The Accurate Reloading Forums THE ACCURATE RELOADING.COM FORUMS Rifles Small Calibers Kimber Montana in 6mm Ackley?Go | New | Find | Notify | Tools | Reply | |
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Ok, so I just got a darling little Kimber Montana in 243. Seems to shoot well, but being the PITA that I am, I want something different, and truthfully I've never been terribly happy with the 243. So.... I want to rechamber it into a 6mm Ackley. Now I know the OAL on a 6mm is like 2.825 In, so I may have to seat bullets a little bit deeper. Since Kimber already builds the Montana in 257 Roberts, I don't see a problem with feeding. What does everyone think? | ||
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Suppose it will fit. If the 243 as it is shoots well then just go hunting. I have been there and done that with the 'Ackley Improved' stuff and these days the very thought seems like work, trouble. I have a nice Kimber 243 Montana. Get the 'power' or optic that your eye likes instead of what someone else says. When we go to the doctor they ask us what lens we like! Do that with your optics. | |||
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 There is another answer to your quest, and Cooper may well handle it for you. Mine is a 1 in 10 twist and I would have liked a 1 in 8. Next time  Member NRA, SCI- Life #358 28+ years now! DRSS, double owner-shooter since 1983, O/U .30-06 Browning Continental set. | |||
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Are you talking about a 243 AI or a 6mm Rem AI? I just did a quick look on reloadersnest and the 6mm Rem AI is impressive! There is a 100gr load there at 3400+ fps! Looks to be about 100fps avg faster then a 243 AI, and probably about 2-400fps faster then a standard 243 Win. If your magazine box is the limiting factor, the 243 AI might be a better choice. If you think every possible niche has been filled already, thank a wildcatter! | |||
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I'm definetly thinking 6mm Ackley. The 22 inch barrel would slow things down just a bit, but I should gain a good 200 fps over 243 - at least. The 243 Ackley is sure doable, but the gain is rather minimal compared to the standard 243. The 6mm is helped considerable by AI'in it. I think I may just go ahead and talk to a 'smith about it. I'll let you guys know what happens! | |||
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I currently have two 6mmAI's and have used three others in the past. Mine is on a SA Rem 700, and I have no problems with feeding or anything else. It is a very effective deer caliber. and case trimming is almost nil. It will only gain about 60-75 fps over the standard 6mm, unless you lean to hard on the throttle. I have done that in the past in my younger days going up to over 3300 fps in a 22" bbl, but it was way too hot. The 95g partition and 90/95 ballistic tips are very good loads for deer sized animals. Accuracy has been outstanding for all of my 6mmAI's. I have a load in my varmint rifle which goes 3600 fps with no strain on the gun with a 65g V-Max that shoots like a bench gun. If you can live with ballistics slightly better than the 6MM, it is one heck of a fine cartridge. You can go higher, but only at excess pressures. John Barsness did a fine short article about this cartridge and his findings corresponded with what I have found over the years. | |||
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95 grain VLD at 3400+ fps in my 6mm AI with a 26" barrel, shoots pretty flat. Love shooting precision and long range. Big bores too! Recent college grad, started a company called MK Machining where I'm developing a bullpup rifle chassis system.  | |||
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sambubba - was this Barsness article in Handloader? If so, could you tell me the issue? I'd like to read it. | |||
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I have 'improved' chambers in rimless, rimmed and belted rounds. After a lifetime of use I see them as a hobby with more time spent than gain. In fact I knew Lysle Kilbourn and discussed things with him. Here is a very recent quote from Barsness on a similar 'improved' round. "Melvin is a believer in the .257 Ackley, and also believes Douglas barrels in .25 are among their best. I ran a NULA .257 Ackley with a #2 stainless barrel for a while and it was VERY accurate. But I never could see any advantage in the field over the standard .257, so eventually it went down the road. The guy I sold it to also got weary of fire-forming and sold it after one hunting season. But whatever...." Link Get the 'power' or optic that your eye likes instead of what someone else says. When we go to the doctor they ask us what lens we like! Do that with your optics. | |||
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Prairiegoat, it was in one of the two Wolfe magazines and is also in loaddata.com. PM me and I will try to get the info to you. sambubba | |||
