260 Rem AI velocities

[Terry_M]

I've been working on loads in a 260 Rem AI.
140 Berger Hunting VLD
H4831
RL17
H4350
IMR7828 SSC

What velocity should I be seeing? So far RL17 has given 3043fps with light ejector marks, but no other signs of pressure. Everything else has shown pressure before hitting 3000fps

26" Douglas XX 8tw
Rem 700

Any feedback from others who have experience with this cartridge would be greatly appreciated.

43gr H4350 is 2885. I used this for hunting this fall. My wife took her elk with it. Very accurate, and very lethal.

 

[SHootSTraight22]

This is why I like everyone to at least try their cartridge with Palma Lapua brass.. That cartridge you have there is so much more capable I feel.. I base this on the velocities I get with my 6.5x47..

 

[Terry_M]

Ahh knew I forgot something.

Brass is all LC LR 08.

Primers CCI 200

 

[MattPeetz]

Your speeds seem to be about normal. You may look at the IMR7977 powder.
I am getting good results so far with some 155's in my 30" barrel.

 

[Terry_M]

Thank you for the suggestion. I'll give it a go.

 

[SDDasher]

Your speeds seem to be about normal. You may look at the IMR7977 powder.
I am getting good results so far with some 155's in my 30" barrel.

I just picked up a lb of IMR 4451 to try in my 22", 1x8.5 Brux Tikka T3, hunting rifle with the Berger 140&130 hunting VLD's. I Will let you know how it does in my gun.
Currently I am loading to 2.895 col in an AICS 5 round mag which is yielding good groups with H4350 but not the velocity I would like @ 2675. I'm testing RL17 tomorrow.
In my match 260AI the node in my 30" 1x8.5 tw Brux is 2888fps behind CCI BR2's, Lapua 260 Brass with 43.8 grains of H4350.

 

[SHootSTraight22]

Your speeds seem to be about normal. You may look at the IMR7977 powder.
I am getting good results so far with some 155's in my 30" barrel.

I just picked up a lb of IMR 4451 to try in my 22", 1x8.5 Brux Tikka T3, hunting rifle with the Berger 140&130 hunting VLD's. I Will let you know how it does in my gun.
Currently I am loading to 2.895 col in an AICS 5 round mag which is yielding good groups with H4350 but not the velocity I would like @ 2675. I'm testing RL17 tomorrow.
In my match 260AI the node in my 30" 1x8.5 tw Brux is 2888fps behind CCI BR2's, Lapua 260 Brass with 43.8 grains of H4350.

Have you ever ran a pressure test with this case?? I just thought you would have more velocity with a 260AI?

 

[Terry_M]

I filled a couple fired cases with water and weighed them on an RCBS digital scale. It measure 55gr water in Lapua and LC LR brass.

I was expecting 56 or 57 grains H2O capacity.

I adjusted QL to match what I weighed and it matches the velocity I'm getting over my Chrony and a Magneto Speed I borrowed from a friend.

I had the throat cut short so I could reach the lands with long bullets like A-Max or Berger VLD's.

 

[MattPeetz]

Mag feeding?

 

[Terry_M]

Mag feeding?

Yes. 2.910 is max length in my AI mags.

 

[SHootSTraight22]

I filled a couple fired cases with water and weighed them on an RCBS digital scale. It measure 55gr water in Lapua and LC LR brass.

I was expecting 56 or 57 grains H2O capacity.

I adjusted QL to match what I weighed and it matches the velocity I'm getting over my Chrony and a Magneto Speed I borrowed from a friend.

I had the throat cut short so I could reach the lands with long bullets like A-Max or Berger VLD's.

Have you ever shot charges up until you see ejector marks on the case head? Preferably using H4350??

 

[Terry_M]

I filled a couple fired cases with water and weighed them on an RCBS digital scale. It measure 55gr water in Lapua and LC LR brass.

I was expecting 56 or 57 grains H2O capacity.

I adjusted QL to match what I weighed and it matches the velocity I'm getting over my Chrony and a Magneto Speed I borrowed from a friend.

I had the throat cut short so I could reach the lands with long bullets like A-Max or Berger VLD's.

Have you ever shot charges up until you see ejector marks on the case head? Preferably using H4350??

I did. Ejector marks and flattened primers started at 44gr, and that's where I stopped.

