Need HELP: POI shifting throughout course of fire

[The Zebra]

Fellow shooters, I need some help here. I am stumped, to say the least. I have a Remington 700 SPS Tactical in an AICS AX chassis. The barrel has been cut down to 18.5" and threaded for a suppressor by TBAC but these problems started before that. Basically, my POI shifts as the barrel/gun heats and cools and I can't figure out why. I have cleaned the barrel. I have taken down the gun and made sure every torque value is correct, all the way down to the turret knobs. I don't know what else to do. The barrel has about 4k rounds through it, most of which are my loads (175SMK over 44.7 Varget, Lapua brass and CCI BR-2 primer).

After going through the gun again, here is what happened at the range today. 91*F, 87% humidity and 50ft above sea level. The first pic is me re-sighting in since the take down (100 yards). Notice that the first round looks like it is part of the top right target. It is marked #1. Then you see 2, 3 and 4. The 5th round was just to the left of center so I adjust 1 click right and shoot again. Nothing changed so I adjusted another click right and again no change. I continued to do this for about 4 more shots and then began to realize the as I would adjust, the POI shift would actually negate my adjustment. At about round 7, the POI stopped changing and you can see a nice group circled and labeled 5-13.




After letting the barrel cool for about 10 minutes, I loaded another 10 round mag and started on another target. First impact was north of the center of the bullseye as seen in the following pic. As you can see, every shot in this string began drifting further left. I made no correction and continued to aim for the center of the bullseye. I believe I pulled #7 which is why it is a bit low. This pic is quite obvious that the POI is shifting.




Without letting the barrel cool, I loaded another 10 rounds and immediately began firing at another target, aiming for the center of the bullseye. You can see that rounds 1-4 had some vertical movement which could be my fault (probably is). Then, rounds 5-7 made a nice little group just to the left of 1-4. I am still aiming at the center of the bullseye. I shot #8 and #9 and couldn't find #10. I think it may have been in one of the other groups.




So, I scratch my head and let the rifle cool again. After about a 15 minute break and some much needed hydration, I load another 10 rounds. As you can see, rounds 1-5 make a nice group on the left side of the fresh bullseye. Rounds 6-9 are moving to the left further. I really can't say if #10 was that far out or if I pulled it a bit.




At this point, I'm done wasting ammo. All of this shooting was done unsuppressed. Just out of curiosity, I loaded another 10 and attached my TBAC 30P-1 without waiting for the barrel to cool from the last string. Just have a look and see.




Can anybody lend some suggestions? I'm out of ideas as to why this is happening. Pic of the rifle:

 

[fdkay]

Since the barrel has come off at least once, have you retorqued the barrel/action itself and checked headspace?

You may have gotten all the life you can out of that factory tube, you could set it back and rechamber, but I would put a new barrel on it, in case it is something more than the throat.

 

[insight3b]

I would be more concerned with the optic at this point. After adjustment the POI doesn't shift=optics not tracking
ETA:
Unable to tell if your rings are aluminum. Have seen similar situation(and other unexplainable POI shifts 100 percent of the time) when aluminum rings are used and the optic weighs more than 28 ounces and is attached to the rifle with aluminum rings

 

[TRTAC]

Might be time for a new tube. Doubt its the NF and if everything is tightened down not sure what else it could be... I would start a slush fund for a new barrel if you want more accuracy out of this gun.

 

[Sniper260]

Metal scope bases =metal scope rings...

Factory barrel? Replace it with a nice custom stainless!!

I have a feeling its barrel harmonics where a new barrel would do the trick.... I had typed a long paragraph but I deleted it to simple just say "new barrel".

 

[TexasGunTrustLawyer]

Tag for education

 

[psinclair]

Parallax gone bad maybe?

 

[Captain Kirk]

I have seen no evidence that using aluminum rings on a steel base would have any effect, 99% of scope tubes are aluminum. I have been using Seekins aluminum rings on steel Surgeon and Pierce action/bases for many years.
I am wondering if you had this issue before you went into the AI chassis, Remington actions have been known to be less than perfect, and may get torqued in the chassis (which is generally true) and cause all kinds of accuracy anomalies. Also, what does it do without the can attached ?

 

[tylerw02]

Sounds like to me you are getting mirage and parallax issues causing the problem. Make sure you set the parallax each shot and position.

Also you are getting some vertical out of the gate.

 

[xXlojackXx]

4k rounds on a factory Rem SPS barrel......running it hot like that.


Time to rebarrel

 

[RTK]

Or never clean it

 

[TallShot]

Another vote on the barrel.

However, being in LA myself, I slightly wonder about mirage and/or parallax. I know mirage is a pita, especially after 9-10 am., and shooting off the ground.

