Home Forums Hunting & Shooting Custom Rifles & Wildcats Real world velocity....243 AI vs. 6-284

I just traded for a little 243 AI in an A-3 with a 27" Hart , 8" tube that I had gotten with the idea of sticking a 6-284 reamer into to really take advantage of the longish barrel. I just went and shot it and it shoot fantazmigorically. The gentlemen I got it from sent with it lots of 105 A-max jetted with RL 22 that he claimed shot into bugholes. I just went out and shot prone off a bipod and shot his reloads into the .4s with no prollem. 87 v-max into the .5s, no prollem. So I am thinking that I might become a 243 AI cat. So answer this.....What is the real edge that 6-284 has over 243 AI in the velocity department, all things equal...same pressures, same bullet, same barrel? 150 fps?

Horrible bore life

Having owned neither, my guesstimate is at the most 50 fps difference. That's what I have seen between the 257AI and the 25-284. 100 grainers for example are good for 3250 in the AI and 3300 in the -284.

Bet you're talking 3-4 grains case capacity difference.

I would leave it as is.

I've owned both, and still own my .243AI. I see no advantage to the 6-284. More powder, marginal velocity gains only with the heaviest bullets.

Can't see spending the money to switch for such a minimal gain. My 30" 6-284 gets just under 3400 fps with the 107 SMK. Sure you'd gain a tiny bit over the 243 AI but you would have to pay quite a bit to do it. Reamer, chamber job, dies, and brass. At least you wouldn't have to fireform the brass to make an AI. BUT if you choose 6.5-284 Lapua brass you would have to neck it down.

Save the money for another barrel/chamber job that's exactly like what you have now!......grin. Sounds like you have a great rifle!!! Congrats.

azshooter, explain why you do not have to fireform the brass for an 243 AI..
6.5x284 is an easy neck job in the 6.284 die.. Using 284 wincester brass requires form dies to get it to 6mm without sizing problems.I have shot a 6.284 for years.Can get the velocity I want without the pressure signs the same velocity produces in the 243 AI.
The 6.284 in a long action give you more bullet and load choices for heavier bullets.
Barrel life for mine is at 1800 rds with only slight accuracy slip.
I would stay with the 243AI if I were you cause you have it and it shoots.

foogle:

It was a typo. The sentence should read: At least you wouldn't have to fireform the brass to make a 6mm-284. (NOT AI) I usually reread my posts, missed this one. Thanks for helping me correct it.

I agree it is difficult to neck down 284 brass without some damaged cases. I took my chamber reamer and a piece of an old 243 barrel and made a forming die to partially neck down the 284 win brass. Finish the necking down with a S bushing die.

If you start with 6.5x284 brass you do not have this trouble. Nor do you end up with over thick necks like you will using 284 brass.

I wouldn't mess with a gun shooting in the .4's. Probably whack 3" off the barrel, but I am not into looonnngg barrels.