6mm / 243 105 GR A-Max - What Cal?

[jrkotz]

Hey guys -

Looking for a new barrel for my LRPV.

I've decided that the 105 gr A max bullet is the one I'd like to base the build around, main purpose is 600 yd bench shoot and prairie dog shooting from 400-700 yards.

The question I have floating around in the ol' knoggin is - what brass should I put behind the bullet?

Looking for MINIMAL brass work with MAXIMUM speed and accuracy. Goal is to have a few hundred rounds to shoot the long distance dogs that my 223 and 204 can't reach.

I'd like to scream the thing out at 4000 fps ;D

But seriously, what do you have in mind? Thanks!

 

[15Tango]

I had 70 grainers going 3850 with no pressure issues out of a .243 Win. I could get a 105 out at 3200 but a 105 at 4000 FPS+? I just don't see it happening. You'd have to do something silly like a 6MM/338 LM or something where you're getting 200 rounds out of a barrel. The new up and coming powerhouse 6MMs are the 6MM SLR and 6MM CM - from reports they're giving same or better than 243 performance with better accuracy and better barrel life, less brass trimming. The 6XC offers a lot as well. The SLR is made from .243 brass and I think the 6 CM was as well, Lapua's available. The 6 XC stuff from Tubb is Norma if I remember correctly.

Wayne

 

[357Mag]

6mm / 243 105 GR A-Max - What Cal?

JR -

Howdy !

If'n minimum brass work appeals to you, and you want a 6mm wildcat of great design; might I suggest the " 6BG " ?

6BG was/is one wildcat designed by former Savage engineer
Robert "Bob" Greenleaf ( BG ).

Bob utilized a .300 Savage "GO" gage and .243 brass.

The chamber has the sharp shoulder of the .300 Savage, with all the bennies that come from operating a .243Win-class case

Speaking of recent memorial events, Bob is also a Pearl Harbor vet. He was serving @ a Marine machine gun training school (linking ammo, etc ) when the attack hit.

They had put the .50s away for the weekend, so the ready-use stuff @ 08:05 Sun 07 Dec '41 was .30 cal.

They had 8 instructors ( one for each gun ).
They engaged the Jap's from Pu Alua Point ( pardon spelling ), which was right @ the coast; on a hillside.

They shot down 5 enemy planes, and one friendly; during all the excitement.

Bob was wounded in-action while his crew did a
" John Wayne " on an in-bound Japanese attacker.

Bob completed his Navy tour at the end of WWII.
He put in quite a few years @ Savage. The Savage 110 bears testimony to the capabilities of Bob's fertile mind.

Bobis STILL with us today, and STILL shooting daily;
WX permitting.


What a guy !

With regards,
357Mag

 

[RJinTexas]

JR, Sorry but your not going to get a .243/6mm 105gr Amax bullet anywhere near 4000fps period.

Regards
RJ

 

[jrkotz]

Big smiley behind "4000 fps" means I know it's a pipe dream.

Just was looking for a somewhat practical, but fast as possible caliber.

That 6 BG sounds interesting!

 

[ollie]

What about a6x284? One step neck down. Lots of speed. Not much barrel life.

 

[357Mag]

JR -

Robert Greenleaf = vet382@comcast.net

While E-mail is not Bob's favortie comm media, you'll probably get a good response out of him about his " 6BG ".

Regards,
357Mag

 

[RJinTexas]

My 28" Kreiger 6x284 turned into a perfectly good tomato stake at just under 1000 rounds, won't do that caliber again. I'm happy with my recently new 6x47L after shooting 88 FB Bergers pushed by 40.0gr H4350 @ 3236 fps(very light load) out of a 28" HV Bartlein, shoots sub 2in groups at 500yds when I do my part. It performed well for me in the dog towns the past two seasons and after 600 rounds there's almost no throat erosion. There's plenty of room to speed this load up without having pressure issues but it shoots great as is and I'm old school if it ain't broke I don't go trying to fix it. Beside this load should give me resonable good barrel life. If your wanting a hot 6mm it's hard to beat the old 6mmAI it's my favorite long range 6mm cartridge. Look at Richard Franklin's gun of the week and artical on that cartridge.

Regards
RJ

 

[Kenny474]

If you want a good caliber that is fast without being as rough on barrels as the 6-.284, why not look to a 6mm Remington or 6mm RemingtonAI? A lot of the long range varmint guys love them and feel it's a much better round than the .243. If I was going to build another fast 6mm, (my 6-284 is toast) I would think really hard about the 6mm Remington, but more on if it would be an AI or not. It also has a nice long neck to help shield the throat from erosion as well, another plus over the other fast 6mm's.

Lapua may not make brass for the 6mm Rem, but the 100 pieces of Winchester I have for my 22-6mmAI build sure seem to be of very good quality, with consistent neck thickness and consistent weight as well.

If you want a fast 6, I really think the 6mm Rem is the way to go. Better than a .243, yet not as rough on barrels as the bigger 6's, what's not to like?

 

[fieldratsniper]

like said before. your not going to get a 105 amax at 4000fps using any practical means. but i dont really see a need to do it anyway. i think kenny474 had the best idea for a good, simple cartridge for what you want to do. a 6mm rem or 6mm rem AI would be great.

from hodgon's load data, the 6-284 only beats out the 6mm rem by barely 100 fps.

but if you really really want to say you have a round that pushes the 105 amax at 4000 fps, you could always neck down a 338LM

 

[Kenny474]

In my honest opinion, anything larger than a 6mmAI is pretty much at the point of diminishing return in the 6mm. You can only go so fast and put so much powder behind a bullet before you start getting less and less gain for the amount of powder you are burning. And I really think the 6mmAI is about the practical maximum for the amount of powder you can use in the 6mm bore without excessive waste and throat erosion.

