Cold Bore Shots, POI Shifts, and Canted Scopes

[eric1115]

Ill have to double check scope ring torque specs. Action and base were mounted at factory and I havent touched them. Scope is a Vortex Strike Eagle 5-25x50 FFP

All my shots were on freshly painted steel at known ranges, 200, 300, 409, 570, 796, 999. Was able to get repeated hits on them.

Ill be shooting 5 round groups at cardboard this weekend from 200-1000 so Ill get a little better idea of all that as well.

I just want to gather as much information and knowledge as I can so I can get the most out of my shooting sessions.

Good info. Factory installed screws are always suspect for me, usually oiled and rarely loctited so they are prone to backing out.

Strike Eagle is not exactly confidence inspiring, if you have intermittent unexplained zero issues, that would be my prime suspect. 300 PRC doesn't take that many zero loss events (or even suspected zero loss) that take 10-20 rounds to sort out before you could have paid for the upgrade to a Tenmile, RS1.2, LRHS, or SWFA that you can have a high level of confidence in.

A hit high on the plate could be higher than expected MV, high in the cone of fire, recoil management error, poor trigger press, or a combination of factors. It could be a lower than expected MV coupled with a compromised position leading to recoil management error that leads to a high hit despite low MV. It could be a scope shift. 10 round group at distance should help smooth out some of the noise and give a true sense of where you can expect to hit at a given distance (and atmospherics when you start getting way out there).

Those 5 round groups will tell you a lot, especially if you don't make corrections within the group and shoot the same solution for all 5 shots. Snap photos and take good notes, that data will be super useful. I see guys at the range chasing their tail, making corrections shot to shot, making a couple hits who-knows-where on the plate, and calling it "data". You can burn 50 rounds doing that and end up with less solid info that a 10 round zero confirmation and a 10 round group at 600-800.

 

[AM_Hunter]

Good info. Factory installed screws are always suspect for me, usually oiled and rarely loctited so they are prone to backing out.

Strike Eagle is not exactly confidence inspiring, if you have intermittent unexplained zero issues, that would be my prime suspect. 300 PRC doesn't take that many zero loss events (or even suspected zero loss) that take 10-20 rounds to sort out before you could have paid for the upgrade to a Tenmile, RS1.2, LRHS, or SWFA that you can have a high level of confidence in.

A hit high on the plate could be higher than expected MV, high in the cone of fire, recoil management error, poor trigger press, or a combination of factors. It could be a lower than expected MV coupled with a compromised position leading to recoil management error that leads to a high hit despite low MV. It could be a scope shift. 10 round group at distance should help smooth out some of the noise and give a true sense of where you can expect to hit at a given distance (and atmospherics when you start getting way out there).

Those 5 round groups will tell you a lot, especially if you don't make corrections within the group and shoot the same solution for all 5 shots. Snap photos and take good notes, that data will be super useful. I see guys at the range chasing their tail, making corrections shot to shot, making a couple hits who-knows-where on the plate, and calling it "data". You can burn 50 rounds doing that and end up with less solid info that a 10 round zero confirmation and a 10 round group at 600-800.

That is precisely why I want to gather as much info as I can because at $3 a round i dont want to be wasting shots that im not gaining any useful information from. If im seeing consistent scope shifts I may upgrade to a Tenmile.

I will see on friday what my 10 round group at 100 is and ill take photos of what my groups are at 200,400,600,800, and 1000 as long as I hit the target

 

[huntnful]

That is precisely why I want to gather as much info as I can because at $3 a round i dont want to be wasting shots that im not gaining any useful information from. If im seeing consistent scope shifts I may upgrade to a Tenmile.

I will see on friday what my 10 round group at 100 is and ill take photos of what my groups are at 200,400,600,800, and 1000 as long as I hit the target

Before that, you really need to check all your torques. Especially coming from the factory. They don't tighten shit. In my eyes it'd be an entire waste of day to go shooting without eliminating some possible issues first.

