Cold Bore Accuracy

rasimcox

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Feb 4, 2022
13
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Tennessee
I’m looking for some help with an issue that I’m seeing with my 300WM rifle. This issue is repeatable, I just can’t figure out why. When I take the rifle out, my cold bore shot will always be .75 MOA high and the second follow up shot with be .5 MOA low. All following shots will stack up on top of one another right on the point of aim.

I do hand load my rounds, using a Hornady 225gr ELD-M bullet and all my dies are match grade even including the seating stem that is specific for this bullet. I weigh out each load and even check my concentric of each round.

I have just replaced the barrel with a new Preferred Barrel Blanks 27” barrel with a 1:8 twist. I feel pretty confident that the twist is more than enough to stabilize this round. I only have 74 rounds through this barrel, but don’t see the problem getting any better.

Any ideas or suggestions would be much appreciated.
 

Wannashootit

Gunny Sergeant
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This is without cleaning the bore between range trips?
Wondering if there's another variable(s) in play here.
 

rasimcox

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Feb 4, 2022
13
5
Tennessee
All testing has been from a bench shooting off a MDT tripod on the front and and rear bag for support.

The rifle is equipped with a Jard trigger with 8 oz pull weight.
 
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SupressYourself

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rasimcox

Private
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Feb 4, 2022
13
5
Tennessee
Have you tried it without the suppressor?

Also, if you let it sit 5 or so minutes and shoot another group, does it do it again?
If so, see this: https://www.snipershide.com/shooting/threads/first-round-flyers.6931386/ You may be witnessing a maddening phenomenon that seems to be a function of certain suppressor and load combos.
I haven’t tried it without the suppressor, but will go out back and give it a try and let you know. Thanks, haven’t thought about that being the culprit.
 
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Pappasniper

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I have to say that its very wild. Ive had very few guns with even a cold bore single shot adjustment. Sometimes changing powder/loads Ill get a couple to foul in but nothing this consistent. I too love 300WM with those 225's, and shoot them often.

Good luck with can off. Maybe spin on a brake when you shoot without a can.

PB
 

rasimcox

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Feb 4, 2022
13
5
Tennessee
I shot a 3-shot group at 250 yards, first shoot was still high but only .75". The second and third shots were touching, so there was not any variation on the second shot. I think I can live with those results, just weird that the can would cause such a problem.
 
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rasimcox

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Feb 4, 2022
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5
Tennessee
I have to say that its very wild. Ive had very few guns with even a cold bore single shot adjustment. Sometimes changing powder/loads Ill get a couple to foul in but nothing this consistent. I too love 300WM with those 225's, and shoot them often.

Good luck with can off. Maybe spin on a brake when you shoot without a can.

PB
I'm loading 68 gr of VihtaVuori N160 and seating the bullet to 2.865" to ogive using a Federal Large Rifle Magnum primer in Hornady brass. I'm obtaining 2,763 fps average with only 20 fps varience between rounds.
 

db2000

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    One other thing that I did forget to mention, I do shoot this rifle in most all cases suppressed.
    I’d be willing to bet there’s your answer. That was going to be my question. Looks like you already know how to prove the hypothesis.
    My SiCo Omega is usually 1”high and left with several different rifles on the first cold bore shot. No other variables. I’ve tested this more than I care to count as I hunt with the suppressor.
    I’ve read on here people bragging on their Dead Air can and that it doesn’t make a difference but can’t speak to that.
     

    rasimcox

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    Feb 4, 2022
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    I’d be willing to bet there’s your answer. That was going to be my question. Looks like you already know how to prove the hypothesis.
    My SiCo Omega is usually 1”high and left with several different rifles on the first cold bore shot. No other variables. I’ve tested this more than I care to count as I hunt with the suppressor.
    I’ve read on here people bragging on their Dead Air can and that it doesn’t make a difference but can’t speak to that.
    I'm actually shooting a Dead Air Sandman L can myself.
     
