Range Report Today’s zero wasn’t yesterdays.

[thejeep]

Well last weekend I shot my first “local match” which included the first shots past 500yards. Boy did I stink it up. This will be observations and lessons learned.

So I zeroed my rifle at a 100 r700 .308 federal gm Berger 185gr. Thursday

To me that looks pretty good especially in regards to elevation.

Well I fire a 100yard shot for zero at the match same at the match location and it was an inch high( approx the bottom side of the square in he pic) I happened to break the shot at the same time I got hit in the face with brake blast and figured screw it was great Thursday. This was a big mistake.

Previously I have shot at 300 ,380, and 500 yards. I had my 300yard drop was 1.3-1.5 Mils
And 500 was 3.2-3.5mils on different occasions.
So I based a jbm drop chart on that with a velocity of 2620.

So I dial 1.4 for 300 and miss, several Wtf!
0.4 high at 200 and 300
0.6 mils high at 1000.

Zeroed again at lunch and see oh my 100 yard zero is high. I wish I remembered exactly how to reset my zero stop(idiot),
But I did remember how to use the zero offset in the calc. And what do you know everything from the first half of the day made sense. And I actually hit some targets.

So what did I learn have a good zero and pay attention to what is happening, don’t blow it off.

Know how to use all your gear.

Don’t set the zero stop to an absolute. Leave some wiggle room.

Get more of my own generated dope and data book.

Get a dbm, because single loading 15rds in 1:30sec is distracting from the shooting aspect.

Try knew things, because outside your comfort zone may make you nervous.

Get a chrono.

Figure out why my scope was off match day. Was it my form or scope function.

 

[soflastg]

different temperature will do that

 

[b6graham]

what scope?

 

[thejeep]

Steiner mil 4-16x50. Shooting again Thursday to thourghly check zero/ return to zero tall target and reset zero stop maybe 0.5 mil low then set turret to zero.

And of course practice shooting in different positions, can’t blame the equip for most of those.

 

[Lowlight]

could be a ring binding issue too, the scopes will dial up and out with no issue but will not come back correctly.

We see it with about 1/4 the rifles in class where they fail to come back to zero throughout the weekend. This is what made us design the scope tracking tool to see what was going on. Most of the time it is a ring issue.

 

[morganlamprecht]

different temperature will do that

no, not at 100 it wont

OP, check zero, bang your barrel on the bench pretty firm in different directions, check it again, dial up and down, check it again, bump the scope on the bench from different directions, check it again

end of the day, it shouldnt move from any of this until you physically bend something...if it does, you have a bedding, mount, or scope issue

 

[thejeep]

Ok I will do that Thursday and respond back.

1 person said temp and one disagreed. What’s the consensus?
There was 20-25f difference those two days, but I have had the same elevation zero for a while even with the change from 175 to 185 was horizontal.

 

[ShtrRdy]

When you set your zero initially, were you shooting off a bench? Then when you checked zero at the match were you some other position?

 

[b6graham]

Temp wont change zero but DA change of a few 1000 could at distance but not what you're seeing...that's too much change too close and very unlikely for such a short time span

Reference DA change for my rifle from -2500 to 3500 (winter to summer in Mass)
1k yards. 6.3mil to 5.8mil

 

[richthe1]

could be a ring binding issue too, the scopes will dial up and out with no issue but will not come back correctly.

We see it with about 1/4 the rifles in class where they fail to come back to zero throughout the weekend. This is what made us design the scope tracking tool to see what was going on. Most of the time it is a ring issue.

Sorry if these are basic questions (beginner here).

How do you fix a ring binding issue?

When doing a tracking test, how do you ensure that the scope and target are perfectly square to each other? A scope manufacturer I spoke to said they don’t recommend conducting a tracking test outside of a lab setting, stating that if the scope and target are not perfectly square/parallel (even if by only a couple of degrees) it will inaccurately show the scope has a tracking error.

 

[thejeep]

When you set your zero initially, were you shooting off a bench? Then when you checked zero at the match were you some other position?

Prone bipod and bag in the dirt.

 

[LawnMM]

Sorry if these are basic questions (beginner here).

How do you fix a ring binding issue?

Unfortunately, by buying a better set of rings

 

[thejeep]

Initial assessment is pointing to loose action screws. Visible wobble of ba in the stock with light pressure applied to barrel (face palm).
I looked no further because I was really working on running some wiring.

Any one happen to know torque spec of r700 screws and Mcmillan htg stock bedded with marine Tex?

 

[Lowlight]

65 to 72 inch pounds

 

[Peterpan]

I had a similar problem with a 300wsm the scope base screws would loosen after a couple range trips even though they were torqued. I ended up having my Smith pin the base and that solved the problem. I never had that problem with any other setup but that was a problem and caused me alot of grief years ago

 

[thejeep]

Thanks.

 

[Hondo64d]

Thanks.

