Completely lost zero mid shooting session. Looking for troubleshooting tips

[Ward1987]

Heading out to Wyoming in a few weeks for a deer and antelope trip. Have been at the range the last two weekends shooting my 6mm CM and 300 Win to get ready for the trip. Last weekend spent most of the morning selecting ammo, getting zero at 200 then verifying drop at 500. The 6cm is a Seekins PH2 w/Mark 5HD 3.6-18, and was/is shooting lights out, 7.25MOA up at 500 and 3.25MOA up at 350. The 300 Win was also boringly accurate. It's a 700 I had a lilja barrel put on, with a Mark 5HD 5-25. Today checked zero again at 200, dead on. Then dialed 5.75MOA for 500 I was shooting last weekend, again just stacked shots in a 3-4 inch circle. After that figured I'd check drop at 350 to see if the I had the Hornady app dialed for that as well. I dialed 2.5MOA up and first shot was 7" high and 2" right, then the next three weren't even on the target. Dialed it back to 5.75MOA to go back to 500, again not even on the paper. Was wondering what was going on, so zeroed out the scope to check at 200, not even on target again... Making it worse we are shooing the huge targets in the pic below. The shots felt good but just to double check I grabbed my 6mm and rang the 7" gong at 500 3 times in a row.

So at this point I'm convinced something went haywire. Tried a different box of the same 300 win ammo (Barnes 165 TTSX), same results, shots are nowhere to be found.. I have this gun set up with a Leupold pick rail bedded to the action, ARC 35mm med rings and the previously mentioned Mark 5HD. I pulled the scope off the rail, checking the torque on the base screws - all good, checked the torque on the pic rail screws - again all good, and finally the torque on the rings - same thing. A quick look over the gun and everything seems perfectly fine and functioning as normal. Just seems to completely lost zero out of the blue, with the previous box or two of ammo shooting fantastic.

At this point I'm at a bit of a loss, other then the scope just crapping out, I can't think of anything that was cause things to go south so suddenly. Looking over the scope it seems like everything is functioning as it should and no new rattling etc that might indicate something broke internally. Anyone have any thoughts on what else I should check? Is there a simple way to test the scope? We were getting towards the end of the range session and my buddy needed to get back for his kids swimming lesson, so just set the gun aside and kept ringing steel with 6mm. Thankfully that gun is dialed in awesome and will be making the WY trip.

Thanks a ton for any help!
Zane

 

[hiker270]

I would try another scope just to see if that's the issue.

 

[Cameron.25]

Those scopes losing zero have been discussed at length on here, I'd put my money on it being the leupold. Look up the drop test threads, then get a nightforce, trijicon or SWFA is my advice

 

[ResearchinStuff]

it sounds like you already tested the scope and found the problem, but if you're still unsure move the scope from the 6 creed over to the 300. the mark 5 did poorly on its evaluation: https://rokslide.com/forums/threads/2x-leupold-mark-5-field-evaluations.278289/

might be irrelevant, but you may have also just dialed the wrong way, in your post you wrote that you adjusted up when the target moved closer by 200 yards. that's worth a double check.

 

[Ward1987]

I may have worded that wrong as far as how I was dialing, but did double check when we were shooting - 5.75 - 500, 2.5 -350 and 0 - 200. Will try swapping a different scope if there's a chance, but likely won't be till after the trip west.

This 5-25 is a new scope for me, but have been really happy with the 3.6-18 which I've had on the 300 win, my 308 and now the 6mm. Just now it held the 5-25 firmly on the kitchen table, looking across the street and dialing windage/elevation, which moves the reticle around as you'd expect. Just suprised things could go that far south to be off that huge target without any other symptoms. Sounds like it may need to head back to Leupold. Had read about zeroing issues but seemed like that was more with the vx-5/vx-6. Oh well, at least it was discovered at the range and not at an animal.

 

[Carl Ross]

Toss the MK5 that’s working on your Seekins on the 300 Win and find out if your 5x25 went haywire (I give it high odds). It’s easy enough to confirm that way.

New scopes are the most suspect to me, and it wouldn’t be a total anomaly if that model had an issue. I know plenty of people who actually shoot and have good luck with MK5 5-25’s, but I know of some that were completely broken too.

