My new 260 AI build ...

[Joe R]

I have been shooting F-TR for a couple of years and I've been having great fun at it. A few months ago a friend of mine, Robert, built himself a new 260 AI with Ben Steinsholt reamer and just couldn't stop talking about how well his rifle was doing even while fire forming brass.

After talking to Ben Steinsholt I decided that I should broaden my skills beyond the .308 and that the 260 AI was a good candidate that fit my criteria (I have lots of Lapua Palma brass on hand). So I embarked on that project. Last Friday I went to Austin and picked up the rifle that Tommy Shurley built for me.

Over the weekend I prepped some brass and had some very interesting handloading experiences. The necking down process resulted in brass that had 5-10K of runout at neck. When I went to seat the bullets the necks were so tight that I couldn't use my hydro press and had to muscle down the rounds with my Sinclair harbor press. The results were horrible, I had rounds that had massive amount of neck tension, seating depth varied as much as 30Ks, and I had 10-20K of runout. And then there was the little hump at the shoulder/neck junction made me wonder if the whole thing might just explode in my face.

Today, I finally got the courage to shoot it for the first time at the 100 yard line. At first my expectations were very low, just fire a few shots to break in the barrel and then shoot a few groups of threes just to get the velocities. If I managed to get on paper I would go home satisfied. I mean with ammo like that you have to be realistic right?

Much to my amazement within four rounds I was not only on paper but I actually hit a bullseye on my 18"x18" target. Well, I cleaned the barrel after that, and I figured that I had already achieved more than I expected. Now it was just a matter of getting some baseline velocities. Well, here's what happened.



and I wasn't even in the node. Here's what the brass and rounds looked like before and after firing.



Here's the reamer that made it all possible.



and here's my rifle and its specs with a lot of guidance from Ben S.


260 AI, Bartlein 8 twist, 30" straight tube, Kelbly F-Class Panda, Kelbly trigger, Kelbly scope rings, March 10-60 scope and Shurley Lowrider XL stock.

Now I know why Robert was so ecstatic. I just can't wait to see what it can do with formed brass, proper seating and neck tension.

Regards,

Joe

 

[ShootDots]

The Shurley Brothers sure do phenomenal work Joe! Beautiful rifle indeed!!!

 

[Sniper338]

What powder you using? With a 30 inch tube seems like you should be getting more speed than that. 45.5 looked good tho!

 

[Joe R]

What powder you using? With a 30 inch tube seems like you should be getting more speed than that. 45.5 looked good tho!

H4831sc, I may have to change to H4350 if I run out of case capacity before getting to ~2850.

 

[ShootDots]

H4831sc, I may have to change to H4350 if I run out of case capacity before getting to ~2850.

Joe, I have a 30" Krieger. I am shooting the Berger 140 LRBT's at 2915 with 47.5grs of H4831SC. The reason you are getting lower velocities is due to the shoulder blowing out to 40 degrees as the case expands, lowering the pressure. Once you develop a load with the fireformed cases, the pressures will rise and the velocities will go up. With the "Palma Brass", should you feel the need, you could get to 3000 f.p.s. I never felt the need to get up there.

 

[Sniper338]

Yeah i was thinking its low because my 260 TAC with a 28 inch tube shoots alittle faster with H4350

 

[Ledd Slinger]

I wonder why your fired case shoulder is so rounded?? Must have been a really low pressure load. Looks like it was hydroformed or fireformed with a light load of Unique. Your reamer seems to have a nice sharp shoulder. Just odd to see a rounded Ackley shoulder after firing a bullet down the barrel at over 2800 fps...

 

[Ledd Slinger]

I wonder why your fired case shoulder is so rounded?? Must have been a really low pressure load. Looks like it was hydroformed or fireformed with a light load of Unique with tissue paper in the neck. Your reamer seems to have a nice sharp shoulder. Just odd to see a rounded Ackley shoulder after firing a bullet down the barrel at over 2700 fps...

