What's going on here?

[AlanF]

I used what I consider to be a very good and near new Bartlein at Lang Lang at the weekend and had a big problem with vertical in the first couple of shots at both ranges. The first shot was about 1.5 minutes above where it settled to, the second shot was in one case high again, the other it started to come down, and it had pretty much settled by the third. I don't believe its got to do with a clean barrel, because the barrel was fouled with two shots about 3 hours before the first range, with no cleaning in between ranges. It settled to same reading on the vertical turret at both ranges. I have heard of one other experienced shooter with a similar problem using a particular barrel, and he never worked out why it happened. There was absolutely no sign of the problem at 120 rounds, and it has now done 230.

Here's some Hexta links to illustrate the deterioration :

Round count 120, 600yds Brisbane http://shooting.hexsystems.com.au/shooting/68906
Round count 216, 500yds Lang Lang http://shooting.hexsystems.com.au/shooting/77032
Round count 228, 500yds Lang Lang http://shooting.hexsystems.com.au/shooting/77669

Presumably there are others who have experienced this. Has anyone figured out what's happening, and better still, found a solution?

[Razer]

This may sound too simple, but, the first thing that I would do is try another scope(or barrel) to at least eliminate the possibility that all is not well with the internals.
Just because the vertical turret is settling to the same reading doesn't mean that the internals are not infinitesimally adrift!
A change of barrels would quickly resolve whether or not the scope was the cause?
I have had a scope that tracked perfectly but caused a similar problem. It was fixed under warranty and, from memory, was to do with an 'O' ring.

[Matt P]

Did you reload in the manvan again ????

[AlanF]

Did you reload in the manvan again ????

Yes. My reloading gear is permanently installed in the van, but at home I prefer to eat and drink in the house!

Ray,

It could be the scope but would have to have happened since I last used it on another barrel a week earlier when there was no such problem.

I expected that someone else would have experienced this exact problem - I do know of an F-Std shooter who had a barrel that did this for years, and it was the same shift, about 1.5 MOA high on the first shot, then settled after one or two.

[Tim N]

Did you put the lid on the spuds while cooking
Bacon fat might be another cause of a velocity spike

Or Rear bag settling on first shots?
Got to love the "random" stuff

[Steve N]

Might be a Queensland barrel. Seems to shoot OK when it has had a couple of barrel warmers.
As nothing else has changed I would check it doesn't have a build up of fouling somewhere in there. 200 shots is enough if you're not cleaning properly.

Send it up here and I can test it in some warmer weather if you like.

Steve

[BATattack]

Did you make adjustments before it "settled" or did it just settle back to original sighting position?

I have also seen scope issues where the reticle movement effectively stops while winding the turret and then re starts or jumps creating a dead spot with erratic tracking. Not saying this is what is going on but worth considering.

I'd be very interested to put a chronograph in front of it to see if it's a load / fouling issue or a harmonic / stress issue. If the velocity is stable and the issue is repeatable additional stress relieving may be needed.

[plumbs7]

Earlier this year I had a similar problem and traced it down and the Bart barrel it was too. But I didn't have the barrel torqued up enough and the action screws were a little lose.
At the first few shots excessive vertical and there seems to be some excessive harmonics that shake things that are lose and then behave after few rounds and carbon ( lubricant) is layed down and then the barrel behaves . Before I picked it up ( barrel not torqued correctly) it took 6 rounds to settle and now 2 shots .
This maybe even more pronounced with a naked barrel.
Could even be a partially lose scope mount not torqued up enough. I'm not telling you anything you don't know but have you checked over the gun , pulled the barrel and reinstalled it , scope action etc ?
Anyway I could be totally wrong ! , but yes it's frustrating and hopefully you will find the problem.
Regards Graham.

[AlanF]

All good suggestions - I will do some testing with a chrono before doing anything else to see if the high shots are high velocity - should narrow the search. If the velocity follows the shots then it could be extra pressure from some sort of fouling. Otherwise it could be a multitude of things, most which can be eliminated by substitution e.g. change scope. And I can try tightening things up. Probably won't get to it till next week, but will keep you posted.

Meanwhile if anyone else has experienced this same thing, please join in.

[Razer]

Ray,

It could be the scope but would have to have happened since I last used it on another barrel a week earlier when there was no such problem.

I expected that someone else would have experienced this exact problem - I do know of an F-Std shooter who had a barrel that did this for years, and it was the same shift, about 1.5 MOA high on the first shot, then settled after one or two.

********************
Alan.
Does this mean that you changed barrels in the same action or that you have QR rings and changed actions?
If you changed barrels then do you remove scope to do so? If QR rings are used, then there may be a problem with them settling back in the same spot from the first shot?
Just another thing to check out!
Ray.

[AlanF]

Ray,

The scope stayed on between ranges, and same thing happened at the second range, so if it is the scope, then its more likely the internals. On the NF Comp used, I have Warne QR rings and always home them forwards in the rail slots before tightening.

I will get to the bottom of this - the barrel is one of the best I've had - definitely worth rescuing .

Alan

[ShaneG]

Hi Alan

I have had a series of intermittent vertical within strings not a consistent pattern such as yours.
I box tested the scope and got unacceptable groups at 100 yards - approx 1".
That night a thought popped into my head about winding the turrets to extremes to settle them?
Shouldn't be necessary on quality scopes.
Anyway I did it and the groups reduced by 75% in size on subsequent box test.
Have sent scope with targets away for service.

This may not be helpful for your issue but.....?

Otherwise I suspect stress relief not correct and barrel changing poi with heat?

Shane

[johnk]

Hasn't it been said elsewhere that scopes need regular exercising by winding them back & forward to the extremes to avoid thee internals gaining a set?

[BRETT B]

Alan , I had the exact same problem with 1 of my 7mm Barrels. the first range after cleaning it would settle as normal but then wait 45 mins and start your second string and it would print high around top of 6 ring sometimes 5 ring high then walk down to center of X ring in 3 to 4 shots. It had me stumped for a while but after changing primer type it stopped doing it. Changing the Primer put me into a slightly different speed node (faster) so I put the original primer back in then changed powder charge slightly to get to the next speed node and it didn't vertical string any more on the first few shots . I do not fully understand why it happened but my testing showed me this particular barrel at the speed node i was running it would vertical string high and change point of aim until the barrel had slightly warmed up where it would then settle.

[AlanF]

Alan , I had the exact same problem with 1 of my 7mm Barrels. the first range after cleaning it would settle as normal but then wait 45 mins and start your second string and it would print high around top of 6 ring sometimes 5 ring high then walk down to center of X ring in 3 to 4 shots. It had me stumped for a while but after changing primer type it stopped doing it. Changing the Primer put me into a slightly different speed node (faster) so I put the original primer back in then changed powder charge slightly to get to the next speed node and it didn't vertical string any more on the first few shots . I do not fully understand why it happened but my testing showed me this particular barrel at the speed node i was running it would vertical string high and change point of aim until the barrel had slightly warmed up where it would then settle.

Thanks Brett. That is exactly the sort of experience I was hoping to hear about. I haven't done any serious testing with this barrel because the way it went at Brisbane it seemed not to need any! I'm running mild loads in it, so will do a ladder test to look for a higher node. It'd be good to know the exact reason for the high shots though - seems counter-intuitive.

BTW congrats on your WA Queens win. Looks like the conditions weren't easy?