Out of curiosity, how old is the NF? Any other scopes to throw on and try out?

 

[TallShot]

Or never clean it

Or that...lol.

My AAC's "spot" for now is between 20-300rds between.

 

[The Zebra]

Since the barrel has come off at least once, have you retorqued the barrel/action itself and checked headspace?

Edit: The barrel has only been removed from the action by a smith to thread. I have never removed the barrel myself. I plan to true the action when I rebarrel it.

I would be more concerned with the optic at this point. After adjustment the POI doesn't shift=optics not tracking

My point here is that the POI is shifting so every time I make the adjustment, the shift negates the adjustment.

Might be time for a new tube. Doubt its the NF and if everything is tightened down not sure what else it could be... I would start a slush fund for a new barrel if you want more accuracy out of this gun.

I do plan to rebarrel and true the action but I'd like to understand the problem first.

Parallax gone bad maybe?

This is a 5.5-22x56 NF purchased in early 2012.

I am wondering if you had this issue before you went into the AI chassis, Remington actions have been known to be less than perfect, and may get torqued in the chassis (which is generally true) and cause all kinds of accuracy anomalies. Also, what does it do without the can attached ?

I didn't have this problem with my Bell and Carlson but I also didn't have this problem when I first switched to the AI. With the exception of the last grouping, all of this shooting was done unsuppressed.

However, being in LA myself, I slightly wonder about mirage and/or parallax. I know mirage is a pita, especially after 9-10 am., and shooting off the ground.

Out of curiosity, how old is the NF? Any other scopes to throw on and try out?

Its very possible that its the Indian and not the arrow but I didn't have this problem before. Scope is less that 2 years old and has less than 800 rounds on it. No heavy use or abuse; just regular range time.

 

[fdkay]

So you cut the barrel down to 18.5" and threaded with out the barrel being removed?

Not that it is impossible, but most folks remove the barrel to do such work.

 

[Captain Kirk]

Still thinking chassis/action interface. Do you still have the B&C stock to put the action back into? It would rule out a very strong possibility (or prove it).

 

[The Zebra]

So you cut the barrel down to 18.5" and threaded with out the barrel being removed?

Not that it is impossible, but most folks remove the barrel to do such work.

I thought you meant by me. Sorry for the miscommunication on that. I edited my second reply to be a little more clear.

Still thinking chassis/action interface. Do you still have the B&C stock to put the action back into? It would rule out a very strong possibility (or prove it).

I don't but I'm sure I can find a friend to lend me a stock.

 

[Bloody_Tailgate]

I'd say throw the scope on a known good rifle. Should be a matter of a few shots to know if there is a problem with it. If you're saying (if I'm understanding you correctly) that when you make an adjustment on the scope, the adjustment is negated by the shift, it seems more probable that the adjustment in the scope is not being made correctly. Expensive shit breaks just like the cheap stuff...we just hope less often!

 

[scotharr]

Here are some suggestions:

1. your groups do not look that bad considering 4K rounds on the barrel.
2. Shoot 5 warm up/zero rounds and adjust the scope to get it on target. then, Immediately after, shoot ten shots in a row WITHOUT touching the turret or adjusting your point of aim. Now examine your vertical and horizontal dispersion. If your vertical is one inch or less and the horizontal is 2" or less, then everything is good to go....especially considering the high round count on your barrel.
3. It's highly unlikely that your scope is at fault....would be last on my list of things to check. However, I would carefully check the mounting system and make sure everything is secure.....rings and base. I have seen so many people with loose rings and rails, it's hard to keep count. Use blue loctite to secure all your screws.
4. If you have an action wrench, check the barrel and make sure it is on tight.
5. Make sure the recoil firm is firmly against the recoil lug stop on the chassis and your action screws are 60 in-lbs or so.

Once again, when I looked at your target pictures, it did not immediately stand out that something was wrong. I got the impression you are cranking on your turret and constantly changing while shooting. It is hard to isolate any problems while doing this. The best way to trouble shoot any problem is to isolate and change one thing and one thing only at a time. swap your scope......swap your barrel... swap your stock/chassis.....each time measure the results before and after. This is the only way to figure it out.

 

[Sharpsman]

Just how many rounds you figure on getting out of a barrel before you see things going to hell in a hand basket??

Shoot it without the 'mule dick' on the barrel and see what happens!!

 

[garandman]

I recently experienced some horizontal shift because I wasn't shouldering the rifle correctly. I was at a new range with new (to me) benches and wasn't getting fully behind the rifle. MIGHT have been the rifle canting slightly on recoil, or maybe I wasn't directly behind the scope, and some angular parallax was happening.

And what scottharr said.

