Factory 260 ammo in a 260 AI chamber?

[Brians356]

When I had my 260 AI made the head space was too long for shooting factory loads.
I did the same process as I do with my dashers. Seat the bullet long and fire forum.
What a great cartridge does every thing a 284 does but with less powder an double the barrel life . Larry

Good to know. Just how long did your 284 Win and 260 AI barrels each last?

 

[savagedasher]

When I had my 260 AI made the head space was too long for shooting factory loads.
I did the same process as I do with my dashers. Seat the bullet long and fire forum.
What a great cartridge does every thing a 284 does but with less powder an double the barrel life . Larry

Good to know. Just how long did your 284 Win and 260 AI barrels each last?

i never built a 284 friends had them they never got 1200 rounds mine was still shooting good at 1800 rounds Larry

 

[Brians356]

When I had my 260 AI made the head space was too long for shooting factory loads.
I did the same process as I do with my dashers. Seat the bullet long and fire forum.
What a great cartridge does every thing a 284 does but with less powder an double the barrel life . La

By all accounts the 260 AI adds at most about 100 fps over the parent 260 Rem. And that ain't nothing to sneeze at. Other threads, on this forum and over at 6mmBR.com, indicate ~2950 fps max for 140-gr bullet from a 26-in barrel (typically w/ H4350.)

Hodgdon's 284 Win data show 139-gr bullet max velocity 3079 fps from a 24-inch barrel (H4350.)

So, conservatively, the 284 adds another 100 fps over the 260 AI. Yes, it uses about 3% more powder to get there. Presumably, if you backed the 284 down 3% it would be running about even with the 260 AI. And, also presumably, barrel life would be similar. But the 284 will always have that extra "passing gear" available, for a relatively small price in powder. Whether that extra 3% of powder will really reduce barrel life by 1/3 is open to conjecture.

 

['Freak]

6.5/243 AI 40°  260 Remington Ackley Improved 40°
http://www.the-long-family.com/260AI.htm
http://www.6mmbr.com/260AIforming.html
http://www.the-long-family.com/images/260%20Ackley.jpg reamer drawing

&& stuff …

Lengths from case head (or breech face) to the neck/shoulder junction:

Sierra V, 5th 260 Rem. cartridge cartoon 1.776” .0045” > AI .0073” > SAAMI Chamber drawing
Sierra V, 5th 260 Rem. cartridge cartoon 1.776” .0045” > AI .0005” < SAAMI Case drawing

Grizzly Ind./PTG 260 Match chamber 1.774” .0025” > AI .0053” > SAAMI Chamber drawing
Grizzly Ind./PTG 260 Match chamber 1.774” .0025” > AI .0015” < SAAMI Case drawing

Chris Long/PTG 6.5/243 AI 40° 1.7715” -0- .0028” > SAAMI Chamber drawing
Chris Long/PTG 6.5/243 AI 40° 1.7715” -0- .0040” < SAAMI Case drawing

SAAMI 260 Rem. Chamber drawing 1.7687” .0028” < AI -0- .0068” < SAAMI Case drawing
SAAMI 260 Rem. Case drawing 1.7755” .0040” > AI .0068” > SAAMI Chamber drawing

Dia. at shoulder datum is .400”, anything 1.630” to 1.640” from head to datum is within SAAMI specs.

 

[savagedasher]

By all accounts the 260 AI adds at most about 100 fps over the parent 260 Rem. And that ain't nothing to sneeze at. Other threads, on this forum and over at 6mmBR.com, indicate ~2950 fps max for 140-gr bullet from a 26-in barrel (typically w/ H4350.)

Hodgdon's 284 Win data show 139-gr bullet max velocity 3079 fps from a 24-inch barrel (H4350.) So, conservatively, the 284 adds another 100 fps over the 260 AI. Yes, it uses about 3% more powder to get there. Presumably, if you backed the 284 down 3% it would be running about even with the 260 AI. And, also presumably, barrel life would be similar. But the 284 will always have that extra "passing gear" available, for a relatively small price in powder. Whether that extra 100 fps will really reduce barrel life by 1/3 is open to conjecture.

