Intrigued by Ackley improved cartridges

[Brians356]

fyrewall,

There are no official pressure data for 250 AI as it is not a SAAMI cartridge. However I did talk to Paul Box at Sierra tech support, and he told me his testing for both 250 Savage and 250 AI ran above 60,000 psi, with the AI a little higher. Hence Sierra's 250 Savage velocities are 100-150 fps faster than the 45,000 limit would allow. For example the standard for 100-gr is 2850, but Sierra publishes 3000.

I'm still measuring case capacities, but I can say that the Creedmoor case body alone (no neck) holds about 2 to 3 grs more water than 250 AI (40-deg) body. The difference is roughly equivalent to 6mm Rem over 243 Win. If I were building my 250 AI today, I would make it a 25 Creedmoor. Plentiful premium brass, no case forming (just neck down), and a bit more capacity.
-

 

[Matt in Virginia]

FWIW,
223 AI, 6BR AI, and 7mm-08 AI have been fun. Would not mind trying a .260 AI on a Borden Ridgeline. Seems like a little extra action length might do that one service.

Regards, Matt.

 

[gemihur]

 

[wboggs]

Had a 30-06AI. Had to burn 2 more grains of powder to get the same velocity with 165 and under. There was some gain with 180+ bullets. I won’t chase that squirrel again.

Less trimming is the major plus for them.

I had one also. 2825fps with the 180 barnes ttsx out of a 24" barrel with max loads. Not that much different than a standsrd .30-06.
My .35 whelan ackley really improved headspace problems but not much velocity increase. I would.do that one again.

 

[wboggs]

Those 30-06 numbers are pretty high.
Mine would never obtain them with a 24" barrel. You could probably find a certain rifle with a certain load that would do it but not in the average setup.

 

[358WCF]

Those 30-06 numbers are pretty high.
Mine would never obtain them with a 24" barrel. You could probably find a certain rifle with a certain load that would do it but not in the average setup.

Try RL26 with 180s. It might put a smile on your face. I run mine at 3100fps (26" bbl). Primer pockets (older WW brass) at 6 firings are still tight. Accuracy is good. I usually run 165s around 3150fps with several powders & have touched 3300fps with 150s but groups are better around 3250. Again, no case life problems with older WW brass. Some pieces have 8-10 firings & are still good to go.

All my Ackleys have done best running at the upper end. I'm sure P.O. would be impressed with the newer powders we have today. Longer barrels give free horsepower.

 

[6MMsteve]

Can just anyone design a case and call it an Ackley? Should credit be given to the cases PO did? You can call it improved or in my case I call it a NAFA. D

you can spec a reamer and call it pumkin bomber if you want, my brother designed a 300 whby reamer to his spec that he wanted and called it 300MP, I forgot what he done, shortened the nk, specs on nk was tight, shoulders were blown out, kept the venturi I can't remember. but it shot smallest group of the day at Penn 1000yd br club

 

[wboggs]

A lot to digest there, for now a few quick comments.

Be careful how you interpret Nosler's case capacity figures, they are not to the case mouth! They are net, to the base of the bullet seated to the stated COAL. So to compare the parent-to-AI capacity change, you must have a common bullet seated to identical COALs. Update: Look at Nosler's data for 55-gr bullet, seated to COAL 2.350" for both 22-250 and 22-250 AI. The net case capacities are 42.4 and 47.0, respectively. That's a 10.8% increase. (In my analysis above I used 11% for 250 AI). So your 13% is likely too high.

The most complete AI data offering (most cartridges) is from Sierra, but no pressures are published. So it's difficult to analyze velocity increase. I did talk to Paul Box there, who related to me the test pressures for both 250 Savage and 250 AI, both over 60,000, and within 500 of each other. That explains the 3000 fps from 100-gr bullet in 250 Savage (SAAMI max 45,000).

Sierra posts 3200 fps for 100-gr in 250 AI, and we know they round down to the nearest 100 fps. So Paul Box saw at least 3200.

I have all of Bob Jourdan's 250 AI data, I'll come back with his data later today.

(See below.)
-

Try RL26 with 180s. It might put a smile on your face. I run mine at 3100fps (26" bbl). Primer pockets (older WW brass) at 6 firings are still tight. Accuracy is good. I usually run 165s around 3150fps with several powders & have touched 3300fps with 150s but groups are better around 3250. Again, no case life problems with older WW brass. Some pieces have 8-10 firings & are still good to go.

All my Ackleys have done best running at the upper end. I'm sure P.O. would be impressed with the newer powders we have today. Longer barrels give free horsepower.

What

Try RL26 with 180s. It might put a smile on your face. I run mine at 3100fps (26" bbl). Primer pockets (older WW brass) at 6 firings are still tight. Accuracy is good. I usually run 165s around 3150fps with several powders & have touched 3300fps with 150s but groups are better around 3250. Again, no case life problems with older WW brass. Some pieces have 8-10 firings & are still good to go.