From the pic, I'd say you have a sweet rifle there. Of everything I see, the SPS barrel is the weak link - even brand new. I'd rebarrel it regardless - its relatively cheap (compared to everything else there) and could NOT hurt, given 4K rounds.

 

[HogBoss]

Since the barrel has come off at least once, have you retorqued the barrel/action itself and checked headspace?

You may have gotten all the life you can out of that factory tube, you could set it back and rechamber, but I would put a new barrel on it, in case it is something more than the throat.

Is it possible to alter the headspace enough to cause an overpressure situation by removing an action/barrel/trigger from the stock, then re-installing it?

 

[AtOne]

.....so I adjust 1 click right and shoot again. Nothing changed so I adjusted another click right and again no change. I continued to do this for about 4 more shots and then began to realize the as I would adjust, the POI shift would actually negate my adjustment. At about round 7, the POI stopped changing and you can see a nice group circled and labeled 5-13.

First, Great post, pictures and descriptions ! Nicely done.

Before you rebarrel I'd do as mentioned above and either borrow another scope to put on your rifle to test it out with or put your scope on another rifle that is a known shooter just to rule the scope as an issue out.

Seems pretty odd that you wouldn't see a POI change when dialing your windage, something could be loose in there if its not tracking.

At least you'll know one way or the other that your scope is either good or bad before you do rebarrel.

 

[Cncjerry]

I'm struggling with the same thing with my .300 win mag. I only have about 160 rounds thru it and the POI shifts a lot depending on temperature. I basically shoot two groups, a warm group and a warmer group. I back-off when it gets hot. Basically, shots 4 and 5 of a 5 shot group start to widen up. This could be me, of course, but it seems like temperature is the culprit as it is very consistent. I get sub MOA for shots 1 to 3 at 100yds and then it opens to 1.25 for shots 4 and 5. Also, once it cools during a range break, the first shot or two could be as much as 3" off target. The barrel is not real light and it is tri-fluted as the gun is a 700 XCR tactical long range at 26". After 7 shots it is so hot you can get burned so I rarely shoot that many.

Anyway, I think it is temperature in my case and maybe yours. I suggest, as I will next outing, measuring the temperature and comparing that to the shot count.

Jerry

 

[Frank]

I don't think every one is really reading and understanding what you are saying. Maybe me included. I think you either have a worn barrel or it has an excessive amount of stress that upon firing(heating up) is causing it to shift the POI. I'm more inclined to think stress with the way it is acting. And it could be the fit in the chassis. Go to the range and without touching the scope, start shooting, assuming it is on paper. Shoot until it quits moving the POI and starts shooting a group. Try to remember the shot order. Do it in a standard cadence, no rapid fire or allowing it to cool. I think this is about what you first posted except you were trying to zero the scope after each shot. Let cool all the way back to room temp before trying to duplcate. I suspect it will repeat the pattern. If so true action, put on a new barrel. May also need to bed action in chassis for best results.

 

[The Zebra]

Here are some suggestions:

1. your groups do not look that bad considering 4K rounds on the barrel.
2. Shoot 5 warm up/zero rounds and adjust the scope to get it on target. then, Immediately after, shoot ten shots in a row WITHOUT touching the turret or adjusting your point of aim. Now examine your vertical and horizontal dispersion. If your vertical is one inch or less and the horizontal is 2" or less, then everything is good to go....especially considering the high round count on your barrel.
3. It's highly unlikely that your scope is at fault....would be last on my list of things to check. However, I would carefully check the mounting system and make sure everything is secure.....rings and base. I have seen so many people with loose rings and rails, it's hard to keep count. Use blue loctite to secure all your screws.
4. If you have an action wrench, check the barrel and make sure it is on tight.
5. Make sure the recoil firm is firmly against the recoil lug stop on the chassis and your action screws are 60 in-lbs or so.

Once again, when I looked at your target pictures, it did not immediately stand out that something was wrong. I got the impression you are cranking on your turret and constantly changing while shooting. It is hard to isolate any problems while doing this. The best way to trouble shoot any problem is to isolate and change one thing and one thing only at a time. swap your scope......swap your barrel... swap your stock/chassis.....each time measure the results before and after. This is the only way to figure it out.

1. This is not acceptable accuracy for me. This barreled action used to shoot 1/2" groups at 100 yards and I like shooting out to 600 and 800 yards. I want to be the weak link in the equation, not my gun.
2. This is what I did. After zeroing (first pic), all other groups were shot without making any adjustments on the scope. I'm willing to accept that the barrel is my problem due to round count. I guess this gives me the excuse I needed to rebarrel and true the action.
3. I also seriously doubt the scope is the problem. I have checked, double checked and triple checked the mounting system. Everything was torqued to spec with my Borka tools.
4. I do not have an action wrench but the threading was done by Thunderbeast Arms Corp. I have to trust their work.
5. Action screw are torqued to 65 inch pounds and the lug is in positive contact with the chassis (as far as I can tell).

