260 Rem AI

[twh731]

Howdy all! I just put in my new member introductory post so ya'll can read it if you like. I am building a Savage SA in 260 AI. Haven't been finding all that much info on reload or ballistic data. I read the demigod write up and that's what got me interested in the AI version. There doesn't seem to be a downside to this chambering and I have already ordered a 26" varmint barrel (in January!!!) from 4D. Still waiting. Anyway, had the left hand action timed/trued by Savage Shooters and purchased a Choate "Ultimate Sniper" stock from Midway ($130 on sale). This is a left hand centerfeed blind magazine receiver so stock options are not very abundant. This rifle was originally the Savage .308 Tactical (model 10 FLP) and it shot very well indeed until last year when it became frustratingly recalcitrant. It seems that the bore has left it's best years in the past. I have purchased some Lapua 260 Rem brass, Lapua 136 Scenar-L bullets and am looking for some good loading data using Varget or H4831sc. H4831 may be a little slow for this application but since the case volume will be slightly larger it may get the heavier bullets out there ok. Powder availability being what it is, I am restricted to what I have, Varget H4831sc, IMR 4007ssc. Anybody have any real life experience with the 260 Ackley, please jump in with comments, suggestions. I think I will use my 7mm expander to expand the neck and then my 260 die to neck size partially, forming a false shoulder of sorts to keep the cartridge from moving forward when the firing pin strikes it. I think I have that correct. Anyway, there you have it. Fire away. Tom

 

[coyotekiller82]

Great choice twh731!!

I built a very similar gun a couple years back.

Savage SA with a Shilen chrome-moly match grade barrel with an S7 contour (savage varmint contour), although I went with a McMillan F-Class stock.

Oh...and it's not backwards either

I haven't shot any pills that large yet...been fireforming with 123gr Sierra MK's and a stout load of H1000.

Any info I found on 139 Scenars was with 47gr of H4831SC, obviously I'd back off and work up, unless you're fireforming, then I'd leave it at a full load to help with getting your cases formed nicely the first time!

I didn't need to form the false shoulder, just screwed the barrel on with a 308 go gauge and I have a nice slight crush fit with a factory 260rem casing.

I've been firforming my loads out to 780 yards and the best group so far was a couple weeks ago with an 8" group...while fireforming!!

I can't wait to actually dial in a load or two with the 130gr hybrid Bergers I have as well as the 120gr A-max!!

 

[twh731]

Thanks coyote. Backwards! I get it! Hah! It's the first rifle I ordered new for myself way back when. I have since learned the art of using right hand tools. I have a standard .308 family GO gauge. So you're saying that you just screwed your barrel in tight on the GO gauge? That sounds easy enough. What I've been reading is that the GO gauge becomes the NO GO gauge for the 260 AI. Maybe I got that backwards. I think I read also that some one put a single paper shim between the bolt and GO gauge to make something like .004 difference. Anyway, if it works for you it should work for me too. Yeah I chose the 136 Scenar-L for ultra longrange workup. Those AMax bullets have a very slippery BC. I use the 162 AMax for my 7mm Rem Mag. Here in NM I have access to over a mile where we have steel set up at various distances. I have actually hit the 1788 yard piece (about 20" x 34") a few times with my 7mm Rem Mag. That's one of the reasons I love living here in the great West! The wind becomes horrendous this time of year though. I am probably trying to stretch this rifles legs a little more than the chambering will allow, but you never know until you try. At the very least it should be a very nice 1000 yard spanker. Tom

 

[coyotekiller82]

Thought you'd get a kick outta my "backwards" comment!! My brother is a lefty who grew up in a RH dominated world too, and like you has learned to use RH guns, but that's no substitute for the proper tool...in your case, a LH action!! I still like to harass him about it every now and again though.

Now that we're all grown and on our own, he has started to fill his safe with lefties!

The go gauge in 308 is all I used. To make it a NO-GO gauge, I add a couple of layers of the clear tape, used for gift wrapping etc, to the back of the GO gauge.

The AI and the factory cartridge chamber off the same datum line, which is the same as the 308 go gauge...screw the barrel on with the extractor removed from the bolt and you should be set!! I always check after with the tape trick to make sure.

