Thinking of converting my 308 to 260AI.

thump_rrr

thump_rrr

CGN Ultra frequent flyer
Rating - 100%
35   0   0
Location
Montreal Qc.
I am thinking of rebarreling my Savage 10BA this coming winter.
It is still consistently shooting under 1 MOA but the lands have moved over 0.040" since new.
The rifle shot 50.9V at the 600y deliberate fire stage of the first Petawawa precision rifle clinic this year, but any gun shooting 1 MOA dialed in with the proper dope should be able to do that.
I would love to make it a consistent 0.5moa gun.
2901911D-FCBA-448F-BE10-50F2FE812FB9_zpsh8fqwoq3.jpg

It has over 3200 rounds down the pipe and by the end of the season it will be closer to 4,000 than 3,000.
By then I will have nearly exhausted my supply of 175gr SMK's that it has been feeding on.
Since I have other rifles to take care of my supply of 168gr SMK's I was thinking of rebarreling to 260AI.
They both use the same parent case therefore the bolt face diameter is the same, it can use the same AICS mags, and I can even neck down my .308 Lapua brass.

The 142gr 6.5mm bullet only drops 11.2moa at 600y vs 14.4moa for the 175gr .30 cal.

Are there any any negatives that I have overlooked?
Any other suggestions?
 
Last edited:
Good move. While certainly flatter shooting than the .308 the place you will notice a huge difference is in wind drift.
I have a fast 155gr load for my TRG that will hang close to my .260 inside of 500m but beyond that the .260 is so much easier to keep on steel that its like cheating by comparison.
Personally I haven't seen the benefit of the AI chambering over the standard .260 in much other than brass life and lack of trimming of cases. Velocities may be 100fps better on average. You may find you rifle likes a lower node and any potential velocity benefit of the improved case is moot.

I'm running 130gr VLD's at 2915 from a 23" barrel with no pressure. Its been a laser!
 
Another question:

Why are you comparing a middle weight for caliber bullet (308-175gr) to a heavy for caliber bullet (260-142gr)??? This comparison is not apples to apples. Using your comparison, you'd be better off going to a 6mmSLR using 105gr hybrids as then you would only require 9.2moa at 600yards.
 
Shooter ----/ said:
What velocity are you getting with the 175's?
Click to expand...
2625

Shooter ----/ said:
Another question:

Why are you comparing a middle weight for caliber bullet (308-175gr) to a heavy for caliber bullet (260-142gr)??? This comparison is not apples to apples. Using your comparison, you'd be better off going to a 6mmSLR using 105gr hybrids as then you would only require 9.2moa at 600yards.
Click to expand...
The 142gr is a bullet I had data on.
I would definitely try working up loads for different weight bullets.
 
Why don't you try a heavier bullet in your 308? I'm getting 2610fps using a 215gr bullet which is giving me 13.7moa at 600yards. That heavier bullet doesn't get pushed around as bad as a lighter bullet.
 
Shooter ----/ said:
Why don't you try a heavier bullet in your 308? I'm getting 2610fps using a 215gr bullet which is giving me 13.7moa at 600yards. That heavier bullet doesn't get pushed around as bad as a lighter bullet.
Click to expand...

I have tried bullets upto and including the 208 A-Max.
My best groups are with 180gr SMK's pushing 2610fps.
The problem is that no mater how much I spend testing new loads the throat is eroding.
It will be cheaper to spend $500 on a match barrel that has better potential for accuracy.
 
My 2 cents since I have competed with both chamberings. First off, the LR ballistics of the 6.5 will be much better then the 308 until you super size the 308 ala FTR specs. Then there isn't as much difference as you think... Recoil with the 308 goes way up but so does the LR energy.

For the 260AI, you will need to get an assortment of tools to prep the cases and be prepared to form cases. Old 308 cases will likely not work ... all brass work hardens when you fire it.. that brass does not want to change shape.

I would strongly recommend starting with new brass.

once brass is prepped, the case life is very long at moderate operating pressures... better learn to anneal. The sharp shoulder really helps to control brass flow into the necks

When rebarreling, you have the option to get a longer barrel which is just "free horsepower"..... go 28 to 30" and reaching 2900fps with the 140gr family is a no brainer. Accuracy goal is also a no brainer with proper load work up. But you can get that in pretty much any chambering with a good quality barrel.

http://www.canadiangunnutz.com/forum/showthread.php/1281196-Budget-build

A customer of mine just did exactly the same thing... all smiles. I would go prefit given the huge difference in cost and very little difference in performance.

With all that ballistics goodness will come the downside... bore life is 1/2 the 308. I doubt you will see 2000rds before groups open up noticeably. My F open rifles all started to show wear around mid to high teens.

To gain bore life and not loose a whole lot in LR ballistics, you can slow down the bullet to 2800fps... now the 260Rem (feeds better too), 6.5 Creedmoor or similar wildcats, and the 6.5X47L becomes oodles of fun. Or just throttle back the 260 AI and better get used to seeing the same cases for a long long time.

Only the 260AI doesn't stack in AICS mags so something to consider. All the dies and stuff to keep it running is now simple... Let me know

Given how much you shoot, you will get a chance to try another chambering next year :)

Then we can chat about 6mm and 7mm and supersized 308's. With prefits, just swap out as you feel... easy, less money, simple way to try all sorts of chamberings. You have at least 50 chambers to explore.