The only changes I made on the scope were in the first pic which was a rezero after taking the rifle down to recheck everything. The scope was never touched after the first pic.

First, Great post, pictures and descriptions ! Nicely done.

Before you rebarrel I'd do as mentioned above and either borrow another scope to put on your rifle to test it out with or put your scope on another rifle that is a known shooter just to rule the scope as an issue out.

Seems pretty odd that you wouldn't see a POI change when dialing your windage, something could be loose in there if its not tracking.

At least you'll know one way or the other that your scope is either good or bad before you do rebarrel.

Thank you on the compliment. When looking for real help, I try to be as descriptive and thorough as possible. I hate when people ask for help and aren't any good at helping people help them.

The part where the scope is not tracking is me making an adjustment on the scope and the POI change negating my adjustment. In the 2nd, 3rd and 4th pic, I did not make any adjustment on the scope and the POI is very noticeable. I think you and some others here have not understood me well when I mentioned my scope adjustment "doing nothing" because the POI was changing. My apologies if I wasn't very clear on that part.

I don't think every one is really reading and understanding what you are saying. Maybe me included. I think you either have a worn barrel or it has an excessive amount of stress that upon firing(heating up) is causing it to shift the POI. I'm more inclined to think stress with the way it is acting. And it could be the fit in the chassis. Go to the range and without touching the scope, start shooting, assuming it is on paper. Shoot until it quits moving the POI and starts shooting a group. Try to remember the shot order. Do it in a standard cadence, no rapid fire or allowing it to cool. I think this is about what you first posted except you were trying to zero the scope after each shot. Let cool all the way back to room temp before trying to duplcate. I suspect it will repeat the pattern. If so true action, put on a new barrel. May also need to bed action in chassis for best results.

The part I highlighted in bold is what I am really afraid of. I don't want this problem to be from the AX chassis because I do like the set up but I will not keep it if it is what is causing the problem. I plan to rebarrel and true action and retest. If the problem persists after that, the AX is up for sale.

 

[sierracharlie338]

Sounds like the barrel is toast. I had the same issue a while back.








Sierracharlie out....

 

[FALex]

have you asked anyone else to shoot some groups with it?

Ask your smith to run a bore scope: check for throat erosion, burrs in the bore, etc...

Maybe slap a different optic on, if it continues, have a different marksman shoot some groups with it.

 

[EventHorizon]

I observed the same thing on a custom rifle when out in the heat and medium shot count. The stock wasn't channelled properly and in the heat was contacting the barrel and causing both vertical stringing and horizontal dispersion.

When hot from rounds check the barrel is still free floating all the way to the receiver with a piece of paper.

Good luck.

 

[sinister]

Since the barrel has come off at least once, have you retorqued the barrel/action itself and checked headspace?

You may have gotten all the life you can out of that factory tube, you could set it back and rechamber, but I would put a new barrel on it, in case it is something more than the throat.

Concur.

While a factory Remington barrel is of fair to good quality they start out very long-throated (lots of free bore jump before the bullet ogive contacts rifling).

With 4,000+ rounds of 44+ of Varget and 175s, try to get a visual borescope inspection to see how far that jump is now and what the condition of your throat looks like. Failing that you could try a Stoney Point gage and see how deep your bullets would have to be to finally touch rifling. A new Remington barrel will often go 2.9+ inches before a 308 bullet touches rifling.

I'll bet you probably have pretty good fire-cracking in the first half-inch of barrel from the throat forward.

The net combination of free-bore and fire-cracking will give you the equivalent of gas blow-by in an engine cylinder, giving you velocity deviations. This will show up as bigger groups; groups with multiple centers; and shots way off-call for no apparent reason.

A good shooter may blame himself before blaming his equipment. Save yourself some pain in the backside -- and start thinking what kind of replacement barrel you want.

 

[Graham]

A good shooter may blame himself before blaming his equipment. Save yourself some pain in the backside -- and start thinking what kind of replacement barrel you want.

I agree. I don't usually say barrel, but in this case it is likely a major factor in what you are seeing.

 

[The Zebra]

The rebarrel was the plan all along but I just haven't made it to that project yet. I guess its time to move it up on the priorities list.Thanks to everyone for the replies.

 

[Raider03]

Hi, this post looks like the same issue a friend is having with an new 350 legend upper. The first five shots group well then the POI shifts.
Let the barrel cool off and the pattern repeats. The manufacture is willing to provide another barrel. I am wondering what is the most likely problem with current barrel? We checked the scope it is tightened now. I just concerned another barrel may not fixe the problem.
Thanks