 

[Formidilosus]

I will see on friday what my 10 round group at 100 is and ill take photos of what my groups are at 200,400,600,800, and 1000 as long as I hit the target

Shooting those intermediate ranges is a waste of time and ammo. Get a real zero- with 10-20 shots centered over point of aim. Slip turrets. See what your data should be for 800 yards. Go straight to 800 yards. If the first shot hit the plate continue aiming center and shoot 5-10 shots. Go to the center of all rounds fired and make the adjustment. Change MV in app to match what the real data you just shot at 800 yards says. Then, all of the data in the app from muzzle to 800 yards will be correct.

 

[PaulDogs]

Shooting those intermediate ranges is a waste of time and ammo. Get a real zero- with 10-20 shots centered over point of aim. Slip turrets. See what your data should be for 800 yards. Go straight to 800 yards. If the first shot hit the plate continue aiming center and shoot 5-10 shots. Go to the center of all rounds fired and make the adjustment. Change MV in app to match what the real data you just shot at 800 yards says. Then, all of the data in the app from muzzle to 800 yards will be correct.

How far is far enough to get good data? I worry that the further I’m shooting, the larger the group size which in turn could make my observations less precise. Can I use data for my 223 at 400 yards? 600 yards? Or does it need to be 800 yards and beyond?


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[AM_Hunter]

Shooting those intermediate ranges is a waste of time and ammo. Get a real zero- with 10-20 shots centered over point of aim. Slip turrets. See what your data should be for 800 yards. Go straight to 800 yards. If the first shot hit the plate continue aiming center and shoot 5-10 shots. Go to the center of all rounds fired and make the adjustment. Change MV in app to match what the real data you just shot at 800 yards says. Then, all of the data in the app from muzzle to 800 yards will be correct.

The shots at 200 - 1000 im referring to are for the shooting competition im participating in on saturday. I will be trying to shoot 10 rounds to confirm zero on friday after work, and if I have time another 10 rounds out at 600 or 800 if I can get a target set before sundown, otherwise I will have to wait till after our shoot is done to maybe shoot another 10.

 

[Castle Rock]

Regarding your first couple of shots being high, that is a given if you have cleaned your barrel and there is any residual oil or solvent
Have you checked turret movement with a tall target test.?

 

[AM_Hunter]

Regarding your first couple of shots being high, that is a given if you have cleaned your barrel and there is any residual oil or solvent
Have you checked turret movement with a tall target test.?

I had not cleaned my barrel since the last time I shot it. However the rifle had been sitting for awhile and it is possible some dirt or debris somehow got in the barrel or did something that caused the round to shift, not likely but a possibility. I have not had a chance to do the tall target test on it yet but that would be a good idea

 

[Harvey_NW]

Seems to all come back to confirming my zero. Ill see if I can pickup an extra box of ammo and do a 10 round group at 100 friday night and be able to check to see if there is a cold bore shift or not.

Different lots of ammo can account for zero shift and notable difference in velocities as well, something to keep in mind.

 

[AM_Hunter]

Different lots of ammo can account for zero shift and notable difference in velocities as well, something to keep in mind.

Very true, couldn't imagine it would be a 2moa shift though could it?

 

[ResearchinStuff]

it could easily be that. guys have seen really dramatic lot to lot variations in factory stuff, particularly with hornady ammo. there's no guarantee that the powder is even the same type lot to lot on factory ammo.

to summarize the issues you've relayed so far:
1. unknown torque on action screws
2. unkown torque on the rail screws
3. unknown torque on the ring-rail screw
4. unknown torque on the scope caps
5. questionable scope
6. no consistency in your ammo
7. unknown zero
8. potential lubricants on all screws with unknown torque

not saying you can't fix all of that before saturday, but you've got a lot of work to do to give yourself a real chance.