All my Ackleys have done best running at the upper end. I'm sure P.O. would be impressed with the newer powders we have today. Longer barrels give free horsepower.

What can you get with older win brass in .300wm and fire
formed 300 wby using 180s and RL26?

 

[Bill Norris]

The .260 is not included on the chart but I'm thinking it would place fairly high. According to the newest Nosler Reloading Guide just over 2800 fps is about the most you could expect from a 140 gr. bullet shot from a 24 inch barrel. With the right 260AI load combination one can get up to 3000 fps and some may get a tad over especially with a 26 inch tube.

 

[gemihur]

Read these and all your questions will be answered

A really great read.

 

[6MMsteve]

2019
got me again

 

[INTJ]

I shoot four AI cartridges quite frequently. The 6 BRA and 300 SAUM IMP in 1000 yd BR rifles--these are exceptionally accurate.

It shoot a lot of 280 Acks and 338 Lapua IMPs at work. The 280 Ack will shoot a 180 grain Berger at 2800-2850 with H-1000. The 338 Lap IMP will shoot at 300 grain Berger at 2900-2950 with N570. The Lapua IMP seems to shoot better for me than the straight 338 Lapua.

Peterson makes 280 Ack brass, and that seems to have done a lot to popularize it.

 

[WVRJ]

When it was time to replace the worn out barrel on my M700 280 Rem. I put on a very good barrel chambered for the 280AI.I can run 160 grain bullets faster in the 280AI than I could run 140's out of the 280Rem.Case trimming is almost eliminated and the new barrel will shoot waaaaay better than the old one.Both were Shilen barrels.The 280AI SAAMI pressure rating is a little higher,and that may also add to the Improved round's velocity advantage.Being able to shoot 280 Rem in it if necessary is an added bonus.Ringing steel at 1,000 yards is easier and the accuracy improvement alone was worth the effort.Would I do an AI rifle again?In a heartbeat.

 

[358WCF]

What

What can you get with older win brass in .300wm and fire
formed 300 wby using 180s and RL26?

I couldn't tell you as I have no rifle in either chambering. My 300 H&H sure perks up with 180s & 200s using RL26 using older WW brass. What does this have to do with the discussion of Ackley improvements?

 

[drop_point]

The .260 is not included on the chart but I'm thinking it would place fairly high. According to the newest Nosler Reloading Guide just over 2800 fps is about the most you could expect from a 140 gr. bullet shot from a 24 inch barrel. With the right 260AI load combination one can get up to 3000 fps and some may get a tad over especially with a 26 inch tube.

I don't know if its due to the throat or even just a fast barrel, my 24" .260 has two nodes with 140 Hybrids. One is at 2930 fps with no pressure. The other node is 2820 fps. I ran the higher node for the first half the barrel's life. I got 6x firings on Rem brass before the pockets get slightly loose. I decided to shoot the lower node and I'm getting 10x. My barrel will be toast anytime, or so I've been thinking the last 100 rounds or so. Its got around 1700 rounds on it.

No doubt the .260 Rem AI should get to 3,000 fps.

 

[gemihur]

All my Ackleys are in contender barrels
Diminished breech thrust is a benefit the platform appreciates.
222 Rem Mag Imp, 223AI, 30-30AI, 358x444 IMP not to mention ALL TCU chambers wear an Ackley shoulder wish I had more barrels with the improvement

 

[Bill Norris]

After getting Zack to build my first 260AI 700 and mounting it into a B & C M-40 stock I realized quickly I wanted a bench rifle in that caliber. So I sent Zack my 40X and had him convert it from a 6mmBR to the 260AI as well. It was a good decision no doubt. I have enjoyed both of them as much or more than any other rifles I ever owned. I have been able to shoot tiny bug holes with both and no fuss from either of them.

Since then I have two close friends here locally that have had Zack build the 260AI for them as well. Same performance from both of these rifles.

 

[wboggs]

I don't know if its due to the throat or even just a fast barrel, my 24" .260 has two nodes with 140 Hybrids. One is at 2930 fps with no pressure. The other node is 2820 fps. I ran the higher node for the first half the barrel's life. I got 6x firings on Rem brass before the pockets get slightly loose. I decided to shoot the lower node and I'm getting 10x. My barrel will be toast anytime, or so I've been thinking the last 100 rounds or so. Its got around 1700 rounds on it.

No doubt the .260 Rem AI should get to 3,000 fps.

My standard 260 has an accuracy node at 2920 with 142smks. But, I'm running a 30" 1-8. No pressure problems with H4350. My buddy runs close to 3000 with 140 berger hybrids and 30" barrel. He never has to trim