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September 15, 2010, 08:57 PM | #1 |
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ackley improved- to do or not to do?
I have been shooting the guts out of my rem .243 and the barrell is nearing its appointment with the crematorium. I am happy with the caliber and have all of the reloading equipment for it. I plan to rebarrell the rifle and I was also toying with the idea of redoing it as an ackley. Thoughts on the pros and cons of this?
Thanks, Toddco |
September 15, 2010, 09:10 PM | #2 |
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OK, if you are going to re-barrel, why wouldn't you chamber in the Ackley? Better brass life, increased performance and the KOOOL Factor. Some will argue that it's not worth the effort due to the HIGH cost of Ackley dies. This is simply not true. In the 243 and other 308 based cartridges the dies are inexpensive. The standard Lee Collet neck die will work in the 243 AI. The standard seating die (RCBS) will also work with the 243 AI. When it's time to bump the shoulder back a $30 Redding body die in 243 AI is all you need.
I just had my son's Savage 7MM-08 chambered in 7MM-08 AI. Nice, easy on the brass and excellent performance. here are some of my Chrony numbers from a few weeks ago. 160gr Nosler Partitions. Hunter. 48gr---2705fps 48.5gr-2724 49gr---2766 49.5gr-2797 50gr---2820 50.5gr-2850 51gr---2884 51.5gr-2893 52gr---2894 MRP 47gr---2626 47.5gr-2722 48gr-error 48.5gr-error 49gr-error 49.5gr-error Replace battery 50gr---2704 50.5gr-2744 51gr---2781 51.5gr-2803 52gr---2833 DP-86 47gr---2667 47.5gr-2710 48gr---2742 48.5gr-2746 49gr---2781 49.5gr-2833 50gr---2843 50.5gr-2869 51gr---2888 51.5gr-2910 |
September 15, 2010, 09:14 PM | #3 |
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I love my 243ack. It holds a few grains more powder that the standard 243. I set my 17lbs rifle up for 1000yd benchrest and chose the ackley over some of the other 6mm's. My favorite load is a Berger 105gr VLD over H1000 or H4831SC. I do not think you will be disapointed. Remember you can still shoot regular 243 Winchesters through it in a pinch.
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September 15, 2010, 09:14 PM | #4 | |
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Quote:
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September 15, 2010, 11:20 PM | #5 |
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If you ever followed any of Parkers readings, he always stated that for every bore diameter there is an optimum bullet weight. That's a bullet weight that carries the most weight but does not sacrifice speed. In a .243 bore you have 60 gr bullets that can fly at the speed of light but don't carry much weight and has less energy at distance. You can shoot the heavier bullets like a 105 gr and carry more energy but not at the same speed as the 60. His opinion was that the 87 gr bullet was the optimum weight for the .243 bore, bullet construction not considered. Going to an Ackley chambering will net you about 200'ps more over a standard 243 chambering for the 87 gr bullets, per Ackley data. But you will burn 5 grs more powder to get it. Is it worth it to you? Is velocity the prime reason for wanting an Ackley chambering. If so, the 6mm/284 is eons ahead of the Ackley chambering pushing 100 gr bullets faster than an Ackley can push an 87gr. If you just want something exotic, Ackley is a good choice as is the Nieomiller where the shoulder is slightly pushed back yielding the sharper shoulder with the sides blown out to give more case capacity. You also get a longer neck which is suppose to help with holding the bullet straighter in the case for less bullet yawl. But ultimately you need to decide what it is you're looking to achieve by going the different road. If accuracy is the quest, consider a 6BR chambering. The guys are now shooting prairie dogs (targets) reliably at 1 mile with this chambering with 95gr Bergers at 3100'ps. So consider what you are trying to achieve and then pick a chambering. There is no right or wrong answer by the way.
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September 16, 2010, 07:56 AM | #6 |
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In .260, you can get an extra 200fps easily out of switching to AI.
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September 16, 2010, 10:43 PM | #7 |
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The best of the AI's is the .257 Roberts AI. I've got one and it can approach 25/06 loads while using less powder. Very mild mannered and easy to shoot rifle. And _so far_ I haven't had any big problems forming AI cases.
Gregg |
September 16, 2010, 10:59 PM | #8 | |
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Quote:
Prior to Reloder 17, the two most common .260 Rem loads for long range were a 139 or 142 using H4350 or H4831SC at 2830 - 2860 fps. The one guy shooting .260AI got about 2950 fps on his first barrel. Second barrel was 2900-2930. With Reloder 17, the standard .260 Rem shooters are now getting 2900-2975 fps. The .260 Ackley guy is still using H4831SC. I am loading a 139gr Scenar at 2900 fps using RL17 in my AI-AW.
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September 17, 2010, 08:04 PM | #9 |
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Im happy with my 243ack. I dont see myself changing anytime soon.
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September 17, 2010, 10:23 PM | #10 |
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What Steve4102 said. I don't have a 243 AI but I do have a 280 AI. The entire range of the AI calibers is great. Too bad they never caught on better. If it were me I'd send it to Hart and have a Hart barrel screwed on it. Of course there are many great custom barrel makers I am just partial to Hart from my old benchrest days.
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September 18, 2010, 12:15 AM | #11 |
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To amplify Zak's comments, the 260 has a perfect expansion ratio - the bore to capacity. Most of the AI calibers on the 2 inch(308) case don't gain any marked improvement. If you shoot standard stuff in an AI, you'll have some accuracy/velocity challenges.
PS. Just thought of one other thing you might consider. When I had my .338-06 built, I had it throated for 250 Partitions. For most hunting, I use 200 Hornady or Speer. In a 22" barrel, I'm getting 2810 over the chrony. I had the same thing done with my 6.5-06, throated for 140 SierraBT. The 6.5 gives 3200 with 120s, 3100 with 125s, and 2935 with 140 Hornady - in a 24" barrel. That is 264Win territory. |
September 18, 2010, 11:27 AM | #12 |
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The AI cases don't add much capacity
so there is little increase in velocity FROM THE CAPACITY INCREASE. However, by making it impossible to fit a standard chamber, the AI case shape change makes it "safe" for handloads to exceed the SAAMI pressure limits in strong modern bolt actions for some of the older cartridges like the .257 Roberts. Going to the higher pressure can substantially increase velocity.
SL1 |
September 18, 2010, 12:32 PM | #13 |
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Handloads generally shouldn't be swapped rifle to rifle without testing anyway.
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