 

[AM_Hunter]

it could easily be that. guys have seen really dramatic lot to lot variations in factory stuff, particularly with hornady ammo. there's no guarantee that the powder is even the same type lot to lot on factory ammo.

to summarize the issues you've relayed so far:
1. unknown torque on action screws
2. unkown torque on the rail screws
3. unknown torque on the ring-rail screw
4. unknown torque on the scope caps
5. questionable scope
6. no consistency in your ammo
7. unknown zero
8. potential lubricants on all screws with unknown torque

not saying you can't fix all of that before saturday, but you've got a lot of work to do to give yourself a real chance.

I should be able to confirm zero on friday. After my shoot on saturday I will likely take off the scope and check torques on rail, rings, ring to scope, action screws, and re-level my scope.

Nothing I can do about inconsistency from lot to lot for factory ammo but ive had good luck with the hornady match 225grs. However my buddy got a hot couple boxes that were seizing up his bolt so you never know. Once I get my reloading setup more established ill just be reloading ammo.

One thing I didnt think about in regards to the MV of the ammo was that the box stated 2810fps out of a 24" barrel, since im shooting a 26" barrel there a potential that it is shooting faster, possibly closer to 2850-2860. Will need to rechrono to make sure however.

 

[Harvey_NW]

One thing I didnt think about in regards to the MV of the ammo was that the box stated 2810fps out of a 24" barrel, since im shooting a 26" barrel there a potential that it is shooting faster, possibly closer to 2850-2860. Will need to rechrono to make sure however.

Skip chrono. Confirm zero at 100 with large sample, true calculator at 800 yards. If 2850 got you impacts last outing, start with that in the calculator.

 

[ResearchinStuff]

Missed one thing on my list above: questionable chronometer data. What chrono are you using?

 

[AM_Hunter]

Missed one thing on my list above: questionable chronometer data. What chrono are you using?

I didnt pay attention to that, it was my buddies chrono. Next time he brings it out ill double check the brand and type

 

[huntnful]

I should be able to confirm zero on friday. After my shoot on saturday I will likely take off the scope and check torques on rail, rings, ring to scope, action screws, and re-level my scope.

Nothing I can do about inconsistency from lot to lot for factory ammo but ive had good luck with the hornady match 225grs. However my buddy got a hot couple boxes that were seizing up his bolt so you never know. Once I get my reloading setup more established ill just be reloading ammo.

One thing I didnt think about in regards to the MV of the ammo was that the box stated 2810fps out of a 24" barrel, since im shooting a 26" barrel there a potential that it is shooting faster, possibly closer to 2850-2860. Will need to rechrono to make sure however.

If you’re going to check zero on Friday. And shoot Saturday. Why would you not eliminate 5 potential issues prior to the zero check, with all of the double checking of screws tightness, instead of afterwards. That doesn’t make any sense at all.

I feel like you want to theoretically improve, don’t want to do any of the steps to improve, or take any of the advice. Like you were looking for a mystical answer or something that involved no work to the issues you’re having.

If you want to be serious about solutions, then be serious about it. There are no shortcuts.

Don’t be afraid to take a few steps back, in order to take even more steps forward.

 

[AM_Hunter]

If you’re going to check zero on Friday. And shoot Saturday. Why would you not eliminate 5 potential issues prior to the zero check, with all of the double checking of screws tightness, instead of afterwards. That doesn’t make any sense at all.

I feel like you want to theoretically improve, don’t want to do any of the steps to improve, or take any of the advice. Like you were looking for a mystical answer or something that involved no work to the issues you’re having.

If you want to be serious about solutions, then be serious about it. There are no shortcuts.

Don’t be afraid to take a few steps back, in order to take even more steps forward.

Because I am shooting in a match with some people on saturday and I already put together a dope card for the ranges ill be shooting at. Im worried if I take off my scope, rings, base, etc, and retorque everything I may not have the same or accurate adjustments. I'd rather keep what I have for now, shoot a 10-shot zero group to check for any POI shifts, and shoot the match then remove and check all torques, relevel the scope, shoot some groups at 100, and then shoot some groups at 800 to true my calculator.

