.260 Rem SAAMI .060" FB?

[lancetkenyon]

I am having a new barrel spun up on a rifle.  I am going with .260AI.  Standard reamers for both .260 Rem and .260AI both use a .060" FB.   I am more that likely going with a longer FB set up to seat the 140 Hyb out a bit further, but need some numbers.  

Does anyone have a .260 Rem and shoots 140 Hyb?  If so, can you give me CBTO with that combo at the lands?  I am thinking this should be about 2.095"?  

 

[STOMP442]

I don't have my data in front of me but your pretty close on that guestimate. I run a standard reamer on mine and have no problems with it. Velocities are around the 2950 mark with half moa or better accuracy. The .260AI is absolutely fantastic! The prefect balance of everything in the 6.5. 

[lancetkenyon]

What length barrel?  

Mine is a 24" 1:7.5" Bartlein M24 CF.

[STOMP442]

All the ones I have built have been 26" 8 twist barrels. 24" Should work just fine. 

[lancetkenyon]

1 hour ago, STOMP442 said:

All the ones I have built have been 26" 8 twist barrels. 24" Should work just fine. 

I figure if I can get 2900fps w. 140 Hybs, I will be happy.  This is going to be mainly a steel ringer/practice rifle....but you know how that goes.  That means it will probably be going on hunts in the near future.  Not the absolute lightest build, but should come in around 10-10.5#.

Lone Peak Fuzion TI w. Wyatt's extended box (2.980" OAL)

24" 1:7.5" Bartlein M24 w. TBAC CB brake

Thunderbeast Ultra 7 (or my new Dominus whenever ATF decides to set it free)

Manners PRS2 (I have two waiting:  One in BDL that was on the previous build, one in DBM w. Accurate mags waiting for my new build)

Timney CE

Either putting the S&B PMII 5-20x50US back on it, or a ZCO 4-20x50. Undecided which way to go.  Depends on if the S&B US fits on the new Defiance AnTi I am building.

[MMACFIVE]

Can you just seat a bullet with the neck to bearing contact you want then measure the CBTO?

[lancetkenyon]

43 minutes ago, MMACFIVE said:

Can you just seat a bullet with the neck to bearing contact you want then measure the CBTO?

I have a 140 Hyb seated where I think I want it.  Fits in a Wyatt's extended box or Accurate mag with a bit of room to spare.  I have that CBTO measurement.  

But I have to see what reamers are available for varying FB (.060", .120", .180", etc.), or else I need to get a custom reamer made to my specs.  I am willing to compromise a bit on FB, but I know I want more than the standard .060".  I just want to verify what CBTO is for the standard .060" FB reamer before I make my decision.  Different lead and throats make a difference in actual CBTO touching the lands with different bullets.

6.5CM w. 140 BMB

.260 Rem case

6.5SLR w. 130 OTM

.260AI w. 140 Hyb (with long FB)

 

[STOMP442]

2900 shouldn't be a problem at all. Lance you can always get a uni-throater and throat your own to your desired specs if using a standard reamer. 

[lancetkenyon]

I thought about a 2-step process with a separate throating reamer if all else fails.

[bryce525]

Love my 260 AI!  49.2 grains of R26 is getting me 2995 fps with a 140 elite hunter.  24" 8 twist barrel.  I used a uni throater to be able to seat the bullet out further.  Shoots sub 1/2 moa all day.

[papajohn]

I too am converting my 260 to 260ai. Mine is a 26" Schneider barrel single shot falling block I built and only have test rounds through it. Want to use 156eol bullets if I can, otherwise

140 vld hunters. Hope to have it done for late fall hunts this year. I will check my freebore now with the 140 vld's but was chambered with standard reamer.

[lancetkenyon]

8 hours ago, bryce525 said:

Love my 260 AI!  49.2 grains of R26 is getting me 2995 fps with a 140 elite hunter.  24" 8 twist barrel.  I used a uni throater to be able to seat the bullet out further.  Shoots sub 1/2 moa all day.

And what is your FB and CBTO?

[bryce525]

2 hours ago, lancetkenyon said:

And what is your FB and CBTO?

My CBTO is 2.154".  The reamer was 0.060" FB and definitely not enough to seat the 140s where I wanted.

[lancetkenyon]

12 hours ago, bryce525 said:

My CBTO is 2.154".  The reamer was 0.060" FB and definitely not enough to seat the 140s where I wanted.

Thank you.  2.188" in my 6.5SLR fits in a factory mag box, and gets 2800fps w. 140s.  

[L Cazador]

On 6/24/2021 at 8:52 AM, lancetkenyon said:

I thought about a 2-step process with a separate throating reamer if all else fails.

Send a dummy round to JGS and have a reamer made. You will need an Ackley case with the bullet seated to where you intend to start. I'm thinking .220" freebore with 140"s. I would not do a 140g. on this case, 130 max weight for 260 Ackley and 26 Inch barrel bare minimum to burn slow powder properly. Good luck!