Hi to all on the forum. A new rifle beckons and the choice is looking to be down to .243 AI or 6MM REM AI. I have shot the .243 before but have no experience with the 6mm rem. It looks to be able to provide all that the .243 can but with knobs on. I would like to build the rifle as a repeater with a drop box so will I need a long action for the 6? Also is the throat erosion actually less with the 6 than the .243 a is rumoured? Any input from you knowledgeable gents (or ladies) would be much appreciated including any general experiences with either of these cases.
ATB

If you go with a Remington and want to load VLD's thru the mag you will need a long action for the 6mm . Will need a shortish throat for a .243 AI in a short action if using VLD's but conventional projectiles will be ok .
The 6mm might be good for another 100 FPS . The .243 has the advantage of Lapua brass being available .
Find it hard to believe that there would be much difference in throat life with the 40 degree Ackley versions of either case .
Fast twists will still shoot good groups with light pills . I'd go with an 8 inch if you want to shoot at seriously long range .

Thanks much appreciated, anyone else with an opinion on this?

Well, I pretty much have to agree with Bushchook on this one. I would choose the 6mm version over the 243 anytime.

The very reason to go with an AI version of either cartridge is to go faster, right? Then why not use the one with the most case capacity? The 6mm Remington version.

As was mentioned, with VLD bullets you may well need the long action with a 6mm Rem AI. However, if you stick with more "conventional" bullets, I do not see the need.

Besides, I just like that long neck on the 6mm Remington. Silly maybe, but there you go. And maybe, just maybe, that is one reason the 6mm Remington seems to give longer throat life than the 243 Winchester. I just do not know what difference the Ackley improvement will make.

But then unless I wanted to do some "really" long range shooting I would just build a standard 6mm Remington and be done with it.
I have one sitting in the closet that has take prairie dogs at over 750 yards, seems like enough to me.

I agree with straight 6mm Rem. I shoot one and will never change. It is extremely accurate and though having only shot it to 500 yds, that distance is definitely more than easy for it.

Straight 6mm on a short action. That's what I use anyways. I don't shoot the VLDs though. 70 NBTs. It's my coyote rifle. The AIs are too much of a pain, why bother. UNLESS, you just want an AI, then go for it.

243AI. Why? One answer, Lapua brass. Another reason, it will feed out of a short action which will provide a more compact and rigid platform vs a LA. I will have to agree that a standard either 243 or 6rem case will do it all without all the trouble of fireforming, AI is more of a "cool factor". Go standard case with a good min. sammi cut chamber and custom barrel. The accuracy will impress you so much you'll forget about the AI.
Yes, I have a 243AI and if done again I would go standard, less work=more trigger time.

Eddie Fosnaugh

Eddie Fosnaugh

Well, I own about 6 different 243s, and love each one of them...
I have built ONE 6 mm Remington on a Long Action... Long Action is the key.. short action, go with the 243....the extra case capacity on the 6mmRem is a waste of time when you have to seat the bullet deep because of action length restrictions....

I haven't seen the big reason for the Ackley as I get plenty of performance out of a 6mm Case when in a long action..... Just when you get it throated at the gunsmith, make a few dummy rounds with long bullets..... that fit the entire magazine length... tell him to make the throat fit these....

The Weatherby guys and the 6mm/06 guys say BS, but as far as my chronograph says.. a long action 6mm Rem that is handloaded easily beats the published FACTORY ballistics of the 240 Weatherby....

To loads I use a lot of;

4064 with a 75 grain Hornady HP with an MV of 3650 to 3675 fps....

47.5 grains of H 414 with a 75 grain HP... with a MV of 3750 fps in a 24 inch barrel....

46.5 grains of RL 19 with a 105 grain Speer/ A MAX/ 107 Sierra HP Match/ Berger 105 grain Match/ 115 grain Berger Match.... all chronograph at 3250 fps...The last two are the most accurate loads....

One final Note! 1 in 8 Twist! or one in 7! to take advantage of being able to seat those long match bullets way out there....95 grain Partitions or Ballistic tips also will run about 3350 fps in the 6mm Rem with the 47.5 grains of RL 19....

A few guys I know with 6 mm RemAIs actually don't get the velocity I do... but then they don't seem to have a throat on their rifle that takes full advantages of their magazine's full length...

With the bullet seated out that far... there is no pressure problems at all on my Remington...

cheers
seafire

Thanks for the info fellas. All very useful stuff. Well, the actions has been chosen and its a Sko L691 long action with a single set trigger. To be mounted in a HSP varmint stock and with a fluted barrel in REMI varmint profile. Any ideas on reamer dimensions or what has worked for you. Seafire, who made the reamer for yours?

Tis the season to be jolly. Apart from critters cos we get more time to chase em this time of year

quote:

Originally posted by zaitsev:
Thanks for the info fellas. All very useful stuff. Well, the actions has been chosen and its a Sko L691 long action with a single set trigger. To be mounted in a HSP varmint stock and with a fluted barrel in REMI varmint profile. Any ideas on reamer dimensions or what has worked for you. Seafire, who made the reamer for yours?

Tis the season to be jolly. Apart from critters cos we get more time to chase em this time of year

The reamer was owned by the gunsmith and I don't know where he got his...I did seat a couple of bullets to make dummy rounds that would fit the full length of the magazine... I took them to the gunsmith with the barrel and told him to ream the throat to fit the dummy rounds.....That is the way I usually have a barrel done....

I spend money on the brass and dies first, before I get the barrel.... Then I seat the bullet at various lengths and then test fit them into the action... If all looks good or feels right, then I buy the barrel....

