Author Topic: Ackley Improved Cartridges (Read 1981 times)

vernonp · « **on:** August 08, 2004, 05:15:40 AM »

I know this is not the Wildcat Forum but I would like to get your opinions on some of these.----------For reloaders it is an economical way to soup up an existing round if you think you need that. I think my favorite is the 257 Roberts Improved. I have two and have really enjoyed them. You can pretty well match the 25-06 velocities with the short actions which I prefer. What are your thoughts.-------vernonp

Buffalogun · « **Reply #1 on:** August 08, 2004, 10:57:35 AM »

vernonp,

I have a 30-30 AI and really like it. It is very accurate. It is worth noting however, that some cartridges can't be improved on as well as others. Generally, the older cartridges which were designed with a generous amount of taper along the body can be improved significantly(30-30, 30-40 etc.). Most newer cartridges have much less taper and won't benefit much from "improving".

Buffalogun

Catfish · « **Reply #2 on:** August 08, 2004, 02:51:33 PM »

What you get from a case by doing the Ackley imp. on it depends on what the case looks like befor it`s improved. Older cases tha had alot of body taper and long case necks are real good canidates as you can get alot of extra case capisity. Cases like the 6 BR are at about max volume you can get and are a total waist of time. If your looking for extra volisity what you get is 1/2 of the % of increased volume of the case. In other words, if you increase the volume of your case by 10% you get a 5% increase in velosity. Hence if your rifle is getting 3,000 fps. with a 10% increase in volume you will get around 3150 fps. With a 20% increase in volume you could expect around 3,300 fps. ect. With most rifles you get an increase of 5 to 10 yrds. on your max point blank range for each 100 fps. So, if you had a max. point blank range of 270 yrds. and increase you case volume by 20% you could expect to get around 300 yrds. max. point blank range from it. With a 5% increase in volume your increase would net you around 5 yrds. increase in max point blank range, definately not worth the trouble.
The greatest thing about an Ackley imp. chamber is that you can still fire factory ammo for the original chambering of the round. Cases will also alst alittle longer with the Ackley chamber, especially if you have it with alittle tighiter that factory neck. For the people that are wanting to get their feet wet in wildcatting one of the Ackley imp. rounds is probibly the best place to start.

gunnut69 · « **Reply #3 on:** August 08, 2004, 07:01:46 PM »

As a rule I don't care a lot for the wildcats as their performance can usually be matched by some other standard cartridge... That said the K version of the Hornet does appreciably increase the precision of the case to chamber fit and greatly lengthens case life.

Bob C · « **Reply #4 on:** September 07, 2004, 12:28:24 PM »

I have a 6mm AI, and this is supposedly one of the less efficient of the AI calibers.

Mine does 3340 fps with a 95 grain Nosler partition, with no pressure signs. It averages 1.15" groups at 100 yards.

With a Sierra 100 grain spitzer at 3100 fps, it gives groups averaging just under 1".

Graybeard · « **Reply #5 on:** September 07, 2004, 05:06:32 PM »

Quote

Mine does 3340 fps with a 95 grain Nosler partition, with no pressure signs.

When you pull the trigger do you hear a rather loud noise that sounds sorta like BANG! Does the bullet exit the barrel? These are two very POSITIVE signs you have pressure. Without it you'd not get the BANG nor would the bullet exit barrel.

Sorry couldn't help myself. What you mean of course is EXCESS pressure signs. BUT sadly there are NO reliable excess pressure signs. Don't doubt your velocity but it does sound a bit high for SAAMI pressure levels in a 6MM Remy which is the same that should be applied to the AI version of same.

Where did you get your load data? That is the single biggest draw back to most wildcats. No reliable pressure tested data. Thus most of them are pushed past SAAMI specs and that NOT the extra case capacity is what gives the majority of the velocity gain.

Some like the .257 AI and the .280 AI have become popular enough that pressure tested data is available in several manuals. The 6 Rem AI is a pretty popular one. Dunno might be some data for it around too. I've always thought it would be a real nice one as I do have a soft spot for the 6 Remy. Sadly the only one I've owned was a Ruger #1B and it was a junker that barely kept bullets on an 8.5"x11" target sheet at 100 yards.

Bob C · « **Reply #6 on:** September 08, 2004, 01:00:58 AM »

The lack of documented data is definitely a challenge with wildcat cartridges.

You can find infromation on the 'net, but I don't trust it unless it comes from a known and reliable source.

I used the existing data for the 6mm Remington as the source of data for the 6mm AI, starting closer to the maximum than to the starting loads.

From there I work up slowly.

The particular loads I mentioned were chronographed, not estimated, and the faster load was 5%-6% more of the particular powder than the published 6mm maximum load.