That must be awesome to have so much room to shoot!! We're not terribly limited up here in Manitoba, but in the south of the province there are mile roads everywhere...not easy to find a place a guy can shoot safely out to a mile. The range across from my parents place (neighbors field) I can stretch out to 3/4 of a mile or so. One of the reasons I enjoy living where I do as well!

Regarding wind...this time of year is horrendous here too...come to think of it, most of the year is windy here on the Northern Prairie! A guy could wait his life away waiting for a calm day to shoot!!

That's impressive...1788 with your 7RM!

Your setup will be a very nice shooter at a grand & as you say, the possibility of stretching its legs out further is all the fun!!!

Good luck with your build and be sure to keep us posted!!

Brad

 

[twh731]

Will do. Now if I could just get my barrel Aaarrrggg!

 

[twh731]

I got my new 260 AI Rem. barrel from 4D. It is a Green Mountain 1:8 twist 26" Chromemoly barrel. Standard dished target crown. I had my receiver timed and trued by SavageShooter while I was waiting on the barrel to arrive. I have to say I was nervous installing the barrel the first time. I was disturbed b/c the barrel nut would not thread onto the barrel. I tried and tried to screw it on but it would only go on about 2 turns and then get really tight, almost like the threads were different pitch. So I put the barrel between to 2x4's and put them in a large vise. I put some moly grease very lightly on the barrel threads and then bit by bit turned the barrel nut back and forth with the barrel nut wrench, moving gradually up the barrel threads. Once it got all the way thru the barrel nut it went on by hand! I assume that the barrel nut threads were cut with a tap and the barrel threads were cut using a point bit on a lathe therefore they were slightly different profile. Next I put the recoil lug onto the barrel and started screwing the receiver onto the barrel. When I figured it was getting close to the proper headspace I put the bolt into the receiver and put the .308 Go Gauge into the chamber. I closed the bolt and screwed the receiver on until it suddenly wouldn't go any further. I noted where the receiver was indexed on the barrel. Then I place a new Lapua 260 Rem piece of brass into the chamber and screwed the receiver on further until it met resistance. It was about 1/2 turn further onto the barrel than with the Go Gauge in place. I then turned the receiver further onto the barrel (with the brass still in the chamber) while checking the bolt resistance. It was approximately another 10th of a turn until I just couldn't close the bolt onto the cartridge anymore. So I then backed off the receiver until the bolt would close with a good bit of resistance. Sorry, no way to measure it other than by feel. Since it was described to me on this forum as a "crush fit", that was what I was going for. I think I got it. I installed the rest of the kit on the rifle and began to figure out how to load a good fire forming combination. I will describe this part in another post here later. Tom

 

[twh731]

As promised, I will describe my fireform load procedure. The caveat is that I am not a gunsmith or professional ballistician so your rifle may require a different approach. I had some old IMR 4064 on the shelf and decided to utilize that for the fireforming procedure and save my "good" powder for working up actual accuracy loads. I used Hornady 120 AMax bullets and Federal GMM primers throughout. I did not bother to run the Lapua 260 Remington brass thru any dies before loading them. The Hornady reloading manual that I have (I think 7th volume) gives 37 gr. of 4064 as the only load listed (and maximum load at that) for the 120 gr bullet. My Sierra manual (don't know the vintage, but it's not more that 15 years old) lists over 40 gr of 4064. I decided to use the lower Hornady load as adequate for my application. So, 37 gr of IMR 4064, and 120 gr AMax, standard Lapua 260 Remington cases, Fed GMM primers. I determined my bullet seating depth by inserting a bullet in an unprimed, empty piece of brass and inserted into my chamber and closed the bolt. I extracted the dummy cartridge and measured the OAL and recorded it in my log book. I screwed the bullet seating die into my Rockchucker and ran the ram up and bottomed the die body onto the shell holder. I unscrewed the bullet seating portion until it was almost all the way out of the die. I put the dummy cartridge in my reloading press and ran it up into the die body and then screwed the bullet seater down onto the bullet. I then extracted the cartridge, remeasured it to make sure it hadn't changed. Put it back in and screwed the bullet seater down a tiny amount and ran the cartridge back into the die. I did this until I had achieved .004" shorter OAL. I loaded 10 rounds with the above recipe and carefully cycled them all thru the rifle (outside in a safe area, of course) to make sure that they would all function before heading out to the range. The cartridges all fit VERY snug in the chamber and I had to lock the bolt with alot of resistance.
At the range my first round struck 2" high and 5" left at 25 yards. I made a scope correction and dialed the wrong direction for my next shotlightbulb. I made the appropriate scope corrections and my next 3 rounds went exactly into the center square. Since I wanted to be sighted on at 100 yards I dialed in about 6 MOA lower correction and my next 3 rounds went into a single hole, literally. I had 2 rounds left for a 100 yard verification and they didn't disappoint me, landing .23" I know a 2 shot group isn't really a group but man was I stoked. Now to fireform the rest of my stash of Lapua 260 Remington brass! By the way, the fireformed brass chambers in the rifle beautifully with no hard bolt work. I think I have achieved my goal. My next step is to find a killer load using the Lapua 136 Scenar-L that I have. I am going to try H4831 first. Tom

