Point Of Impact Shift

[Vapor]

I have this issue with a particular upper.

Specs:
Wilson 18" 1:8 zero taper heavy barrel
Yhm free float quad
Running h2 buffer
Larue trigger
Swfa 12x (currently)
Adm mount
Usually shooting off of a harris bipod and a yhm picitinny adapter


I have twice zeroed two different sets of irons sights. One troy and one sig. They Zeroed just fine. No poi shift.


I have mounted 2 didferent scopes in 3 different mounts and this issue always seems to return. I often get a 3 nice tight holes, then 2 off to one side or the other of the group, like 3 shots in the bull, then 2 off about an inch and a half. This makes no sense to me. I have gotten 1/2" 5 shot groups from 75 Grain frontier hollow points. Usually, when the bore is cold.




This gun should be lights out. Heat shouldn't be affecting it that much.

I have thought of a few things:
1. Harris is coming loose. This does happen. Especially when under load. I assume this could cause shift




2. Shooter error. I try to get a consistent cheek weld, but I often fail to remember a rear bag.

3. I need to attach a bubble level and keep myself flush.

4. Handgaurd or gasblock is loose. This seems unlikely given the irons shoot fine.

5. The pressure from the bipod is causing pressure on the handgaurd which is causing pressure on the barrel nut.


6. I need to check the handgaurd is free floated.

It's not the scope or mount. Everything is torqued down to spec. Plus the old combo of weaver grand slam and warne fixed mount had the same issue.


My guess is the bipod. What do the nygun forum peeps say?


P.s. never had this problem with a bolt gun whose scope and mount were probably installed.

 

[Carlos Hathcock]

"My guess is the bipod. What do the nygun forum peeps say?"

I say you need to slowly taper off the sugar intake.

 

[Vantrepes]

Shoot it off of bags, and see if you have the same issue. Then let someone else who you know is a good shot shoot it, and see if they run into the same problem.

 

[Vapor]

"My guess is the bipod. What do the nygun forum peeps say?"

I say you need to slowly taper off the sugar intake.

It's caffeine sir. It's my go fast juice.

 

[kev74]

What size group at what distance with irons vs. what size group at what distance with scope?

Is it always the last 2 shots that move?

My initial thought is that its the loose nut behind the trigger ( ) , but if it always happens on the last 2 shots, it might be heat related.

Have you tried doing a 10 shot group? That might tell you more if its the gun or you.

 

[Vapor]

What size group at what distance with irons vs. what size group at what distance with scope?

Is it always the last 2 shots that move?

My initial thought is that its the loose nut behind the trigger ( ) , but if it always happens on the last 2 shots, it might be heat related.

Have you tried doing a 10 shot group? That might tell you more if its the gun or you.

Average about 1"- 1 1/2"at 50 yards with the irons. I wasn't really trying today. Just wanted it done. I did get a few sub 1" with the scope on.


I have done ten shots in the past, but I'm trying to conserve with this non sense going on.


I did a final 3 shot that was actually perfect near the end with a different load. Maybe it was just me and the 6 cups of coffee today.


I did almost get carried away by mosquitoes and gnats.

 

[repete]

Maybe it was just me and the 6 cups of coffee today.


I did almost get carried away by mosquitoes and gnats.

Umm ya think? Yes you are getting carried away.

 

[Jaywmustang]

Get a lead sled to try to eliminate human error and get decent ammo just to test your rig. I don’t see a bipod causing these issues unless your just loading it too much but I wouldn’t think so.

 

[Vapor]

Get a lead sled to try to eliminate human error and get decent ammo just to test your rig. I don’t see a bipod causing these issues unless your just loading it too much but I wouldn’t think so.

It could be me. Nothing in this rig is really budget per se. I can re-check the torque and take a rear bag out next time.


I got good enough groups that I set my turrets to zero.

 

[Jaywmustang]

It could be me. Nothing in this rig is really budget per se. I can re-check the torque and take a rear bag out next time.


I got good enough groups that I set my turrets to zero.

Do you have a known good scope to try?

 

[Vapor]

Do you have a known good scope to try?

I have a Weaver Grand Slam tactical 3-10 that is known good scope that showed similar issues. That scope and its twin I have on another rifle are top grade and I know work.


It was probably the bugs, the heat, me, an uncomfortable firing position, and all that. I'll not freak out and try her another day.

 

[Jaywmustang]

I have a Weaver Grand Slam tactical 3-10 that is known good scope that showed similar issues. That scope and its twin I have on another rifle are top grade and I know work.


It was probably the bugs, the heat, me, an uncomfortable firing position, and all that. I'll not freak out and try her another day.

Sometime it’s just a off day. Next time try taking the human element out as much as you can. I usually site in with my rifle in my lead sled and check my zero shooting without it.

 

[Vapor]

Sometime it’s just a off day. Next time try taking the human element out as much as you can. I usually site in with my rifle in my lead sled and check my zero shooting without it.

You're probably right. have a rock jr. I should probably get a bean bag rear and use that next time.


I like to use my Harris becuse it's "real world" if you know what I mean.

 

[Jaywmustang]

My best group to date is with a bipod and rear bag. Just focus in on your fundamentals, if your still off, you need to check your equipment.

 

[Vapor]

My best group to date is with a bipod and rear bag. Just focus in on your fundamentals, if your still off, you need to check your equipment.

Maybe I need to take a known quantity rifle out next time.

Sadly, I feel like I don't shoot for fun much anymore. It's zeroing and serious practice only.


I was slinging some 20 gauge today too, and was dreaming of the days when I would set up shotgun shells and knock them down with an iron sighted .22 at 50 yards.

 

[dsdmmat]

You're probably right. have a rock jr. I should probably get a bean bag rear and use that next time.


I like to use my Harris becuse it's "real world" if you know what I mean.

if you are using a bipod in real world you are in position too long. But even then you are not going to be shooting groups.

 

[Robin]

Barrel wasn't properly stress relieved. Toss it.
Robin

 

[Vapor]

if you are using a bipod in real world you are in position too long. But even then you are not going to be shooting groups.

Depends on the scenario. Bipods can be nice when still hunting or for wood chucks.

 

[Vapor]

Barrel wasn't properly stress relieved. Toss it.
Robin

I suppose it's possible. I'll take her out again and try to remove as much of my error as possible and see. It wasn't shifting when I was shooting iron sights though.

 

[kev74]

Next time, try warming up with the .22, then move up to the bigger stuff.

Shooting .22 helps me work on fundamentals without having recoil hide what's going on. You know you're doing things right when you can watch your hits through the scope.

 

[nortatoga]

I have not used bi-pods much, But a friend of mine does and always talks about pre-loading the bi-pod.

Bipod Basics — How to Pre-Load the Bipod Before the Shot « Daily Bulletin

Shooting really well with a lightweight bipod requires good technique. One thing you want to do with most field-style bipods is to pre-load the bipod with forward pressure. In a helpful how-to article, Accuracy-Tech Blog Editor Rich offers some good advice on bipod technique, explaining how to...

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