That seemed to be OK in this particular rifle with these particular components, but I wouldn't recommend it for anyone else's rilfe or for their components.

Graybeard · « **Reply #7 on:** September 08, 2004, 05:23:14 AM »

Quote

The particular loads I mentioned were chronographed, not estimated, and the faster load was 5%-6% more of the particular powder than the published 6mm maximum load.

That seemed to be OK in this particular rifle with these particular components, but I wouldn't recommend it for anyone else's rilfe or for their components.

I would agree that a 5%-6% powder increase over the parent cartridge "should" be safe for the AI in this case. I've not checked it but you should gain that much extra volume I think. As I said the 6MM Remy has always been a round I favor. I just wish someone chambered it in a nice selection of rifles rather than only in Varmint weight guns as Remington now does. I gave a Ruger a try in the #1 and wow was that a junker. I've been tempted to turn my LW243 into a 6mm or 6MM AI but it is just soooo accurate I hate to mess with it.

I have a huge supply of 6mm factory ammo and cases just sitting waiting for the day I find just the right rifle to use them in.

smoky · « **Reply #8 on:** September 08, 2004, 05:54:28 AM »

In my 7-08 Ackley Improved, I am shooting a load that is 5.8% over the printed maximum for the parent cartridge, with no signs of excessive pressure. In working up this load, I was told that Mr. Ackley often stated that +5% was about where most seemed to work best.

Smoky

Mirage · « **Reply #9 on:** September 17, 2004, 03:27:43 PM »

The 5th edition Sierra has load data for various ackley's including the 6mm remington. Also the Nosler manual has some (22-250, 257, 280?)

Mirage

handirifle · « **Reply #10 on:** September 17, 2004, 05:36:46 PM »

At the range today I spoke with an elderly gent that has a lot more years of handloading than I'll ever have. He was telling me of his thoughts on AI rounds. He was referring specifically to the 22-250. It seems he is on his second and soon to be third barrel for his Ruger #1.

He has shot out the other two.

he says his next rebarrel will be for the 22-250 AI. He claims the more forward shoulder , in addition to the greater case capacity, straighter walls, less back thrust, also causes the powder to burn slower, or at least more evenly. His theory was the sharp shoulder angle seemed to keep the powder from "blowing" out and causing a "fireball" (my words, not his) in the throat of the chamber. Kinda like the new short magnums. His theory seemed to make sense to me. Any thoughts from you guys?

Catfish · « **Reply #11 on:** September 18, 2004, 04:30:13 PM »

The thoughts from another old guy that has been reloading from the 1960`s and plays with alot of wildcats. I have 6 different wildcat rifles all in different cals. at the present time. The thing that causes powder to burn faster is presure. If you take a straigt walled case and blow it out to straight walled you have increasted the case capisity and have slowed down the burn rate. That said, straight walled cases also show presure signs slower than do tapered wall cases so while you are getting less presure it`s not as much as you think. The biggest advantage to straight walled cases with a very sharp shoulder angle is that they have a little more inhearant accuracy and the cases then to last longer. As for the .22-250 imp., I think that tat it`s a total waist of time. You burn out barrels alot faster and gain very little in velosity, but it`s all in what your after and there are some limited advanages to it. Personally I go for things like the .411 Hawk. It uses a blown out -06 case and can push a 300 grn. bullet to the same velosities as a .375 H&H mag., but with about 20 grns. less powder, or the .17 AH with which I can push a 19 grn. bullet to 3,600 fps with 10.4 grns. of H-4227 and get a varment rifle that will shoot point blank to to about 290 yrds. and can be reloaded for about 15 cent a round, not counting cases. The .411 hawk will get me more knock down power at close range than the .375 H&H mag. for about 18% less cost and there is no burnning out barrels with eather of these rounds. But in the end it`s all in what your after and what you like.

Buffalogun · « **Reply #12 on:** September 19, 2004, 08:39:16 AM »

I have two rifles chambered to the 30-30 Win. and one rifle chambered to the 30-30AI. The loads for the two 30-30's can produce velocities around 2,250-2,300- fps. with 150g bullets and charges of around 31-33g of powder, with no signs of excessive pressure. One barrel is 20", the other is 24"

However, the 30-30AI and it's 24" barrel will send a 150g bullet downrange at a velocity of 2,800 fps. all day long with 38g. of powder, with no signs of excessive pressure.

What I see here is an approximately 20% increase in charge weight that is producing an increase in velocity of approximately 22%

Also, 39g IMR 3031 will send a Nosler 125g. Ballistic Tip out of the 24" barrel of my Contender rifle at just under 2,900 fps.

I'd say the 30-30AI is a BIG improvement over the standard 30-30 Win.