 

[coyotekiller82]

Good show Tom!!

You're on the right track with you're process. The snug fit on unfired brass is exactly what is needed!!

How do the shoulders and the neck shoulder junction look after fireforming?? Are they distinctly formed or rounded??

If they're rounded I would increase your charge slightly until they are nice and sharply formed.

If they already look nice and sharp and are distinctly formed, you have yourself a good FF load!!

I hope to get out this weekend to FF the last of my RP brass!

Good shooting!

Brad

 

[twh731]

Thanks coyote, the brass is coming along nicely with sharp defined dimensions. The only reason I chose to use my 4064 is that it's probably 20 years old. It is in a dented steel can that I have kept in proper environmental conditions. It still smells like ether when I open it, but I don't use 4064 in any of my other rifles. I will probably use my cherished H4831 to develop proper 260 AI loads. I also have some Varget if I want to try that, but I think the Varget may be too fast for a 26" barrel and the heavier Lapua 136 gr bullet. I am anxious to try the new 136 Scenar and see if I can keep it stable out to 1500 yards or so. I have 50 fireformed cases now to play with! How is it up in Manitoba? We are starting our nice summer weather here in NM. The winds are starting to abate a bit and still light enough to shoot after 1930 hr. I have been hitting the mountain bike trails more too. I have been toying with the idea of designing a light rifle scabbard to mount on my mtn bike and go out boondocking! Tom

 

[Crashman1]

Sounds like you are well on your way with an awesome rig there. I shot the 260AI last year and it is an incredible cartridge, I shot the 139 Scenars at 2985 fps with a full case of H4831SC, I never tried Varget as I didn't think it was a suitable powder with the faster burn rate. I took mine out to 1150 meters and it was still producing awesome groups at that distance. Good luck with your new rig, keep us updated.

 

[coyotekiller82]

Thanks coyote, the brass is coming along nicely with sharp defined dimensions. The only reason I chose to use my 4064 is that it's probably 20 years old. It is in a dented steel can that I have kept in proper environmental conditions. It still smells like ether when I open it, but I don't use 4064 in any of my other rifles. I will probably use my cherished H4831 to develop proper 260 AI loads. I also have some Varget if I want to try that, but I think the Varget may be too fast for a 26" barrel and the heavier Lapua 136 gr bullet. I am anxious to try the new 136 Scenar and see if I can keep it stable out to 1500 yards or so. I have 50 fireformed cases now to play with! How is it up in Manitoba? We are starting our nice summer weather here in NM. The winds are starting to abate a bit and still light enough to shoot after 1930 hr. I have been hitting the mountain bike trails more too. I have been toying with the idea of designing a light rifle scabbard to mount on my mtn bike and go out boondocking! Tom

Beauty!! It's great up here in Manitoba!! We've been getting above avg temps for the last couple of weeks. Everything is finally turning green & most of the farmers in my area are done seeding. FINALLY some nice weather! Didn't manage to get out yesterday to get any shooting in. I have a couple of days off coming in 2 weeks so I'll for sure get the remainder of my brass FF'd and then I'll be ready to work up an accurate load!

Been thinking about threading my 6mmAI barrel back onto my long action before long as well. 2 guns to get loads for = twice the fun!!

So much to do and so very little time.