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Sorry to disappoint but you need to apply the 4:1 rule . 4% increase in case capacity gives approx. 1% increase in velocity all else being equal . 6mm AI has about 12% more case capacity than standard .243 so expect 3% velocity increase or around 100 FPS with an 80gn projectile . No, not 400 FPS or even 200 FPS . There is so much BS written on the internet about velocities achieved with Ackley chambers . Take most of it with a grain of salt . Most people think that 12% increased capacity equals close to 12% increased velocity and that they can use 12% more powder . Unfortunately it doesn't work that way . Most of the wild reports of dramatic velocity increases come from people who don't know how to read signs of excessive pressure until primers start falling out . I am on my second .243AI which has more capacity than standard 6mm Rem. . Both of those rifles were custom built though so no expense for new dies or a rechambering job. Very little improvement in velocity over the standard case (about 50 FPS) . Don't believe what you are proposing is worth the trouble from a velocity perspective , particularly in a 22 inch barrel . Fireforming is a pain in the butt IMO even when the loads are used on game . Two lots of load development required to find an accurate load for a start . Will also reduce the resale value of your rifle . The hunting imperative was part of every man's soul; some denied or suppressed it, others diverted it into less blatantly violent avenues of expression, wielding clubs on the golf course or racquets on the court, substituting a little white ball for the prey of flesh and blood. Wilbur Smith | |||
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Where the rivers run north, eh? sounds like that area at the base of the hills just east of Sweetgrass....like the Milk River basin. Other than that, most of the rivers I know well which run north are in Northern Alberta, NWT, and the Yukon. All part of God's own country. Anyway, I'd do it just because so many folks want you not to. I don't mind fireforming at all; do it in lots of my chamberings. Also have a few I run at flat out pressures. May eventually blow my fool head off, but so what? Have been doing it for 61 years this year, and haven't had any problems of that nature so far. Might as well go while enjoying myself. (Most of my rifles I operate at profoundly mild pressures, but there are rifles, and then there are OTHER rifles......) My country gal's just a moonshiner's daughter, but I love her still. | |||
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One of the interesting things is you don't give any loading data with velocity or what barrel,twist and maker. If you look at Data published by Speer Wildcat manual # 4 in 1959 about the 244 improved and you see loads with 90gr bullets at 3300pfs plus using a 1/12 twist barrel. Seems like those rifles from those good old days didn't blow up. Today I think we have better barrel etc so building an Ackley chambered rifle should be no problem but I do agree you can get high pressure but you can get that with a standard caliber. In my 6RemAI with Shilen 1/10 twist 26" barrel using 46gr/H-4350 and 95gr Nolser bullet I'm getting 3393fps and if you compare that to loading data at max load for the 6Rem with 45gr/H-4350 @ 3103fps I'd say I'm almost 10% gain. In my 243AI with 26" Hart barrel 1/10 twist I used a max load for the 243 which is 45gr/IMR-4007ssc which had a published velocity of 3319fps for a 80gr bullet but in the 243AI that load gave me 3425fps I worked up 3gr to 48gr/IMR-4007 @ 3705fps. I've said this before I don't understand % give me loads,barrel used,velocity. I like the 6RemAI so much that I had another build but used a Rem long action. I've always used new barrel for my Ackley chamber rifles so I really don't know how rechambering an existing barrel would do. With 9 Ackley chambered rifles I average around 8%/10% increase in velocity and what help is I also shoot the parent calibers. VFW | |||
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Well fellas - thanks for the info. Right now I'm split between re-barreling the rifle with a Lilja tube into a 257 Ackley and making a wonderful little mountain rifle, or just staying with the factory barrel and doing the 6mm Ackley. I already have the 257 Ackley dies, and no rifle to use them on so that may be reason enough! Either way, I'm going the AI route. Mostly because it's a free country and those Ackley rounds are just so sexy! Alberta Canuck - The area I'm referring to is Southeast Montana and Northern Wyoming, where all the major rivers (Bighorn, Tongue, Powder, and Little Missouri) run in a general Northern direction. "Where the Rivers Run North" was also the title of a wonderful book by Sam Morton about the history of the area. | |||
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I have two ackley chambered guns. 22250 and 6mm. I shoot targets not critters. everyone on this forum must be hunters cause I rarely see the word ACCURACY . my guns shoot zero groups routinely. I experiment a great deal so when I get a load shooting like that I change components to see if it can be duplicated with different components.the real advantage to Ackley is less brass flow due to less taper, 40% shoulder, less back thrust on the bolt and the brass lasts longer with little trimming. my fireform load with new brass shoots tenth inch groups. fired brass for fireforming is not good.there is a great deal of load info on internet for ackley cartridges esp 6mm. 6mmack is best with Berger 80g ,and rel 22. 22250 Ackley I think is the best cause you get a 220 swift w/o the problems . I dont just load 4000fps with it but there are 3000fps loads that do tenth inch groups. again Targets not critters.most of the guys with loads on internet hunt with them. good luck. 1 | |||
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6mm Ackley load data on internet: MIKE J'S 6MM ACKLEY IMPROVED RELOADING PAGE has good info. I dont put my loads on here cause my guns are custom guns and handle hot loads . whatever you get off the internet WORK LOADS UP Properly dont just copy them. most guns on there are custom built . | |||
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The Accurate Reloading Forums THE ACCURATE RELOADING.COM FORUMS Rifles Small Calibers Kimber Montana in 6mm Ackley?
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