 

[Joe R]

Joe, I have a 30" Krieger. I am shooting the Berger 140 LRBT's at 2915 with 47.5grs of H4831SC. The reason you are getting lower velocities is due to the shoulder blowing out to 40 degrees as the case expands, lowering the pressure. Once you develop a load with the fireformed cases, the pressures will rise and the velocities will go up. With the "Palma Brass", should you feel the need, you could get to 3000 f.p.s. I never felt the need to get up there.

Ben,
No worries, I'm going to continue working up tomorrow towards the OBT using H4831sc. After I have 50 fire formed cases I plan on using them to finalize the load for the Sept 18 match. Sometime after that I will test H4350 since I already bought one pound of it, but unless there is a benefit (better precision) I'm planning on sticking with the slower H4831sc.

Presently I have no intention of trying to get to the higher node around 3,000 fps. My understanding is that Mark Walker did that with his 7mm and discovered that the primer pockets crapped out after one firing. I don't particularly enjoy brass prep, so I want to get many firings out of my cases.

I wonder why your fired case shoulder is so rounded?? Must have been a really low pressure load. Looks like it was hydroformed or fireformed with a light load of Unique with tissue paper in the neck. Your reamer seems to have a nice sharp shoulder. Just odd to see a rounded Ackley shoulder after firing a bullet down the barrel at over 2700 fps...

I appreciate your observation, however, I believe the roundness you're seeing is probably due to camera movement/shake because I was zoomed in. The case shoulder and neck areas are as crisp as my regular 308.

Joe

 

[JLT]

That's a beauty! Very nice piece of wood on your rifle. Excellent shooting, too.

4831SC and 4350 are the 'referrence' powders for the .260 AI for a reason, but if your barrel likes it for accuracy, Reloder 17 delivers some serious speed at sane pressures in the .260 AI. I'm right at 2,950 with a Barnes Match Burner out of a 26" barrel using 43.7 gr. of Reloder 17. I lucked out . . . my rifle delivers excellent accuracy with this powder and just about every 140 class bullet except for the Nosler CC.

 

[22BRGUY]

In my 260AI rifle I was able to nicely fireform brass using 16 1/2 grs. of Red Dot covered with firmly packed COW and a tightly wadded up and packed toilet paper neck plug. It saved me using up bullets to fireform. Very beautiful rifle indeed Joe and Ben is awesome.

 

[Sniper338]

In my 260AI rifle I was able to nicely fireform brass using 16 1/2 grs. of Red Dot covered with firmly packed COW and a tightly wadded up and packed toilet paper neck plug. It saved me using up bullets to fireform. Very beautiful rifle indeed Joe and Ben is awesome.

I tried that cream of wheat and toilet paper method once in my 22250AI... maybe it was just me but it was messy.. had to clean out that crap everywhere...

 

[22BRGUY]

I tried that cream of wheat and toilet paper method once in my 22250AI... maybe it was just me but it was messy.. had to clean out that crap everywhere...

I didn't have that much of a problem. I used a powder funnel to fill the cases with COW and was careful to not overfill them. Then I compacted the COW with a small diameter rod. Wadding up the tp with my fingers was easy and I compacted that with the rod also. Yes there was a bit of spillage but not that bad I thought anyway. I also wiped out the powder funnel afterwards with a q tip and cloth. I saved using up a half a box of bullets that way which was worth it to me.

 

[Ledd Slinger]

My only AI is my 243 LBC T40. I didn't use cream of wheat. I just filled the case to the bottom of the neck with Unique powder, didn't even measure the charge weight, then stuffed the neck with a really tight wad of tissue paper. You'll know when you have it right because it will give a nice loud 'POP' and the fireformed shoulders come out nice and sharp. If you don't get the tissue paper tight enough in the neck, it will be a softer sounding pop and the shoulders will be a little rounded like the brass in the OP's picture.

I measured the charge weights at first from while trying 15-18gr of Unique, then filling with COW, but the shoulders didn't come out very sharp. I don't measure the charge weight anymore because I figure the tissue paper doesn't have enough resistance to create a lot of back pressure with an excessive charge weight. I'm probably putting more powder than I should in the case, but all the excess pressure just blows through the paper and the cases come out looking perfect. Never had any issues. Though I'm not sure about doing it that way with larger cases like the 260 AI.

