Help me rescope and reload for Christensen Arms Summit Ti.

[luke moffat]

I "settled" on, 64.7 grains of, IMR 7828 with, the 140 AccuBonds and am "happy" with, the Velocity at, 3,125 - 3,130 FPS with, NO pressure, signs showing ! And still, sub MOA ! This load, has about 1,500 ft pounds of Energy at, 550 yards and at, 600 yds it's about 1402 ft. lbs and the Bullet, is still going, 2,123 FPS which should expand, an AccuBond. I plan on doing a lot of practicing, to 700-800 but, NOT looking, to shoot that far, on Game ! I know that, the 140 Classic Hunter, by Berger, would be even better, for distance, on Elk/ Deer but, I haven't tried them, yet !

What pressure and temp did you run your numbers at?

 

[Idaho Lefty]

Luke,.. I started loading from, the Nosler "Data" ,.. That was, a HUGE waste of,..my TIME ! Their Max load of 61.0 grains got me about, 2,930 FPS AKA,...270 Win Vel.,.. LOL ! Data used now, is from, Dupont at, 65.2 of IMR 7828 = 3,135 FPS with, a 140 gr Swift Sirocco, in WIN Brass. I'm NOW at, 64.7 and 3,125 - 3,130 FPS in MY Rifle, I can go a bit higher and still be under Max Pressures as STILL, NO, cratering ! Quick Load shows a Max. charge of, 67.1 Grains at 3,221 FPS and 63,000 PSI. I am using Remington Brass which is a bit heavier/ thicker than Win. so I stay about, 1.5 to 2 grains LESS than, Maximum ! Hogdon Data shows 64.5 of, 7828 with 140's at, 3,081 FPS and 61,900 PSI. Berger shows, 66.3 as, their Max. with their 140 gr "Classic Hunter" at, 3,157 FPS. I will probably try, 65.0 grs of, 7828 (.3 tenths more than, previous load ) next, to get close to, 3,150 FPS in MY, .270 WSM, Rifle. My NEW Load = Remington Brass, WLR.MAG primer, IMR 7828 at, 65.0 grains ( IF, Sub MOA, still ! ) 2.875" COAL with 140 AccuBonds to fit, TIKKA T3, Standard 270 WSM, Magazines. My Rifle is a tikka T3 24" bbl Stainless steel. I'm shooting at 3,200 feet Elevation, here in Idaho and 40-50 degrees ! I will try to get an Arizona "Late Rifle", Elk tag for next year and yes, Temp's could be a bit Warmer, so I will, TEST this load , AGAIN this, Summer, here in ID. for, SAFE pressure, "Signs" ! I don't "Need" to "Hot Rod" this thing to 3,200+ FPS and "worry" about, Summer, Temps ! Hope this Info helps ! Good Luck !

 

[luke moffat]

Ok so you are using 26.9” for pressure and 50 degrees when running your calcs above?

 

[Idaho Lefty]

Luke,.. My objective for, the .270 WSM, is for a "Real World, Hunting Rifle", walking from, dark Timber, to open Sage/ Juniper country and shots from, 50 to possibly 600 Yards Max, on Elk. I am using a 3X9 Burris E1 scope instead of the 6 oz heavier 4.5X14 that, I HAD on my 7mm Rem Mag.
Note; its easier to shoot smaller groups with, MORE magnification ! But you probably already know that ! I have read a TON of "good things" about Nosler AccuBonds for accuracy and effect on Animals

 

[Idaho Lefty]

I am using, an estimated, .485 BC for the 140 AccuBond, at, 3,100 FPS presently. BUT,..I will "verify" my New load at, 200, 400 and 600 yards. Then, my son will make me a "Tape" to,.. "Dial" up to, 800 Yards ( for practice at, longer distances). The AccuBond, is supposed to "expand" at a Minimum of, 2,000 FPS and the Bullet from a 270 WSM can still be traveling, around 1,950 FPS at, 700 Yards if, started at,.. 3,100 FPS !
I'm NOT looking to build, a 1,000 Yard Rifle or,.. "re-invent", the,..Wheel ! Do you shoot, a .270 WSM ? Doug

 

[Idaho Lefty]

26.9 ? I do not have a "pressure" gun, I'm just "Miking" the Base of Cartridge and looking for, "cratered" Primers. Temp's HERE are 40-50 Degree's, Daytime and load Data i used was from,.. Dupont, Hogdon, Quick Load, and Berger and I'm still NOT going,.. 3,200 FPS so, NOT too "hot", yet !

 

[luke moffat]

I guess I am not being clear in what I am asking.

When you figured 1500 ft lbs at 550....what atmospheric conditions did you plug in when figuring the energy and velocity? IE, what barometric PRESSURE, and temperature, or what DA.

 

[Idaho Lefty]

I guess I am not being clear in what I am asking.

When you figured 1500 ft lbs at 550....what atmospheric conditions did you plug in when figuring the energy and velocity? IE, what barometric PRESSURE, and temperature, or what DA.

Luke, I use the Ballistic Calculator results, from Berger,.. 3,200 ft., 49 Degrees approximates, where I shoot, in Idaho, now, but I will be Hunting HIGHER at, 5,000 to 8,500 ft in Ariz or, Id. My son, makes my "Tapes" at, 6,500 ave. feet of, Elevation. I do not know the Barometric pressure he uses. I just use the Berger "Data" to get me an "Idea" of the Bullets "performance level". My son probably figures "Baro Press" in, on his Program, to make the "Tape", tho. After we "verify" the BC and "drops" at 200, 400 and 600 yards. I feel that, 550-600 Yards is about, Max for ME to shoot/ kill an Elk reliably, with that, AB 140 load at 3,150 FPS. What do you think ? Of course, the WIND makes, a HUGE difference as, to how far realistically,.. an "ethical" shot, is ! We carry "Charts" and a Wind Meter, always ! I've passed up "iffy" shots with, Bow or, Rifle.

