anyone one have any load data for this cartridge?

quote:

Originally posted by merlinron:
anyone one have any load data for this cartridge?

Strangely, it does not seem that Ackley himself ever published data for a 6.5X270 Ackley Improved. Could it be that someone else originated this cartridge, and called in an ACKLEY IMPROVED just because it has the same neck length and shoulder angle as it would have if Ackley had made an AI from a .270 case instead of an '06 case?? (He does show a ".256/'06 IMPROVED". This would be close to the same thing.)

Anyway, it would HAVE to be close in dimensions, including case capacity, to the 6.5X'06 Improved. For this round, with 120-grain bullets, you can start with 53 grains of IMR 4350. For 140-grain bullets, you can use 51 grains of IMR 4350 or 53 grains of H4831 as starting loads.

You will have to work up maximum loads in your own gun, as you know. And some of those loads Ackley shows in his books look pretty hot to me!! It would be even more difficult to determine maximum loads for rifles that are chambered for someone else's wildcat cartridges than it is for those cut for standard rounds.....

The 06, 270 and 25-06 have the same headspace. So would the AI versions. The 270 will have a little more gross capacity due to its longer neck. However loaded to the same OAL they have the same net capacity. 6.5-06AI data should work fine. If you can't find 6.5-06AI then start with 6.5-06 data and increase your max by about 4-5%. I lean towards powder 4831 or slower. MRP and RL22 are my choices.

For what it's worth the 6.5-280AI gives a very slight increase since the 280 case has the shoulder moved forward to keep it from chambering in a 270. Sure not enough to worry about. If you have not already built it then a 6.5Gibbs, 260Howell or 264Hawk give you the largest capacity on a 06 base. Sure not worth redoing however.

quote:

Originally posted by ramrod340:
The 06, 270 and 25-06 have the same headspace. So would the AI versions. The 270 will have a little more gross capacity due to its longer neck. However loaded to the same OAL they have the same net capacity. 6.5-06AI data should work fine. If you can't find 6.5-06AI then start with 6.5-06 data and increase your max by about 4-5%. I lean towards powder 4831 or slower. MRP and RL22 are my choices.

For what it's worth the 6.5-280AI gives a very slight increase since the 280 case has the shoulder moved forward to keep it from chambering in a 270. Sure not enough to worry about.

You have it right, IMO!!

hi fellas...
thanks for the replies.
i,ve been around the block with ackley improved cartridges a few times. i just thought maybe someone might have one. most of the stuff said above i know well. i am assuming the combination is right on the boarderline of overbore because it seems a little unpredictable as far as chamber pressures with what would be thought of as the right powders. 6.5-06 loads when upped 5% and backed off 10% for a starting load seem to work ok if the powder is just about charcoal and primers flatten real soon after that. it seems too soon, by what my other acklet guns show. i've checked headspace several times and it's good, the bore is long throated with normal 6.5mm throat diameter. brass is made from .270 win. cases,so i can't imagine the necks are thick...270 down to 6.5 isn't much of a squeeze.

Not sure this helps any but the only difference between the 6.5-06 and the 6.5-270 is that the .270 case is about .046 longer than the .30-06 case.....I assume you trim cases to spec.

vapodog,
there is a little difference in a 6.5x.270 and all the '06 case based variants.
cases have been trimmed to .270 spec.... made from .270 cases. dies, reamer and go- guage were made off of .270 case "head to neck" dimension of 2.156" as compaired to 2.109" for '06 case. the 40 deg. shoulder takes off from there, resulting in a case with a bit more volume than '06 case cartridge.
i fireform from empty .270 cases.... sizing down to 6.5 has the minor shoulder diameter (neck to shoulder junction) holding the case against the bolt face instead of the major shoulder dimension as in the '06 based variants. it's a "true" 6.5x.270 that won't let the bolt close if put in an '06 based chamber, the major dia. of the shoulder is .047" further foward on the case than anything on an '06 case. actually, more truely in between a 6.5-06 and the .264 winchmag. as said it gives a bit more volume, but i think it is real close to being overbore. makes me wonder how the .264 winchmag gets away with all that powder!

quote:

Originally posted by merlinron:
vapodog,
there is a little difference in a 6.5x.270 and all the '06 case based variants.
cases have been trimmed to .270 spec.... made from .270 cases. dies, reamer and go- guage were made off of .270 case "head to neck" dimension of 2.156" as compaired to 2.109" for '06 case. the 40 deg. shoulder takes off from there, resulting in a case with a bit more volume than '06 case cartridge.
i fireform from empty .270 cases.... sizing down to 6.5 has the minor shoulder diameter (neck to shoulder junction) holding the case against the bolt face instead of the major shoulder dimension as in the '06 based variants. it's a "true" 6.5x.270 that won't let the bolt close if put in an '06 based chamber, the major dia. of the shoulder is .047" further foward on the case than anything on an '06 case. actually, more truely in between a 6.5-06 and the .264 winchmag. as said it gives a bit more volume, but i think it is real close to being overbore. makes me wonder how the .264 winchmag gets away with all that powder!

