Sako308,

Is trajectory an issue at the ranges you intend on shooting?

I ran a few numbers in the Ballistics program and found this:

308 win. 180 grn w/ a BC of .501(Sierra SBT) @ MV of 2500 fps drops 28.5" at 400 yards when zeroed at 200.

6.5/284 140 grn w/ a BC of .495(Sierra SBT) @ MV of 2950 fps drops 19.7" at 400 yards when zeroed at 200.

If range is over 200-250 you would probably be better served w/ the 6.5/284 but, if you intend on shooting at close ranges, go the 308 route. At close range the 308 will pack a punch but, that 6.5/284 would probably pack a pretty good punch too. The 6.5/284 may give you the best of both worlds.

Good Luck!

Reloader

Well it seems my .257 Ackley Improved has run it's course and I now have a medium (short) action Sako in need of rebarreling. I am torn with two cartridges both with great respect, the .308Win (with a 1 in 9 twist)for 180 grain bullets and lower weights, and a 6.5/284 with a 1 in 8 twist)utilizing 125 and 140 partitions. All feedback would be appreciated. This is a general purpose rifle in a sporter configuration and a barrel length expected to be 24 to 26 inches in length, of a medium contour. I don't expect anything particular from this project however accuracy is a must. Your opinions are appreciated and desired. Thanks in advance, and good shooting.

I would choose .308

Both are good so you can't make a bad choice

I would, and will myself some day in the future, choose the 6,5-284. I have a 6,5 Swede today and this might be the basis for such a project. Go with the longer barrel!

26" is to long go with a 24 or shorter in .308

The .308 would be my choice with a barrel shorter than 24".

It's not common to rifle barrels 1-9 for hunting rifles in .30 cal. For bullets 180 and less 1-10 would be easier to get.

how about a plain old 284?
woofer

You liked the .257 enough to shoot out the barrel and you already have the dies.

Thanks fellas, I must agree that 24" might be a touch long for the .308, but I think the faster twist will aid in killing power. Just an opinion, but I think rotational forces will be beneficial for terminal performance. I have a 6.5/284 in a long heavy barreled rifle and have been nothing short of amazed at it's performance. So of course I am thinking it would make a super medium rifle as well. Yes either one would be a winner I guess. Still on the mental fence though. Thanks again.

Sako;



As few points when I looked at building a 6.5 mm cartridge on a Winchester Model 70.



I looked seriously at the 6.5 /284. I had a friend who had one and did some serious handloading and testing to see its potential. What disappointed me, and increased my faith in the 260 Remington, was that I was not able to get the 6.5/284 to increase the performance of the 260 by much at all, but the powder comsumption increase I did notice.



So I played with the 6.5 x 55 and tested the day lights out of it also. I already had a couple of rifles in it.



And since I knew a few people who had 257 Roberts AIs and 6.5/06s, I talked to them about their experiences also.



So what I settled up was necking the 257 case up to 6.5 mm to the 6.5 x 57. ONLY to find out that it is one of the oldest centerfire rounds out there. It was evidently made before the 7 x 57 and 8 x 57 rounds, for the Portugese government.



Being fielded by Portugal was one reason it probably did not set the world on fire.



I look at it as a 257 Roberts that will take bullets over the 120 grain max size for a 257. I have seen it called the 6.5 Roberts, the 6.5 x 257, the 6.5 x 57 and a couple of other names. All I can say of it, it sure is more powder efficient than the 6.5 x 284 or 6.5 x 06, yet it will obtain the velocities that those I know get from the other cartridges. for instance I have chronographed 100 grain ballistic tips out of this rifle at 3500 fps. The 264 Mag doesn't beat that by much at all, and has to be handloaded to do so. 129 grain bullets, and 125 grain partitions have hit 3100 fps easily and that rivals a 270 any day.



Accuracy has been second to none as in all 6.5 bores I have.



With your 257 barrel, you could just have it bored out 7/1000ths and you are done.



Just the road when I went down after a lot of research.



Cheers and good shooting

seafire

Seafire, Thanks for your input. I spent the day down in my dungeon AKA loading room, and was comparing both cases visually and working them through the action. I must agree that the 260 Remington has been a strong contender in the mix. I simply have been so awed by my 6.5/284 long distance experiences. But since you mention it, the 257 AI is just about the most light rifle you can have on a short action. I have used the .257 AI extensively in Africa and throughout North America on medium to light game. Thinking of using that case but increased to the .264 diameter does indeed have appeal as I believe it would feed more reliably than the .284 Win case. I shall adjourn back to the dungeon and make a few dummy rounds of your suggestion. Thanks again.