My reloading books show it takes 12% more of RL 22 to match the speed I was getting out of my 260 AI Nosler say that is near max.
Nosler manual 26'' barrel 140 gr RL22 max is 52.5 2925
My 260 AI with 30'' barrel 47.2 gr RL 22 was 3020 FPS
That is 11% . My math can be bad but 47.2 plus 11% is 52.292 Larry

 

[Brians356]

My reloading books show it takes 12% more of RL 22 to match the speed I was getting out of my 260 AI Nosler say that is near max.
Nosler manual 26'' barrel 140 gr RL22 max is 52.5 2925
My 260 AI with 30'' barrel 47.2 gr RL 22 was 3020 FPS
That is 11% . My math can be bad but 47.2 plus 11% is 52.292 Larry

May I assume that comment "Nosler manual 26'' barrel 140 gr RL22 max is 52.5 2925" is for 284 Win?

That's pitiful. Either RL-22 is a poor choice for 284 Win, or Nosler's data are suspect. Hodgdon report 3079 fps max from H4350 from only a 24" barrel! That's ~150 fps faster, from 2 inches less barrel.

For further consideration:

Terry Cross over on 6mmBR reported his 260 AI with 48.5 grains of H4831 produced 2935 fps. from a 139gr bullet from a 26" barrel.

http://www.6mmbr.com/gunweek046.html

 

[savagedasher]

My reloading books show it takes 12% more of RL 22 to match the speed I was getting out of my 260 AI Nosler say that is near max.
Nosler manual 26'' barrel 140 gr RL22 max is 52.5 2925
My 260 AI with 30'' barrel 47.2 gr RL 22 was 3020 FPS
That is 11% . My math can be bad but 47.2 plus 11% is 52.292 Larry

It is a 6.5 284 Norma it is the most accurate tested the speed that it was the most accurate at was 2761 Twist the number any way you want A 6.5 284 is 11% over bore . Larry

May I assume that comment "Nosler manual 26'' barrel 140 gr RL22 max is 52.5 2925" is for 284 Win?

That's pitiful. Either RL-22 is a poor choice for 284 Win, or Nosler's data are suspect. Hodgdon report 3079 fps max from H4350 from only a 24" barrel! That's ~150 fps faster, from 2 inches less barrel.

For further consideration:

Terry Cross over on 6mmBR reported his 260 AI with 48.5 grains of H4831 produced 2935 fps. from a 139gr bullet from a 26" barrel.

http://www.6mmbr.com/gunweek046.html

 

[Brians356]

>> It is a 6.5 284 Norma it is the most accurate tested the speed that it was the most accurate at was 2761 Twist the number any way you want A 6.5 284 is 11% over bore .

Larry, Larry, Larry. Your original statement was:

"What a great cartridge does every thing a 284 does but with less powder an double the barrel life ."

Most chaps will consider "284" to be shorthand for "284 Winchester", not for "6.5-284" of any flavor. All my analysis was for 284 Winchester (a 7mm cartridge.)

Never mind. You need to be more careful, chum.

 

[savagedasher]

>> It is a 6.5 284 Norma it is the most accurate tested the speed that it was the most accurate at was 2761 Twist the number any way you want A 6.5 284 is 11% over bore .

Larry, Larry, Larry. Your original statement was:

"What a great cartridge does every thing a 284 does but with less powder an double the barrel life ."

Most chaps will consider "284" to be shorthand for "284 Winchester", not for "6.5-284" of any flavor. All my analysis was for 284 Winchester (a 7mm cartridge.)

Never mind. You need to be more careful, chum.

I never changed the caliber You did . Sorry Larry

 

[Brians356]

>> It is a 6.5 284 Norma it is the most accurate tested the speed that it was the most accurate at was 2761 Twist the number any way you want A 6.5 284 is 11% over bore .

Larry, Larry, Larry. Your original statement was:

"What a great cartridge does every thing a 284 does but with less powder an double the barrel life ."

Most chaps will consider "284" to be shorthand for "284 Winchester", not for "6.5-284" of any flavor. All my analysis was for 284 Winchester (a 7mm cartridge.)

Never mind. You need to be more careful, chum.

I never changed the caliber You did . Sorry Larry

LOL Got it. "284" = "6.5-284" naturally. Have it your way. :