Custom 6.5 creedmoor DRAMA!

[Danny25790]

Hoping someone can help me out with an issue I'm having with my custom built rifle.
It is a 6.5 creedmoor, proof research barrel, rem700 blueprint action, jewel trigger in a PSE Etac stock.

The drama I'm having is with factory ammunition, I've tried hornady precision hunter and going to try sako gamehead pro's tomorrow.
I zeroed to start with which was pretty good, and then shot a confirmation group of 5 rounds which was less than 1/4 MOA which I was pretty impressed with, I then went on to shoot some more rounds after Letting the barrel cool for a while to find the zero had changed by about 6 inches lower, I adjusted so I was on target and let the rifle cool once more and then shot another group to find it was low again and also the groups were no smaller than 2.5-3 inches.
My question is, is this the ammo being Inconsistent or potentially a problem with the rifle/scope? All mounts are tight and moderator was also checked and tight. I am a very confident shooter and also had a colleague of mine shoot it as well who is also a confident shooter and had the same results.
So now I am just baffled and any help/advice would be much appreciated

 

[HandB]

If scope and mounts are solid, I usually find loose action screws and/or barrel touching forend are responsible for mystery changes in POI.

 

[User00040]

Check that your action screws have not worked loose.

Talk to whoever did the work.

A very common problem with re-stocked rifles is the front action screw not protruding sufficiently, thus coming loose easily.

I'd also double check the scope.

 

[KRS]

My first thought was that the moderator may have worked slightly loose - this has caused numerous problems on ranges I've run in the past, but you have checked that. Is there any possible internal damage to the moderator - clipping maybe? As others have said - presumably you also checked the action/stock screws were still tight?

 

[Mungo]

I shoot a T3 with a PSE stock, factory Hornady Precision Hunter. No problem at all.

What you describe sounds like something is loose. Scope mounts most likely culprit, but moderator and action screws also likely. After that, other moderately likely things are: scope has let go; some bit of crud is interfering with the action-stock fit; and (let’s be brutally honest) your shooting consistency is less good than you believe.

 

[paul o']

Try walking the scope around see if its tracking you can print off grids on line to match your scope. Then fire one zero then click say 4 grids up and down and end up back at zero 4 rounds, that will show you if its the scope setup . do it without the mod then with the mod if pos the poi will prob change so shoot a zero set and test again repeat see what changes , let if go cold between tests . that will give a result if its the mod . white pen around the exit hole will show any clipping .

 

[Danny25790]

Try walking the scope around see if its tracking you can print off grids on line to match your scope. Then fire one zero then click say 4 grids up and down and end up back at zero 4 rounds, that will show you if its the scope setup . do it without the mod then with the mod if pos the poi will prob change so shoot a zero set and test again repeat see what changes , let if go cold between tests . that will give a result if its the mod . white pen around the exit hole will show any clipping .

Could you explain the white pen around the exit hole in regards to clipping please? And I think checking the scope is tracking correctly is a good idea

 

[Danny25790]

Thank you all for your rapid responses, I have checked the action screws and all are nice and tight, have also checked the scope mounts and all are also tight, the mod is brand new and only shot on this rifle but will double check it tomorrow to see if there are any damages on the inside of it.
As for shooting consistency both me and my colleague are British army snipers, we train every week in our own time so we are well aware of what we are capable of and the difference between a good day and a bad one, it's a very rare thing that we both are having a bad day, before taking out this 6.5 I was shooting .338 lapmag and had no dramas whatsoever shooting accurately all afternoon.

 

[paul o']

I had a rifle that was screw cut out of line and we found that out by painting inside the exit hole this showed a dark line showing up the problem the round was clipping the edge on leaving the mod and changing the poi each time we fired . removed poi was back on so I had it recut by another smith this worked out perfect mod was a husher mk1

 

[scotch_egg]

Thank you all for your rapid responses, I have checked the action screws and all are nice and tight, have also checked the scope mounts and all are also tight, the mod is brand new and only shot on this rifle but will double check it tomorrow to see if there are any damages on the inside of it.
As for shooting consistency both me and my colleague are British army snipers, we train every week in our own time so we are well aware of what we are capable of and the difference between a good day and a bad one, it's a very rare thing that we both are having a bad day, before taking out this 6.5 I was shooting .338 lapmag and had no dramas whatsoever shooting accurately all afternoon.

That’s because the 338lm was a factory Accuracy International.

Also try ukvarminting.com runs along side here catering for different needs. Lots of ex services on there.