I have found a bag of brass wasted, and a die set that may not be used, can be sold for not that much of a loss... is a cheaper way to go first.. than buying a barrel and then finding out that you don't want the cartridge combo...It has saved me from more than a couple of disappointments...

I just did that before ordering a barrel in 243 WSSM recently.... got the die and some brass and loaded up some dummies that looked great and like they had long range potential... but then on the reload info, I found that the WSSM doesn't give me anything that the 6 mm Rem isn't already giving me....

This is on a Savage project... So instead I might go with a varmint weight barrel in 257 Roberts or a 250 Savage... set up for shooting 75 grain and 87 grain varmint bullets...

cheers
seafire

Zaitsev,

I know I'm kinda' late to this conversation but I couldn't resist as the 6mmAI is my favorite groundhog cartridge. Check out the following web address for some good info on this topic from noted gun builder, Richard Franklin http://www.6mmbr.com/gunweek042.html

Also, check out Richard Franklin's website at http://www.richardscustomrifles.com/ for some more info on the 243AI / 6mmAI debate.

Ernie B
in MD

If you're going with a full length Sako action (3.65" magazine), then why not take advantage of it and use a 6mm/06 AI case? You will get only marginally more velocity on the top end as compared to, say, a 6mm REM AI, but you can achieve top velocities with slightly lower pressures. The down side is that you'll have a little more recoil, burn a little more powder, and the extra powder won't be helpful to bore life.

I have both .243 and 6MM Remington. Like them both. The Remington in my opinion is a little better with the heavier bullets and the .243 excells with the 70's and under. I had considered the same AI question you have for sometime. I made another decision and have a 6MM/284 and is has both of them beat. Which you can also get Lapua brass for.

Hi Jay, I too have looked at some of the higher capacity 6mm cases such as the European 6x68 etc. I have not come across the 6 284 though, how does that compare with the other two in terms of ballistics?
I had thought that the 6mm would be better with the heavier bullets so the reamer has been ordered with a throat to optimise 87 through 107gr bullets. Just waiting for the Krieger 1:8 twist barrel to get here amd then we're in business. Would be interested to know any load data or fireforming tips any of you have with regard to the brass for the 6mm as i intend to fireform prior to shooting rather than just jamming loads down the smokepole. I've a feeling that barrel life will not be great in any case so I intend to maximise it!

ATB

'let the bullets whisper gently'

Zaitsev

The 1 in 8 Krieger should be a good choice of barrel for 6MM. The 6MM 284 compares with the 240 Weatheby with and the 6MM 06 pretty closely. The 6MM now has quality brass available for it this wasn't true when I had mine built. Now you can get 6.5 284 Lapua and just neck it down it's ready to shoot a very simple process. You might have to turn the necks just a bit. Barrel life will be short I've heard some say 700 rounds some 1000. I'll give you a couple of websites to look at they started my 6MM 284 curiosity. The second site is pretty old and you can get much higher velocity with RL 22 and RL 25. If you haven't ordered your barrel I'd go with a 28" barrel maybe even a 1 in 7 and shoot some of those really long 115 Gr. VLD's. I've shot my gun very sparingly. The initial results have been very impressive. But I don't have any VLD data to share with you yet. Mine is built on a Rem action with a 40X barrel 27.5 inches with a 1 in 9 and something twist.

I have a Nightforce 8 X 32 mounted on it. No it isn't a carry rifle. My gun reaches 3400 fps so far with Berger 95 Gr VLD's. That's not a Max load.

Aucton Gun works

6/284 heavy

Hi Jay, thanks for the info. The barrel I have ordered is a 28inch but this will not be a very heavy profile as the gun wil be doing many duties. Custom semi heavy fluted profile so we'll see how that works out. The load data for the 6-284 looks similar to the 6mm AI but we'll just have to see how they compare as the reamer is already ordered in 6mm AI. Whats the best brass you have used for the 6MM Rem as i hear conflicting opinions from many, some saying reduce 7x57 brass (norma) some saying use remi or winch. What have you had good luck with and how do you form it?

ATB

Zaitsev

The 7X57 would be the brass to use with your gun.

I started shoot the 243 back in the 60's and presently have two and one 6mmrem and two 6mmremAI and I've replaced barrels more often on the 243 than the 6mmrem. Kind of the reason Tubbs is using the 22-250 case for the 6x. I haven't stopped shooting the 243 kind of like with my 6-284 you know your going to have to replace barrels sooner and if I had to worry about it then shouldn't shoot the 243 or 6x284. Just my .02

quote:

Originally posted by zaitsev:
Hi to all on the forum. A new rifle beckons and the choice is looking to be down to .243 AI or 6MM REM AI. I have shot the .243 before but have no experience with the 6mm rem. It looks to be able to provide all that the .243 can but with knobs on. I would like to build the rifle as a repeater with a drop box so will I need a long action for the 6? Also is the throat erosion actually less with the 6 than the .243 a is rumoured? Any input from you knowledgeable gents (or ladies) would be much appreciated including any general experiences with either of these cases.
ATB

Years ago I traded away my 6mm Rem 700VS
because I could not feed through the magazine the handload that shot best, and that was only a (L O N G discontinued) 70gr Nosler HP

Those bullets seated out to 0.004 short of the rifling would land in a single hole out to 250yds, but they were a good 0.075" too long to fit into the magazine.

If I were going to build a 6mmRem or 6mmRem-AI
it would be on a long Rem700 action.

I still don't understand how Remington thinks that a necked down 7x57 should be chambered in a 308Win length action.


AllanD