 

[Dusty Stevens]

The 260ai is one of those cases like a 308ai that just dont improve as much as the trouble to do it. Now a 250sav ai and a 22-250ai are definitely worth it.

 

[Dusty Stevens]

I didnt mean that as a discouragement i was just making conversation. I love to see folks try new stuff. I help folks do it every day

 

[Terry_M]

I didnt mean that as a discouragement i was just making conversation. I love to see folks try new stuff. I help folks do it every day

Ah I took no offense. I've had fun with this project. I'm going to see if I can get my smith to lengthen the throat a little and I've read about a bore rider?? or a tool that cuts half the rifling out for the first 1/2" of so.

 

[savagedasher]

Mine shot 2950 With MRP and 30'' barrel using 140 GR Bergers When I shot faster primer pockets didn't last.
At that speed was the best accuracy. Speed means nothing if it don't shoot. Larry

 

[daj]

Terry,
I short throated my 260Imp30 to start with then used a throating reamer to set up 140Vlds at an OAL of 2.955". At 45.3gr H4350, my 28" Heavy Palma barrel liked to run at around 2930fps. I'm on 15x reloads of Lapua 243/260 brass and never have to trim cases to length. For me, improving the 260 was more about brass life and stability than velocity gain.

 

[Terry_M]

This is the first rifle I've ever worked on velocity with an anticipated goal in mind from the outset. I want to hit 3000fps with a good stable *safe* load. Something that can preserve brass life, but if I only get 5-6 loadings I'll be happy. I know 2900 - 2950fps is more realistic.

Typically I would plug different powders into QL and then start 10% low and move up .3 - .4 grains at a time with 3 shot groups to see which performed best at 200yds. Then load up ten of the rounds that shot the best and get chrono numbers, by shooting 2-5 shot groups, at 100yds, over the chrony.

I guess my next option is to pull the barrel off and put it on a long action so I can have it throated out until the bullets can be loaded above the case neck junction and cram as much powder as possible in the case. That is if the 7828 and or 7977 don't deliver what I'm after.

I've heard that the spacer can be removed from the AI mags to allow for longer bullet seating. Have any of you done this? Is the gain worth modifying the mags?

 

[SHootSTraight22]

I filled a couple fired cases with water and weighed them on an RCBS digital scale. It measure 55gr water in Lapua and LC LR brass.

I was expecting 56 or 57 grains H2O capacity.

I adjusted QL to match what I weighed and it matches the velocity I'm getting over my Chrony and a Magneto Speed I borrowed from a friend.

I had the throat cut short so I could reach the lands with long bullets like A-Max or Berger VLD's.

Have you ever shot charges up until you see ejector marks on the case head? Preferably using H4350??

I did. Ejector marks and flattened primers started at 44gr, and that's where I stopped.

At that 44gr area was the ejector marks bad enough that you saw them on 3 out of 5 rounds??

 

[SHootSTraight22]

This is the first rifle I've ever worked on velocity with an anticipated goal in mind from the outset. I want to hit 3000fps with a good stable *safe* load. Something that can preserve brass life, but if I only get 5-6 loadings I'll be happy. I know 2900 - 2950fps is more realistic.

Typically I would plug different powders into QL and then start 10% low and move up .3 - .4 grains at a time with 3 shot groups to see which performed best at 200yds. Then load up ten of the rounds that shot the best and get chrono numbers, by shooting 2-5 shot groups, at 100yds, over the chrony.

I guess my next option is to pull the barrel off and put it on a long action so I can have it throated out until the bullets can be loaded above the case neck junction and cram as much powder as possible in the case. That is if the 7828 and or 7977 don't deliver what I'm after.

I've heard that the spacer can be removed from the AI mags to allow for longer bullet seating. Have any of you done this? Is the gain worth modifying the mags?

If your serious about reworking the throat you may want to try this chamber I have here.. It basically looks like a Dasher neck/shoulder area.. The shoulder is 40 degrees... But the shoulder looks shorter than a AI case.. My shoulder is just .136 tall.. The 6.5 neck is .200 tall... Just go over to the 6mm Dasher Ultra Mag thread and look at them measurments.. They came off a 308 Palma case sized to this Improved 260 cartridge.. I'm going to try it in a 6mm... If yall are interested I can measure its water capacity maybe or just feel it up with H4350 for us to see what it will hold... I think it will get your 3,000fps with 140gr bullets...