work up ?

6mm Rem. Brass ! Better shoulder angle , dies cheaper , No fire forming !

Load and shoot , will do what a 243 Ackley will do for less ?

Been there Done that Ackley thing ! to much work and time .

 

[Phil]

I was running 3225 fps in my 27" with a 115 Dtac. I settled at 3153 fps, quite a bit less vertical at 1000 yards. The powder is H1000.

Which cartridge is that with?

I`m pretty sure Don is shooting the 6mm Competition Match......

He has a lot of experience with this cartridge and if very forthcoming with first hand information, all you have to do is ask him.......

 

[Dgd6mm]

I was running 3225 fps in my 27" with a 115 Dtac. I settled at 3153 fps, quite a bit less vertical at 1000 yards. The powder is H1000.

Which cartridge is that with?

6mm Competition Match

 

[Liven The Dream]

I am shooting the Old Rem. 6mm/244 case. side by side it is a copy of 6.5x55 Swede.

 

[AckleymanII]

Don, I did not know the 6.5x55 was a copy of the 7x57? 7x57 is the parent of the 6 Rem?

I have had a flock of the 243 AI's with the 40* shoulder angle, never a feeding issue from the Rem 700 magazines, why are some of you wanting a 30* shoulder angle?