I had a rig that was changing POI on me. Actually changed .9 mils in elevation over the course of a match. I ended up rebuilding the whole rifle one piece at a time before I fixed it. 1st thing I replaced was the scope. Shift continued. Put scope in a scope checker and it was tracking and returning to zero fine. Was using a barrel nut setup with Criterion barrels so tried all three of my barrels. All of them exhibited POI shift to one degree or another. Replaced base then rings. Shift continued. Replaced chassis with McMillan A6, bedded by Jon Beanland. Shift continued. Finally had Jon install a Bartlein barrel in a conventional shouldered setup. No more shift. In fact, it is now the most reliable, consistently accurate rifle I’ve ever had.

The only component in the rifle that did not change was the action. I still am not certain what was causing the shift. My best guess is that the threads on the action are a little oversized or the barrel threads were a little undersized or a combination of the two. This was corrected with the barrel install because Jon cuts the threads to fit the action.

Probably no help but something for you to think about.

John

 

[thejeep]

Action screws were only finger tight. I cleaned them off with acetone, removed some bedding from the barrel channel for 4 bills of clearance, and reinstalled everything. Tightened screws finger tight, banged the butt on the ground several times and worked them up to 65in/lbs. And made sure the internal mag box wasn’t compressed (floorplate)
.
Some pistol parts came in the mail so I’m going to wait till tomorrow for the range. Hopefully with a good groups and some pics.

 

[thejeep]

12shots total. 2 groups with a correction and 2 shots fn with zero stop. Center group was last.

Question :
Is there any reason to have a little wiggle room to dial lower than a 100 yard zero.

For instance set the zero stop for 0.5 mil below 100yd zero and then dial up 0.5.?

Or is it better to make the stop dead center at 100yds?

And I’m not done with the zero yet I know it’s low but range is short at 96yds and will revisit when I have time.

 

[Hondo64d]

I prefer to set the zero stop so I have .5 mils below zero available for a different load, etc.

John

 

[Nik H]

@thejeep

I learned your lesson the hard way myself. Now, I always check zero every time I shoot. Takes a lot of mystery out of the equation. Not only will different atmospherics affect the zero but different lighting on the target will also affect it as it will affect your true POA. I really struggled with that one but I listened to another member here and low and behold, he was right.

I learned that the hard way at 400 and 500 yards.

There is no shortcut when you are trying to maximize scores. Get a zero refresh before you shoot...even if it is the day before.

 

[Inifinty]

@thejeep

I learned your lesson the hard way myself. Now, I always check zero every time I shoot. Takes a lot of mystery out of the equation. Not only will different atmospherics affect the zero but different lighting on the target will also affect it as it will affect your true POA. I really struggled with that one but I listened to another member here and low and behold, he was right.

I learned that the hard way at 400 and 500 yards.

There is no shortcut when you are trying to maximize scores. Get a zero refresh before you shoot...even if it is the day before.

Can you expand on the lighting thing. Trying to understand to know what to expect.

 

[Nik H]

Can you expand on the lighting thing. Trying to understand to know what to expect.

I would reach out to @Skookum for an explanation of lighting effects on your POA.

 

[Deleted member 113831]

I would reach out to @Skookum for an explanation of lighting effects on your POA.

It's pretty hard to explain without knowing any specifics. If you are shooting in a different lighting condition than you zero'd in, there is a pretty good chance your zero will be off.

In general terms. If you zero in a light neutral condition (heavy overcast for example) and are shooting in bright sun, then you shots will likely be low. If you zero'd in bright sun and a cloud comes over, then your shots are going to go high.

The target image will deflect toward the warmer air. So if you are hitting everything just fine, and then aim at a target in the shadows, your shots will miss off toward the sunny side.

If you are on top of a hill or ridge shooting down into a valley with cooler air, the shot will go high.

Terrain features between you and the target can add another layer of fuckery to it.

I've seen effects as small as 0.2 mils and as much as 0.8 mils in extreme compounding factors. However, 0.3 mils comes up enough over and over again, that I use that as my default average guess when I know I'm facing one of these situations.

 

[Subwrx300]

I definitely agree that temps in general don't cause a massive (1"+) zero shift, but ammo temp might but is pretty unlikely. Sounds more like a combination of fundamentals (shoulder pressure, bipod load and recoil control).

+1 to @Nik H on confirming zero whenever possible. In fact, when confirming dope at long range, I have a 100yd target setup on same range and will shoot the following to confirm return to zero during testing:

1. 100yd zero confirm 5 shots
2. 700 yards 5 shots
3. 100yd 2 shot
4. 1050yds 5 shots
5. 100 yd 2 shots
6. True MV and BC based on above data
7. Then for all other distances to confirm solution:
8. XXX yards 3 shota
9. 100yd 1 shot

As long as my RTZ 100yd groups are within .25" of avg POI of original zero, data is good to go. If not, I will probably use another rifle for matches until I can verify reason for shift (scope, barrel heat, mirage, etc).

But if your ammo is very temp sensitive it could change POI quite a bit if it's on edge of a node for the barrel movement. I had a 224V load with CFE that would move around .5"-.75" based on temp. But in my case warmer ammo shot lower than cooler ammo.