I never said I didnt want to take any of the steps to improve, I said I will do all of them after the match and do further testing based on everything everyone has said so far. I am not taking any shortcuts nor did I say I was going to.

I came here asking for input and information on possible causes for the POI shifts and some other things and got a plethora of good information and valuable insights on causes and how to remedy them, all of which I plan to look into.

Appreciate the feedback and advice given from everyone that has contributed.

 

[huntnful]

Because I am shooting in a match with some people on saturday and I already put together a dope card for the ranges ill be shooting at. Im worried if I take off my scope, rings, base, etc, and retorque everything I may not have the same or accurate adjustments. I'd rather keep what I have for now, shoot a 10-shot zero group to check for any POI shifts, and shoot the match then remove and check all torques, relevel the scope, shoot some groups at 100, and then shoot some groups at 800 to true my calculator.

I never said I didnt want to take any of the steps to improve, I said I will do all of them after the match and do further testing based on everything everyone has said so far. I am not taking any shortcuts nor did I say I was going to.

I came here asking for input and information on possible causes for the POI shifts and some other things and got a plethora of good information and valuable insights on causes and how to remedy them, all of which I plan to look into.

Appreciate the feedback and advice given from everyone that has contributed.

I do understand how you’re justifying it to yourself. I’m thinking more along the line of you’re totally wasting time if you go out Friday and have a wandering zero and POI shifts AGAIN because you did absolutely nothing to possible mitigate it, other than hope it doesn’t do it again.

Tighten things or at least checking them isn’t going to affect your dope card. Maybe your zero slightly. But that’s what Friday is for. To re-zero.

While the scope mounted as is. Check the ring torque around the scope tube. Leave the rings on the tube, and loosen them from the rail. Then the scope stays exactly where it was, because it stays in the rings.

Once the rings are off the rail, tighten the rail down, and then put rings back exactly where they were.

Then check action screws. It is very very simple and will cause few to zero issues to your system.

Edit to add that I’m not sure I’m that gun even has a rail. If it doesn’t have a rail it sucks more to redo everything. But I’d do it anyways still.

Good luck in the competition!

 

[AM_Hunter]

On another note, what process do you guys recommend for cleaning and retorquing all the screws? I read @Formidilosus post from 2017 about removing all the screws, wiping them clean, applying blue loctite, and re-inserting and torquing to specs.

Manufacturers say to torque to around 18in-lbs and not use loctite. Read on some posts people saying torquing to 18 isn't enough and to torque to 25-35 and even someone that said 60... Since ill be retorquing this weekend any input would be greatly appreciated.

Thanks

 

[AM_Hunter]

I do understand how you’re justifying it to yourself. I’m thinking more along the line of you’re totally wasting time if you go out Friday and have a wandering zero and POI shifts AGAIN because you did absolutely nothing to possible mitigate it, other than hope it doesn’t do it again.

Tighten things or at least checking them isn’t going to affect your dope card. Maybe your zero slightly. But that’s what Friday is for. To re-zero.

While the scope mounted as is. Check the ring torque around the scope tube. Leave the rings on the tube, and loosen them from the rail. Then the scope stays exactly where it was, because it stays in the rings.

Once the rings are off the rail, tighten the rail down, and then put rings back exactly where they were.

Then check action screws. It is very very simple and will cause few to zero issues to your system.

Edit to add that I’m not sure I’m that gun even has a rail. If it doesn’t have a rail it sucks more to redo everything. But I’d do it anyways still.

Good luck in the competition!

Youre right, that I can do. For that process, do you recommend backing out one screw on the ring at a time and retorquing it to manufacturer specs or backing out all the screws on one of the rings, while leaving the other attached, and then retorquing them down together?

And do you think I should torque them to 18in-lbs for ring to scope, 30in-lbs for rings to rail, and 20in-lbs rail to action or is there another value people are going by?

Edit: The gun does have a 20MOA rail that is included with it, factory installed.

Thanks