 

[robby denning]

Just wanted to give you guys an update on this gun.

I've decided to swap my 26" barrel for a 24". Simply a personal preference for quick handling, fast shooting guns. 26" was fine, but I still never got used to the length (besides, this is Rokslide and this is what we do...)

Now that I've seen the velocities of the RL 26 and H4831SC, I'm not worried about the velocity penalty of a shorter barrel.

So, gun is on it's way to Christensen's right now. I'll revive this thread once it's back and I can get some range time. Thanks!

 

[Matt Cashell]

I heard you mention this issue on the Avery Adventures podcast, Robby. I hope the new barrel is a shooter too.

I like a 24 in barrel, especially for a short mag.

Looking forward to how this turns out.

 

[VernAK]

I sure like that Christianson Arms Summit TI ......even more if they offered it in 6mm Creedmoor.

 

[robby denning]

I sure like that Christianson Arms Summit TI ......even more if they offered it in 6mm Creedmoor.

I’m surprised they don’t with so much talk about it.
Ya, I’ll keep you posted on how it comes back together.


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[N2TRKYS]

Robby,

I wouldn't hesitate to run it down to 22". My 7 SAUM(Remington Model Seven) has a 22" barrel and will still sling 160 grain Accubonds 2960fps with RL26 and IMR7828SSC as a close second. Just a thought.

 

[robby denning]

Robby,

I wouldn't hesitate to run it down to 22". My 7 SAUM(Remington Model Seven) has a 22" barrel and will still sling 160 grain Accubonds 2960fps with RL26 and IMR7828SSC as a close second. Just a thought.

I thought about it! Too late now.


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[robby denning]

OK, time to update this thread. I received the gun back with the new 24” barrel earlier this summer.

I know some guys will roll their eyes, but I do like the 24” barrel better. Gun is more balanced (aesthetically), and fits in my scabbard correctly. I feel like it handles better, probably because I’ve been shooting 24 inch barrels most my life.

I re-installed the vortex HD 2.5–10X that I ran last year.

I headed to the range wondering three things:

1) would the POI have moved with the barrel switch and taking the scope off (mostly just curious)

2) would the gun still shoot sub-MOA like it had with the 26” (it should as it’s guaranteed for 1/2-MOA)

3) How much velocity did I lose?

Answers:

1) yes, the POI changed significantly. First group was 4” right and 5” low from last barrel. Again, this was just out of curiosity.

2) yes, the gun easily shot sub-MOA. After my sight-in, 1st group was 0.88”

3) So now the big one, velocity. Using the same loads as last year-140gr Berger Classic Hunter in front of 67gr RL26- this is a three shot group average velocity.

26” Barrel: 3357 Fps
24” Barrel: 3299 fps

So a loss of 58 fps. Amazingly, Mike from Hells Canyon estimated I’d lose about 60 fps!

So this is a good trade off so far. I say so far because there is a problem. Stay tuned.

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[robby denning]

So the gun shoots great but it’s developed a sticky bolt! And I don’t just mean after the shot, but even chambering a round; it just gets a lot worse after launch the missile.

Yes there are signs of pressure on the primer. I think you can see it on the left case easy enough

I’m surprised that this has developed going to a shorter barrel, But even more confounding to me is why is my bolt stiff when chambering a round? Remember, this is the same loads and actual cartridges that I shot last year in the 26” barrel and had no signs of pressure then.

Can the chamber dimensions change when they re-barrel a rifle? I’m sure that’s a dumb question.

I have not called Christensen’s yet. I was hoping to get some feedback from you guys on this. Obviously I can back off my load of grain and see if that stops the cratering, but if it doesn’t stop the chambering issue, I’ve got a problem.




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[mcr-85]

The chamber might be a little tighter in the shoulder than your last chamber. You may have to pull your bullets and resize and get more shoulder bump.

As far as your pressure signs and flat primers, I'd pull the bullets and drop a grain or two and see how that does.

Someone else probably knows better than I do tho.

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[Stid2677]

You need to start as if this is a new rifle and re run all your measurements. Measure the throat and fired brass shoulder. Do another work up to find pressure, as the velocity and pressure may shift as you shoot and clean the barrel.

I believe if you have a sift bolt closing on a loaded round, you are either forcing the bullet into the lands or the shoulder against the chamber.

I read early in the thread that you mentioned the bolt cycle was rough, my CA BA Tactical was the same. I used just a dab of JB paste on the bolt and sat and watched TV, I would cycle the bolt a hundred times each commercial until it cycled smooth as glass. Mine would bind just a bit as the bolt moved forward from full back, the bolt handle is off center enough to cause the bolt to be a bit rough as the fluting moved across the action. Once smooth I cleaned, oiled and reinstalled the bolt.

Good Luck

 

[elkguide]

The simple answer is yes, re-barreling can/will change chamber dimensions.
As has been said, start over just as if you had a new rifle. If you are having a hard chambering of a shell, you are likely hitting the lands, thusly causing the bind and the raised pressure.

Nice looking rifle, now start over and show us some sweet, one hole targets!

 

[Axlrod]

I have a CA ridgeline in 28 Nos. with Nos brass I hit press. early with 180 gr. Berger's. I tried some Bertram brass and was able to run max loads.
The issue with my gun is the neck is tight and the Bertram brass is thinner in the neck. With the nos. brass I couldn't put a bullet back in a fired case and it does go in a fired bertram. You may have to turn your case necks.