Well, if you have worked your loads up to what seems to be maximum in your rifle, then I must assume that that load is indeed the maximum load for your rifle. And any data you might find for the 6.5X270 AI will only be suitable for the rifle that data was developed in, and not for yours.

In other words, you already know what works correctly in your individual rifle. So you may be "questing for the Holy Grail" here....

Nosler #5 has 6.5-06 data.

Use it as a starting point. Use normal handloading work-up procedures and you can expect to go about 5% over those loads.

quote:

there is a little difference in a 6.5x.270 and all the '06 case based variants.
cases have been trimmed to .270 spec

OK you have me confused. Below is a drawing. What I did was overlay a 30-06, 270 and 6.5-06. The black is the 30-06 the blue is 270 and the red is a 6.5-06. When an 06 or 270 is necked down to 6.5 the shoulder neck junction will move forward. Thus the red line overlays the back and blue along the shoulder. If you then take a 40 degree shoulder from that point using either a 06 or 270 parent it will never fit in a 06AI chamber. You might crush it in a 270AI but only because the junction of the shoulder and neck of a proper AI should be moved back from the parent. The various 25-06AI. 6.5-06AI 270AI are based on the parent converted to AI by blowing out the case converting to 40 deg and setting them back. They are NOT a 30-06AI necked down to the various calibers. A 6.5-270 will have a little more gross capacity than a 6.5-06 simply because the neck is longer. If you then load to the same OAL the net capacity is the same.

Heck a 25-06 is overbore. I used my wildcat 280 case in 257 (pretty much a 25Gibbs) from a 24" barrel I simply burned more powder to reach 25-06 velocities. Same case is 6.5 in a 26" barrel I can match or beat my handloads for a buddies 264Wmag.

In your case you simply might have a slow barrel. I've had rifles built using barrels from the same source same reamer, case, powder, primer, bullet be 100-150fps different. Heck I've had std cases that couldn't reach book max and the next rilfe same caliber would go several grs beyond. Each rifle, case, chamber is different.

You didn't mention powder. What I found to take advantage of greater capacity from a AI or my own wildcats lean to the slower powders. Faster powders gave me less if any gain before pressure signs.

ramrod and vapodog,

you are absolutely correct!!...i stand humbly corrected, what was i thinking? after looking at all three in the nosler#3 book, i called my 'smith and asked him about it and i mis- understood what he had told me about the reg. .280 and .270 case. i thought he was talking about the improved versions at the time. total brain-fart on my part. that's what i get for not fooling with the stuff for about ten years and then jumping in with both feet.

to add,....
it definately needs to have slow powders.certainly, 6.5-06 data should work,but my gun does definately reach max sooner than what is listed with just about any bullet i try.i guess that's why we play these games.

ramrod...what is the reason for the "slow barrel" do they show a bit more pressure from being tight?

quote:

ramrod...what is the reason for the "slow barrel" do they show a bit more pressure from being tight?

I will try a simple answer it will probably be my brain fart. As to brain farts if I had a $ for each one I've had in 58 years I would be rich.

Taking two barrels cut as close to the same as possible with the same reamer, brass, powder etc. For a VERY simple look. Work up a load in one you determine to be max pressure and record the velocity in that barrel fire that load in the other if the bore is larger then the velocity might drop. If the other bore is tighter you might see a gain in velocity as well as pressure signs. Is one smoother than the other? Heck maybe a slight increase in bore reduces friction so you get a velocity gain but when the bore gets too large you get blow-by. Too tight you might see a lot of pressure and friction removes the velocity gain. Heck I might be having my own brain fart and have them backwards.

When comparing a 6.5-06 book load and simply trying to say since your case has a 4% increase in capacity you should be able to use 4% more at max you have far more issues. Barrel, chamber dimensions, brass (even same manufactures can differ by lott as to dimenisions, capacity hardness). Add powder lotts, primers, atmospheric pressure and the list goes on and on.