Buffalogun

JC · « **Reply #13 on:** February 24, 2005, 05:49:12 AM »

HEY GB,
My 6MM AI started out as a WallyWorld Rem700 adl in 243. I scrapped the stock and barrel and gave Shilen and MPI a whirl. I did opt for a heavier barrel due to my hunting situations. A #5 taper in 1/8 twist would cure what ales you.

beemanbeme · « **Reply #14 on:** February 24, 2005, 10:55:08 AM »

20% increase in capacity and a 21% increase in velocity.
Isn't that kinda like the fellow that bought a new carburator that would boost his gas mileage 50% and a new set of plugs that would increase his gas mileage 40% and a new, super slick motor oil that would increase his gas mileage by 20%. And now he can't go anywhere. Every time he starts his car, the gas tank runs over. :-D

Don Fischer · « **Reply #15 on:** February 24, 2005, 02:29:19 PM »

I didn't notice that anybody mentioned it but the 7x57 case, witch is the 6mm and 257Roberts case, is a bastard case for a short action. The problem I found was that, with the 6mm, seating 100 gr bullet's out to just off the lands, the round's wouldn't go into the magazine. Perhaps short throating and lighter bullet's would fix that. In the case of the Robert's Improved, I'm guessing your thinking 100 gr or heavier bullet's.
If that's the case, a short action will work but your gonna have to stuff the bullet's in deep enough to clear the magazine well.

roper · « **Reply #16 on:** February 25, 2005, 05:40:24 AM »

I've got a 222AI,(2) 223AI,(2) 22-250AI and (2) 6mmremAI also had a 7x57AI.. I normally see about 10% increase in velocity and less than a 10% increase in powder used. If you worry about that usage etc then the AI case isn't for you. I have found case life very good and I just like the AI case. I'm really impressed with the 223AI I picked up about another 100yds in range for PD hunting. I've got a 223,222 and 6mm rem so I have something to compare the AI's too. Well good luck.

beemanbeme · « **Reply #17 on:** February 25, 2005, 06:04:53 AM »

I don't really have a dog in this fight as I've never owned an "improved" rifle. However, from reading about them, it seems the more authoritative articles state a 4 to 1 ratio is about what you can expect. That is to say, if you increase the powder capacity 4% you will gain a 1% increase in velocity. And that is not guaranteed.

Catfish · « **Reply #18 on:** March 02, 2005, 01:12:26 PM »

I think that it`s closer to 1/2 the % in velosity for the % increase in volume. Ie. a 10% increase in volume would get you a 5% increase in velosity. With the .257 Roberts, one of the more poplure to A.I., the parent case has a voulume of 52.43 cc of H2O. The .257 A.I. has a voulume of 59.35 cc of H2O. An icrease of 6.92 cc or of abt 13%. Hence you would expect a velosity increase of abt. 6.5% According to my Serria manual the fastest I can push an 87 grn. bullet with the .257 Roberts is 3,300 fps. With the .257 AI I can push it to 3,500 fps. , an increase of 200 fps or abt 6.25%. Ackley improved case have other advantages also. BUT, unless your very demanding, do alot of shooting, and want to put alot of money in a custom gun, the advantages are a mute point.

Donaldo · « **Reply #19 on:** March 02, 2005, 05:09:23 PM »

Hey Roper,
Tell me about your 223 AI. I have been thinking about changing barrels on my Savage 110. It is presently a 223. I was just a wondering how much more case capacity and velocity one could expect with the AI version?

Graybeard · « **Reply #20 on:** March 02, 2005, 06:28:57 PM »

Quote

HEY GB,
My 6MM AI started out as a WallyWorld Rem700 adl in 243. I scrapped the stock and barrel and gave Shilen and MPI a whirl. I did opt for a heavier barrel due to my hunting situations. A #5 taper in 1/8 twist would cure what ales you.

Just now noticed your post as I've not visited this thread in awhile. I have picked up an older Ruger 77 tang safety gun is 6mm Rem. I'm hoping will work out well for me. I like the rifle quite well really and if needed might rebarrel it to have the 6MM I've been wanting.

Most folks knowledgeable about such matters agree that one to four is the correct ratio. If you increase volume by 4% you gain only 1% in velocity as a result. Kind of a matter of physics really. Any additional gain you get over that is because of higher pressures not the increase in volume.

lilabner · « **Reply #21 on:** March 03, 2005, 03:15:29 AM »

GBs reference to SAAMI specs triggers one of my pet peeves. Look at the SAAMI pressure rating for the 30-06 and tell me why it makes sense for a strong, modern bolt gun. I believe there is no question that the rating is based on the wide variety of rifles chambered for the round, including lever and pump actions and some military conversions of dubious quality. There is no inherent weakness in the '06 case - look at the SAAMI numbers for other cartridges based on the '06.