 

[22BRGUY]

My only AI is my 243 LBC T40. I didn't use cream of wheat. I just filled the case to the bottom of the neck with Unique powder, didn't even measure the charge weight, then stuffed the neck with a really tight wad of tissue paper. You'll know when you have it right because it will give a nice loud 'POP' and the fireformed shoulders come out nice and sharp. If you don't get the tissue paper tight enough in the neck, it will be a softer sounding pop and the shoulders will be a little rounded like the brass in the OP's picture.

I measured the charge weights at first from while trying 15-18gr of Unique, then filling with COW, but the shoulders didn't come out very sharp. I don't measure the charge weight anymore because I figure the tissue paper doesn't have enough resistance to create a lot of back pressure with an excessive charge weight. I'm probably putting more powder than I should in the case, but all the excess pressure just blows through the paper and the cases come out looking perfect. Never had any issues. Though I'm not sure about doing it that way with larger cases like the 260 AI.

I know you are a very accomplished shooter/reloader for sure but filling the case like that would prolly be too suspenseful for me. Glad it worked though for you.

 

[Ledd Slinger]

I know you are a very accomplished shooter/reloader for sure but filling the case like that would prolly be too suspenseful for me. Glad it worked though for you.

It was very suspenseful for me as well. I started with a very low charge of 15gr and COW to avoid an explosion, then worked up until I no longer needed COW and eventually had the case full. It was kind of like working up a load with a powder for which there is no load data. Started very cautiously. After that, I just started filling the case up to the bottom of the neck without weighing the charges. It eliminated me having to use the messy COW that left all kinds of crap in my bore. I'm no way condoning this practice for other people with other chamberings in their rifles, but it worked for me with my cartridge.

 

[Joe R]

In my 260AI rifle I was able to nicely fireform brass using 16 1/2 grs. of Red Dot covered with firmly packed COW and a tightly wadded up and packed toilet paper neck plug. It saved me using up bullets to fireform. Very beautiful rifle indeed Joe and Ben is awesome.

Dennis,
I decided to give your COW method a try. I decided that don't want to waste barrel life on fire forming brass. I couldn't find Red Dot locally, but I did find Titewad. So I loaded one round and dropped 8 grains of Titewad, filled the case with COW, took it out to my garage and I pulled the trigger. When I opened the bolt to my amazement, there was a perfectly formed 260AI case. Well, I stuffed another 149 cases and tomorrow I'm going to the range and make some noise. I need to get ready for the 600 yard match on the 18th.

Thanks again,

Joe

 

[22BRGUY]

Dennis,
I decided to give your COW method a try. I decided that don't want to waste barrel life on fire forming brass. I couldn't find Red Dot locally, but I did find Titewad. So I loaded one round and dropped 8 grains of Titewad, filled the case with COW, took it out to my garage and I pulled the trigger. When I opened the bolt to my amazement, there was a perfectly formed 260AI case. Well, I stuffed another 149 cases and tomorrow I'm going to the range and make some noise. I need to get ready for the 600 yard match on the 18th.

Thanks again,

Joe

Good to hear Joe.

 

[shepherm]

Yesterday I formed 100 260 AI. I used 9 grains of titegroup. Although its a simple process plan on it taking some time, because your barrel is still going to heat up on you. Also make sure you clean your brass good when you are done. I haven't ever had a problem but I heard the other day a guy didn't clean them good, or maybe not at all, and he few had some cow left in the case causing pressure problems with his loaded ammo.

 

[Terry Altom]

Dennis,
I decided to give your COW method a try. I decided that don't want to waste barrel life on fire forming brass. I couldn't find Red Dot locally, but I did find Titewad. So I loaded one round and dropped 8 grains of Titewad, filled the case with COW, took it out to my garage and I pulled the trigger. When I opened the bolt to my amazement, there was a perfectly formed 260AI case. Well, I stuffed another 149 cases and tomorrow I'm going to the range and make some noise. I need to get ready for the 600 yard match on the 18th.

Thanks again,

Joe

Ok, now you guys have me curious. Seems like I've got some WSF somewhere. One question, did you expand and form a false shoulder?