I am not positive as to what the 6mmAI will hold as far as grains of water, but I think the 6mm will hold about 10grs less than the 6-284. And for that 10grs of extra capacity, the 6-284 is only about 100fps faster at the most. Not much gain for all that powder. In my manual, it states 48grs of RE22 for 3205fps in the 6mm for a 100gr bullet, now in the 6-284, 55grs of H1000 will get you to 3229fps. Not much gain for 7grs of powder.

I don't think you can do better for a good, practical and fast 6mm than the 6mm Remington or 6mm Remington AI. It has much to recommend it over any of the similar sized rounds, such as the .243, .243AI, or 6-284.

Good solid round with cheap and easy to find brass. Plenty of good load data available. Doesn't need any special forming or treatment. Even with the 6mmAI, you just load and shoot, forming is that easy. No false shoulder BS or other trickery. Just simply load and shoot with a standard load. You can even use factory ammo if the chamber is cut properly.

I don't see a better alternative with comparable velocity anywhere. At least none that are this easy to load for.

Kenny

 

[MQ1]

I'm with RJ on a the 6x47L...

I have found the 6x47L to be very efficient with an 8 twist and 105-107 grain bullets. With the Lapua brass, your prep is minimal, and I don't believe you give up much, it anything, to a straight 243.

When I was originally looking for a do-all 6mm, I posed the same question to Dan Dowling. We ended up deciding on a 12 twist 243AI, because brass forming is easy, lots of good selection of quality 243 brass, and minimal case stretch means more time shooting and less time maintaining brass. I have never regretted the decision...plus the speed is there, and with a 26" barrel I have been seriously impressed at the grouping out to 500-600 yards with 70 grain bullets.

I think that a 6mm Remingtion AI would be great, and looking at the pressure capability difference between the .243 and the 6mm remintion, I cannot help but think that would be a great choice as well...The cons are that you will not have quite the selection of brass...no Lapua, and if you need Wal-Mart ammo in a pinch, you will not have the selection as you would with a .243 (not that this is necessarily a concern).

I have found that of late, the Winchester bulk brass in 6mm Remingtion and .243 is on par in terms of weight consistency as Lapua, much to my surprise.


Good luck making a choice.....
MQ1

 

[jrkotz]

Wow guys, thanks to all of you, great info. Sounds like 6mm is getting a lot of nods, more than I expected. I assumed that 243 was more popular. Also, 6x47L is getting some attention. I'm going to have to do some load comparisons between 6mm/6mm AI 243/243 AI and 6x47L.

 

[MarkS]

jrkotz,

First thing don't build a gun around one bullet. I did this once and the bullet would not shoot. when I was hurting on what to shoot. Second, You said you are going to shoot 600 yd benchrest. None of the bigger 6mm will run with the 6BR and the 6BR IMP. You need to remember Speed want get you anything if it is not accurate. I would go with a 6BR IMP ( 6 Dasher or 6BRX ). They will give you all the speed you will need and accuracy past 1000 yds. PD are very small, you need all the accuracy you can get. For 600 yd Benchrest you need even more.

Mark Schronce

 

[jrkotz]

Thanks the info guys. I've narrowed it down to 6 BR, 6x47L and 243AI

I am building this on a short action Savage LRPV, with right bolt, left port.

Again, the goal is minimal brass prep, and hopefully reasonable barrel life for out to 400-600 yds at prairie dogs. I'll shoot our local groundhog match with it too.

I like the fall back option of the 75 and 87 Gr V-Max's.

I'd love to go 243 AI, but fire forming is NOT appealing. I'm really liking the 6x47L, seems like a good 'mid 6mm' cartridge - balancing MV with easy brass prep, lapua brass, and decent barrel life.

Any other thoughts before I 'pull the trigger' on a new barrel?

 

[jrkotz]

jrkotz,

First thing don't build a gun around one bullet. I did this once and the bullet would not shoot. when I was hurting on what to shoot. Second, You said you are going to shoot 600 yd benchrest. None of the bigger 6mm will run with the 6BR and the 6BR IMP. You need to remember Speed want get you anything if it is not accurate. I would go with a 6BR IMP ( 6 Dasher or 6BRX ). They will give you all the speed you will need and accuracy past 1000 yds. PD are very small, you need all the accuracy you can get. For 600 yd Benchrest you need even more.

Mark Schronce

I absolutely agree. My hangup is I'm a numbers guy, and more MV = less dope into the wind, and trust me, the plains of SD, CO and KS that I shoot dogs on has NO lack of wind. Best I could hope for out there is a full value wind. So you see my dilemma, with a good handload in a good barrel, I'm confident I can get a barrel to shoot for me.. now just to decide on a caliber.

 

[1000yardstare]

Why not just a straight 6mm Rem. No brass prep, great velocity.

One of my few successful rifles built on an M98 action was a Parker Hale 1200 originally in .30-06 rebarreled to 6mm Rem with a 26 inch McGowen barrel, Fajen prone stock.

Had permission from a golf course owner in the far out boonies of southern Ontario in the 1980`s to clean out groundhogs. Went in at dawn before members showed up. I invented Caddy Shack before the script was even written. The accuracy and range of the 6mm Rem constantly amazed me.

 

[HillbillySniper]

Try a 6 WSM if you want to git that kinda speed not sure of barrel life ;D good luck with your build

Hillbilly

 

[treeman]

my vote goes to the 6mm rem 1-8 twist excelent accuracy decent barrel life and flat shooting. what else do you want??

Treeman

 

[blacknwhite1]

If you guys were going to choose between the .243 win and the 6mm rem...which would you go with?