I think the 6.5x57 is a good idea. I've been wrong before and I may be wrong now, but the .257 groove dia. exceeds the bore dia. of the 6.5. It probably can be rebored but the rifling may be just a little shallow and or trace of the old rifling. roger

Reloader, I to have run some numbers, and don't think that I would get 2950 from the 140 grain projectile in the 6.5 bore if I stuck to a 24" barrel. My guess is more like 2750 ft/sec's and then the larger caliber has the advantage. Especially if using a 165/168 grain .30. My current 28" Hart 6.5/284 has pressure issues when exceeding 3000 ft/sec, but wow what it does at that speed. I think we all know that any of the possible choices would suffice, it's more a question of what fits in the current hole in the rack. I do believe that I would be interested in accuracy and effectiveness to the 600 yard range. Thank you for the input.

I would tend to agree with Seafire except that the 6.5x57 and the 6.5x257 are two different calibers. Hornady lists the 6.5x57 in its reloading manual. If you liked the 257 Ackley Improved why not neck it up to 6.5? P.O. Ackley lists this caliber as the .260 AAR, and it would be a sweetheart of a caliber. As far as reboring goes I think I'd just put a Lothar Walther on it. Good luck on whatever you choose. Paul.

It sounds to me like you do a lot of shooting, hence the barrel on your 257 IMP. If you want the barrel to last longer go with the 308.
David

I was at the range yesterday and a fellow had a high-tec(gunsmith) rifle on a med 700 action chamber in a 284, action was reworked and cut out to handle the 284 case and bullet set out and had a sporter barrel at 24". My 6.5/284 is on a win 70 action. If I had a choice between a 308 and 6.5/284 I'd take the 6.5/284 any day. Both my 6.5/284 and 308 have hart barrels and are tight neck. I think the 142smk is what making the 6.5/284 such a great long range case. If I was looking at the 140gr smk maybe a 1/8.5 twist barrel I'd think along the lines of a 6.5x55AI last choice would be a 260AI. Don't know much about the 257 cal as don't own one, but have know afew guys with 257AI and they really likes them. I'm a great believer in twist to bullets kind of build things around the bullets I want to use. I've got 30 cal twist from 1/18 to 1/10. I think a 1/9 twist 30 cal would be great for say the 190 gr lvd bullets my only question would be do you have enought case in a 308. Just my .02 worth! Good Luck

308Sako, Either Caliber would be fun I would try the 6.5x284 because I already have several 308's, don't you too. Choose the twist to fit the bullets weights you want to shoot.
However, the rotational energy of a bullet adds almost nothing to the killing power of a projectile. It is usually only about 1/4 of 1% of the energy of a bullet. Think about this, does a gun kick backwards or twist in you hands more? With equal and opposite reactions it's obvious that the rearward thrust is tremendously more than the rotational. "Understanding Firearms Ballistics" by Robert Rinker has a more detailed treatis on this if you want to explore it further........DJ

DJPaintles, Thank you for the referral on the knowledge issue of rotational energy. Regarding the original quere; the decision has been made and the rifle will remain a .257 Ackley Improved. As when you get down to it, it's tough to put more steam in a short action. I know what it will do and that's what matters most when leveling it at game. I do indeed have several .308's, and many other calibers as well to play with, and many bullets still to fly. I must thank Saeed, and the forum for the opportunity to reach out to fellow shoters and get erudite and educated responses in a timely fsahion. I can only imagine the mental wanderings of W.D. M. Bell or John "Pondoro" Taylor and other's who had to wait for the passage of steamers and carrier pidgeons for their answers! We are lucky and we are enriched. Thanks again.

Don't know if what I have to add will help any but I'll throw it into the mix anyhow. I've never had a 6.5X284 but I do absolutely love my original 7mm variety version of this case! As you've already stated VERY impressive! I also just like the look of the cases with that rebated rim, and the fact that not just everyone has one.

Some of the others mentioned the 6.5X57 and 6.5X257 and I will second the fact that they are 2 different cartridges. I can't yet tell you how I feel about their performance. Maybe I'll have some solid information here soon. Last fall I bought a Japanese Arisaka T-38 rifle that had been rechambered to the 6.5X257 and have just recently obtained dies for it, so like I said..........SOON HOPEFULLY! Planning ahead for future projects I've also already got dies for the 6.5X57 and a set I got free for a 6.5X257Rob Improv. 40 degree. The latter I would tend to think should get you pretty close to your 257AI but don't know, I'm looking forward to finding out!!! Just WAY too many guns to build and too little time and money.

As far as the 308 I'll second the question of "Don't you have enough already, I know I DO" But then again maybe you're not me. That would probably be a good thing!

As far as barrel length I'd have no problem with a 26" tube, but that's me. I personally feel that the extra couple of inches offers more than any hinderance it causes in swinging the rifle. After all it's a rifle, not a shotgun or club!

Didn't the 6,5-284 score high in long range competitions ?

I think i remember an article about a world record on 1000 yrds with that calibre ! I'm not sure, but maybe other here have more input i that matters.

BTW: Are building an 6,5-284 my self for long range target shooting in addition to my 300WM and 338WM.

Best of luck with your choice

How about a 6.5X55 AI?