260 ai Reamer spec and load data

[806guns]

I have decided i want a 260 ai in my life. This will be a a target/hunting rifle. Maybe a Nrl Hunter one day match. I have been searching hed through threads and forums. Manson offers the best reamer imo that I have found without going a custom route.

Anyone have any feedback with this reamer? I have about 12lbs of H4831SC so It will be perfect for this setup.
22" or 24" 8 twist medium palma fluted or similar contour
Will be one of three barrels for my Origin medium action load up to 3.2"
Plan on using 144gr up to 153, 156 mainly.
Alpha will he doing a run of SRP brass in 6-8 months. But I have a lot of starline brass.

 

[Hydra6]

Watching with interest. I have an old school PRS rig in 260 I used on a one day NRL Hunter event. I have been running 140s but picked up some 156s to try.

 

[Wrench]

I've built a lot of 260ai's and 4831 will push a 140 just under 3k with ease and good accuracy.

For PRS the shoulder is steep so feeding can be an issue if the draft angle isn't right and I put a bit more chamfer on the chamber.

I don't have my reamer print handy to compare.

 

[806guns]

Cant tell me this cartridge is dead ?

 

[sierracharlie338]

No feedback with that specific reamer but the 260ai is one of my favorite cartridges. IMO one of the best all around cartridges out there.

 

[codym]

No feedback on the reamer, mine was done by spr with shorter free bore for a SA. Mine would not feed consistently out of a manners lhrs and mdt adjustable bm but feeds well out of multiple xlr chassis. RL 16 was the ticket in mine with the 156’s but that’s currently impossible to find. Also had to have 18 thou faced off my SAC die to get the shoulders bumped back. Excited to hear how yours turns out. I just got a proof 1/7.5 back from WTO in straight 260 for my razor ti in med action throated long for the 153’s

 

[806guns]

No feedback on the reamer, mine was done by spr with shorter free bore for a SA. Mine would not feed consistently out of a manners lhrs and mdt adjustable bm but feeds well out of multiple xlr chassis. RL 16 was the ticket in mine with the 156’s but that’s currently impossible to find. Also had to have 18 thou faced off my SAC die to get the shoulders bumped back. Excited to hear how yours turns out. I just got a proof 1/7.5 back from WTO in straight 260 for my razor ti in med action throated long for the 153’s

Definitely post up the oal for that medium action when you get a chance.

 

[codym]

Will do

 

[Mike D Texas]

I have decided i want a 260 ai in my life. This will be a a target/hunting rifle. Maybe a Nrl Hunter one day match. I have been searching hed through threads and forums. Manson offers the best reamer imo that I have found without going a custom route.
View attachment 1063094
Anyone have any feedback with this reamer? I have about 12lbs of H4831SC so It will be perfect for this setup.
22" or 24" 8 twist medium palma fluted or similar contour
Will be one of three barrels for my Origin medium action load up to 3.2"
Plan on using 144gr up to 153, 156 mainly.
Alpha will he doing a run of SRP brass in 6-8 months. But I have a lot of starline brass.

I like the looks of this reamer. I bet mine is close to this after I lengthened the throat after chambering with my gunsmith’s reamer.

I may have to pick one of these up for when I toast this barrel.

 

[wind gypsy]

Thats quite a bit of freebore. Might be long if you're a lands chaser and want to use 140/144 type bergers.

 

[Half Nocked]

I love the 260ai, I'm running one off a tikka action and preferred barrel, 23". H4350 and H4831sc, has been a dynamite combo. My tends to like the H4350 a little better, but I'm running 125grain tipped Hammer Hunter bullets at around 3200fps, with less than 10sd in velocity. I hit pressure around 47grains and backed off to 46.5grs. It's been a great hunting combo up 600yds, which is the furthest I shot at a critter.

 

[Bater]

Favorite cartridge hands down. Mines a 19” PBB pushing 130TGK’s at 2910. Alpha SRP is about as good as it gets and literally lasts forever.

 

[Mike D Texas]

Thats quite a bit of freebore. Might be long if you're a lands chaser and want to use 140/144 type bergers.

I normally shoot 144s in mine and seat them at 3.100”’ish. OP says he’s working with a medium action that allows 3.200”. Should be good to go. Ray at Manson could probably confirm though.

 

[806guns]

Little update on this project.
I aquired a Tikka from a fellow member. Its setup for a 6.5 Saum. The bolt and barrel may get swapped out for a 260ai.

 

[806guns]

Well placed an order from Preferred Barrel Blanks with a 22" 260ai with there reamer. Did the Tikka 80% prefit they have that only takes 2 weeks to ship.

 

[Kimber7man]

Had mine done earlier this year. I think the reamer has .130 freebore but will check. Guy I borrowed it from spec’ed it to run 140’s around 2.95” COAL.

 

[806guns]

Shot 140gr berger in a 22" 6.5 saum at 2921 fps with 59gr h1000 not at pressure and could do more im sure

114gr Mcguire Ballistics at 3290fps 63gr H4831SC(close to pressure)

This is for reference im hoping the 260ai will be able to get close to these speeds.

 

[NWBLKTAIL]

View attachment 1068632
Favorite cartridge hands down. Mines a 19” PBB pushing 130TGK’s at 2910. Alpha SRP is about as good as it gets and literally lasts forever.

Was this a prefit?

260ai is on my short list of cartridges I want to shoot

 

[Bater]

Was this a prefit?

260ai is on my short list of cartridges I want to shoot

Yes

 

[Kimber7man]

Shot 140gr berger in a 22" 6.5 saum at 2921 fps with 59gr h1000 not at pressure and could do more im sure

114gr Mcguire Ballistics at 3290fps 63gr H4831SC(close to pressure)

This is for reference im hoping the 260ai will be able to get close to these speeds.

Yeah you could go higher. My standard load for the 140 is 61.0 H1000 - using R-P and ADG brass in different rifles.