Simple answer is book data is a reference point. Each and every rifle is a case in itself. While you can minimize the differences you can never really remove all of them.

Do a search for slow barrel or fast barrel. There have been numerous discussions with imput from far more knowledgable members than myself.

i will do the search.
as far as book loads go, i only look to see if things are more or less following suite, realizing it is just a reference and every gun is in a world of it's own. as said my 6.5 seems to live nicely at less charge wieghts than what is usually listed... i see serious primer flatening as the charge approaches standard 6.5-06 max loads in this gun, headspace, etc. good with .020" skip, but velocities seldom approach what is more or less "expected" out of an improved chamber. i do know that my 'smith prefers to chamber tight. after all, the "ackley" isn't necessarilly about increasing velocities!, and i'd rather have a tight chamber than a sloppy one. so it doesn't bother me. neck dia. seems about right, i don't remember what the dia. is, but spent cases won't quite hang onto a new bullet and i never had a split in 15 yrs.

quote:

but velocities seldom approach what is more or less "expected" out of an improved chamber

Guess it depends on the expectations. I've tested a lot of AI and other improved and blown out wildcats. Some with pressure equipment. On the 06 case a 1 for 4 increase at equal pressure is what I came to expect. So on an 06AI with 4% capacity increase a 1% velocity. To reach many of the published velocities I found some super high pressures. I have trouble reaching many of them with my case and it gives around 11% capacity gain. The AI style case hides the pressure signs you normally look for. Doesn't mean pressure is not there.

I don't know that velocities published for parent cases is not a good target for the AIs.

So what velocity are you looking at with 130 Grain bullets in a 22" barrel?
Butch

My last 6.5 wildcat was a 6.5-.270, and it did very well with my previously developed 6.5-06 loads. I found I could heat some loads up a bit in the light bullets (100-139gr), but the 160 grain loads were pretty set in their ways, according to my memory.
LLS

BUT, since you have already reached maximum loads for your rifle with various powders & bullets, you already know what your rifle's MAXIMUM LOADS ARE, at least for those powders & bullets. IF those bullets are satifactory for your uses, I am wondering what it is that you are still looking for??

there's lot's of different bullets and powders out there, to say i've found the best combination possible is impossible. i've found the best i can with what i've tried, so far, but i'm always looking and open to try something different for all my guns. especially this 6.5x.270, because it seems a bit pressure-pushy.

quote:

i've found the best i can with what i've tried, so far, but i'm always looking and open to try something different for all my guns.

I understand. What I try to do is identify the bullet(s) I think will give me the capabilities I need, whether for target shooting or some kind of hunting, then try to develop loads which will provide the best accuracy with a particular bullet.

This approach, of course, presupposes that one has identified the powder types which will provide the velocities you want with a given weight of projectile, and that you have a pretty good idea of how much of that propellant is safe as a starting load with that bullet....

I would say that with the round you are loading for, the powder must be slower than IMR 4350 for any bullet much over 120 grains in weight.

I once owned a 6.5 Gibbs, which you may know, is even "more of a good thing" than the 6.5X270 AI! I had the Gibbs chamber cut in the Dark Ages, back in 1958 or so. Failing to find any published loading data, I proceeded to load up a few rounds with 160-grain bullets, and TOO MUCH IMR 4350 - don't remember the exact load any more, but do remember the blown primer and having to use a wooden mallet to open the bolt! Fortunately, the action was a good M98 Mauser, and the barrel was made by Schultz & Larsen. Therefore, there was no damage other than my embarrassment! But I did learn one thing-find a safe starting load before you go any further!!

Good luck....

quote:

i see serious primer flatening as the charge approaches standard 6.5-06 max loads in this gun, headspace, etc. good with .020" skip,

I know you say you have checked and rechecked the headspace. But your situation sure sounds like a 270 case being fired in a chamber set for for a 06 case. If it were mine I would either shorten a few cases or form a couple on 06 brass and see if they behave the same way.

ramrod,
that issue came up when i built the gun. as .270's are longer, i requested the reamer ground to .270 OA.(2.540") case length to take advantage of the longer neck. that's where the "true 6.5x.270 ackley" comes from. i own a .270 also so brass is always at hand. i own an '06 also, but everbody has a 6.5-06, so i wanted something else.
the gun actually started life as a 6.5x.257 roberts improved, i shot that for a while and then decided to have it re-chambered to it's present chambering. gunsmith did set the barrel back as it should be. he actually set it back enough(1/4" IIRC) to make sure the entire chamber got a fresh cut, just to be sure it got a good smooth chamber.