Highlandsjohn
Well-Known Member
It sounds and smells of bs.
consistent odd grouping
- Thread starter Mungo
- Start date
It sounds and smells of bs.
Moray Outfitting
Well-Known Member
There's been neater jobs - but bedding generally a thankless task and I'm in no position to judge via pics. The critical bearing points look ok - was it pillar bedded as well? Rear tang area looks like has a bit of filler over the top of a pillar tube, in theory it should nestle either onto skim of the compound or dead flush pillar tube surface. To be honest ascetics is secondary to whether it does the intended purpose - how does the action sit in the stock? Does it tighten down centrally and the same way every time? Action pressed into the stock, is there any rocking or other movement? When offered up, does the recoil lug fit snugly in the recess for it, or is there breathing space on the front face and bottom - test with a tiny bit of blu tack.
With the repeatable first cold shots going on the money, my suspicions continue with the barrel end of the gubbins. Have you tried the business cards yet or are you just teasing now....
With the repeatable first cold shots going on the money, my suspicions continue with the barrel end of the gubbins. Have you tried the business cards yet or are you just teasing now....
Nope. It doesn't. I don't know of any test that wouldn't involve a lot of hardware. The simplest is observation from a free floating barrel. If it is truly free floating, and the ammo is of consistent quality the groups will be somewhat circular regardless of whether or not the gun 'likes' that particular ammo. If the barrel is stress-walking you get what you've gotten.~Muir
I quite accept that the current symptoms are consistent with stress-walking...but the problem I have is how or why would that appear after a period of it not being evident?
As a blacksmith I deal with spring-back and plastic memory in everything I make. As far as higher carbon steels go my only knowledge is gained from empirical observation...I have not progressed beyond the "Greasy Stick" temperature guide for setting and tempering spring steel...
I do know that, even after hundreds of years with both wood and metal, if you cut away one side along a length, it can release pressures of tension or compression which can then distort and bend the parent bar.
What I can't get my head around is what has caused this change to appear now, in the 18 months since it was working fine?
Alan
bewsher500
Well-Known Member
If the barrel is responding to tension in the material itself and walking from the relieved stress it would have done this from the beginning
I can't see how the age of the barrel can be of relevance. It is not made of cheese, they don't just go off
if it was worn out it wouldn't group at all
If it had been cooked with extended shooting periods and long strings it would display those symptoms as above and wouldn't group
if the crown or throat were an issue....it wouldn't group
I can only assume that the shots returning to the first POI when cooled comes down to physical interference due to barrel heat or position when warm or having fired the first shot
a bore scope would be nice to exclude internal condition
Maybe the original bedding held it at bay? I have seen really accurate #4 Lee Enfields have their accuracy turned to crap because some ham-handed garage gunsmith had "sporterized' it by simply cutting off the forend before the first band and tossing the handguards. AJ Parker used to write about the correct way to 'pack' a barrel on a No1 Lee by placing winds of cloth tape at various intervals to stabilize the bedding and harmonics. All this is not exactly the same as Mungo's situation but it shows that free floating is not always best and that a barrel left to it's own devices can become unpredictable. I am reminded of a young man who brought me a SAKO 7mm Rem Magnum to look at. He was getting MOA despite the fact that the factory negligently left a pad of wood in the end of the barrel channel pushing against thee barrel. When he removed it to free float the barrel he was suddenly getting just under 2 MOA. I told him to put the wood back...~Muir
bewsher500
Well-Known Member
pretty sure all sako 75s are designed as free floated from new
So...
...not to put too fine a point on it, it's all gone to sh*t.
All the consistency that had been present has disappeared since I took the action out of the stock.
When shot as normal (without a shim under the barrel), it strings horizontally, producing a line about 4 inches long. The cold bore shots no longer group together - they land relatively randomly within the string.
When I added a shim under the front end of the barrel, it strings vertically, producing a line about 3 inches long. Cold bore shots again landing unpredictably in the string.
...not to put too fine a point on it, it's all gone to sh*t.
All the consistency that had been present has disappeared since I took the action out of the stock.
When shot as normal (without a shim under the barrel), it strings horizontally, producing a line about 4 inches long. The cold bore shots no longer group together - they land relatively randomly within the string.
When I added a shim under the front end of the barrel, it strings vertically, producing a line about 3 inches long. Cold bore shots again landing unpredictably in the string.
AN DU RU FOX
Well-Known Member
if you dont mind the question what did you have it bedded for?was there a particular reason?
Last edited:
I had convinced myself that the movement I was seeing in the shot pattern was due to the action moving in the stock.
There was certainly some movement: it was fairly easy to push the barrel out of alignment in the barrel channel.
AN DU RU FOX
Well-Known Member
cheers ,but was the original pattern ,ie before bedding, same/simular as we are seeing now after bedding,it seems too me like you have exhausted all avenues,scope/shooter/ammo/tightening/cards shims etc and basically the only thing i see thats made any difference good or bad is the bedding,i feel for you mate hope you sort it,
Last edited:
No.
When I first got the gun, it shot respectable groups consistently.
Then, about 18 months ago, things started to shift. It would shoot two almost through the same hole, then wander. Let it cool, and it would shoot another 2 almost through same hole - but the POI of that group would have shifted from the POI of the previous cold bore shots.
The clear stringing is new as of today.
Highlandsjohn
Well-Known Member
Sorry your-having the bother Mungo. These rifles are normally very accurate. Don't give up on it,I still believe it's fouling on the stock. Try this...
When it has no packers, just bare rifle with the tork screws tight. Slide a piece of paper under the barrel ,all the way along it, to make sure the full length of the barrel is clear of the stock. After firing a shot it should still have that same clearance, if not the action has moved in the stock...
When it has no packers, just bare rifle with the tork screws tight. Slide a piece of paper under the barrel ,all the way along it, to make sure the full length of the barrel is clear of the stock. After firing a shot it should still have that same clearance, if not the action has moved in the stock...
I am no expert but those photos show fairly classic bedding issues from the look of it. The action screws may be tight but I am wondering if they are bottoming out in there holes and so feel tight but theya re not really tightly squeezing action to stock and it is moving with each shot slightly.
Similar threads