Once set up, swapping barrels takes a whopping 10 minutes. Yes, you can even swap barrels at the range....

Fun, fun, fun...

Jerry

PS a 7-08 or 7X57 reg or improved with 162/168gr bullets are formidable combos as well.... just saying.
 
Mystic Precision said:
My 2 cents since I have competed with both chamberings. First off, the LR ballistics of the 6.5 will be much better then the 308 until you super size the 308 ala FTR specs. Then there isn't as much difference as you think... Recoil with the 308 goes way up but so does the LR energy.

For the 260AI, you will need to get an assortment of tools to prep the cases and be prepared to form cases. Old 308 cases will likely not work ... all brass work hardens when you fire it.. that brass does not want to change shape.

I would strongly recommend starting with new brass.

once brass is prepped, the case life is very long at moderate operating pressures... better learn to anneal. The sharp shoulder really helps to control brass flow into the necks

When rebarreling, you have the option to get a longer barrel which is just "free horsepower"..... go 28 to 30" and reaching 2900fps with the 140gr family is a no brainer. Accuracy goal is also a no brainer with proper load work up. But you can get that in pretty much any chambering with a good quality barrel.

http://www.canadiangunnutz.com/forum/showthread.php/1281196-Budget-build

A customer of mine just did exactly the same thing... all smiles. I would go prefit given the huge difference in cost and very little difference in performance.

With all that ballistics goodness will come the downside... bore life is 1/2 the 308. I doubt you will see 2000rds before groups open up noticeably. My F open rifles all started to show wear around mid to high teens.

To gain bore life and not loose a whole lot in LR ballistics, you can slow down the bullet to 2800fps... now the 260Rem (feeds better too), 6.5 Creedmoor or similar wildcats, and the 6.5X47L becomes oodles of fun. Or just throttle back the 260 AI and better get used to seeing the same cases for a long long time.

Only the 260AI doesn't stack in AICS mags so something to consider. All the dies and stuff to keep it running is now simple... Let me know

Given how much you shoot, you will get a chance to try another chambering next year :)

Then we can chat about 6mm and 7mm and supersized 308's. With prefits, just swap out as you feel... easy, less money, simple way to try all sorts of chamberings. You have at least 50 chambers to explore.

Once set up, swapping barrels takes a whopping 10 minutes. Yes, you can even swap barrels at the range....

Fun, fun, fun...

Jerry

PS a 7-08 or 7X57 reg or improved with 162/168gr bullets are formidable combos as well.... just saying.
Click to expand...
Thanks for all the advice Jerry.
I think I will go 260 Rem if the AI doesn't work well in AICS mags.
I have no objection going with a longer barrel as long as it fits in my drag bag/ shooting mat.
Would fluting and threading for a muzzle brake add a lot of time to an order?
As I mentioned in the original post I won't be ready to touch the rifle till the end of October..
I am already setup for annealing so that is not an issue.
Thanks in advance
 
Sure, but if you bought into the short barrel craze, you'll never get there. I'm using a 31 inch tube.

Mine is a worked up load for my particular rifle used in competition. I would strongly recommend starting with a much lower load or contacting Berger themselves for load data. Weather conditions (rain) has caused over-pressure. I use 48grs of H4350 lit with a Federal 210.

As for the throat erosion part of your post, do you expect that the 260 won't cause throat erosion?
 
Shooter ----/ said:
Sure, but if you bought into the short barrel craze, you'll never get there. I'm using a 31 inch tube.

Mine is a worked up load for my particular rifle used in competition. I would strongly recommend starting with a much lower load or contacting Berger themselves for load data. Weather conditions (rain) has caused over-pressure. I use 48grs of H4350 lit with a Federal 210.

As for the throat erosion part of your post, do you expect that the 260 won't cause throat erosion?
Click to expand...

Appreciate it, thank you. I'm running a single shot with 30" barrel. I understand the importance of working up slowly.
 
Shooter ----/ said:
Sure, but if you bought into the short barrel craze, you'll never get there. I'm using a 31 inch tube.

Mine is a worked up load for my particular rifle used in competition. I would strongly recommend starting with a much lower load or contacting Berger themselves for load data. Weather conditions (rain) has caused over-pressure. I use 48grs of H4350 lit with a Federal 210.

As for the throat erosion part of your post, do you expect that the 260 won't cause throat erosion?
Click to expand...
It's not that I'm not expecting the throat to erode on the 260.
It's that when I start off with a new barrel I can chase the lands for a long while.
My barrel already has 0.040" of throat erosion pushing me to the limits of my magazine length.
On top of that it's a factory barrel which does not have the inherent precision of a match barrel.
 
thump_rrr said:
It's not that I'm not expecting the throat to erode on the 260.
It's that when I start off with a new barrel I can chase the lands for a long while.
My barrel already has 0.040" of throat erosion pushing me to the limits of my magazine length.
On top of that it's a factory barrel which does not have the inherent precision of a match barrel.
Click to expand...

I didn't realize that magazine length was a concern. My bad.
As for the match barrel, it's addicting to shoot them! All my centerfires wear them now!
 
You must log in or register to reply here.
Back
Top Bottom