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A little conundrum

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A little conundrum

Postby Fenrir » Sun Feb 21, 2016 5:26 pm

I went to the range this morning with Nat (my eighteen year old) for a session of plinking with the .223 and the .308 both at 100 yards. The .223 behaved faultlessly and so did the .308 to start with then the POI shifted. For the first dozen rounds or so we were aiming at and hitting those one inch shoot and see dots then for no reason the POI moved about eight inches to the right of the POA, thinking it was a flyer the next two shots cloverleafed with the errant shot so obviously something has shifted. Checked the mounts and all were good so we rezeroed and all was good again for another dozen rounds or so then the POI jumped to the right of the POA by a couple of inches and it continued to hold the same POI. Rechecked the scope mounts and checked all the action mounts, everything is nice and tight. Re zeroed for the second time and everything is going perfectly then after a few more rounds the POI jumps to the right of the POA by another couple of inches.

If it was duff ammo i wouldn't expect the groups to stay tight which they did, it was just that they jumped to the right by a big margin. There was no detectable vertical shift and it wasn't a steady deterioration, it was sudden from one shot to the next and the POI didn't move from its new position.

Needless to say there was a lot of humming and hawing but other that loose action or mounts nobody had a suggestion of what might be the cause. Prior to today it has shot flawlessly and very accurately.

It is a .308 with a Barnard action shooting through a slow twist 30 inch heavy Lilja barrel, a jewel trigger (very light) all in a Dolphin chassis. The scope is Sightron SIII 8-32 with simple cross hair reticle and eighth MOA click.

Does anybody have any ideas what could be causing this before I give up and send it back to Dolphin to fix.
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Re: A little conundrum

Postby Keef » Sun Feb 21, 2016 5:49 pm

Do you have an alternative scope you can put on the rifle Simon?

This would eliminate any scope fault which might be in the zeroing mechanism before you think about sending the rifle back to Dolphin.
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Re: A little conundrum

Postby Deallad » Sun Feb 21, 2016 11:01 pm

Was thinking the same Keefee

Sounds scope related to me too

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Re: A little conundrum

Postby flintlok » Mon Feb 22, 2016 2:33 am

I had a similar issue with GSG Stg. 44. The barrel is pressed fit by being bolted between two receiver halves. The bolts loosened and shot different groups with every magazine change. I played with the scope however it the bolts were the problem. In any case the gun probably shoots fine. Something's loose. Usually if the scope troublesome the groups will open up and tends not to group. If group pattening changes between magazine loads the it's the hold on the gun moving something that's loose.
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Re: A little conundrum

Postby Bushdog » Mon Feb 22, 2016 8:12 am

I agree it sounds like it might be the scope - as others have suggested, if you can, try a different scope.

Flintlok - my experience of GsG guns suggests they all have terrible trouble with wandering zero for all sorts of reasons, no doubt you have identified one of them. The biggest problem with them is surely the hopelessly thin barrel sleeves - not a problem for the OP, though with a Lilja barrel on a good action.
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Re: A little conundrum

Postby Fenrir » Tue Feb 23, 2016 1:11 pm

Thanks for that, I have another SIII on my Remington so should be an easy enough swap.
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Re: A little conundrum

Postby gun nut » Tue Feb 23, 2016 8:54 pm

I had a similar problem with the scope on my old underlever. It would jump about 3" to the right and stay there for a while, before jumping back again. It was definitely the scope. It sounds like a scope issue to me.
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Re: A little conundrum

Postby Deallad » Wed Feb 24, 2016 3:44 pm

Just another thought,

could it be temperature related metal expansion?

If the action is tight in the stock the steel heats up and transfers the heat to an aluminium the ally could be holding tension on something

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Re: A little conundrum

Postby Cam » Wed Apr 06, 2016 9:47 am

@ Fenrir

Did you get a resolution this issue?

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Re: A little conundrum

Postby Fenrir » Tue Apr 19, 2016 1:22 pm

I haven't been shooting since Cam. I am intending to give it another try at some point but when that will be i have no idea.
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Re: A little conundrum

Postby Keef » Tue Apr 19, 2016 3:23 pm

Fenrir wrote:I haven't been shooting since Cam. I am intending to give it another try at some point but when that will be i have no idea.


That's two months without shooting - how do you cope with the withdrawal symptoms?
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Re: A little conundrum

Postby Fenrir » Wed Apr 20, 2016 6:30 pm

Keef wrote:
Fenrir wrote:I haven't been shooting since Cam. I am intending to give it another try at some point but when that will be i have no idea.


That's two months without shooting - how do you cope with the withdrawal symptoms?


I have had one session on the indoor range with the MLP, in the last two months; that is it. :(
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