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2 shots together, third flies?

Mram10

Cast Iron
Joined
Dec 17, 2017
I have a couple Christiansen arms barrels I used for a 300 rum and 7-300wm. The first 2 shots from each are usually within an inch at 400yds, but the third flies off about 3 inches away. Shot off front rest and heavy rear bag on concrete bench. Shots are in succession then rest rifle for 10 minutes before next 3 shot group. Guessing heat is the issue. Thoughts?
 
Loaded into a magazine or single loaded? If magazine loaded try this. Load 3, fire two and set the third aside. Do this 3 times, then take the 3 rounds set aside, single load them, and see what group you get.

If you are single loading, use your watch and reduce your rate of fire to allow the barrel to cool between shots. That may not be a solution, but will help you identify the problem.

What occurs with shots after the third? Do they group with the 3rd shot, or off on their own?
 
yes get a 5-10 shot group to see how its patterning. 3 inches seems a bit much for a cold bore difference at 400. but its not unheard of.
 
Thx guys. Rounds are loaded both individually and from mag. No difference there. I will try larger groups with min time, then 5 shot groups with 2 min cooling to see. Heat is all that makes sense. Thin steel barrel surrounded by carbon fiber is great for weight, but not a fan for heat
 
Just a question:

In that caliber, Why would you need three shots?

;-)

Humor of course.....
 
I have a couple Christiansen arms barrels I used for a 300 rum and 7-300wm. The first 2 shots from each are usually within an inch at 400yds, but the third flies off about 3 inches away. Shot off front rest and heavy rear bag on concrete bench. Shots are in succession then rest rifle for 10 minutes before next 3 shot group. Guessing heat is the issue. Thoughts?

I'd look into more time between shots, barrel heat from these ultra mags introduces much heat into the bore, changing the harmonics.
 
Is the barrel free floating? Maybe you need a little pressure under the barrel at the fore end tip of the stock.
See if a single or double thickness of business card fits in between barrel and fore end.Re-mount the barreled action to the stock with the business card between barrel and fore end tip and shoot your 3 shots. I did that once and found I had to bed the barrel into "Acra-Glass" at the fore end tip. Of course when you do this you have to have the barrel shimmed while the acra glass hardens....I'm sure there must be something on utube, if you're not familiar. It worked for me, although it was only a .270. Afterward the rifle would put 5 shots in 1.5"- 1.625" @ 200 yds. with handloads. That's a lot better than I can shoot without a rest. Hope this helps.
Perhaps you already know about this. Anyway, good luck. PB
 
Cal, funny. I shouldn’t. just need it for load testing. Prefer 5 shots to test, but don’t want to lose too much barrel life
 
Packard, it’s free floated to same way I’ve done all the others. It seems the barrel is the only new variable. I’ll try something in between to see if it helps though
 
Are these the skinny steel tubes inside a carbon fiber wrapper? I'm guessing the steel part of the barrel heats up much faster than a regular barrel. Then when it gets hot, it expands more than the wrapper. Its hard to imagine how that could be anything but bad for accuracy.
 
Yes, std bull carbon fiber wrapped barrel. Heat makes sense to me. I’ll take them out this week and post pics with 5 min between shots to allow cooling.
 
Yes, std bull carbon fiber wrapped barrel. Heat makes sense to me. I’ll take them out this week and post pics with 5 min between shots to allow cooling.

In the long range classes I used help teach, we would suggest to folks with barrel torching rounds, to stand the weapon upright on the buttstock with the bolt open, and allow the chimney affect to help cool them more thoroughly and rapidly.YMMV
 
Steve, good advice. I do that as long as it isn’t windy and blowing dust in my chamber. Always set in shade also
 
I would try stopping at 2 shots and let it cool back to normal and then shoot the same target and see the group.
 
just stop and think about it,
you use that kind of barrel to make the gun as light as possible,
so you can hump it up and down and over hills to take one shot at your game.

so what is important is the first shot out of a cold barrel, and maybe the second shot.

that the third one is a bit of a flyer isn't a great shock, now is that third one
flying consistently to the same spot?

probably need to use a sled and just worry about how that first shot is hitting.
 
I built a 17HMR on a 10/22 with a Majestic Arms 17M2 barrel with Lothar Walther liner
The Majestic arms barrel would always make the first two hole touching at 50y [very close with 17 cal holes] and then the 3rd shot on is a flyer .

That was it for me a thin tensioned barrels and carbon wrap.
 
Hmm, two different rifles, one shooter. Do you have a rifle that doesn't do this? A buildup of nervous tension can do this, especially with more powerful cartridges.
 








 
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