 

[paul o']

Some on here aswell lol

 

[Mungo]

As for shooting consistency both me and my colleague are British army snipers, we train every week in our own time

I was under the impression you guys had a checklist to work through when a rifle gave inconsistent results?

 

[MarinePMI]

Snell's law would be my guess. CF barrels heat up faster, causing mirage off the barrel which can cause a vertical shift (up or down depending on the direction of the sun/light), especially if on high magnification. Got a mirage band handy or one that can be borrowed?

What range was your zero? 100yds? Or was the six inch shift seen at a further zero range? (6" is pretty large of a shift for a 100yd zero)

Anyways, just a guess from out in left field, given that you have checked everything else...

As mentioned previously, a tall target test (either optically, or firing on paper) would rule out the tracking on the scope, or the erector assembly potentially binding.

ETA: Oh, how many rounds do you have down the barrel?

 

[topscots1]

Strip the whole rifle down, clean out any excess oil in the barrel channel, pay particular attention to the action points of contact. Clean the barrel thoroughly and dry.

Remove the scope from the mounts. And remount.

What scope and mounts are you using ?

I’m assuming it’s a piccatiny rail, remove the rail clean any excess oil of clean the screws and holes for the rail. Fit the rail and loctite in to place.

Reassemble the rifle, fit the scope and run a ladder test on the scope.

Don’t start with Hornady or Sako, start with cheap ammo. Privi, American eagle, S&B

What twist is the barrel ? What he of ammo are you using ?

Try different grs of rounds.

Run a mini barrel break in fire three clean the barrel for thirty rounds. Then see where you are.

It is likely the mounts or the MOD. If the mounts aren’t the best even with the screws right this will happen.

However if the barrel does not like the weight of round this can cause large groups. I’m assuming all the ammo you tried was the same Gr and type. SP or target ammo not a mixture ?

 

[Danny25790]

I was under the impression you guys had a checklist to work through when a rifle gave inconsistent results?

I have checked everything that I can think of although I hadn't checked the tracking yet but will do in the morning. I'd rather ask the question than keep it to myself

Snell's law would be my guess. CF barrels heat up faster, causing mirage off the barrel which can cause a vertical shift (up or down depending on the direction of the sun/light), especially if on high magnification. Got a mirage band handy or one that can be borrowed?

What range was your zero? 100yds? Or was the six inch shift seen at a further zero range? (6" is pretty large of a shift for a 100yd zero)

Anyways, just a guess from out in left field, given that you have checked everything else...

As mentioned previously, a tall target test (either optically, or firing on paper) would rule out the tracking on the scope, or the erector assembly potentially binding.

ETA: Oh, how many rounds do you have down the barrel?

I've never worked with carbon barrels before so this is actually interesting as I wasn't sure what would heat up faster and wether the core of the barrel would be hotter than the external wrap if that makes sense.

 

[xavierdoc]

If you don't know the source of the error, do your tracking/box scope test optically; there's no point trying to do it shooting if the rifle/scope combo is not consistent.

Alternatively, put the scope on a known good rifle/ammo combo and see if it shoots predictably and passes scope tests.

 

[Danny25790]

Strip the whole rifle down, clean out any excess oil in the barrel channel, pay particular attention to the action points of contact. Clean the barrel thoroughly and dry.

Remove the scope from the mounts. And remount.

What scope and mounts are you using ?

Reassemble the rifle, fit the scope and run a ladder test on the scope.

Don’t start with Hornsby or Sako, start with cheap ammo. Privi, American eagle, S&B

Run a mini barrel break in fire three clean the barrel for thirty rounds. Then see where you are.

It is likely the mounts or the MOD. If the mounts aren’t the best even with the screws right this will happen.

The mounts are tier1 tactical mounts(6 screw) and the scope is a S&B PMii 5x25-56. I think examination of the mod is a definite and also checking tracking, failing that I'll strip it right down and deep clean everything.

 

[topscots1]

Have a look at the piccatiny rail, I had a custom remi built down south, possibly the same place.

The rail hadn’t been loctited in place.

I caught it in set up, worth a check.

The mounts and scope should be good.

If the rail Dosent work try another scope.

PM 2s have been known to fail.

I’m sure a good strip and degunge will fix the issues.

 

[Muir]

It's not the ammo. It's definitely not the stock. I'd look to the scope. Replace it with anything handy and try again.~Muir

 

[75]

I had a brand new Jet Z mod years ago - was throwing zero off every time I re-fitted it. Rifle shot tight groups but POA moved dramatically. Tried all sorts until finally noticed a gert big bit of swarf rattling around inside the thing. Replaced under warranty and consistency restored!