 

[Ward1987]

Unfortunately it's a combination of some must finish house projects before we head west and a lack of 500 yard ranges close by, I doubt I'll be able to get time to do another proper range session. I was leaning towards using the 6mm anyway, so going to leave that one as it is. Prior to the 300 wetting the bed, both guns were shooting lights out to 500, but I absolutely love the ergo's of that PH2 stock. The 300's a regular sporter style so not really apples to apples, but between the palm swell, vertical grip and thumb shelf it just feels like second nature shooting further distances off the bipod. The reduced recoil is probably part of it to, was able to spot impacts at 500 yards using 3.6X, so cool..

I did pull everything apart on the rifle in question though. Every screw was tight and everything looked right where it should be. Action screws were also tight, but given how haywire things went and how suddenly, that never seemed likely to me. I'm not big on assigning cause without knowing exactly what happened, but doesn't seem like it could be anything else at this point. I will say the 3.6-18 I bought brand new, and the 5-25 was a 'like new demo' from Eurooptic, though I'm not sure that has anything to do with it as the scope was still in the factory shrink wrapping when it showed up. Could just be an ealier run or something?

Either way, I did put the rail back on and swapped over a proven vx-3 2.5-8 on it. It has the boone and crocket reticle so if I can sneak away and get it zero'd at 200, I at least have all my drop data on the gun and can use the reticle. At this point though it'll likely just be a backup to the 6mm. Elk isn't on the hit list, just muleys and antelope so think I should be alright.

Gonna try to get it sent back to Leupold see what they say. I would probably be more worried if it was just wondering a little bit or coming mostly back to zero. This was shooting/tracking perfectly up until the train just went completely off the tracks. Working in the engineering field, it's problems like these that are usually easy to find root cause. The off/on sometimes works sometimes doesn't type are usually a lot trickier, or just inherent in the design. If Leupold comes back saying nothings wrong or sends it back and it happens again I'm sure i'll change my tune and start looking at some Nightforce options.

Either way thanks for all the feedback!
Zane

 

[JollyRoger]

Other things to rule out that I've had happen or seen happen:
- Action screws torqued down correctly
- Pic rail torqued down correctly
- Rings torqued correctly on the rail, as well as the ring caps
- Recoil lug in the right place (this probably doesnt apply to rifles where its attached to the barrelled action)
- Ensure no cracks in your hardware: I have a 223 that has shot awesome since day one. One random day out shooting my shots were all over the map. I looked it over and found a crack all the way through my scope ring just below where the screws go in to the bottom portion of the ring (Warne Mtn techs). Switched to Sportmatch and have been trouble free for the last few years.


ETA: Looks like you posted as I was typing this and have ruled these issues out. Get that scope fixed, sell it, buy a reputable dialer

 

[ScreamingPotato]

Is it possible that your cap slipped and didn't turn the dial? I don't know that scope but if it's like the VX5's those caps only have tiny little screws that apply friction to the actual turret. Sure sounds like something skipped or broke when dialing though.

 

[deadwolf]

I have seen the reticle go south in two Mark 5’s as well as one in a Vortex Razor LHT. From what you describe that is high on my suspect list.


Sent from my iPhone using Tapatalk

 

[Ward1987]

Is it possible that your cap slipped and didn't turn the dial? I don't know that scope but if it's like the VX5's those caps only have tiny little screws that apply friction to the actual turret. Sure sounds like something skipped or broke when dialing though.

When it first happened I was hoping this was the case, but I checked all the cap screws and they were tight. The previous range session I actually missed retightening one on the windage turret when I was zeroing it (there's 2 on elevation, 3 on windage). As I was farting around it dropped on the table. So when it was dialed at 200 I went over all of them again to make sure. This does make me wonder about this though. I seems like as soon as you have one of those screws tight, it'll start 'clicking' as it does when it normally dials. Once you have both screws loose, if it's at zero it needs to be lifted up then turned, but if it's not at zero like when sighting it in, it'll just free spin until you get it back to zero, then have to lift up slightly for it to rotate and drop in into the zero position.

What I wonder is, could it still be slipping to some degree while still giving audible clicks? I don't think so but if so definitely could explain something. The engineer in me wants to start tearing things apart, drives me nuts not knowing exactly what happened and why, but don't want to mess with any warranty voiding.