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    db2000

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    I'm actually shooting a Dead Air Sandman L can myself.
    I’ll look forward to hearing the unsuppressed results. N of 1 is as anecdotal as it gets but hey 😊
     

    rasimcox

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    Feb 4, 2022
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    I shoot this can on my Christenson Arms MPR 6.5 Creedmoor and don't have any issues. Every shots is right where I aim. This is a 30 cal can, so maybe shooting it with a smaller caliber doesn't have the same effect???
     

    rasimcox

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    I’ll look forward to hearing the unsuppressed results. N of 1 is as anecdotal as it gets but hey 😊
    I shot a 3-shot group at 250 yards, first shoot was still high but only .75". The second and third shots were touching, so there was not any variation on the second shot.
     

    db2000

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    Ok. Mine is on CA MPR 6.5 PRC and then a variety of other guns. They all are off a little on the first cold bore shot a 100, then the same POI.
     

    DJL2

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    I’ve never seen a drastic POI shift shooting my Dead Air Nomad 30… certainly not to substantially different, repeatable POI over a ~1.5 MOA spread between my first shot and my second.
     

    rustyinbend

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    I have a little different view from the conventional wisdom in this forum. So your first cold-bore shot is slightly high, and your second cold-bore shot is slightly low ... both to predictable measure ... and everything else is center of target. My reaction is "Congratulations !!!". That's terrific and you know what to expect, and how to manage it. I wish my cold-bore shots were that predictable. There's nothing wrong, quite the contrary, you're a lucky man shooting an excellent rifle. IMHO
     

    Lawnboi

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    How new is the suppressor? Proven on another rifle.

    I have a gemtech that did goofy things till I got some carbon in it.
     

    rasimcox

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    Feb 4, 2022
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    How new is the suppressor? Proven on another rifle.

    I have a gemtech that did goofy things till I got some carbon in it.
    I probably have over a thousand rounds through this can, if not more. I actually thought about if I need to clean my can.
     

    MikeRTacOps

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    I’m looking for some help with an issue that I’m seeing with my 300WM rifle. This issue is repeatable, I just can’t figure out why. When I take the rifle out, my cold bore shot will always be .75 MOA high and the second follow up shot with be .5 MOA low. All following shots will stack up on top of one another right on the point of aim.

    I do hand load my rounds, using a Hornady 225gr ELD-M bullet and all my dies are match grade even including the seating stem that is specific for this bullet. I weigh out each load and even check my concentric of each round.

    I have just replaced the barrel with a new Preferred Barrel Blanks 27” barrel with a 1:8 twist. I feel pretty confident that the twist is more than enough to stabilize this round. I only have 74 rounds through this barrel, but don’t see the problem getting any better.

    Any ideas or suggestions would be much appreciated.
    PM me when you have a moment, I have a few ideas what's going on with your stick...

    Mike R.
     

    SupressYourself

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    Mar 26, 2017
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    I shoot this can on my Christenson Arms MPR 6.5 Creedmoor and don't have any issues. Every shots is right where I aim. This is a 30 cal can, so maybe shooting it with a smaller caliber doesn't have the same effect???
    My theory is that its somehow related to gas volume, possibly coupled with bullet and (suppressor) bore diameter. In my case, my 223 can had this problem on a 22-250, but not on a 223. Also, my 30 cal cans don't have this problem on that same 22-250.
    (maybe?) The larger volume of gas stays in the suppressor longer and / or is more dense, changing the POI on the subsequent shots. You let it set for a few minutes, the gas clears out, and you're back to your 1st round POI.
     
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    rasimcox

    Private
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    Feb 4, 2022
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    5
    Tennessee
    That would kinda explain way I don't see the same effect when using this can on my 6.5 CM, less gas and smaller diameter bullet. I think I might try this can on one of my 308's just to see if I have the same problem. Same diameter bullet but slightly less gas.....?? Worth a shot or two to find out.
     
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