I have a Winchester model 70 feather weight in 7-08. Its a newer one, Morgan , Utah on the barrel. Heres the new issue. After mucho work on this iron, it generally is about a 2" gun. However, when it gets hot, the groups cut in half. This is with a free floated barrel, and same with a pressure point at the forarm tip. I never had one shoot better hot before. Any logical reason for this? Its repeatable. Open to sugestions.
Loosen the middle screw and retighten it last (only just over hand tight).
Th newer model 70s don't have a middle screw. Foot-note, its pillared and bedded, so screw torque should not be the issue.
Something is growing and filling in a gap when it is hot. You sure the bedding and pillar are all "just so".?
I believe the bedding and pillar job is good. When I acquired the rifle, when gripping the forarm tip with fingers somewhat wedged at the barrel/forarm, when tightening or loosening the front action screw you would feel movement, stressing the action.Bedding & pillar job solved the problem.
Might be as good as it is going to get.Have no Idea why it shoots better hot.
Sounds to me like a barrel with some inherent stress in the steel, for whatever reason.
I've had some barrels like that, mostly factory but some custom. One really lightweight .243 Winchester barrel shot like crazy when hot, as in 5 shots under 1/2" at 100 yards, but the first three shots never averaged much better than 1-1/2", no matter what modifications were done to the rest of the rifle.
This rifle took me to school. After pillar/action bedding, 2 different scope mounts, 3 different scopes, lapping rings, different powders, bullitz, seating lengths and free floated and different pressures at forend tip, I'm of the opinion John, you are more than likely correct. I didn't want to admit that, but its the most logical conclusion after all the trials and tribulations I've tried. I learned you CAN'T make every rifle a M.O.A. gun. I am good at buying, but terrible at selling. I love this gun, am for the time being going to live with a 1.5 - 2 inch shooter. After all, one of my favorite writers said he has taken game out to 400+ yards with such a shooter.
Oldotter, do you clean the bore regularly? Some rifles prefer the bore left fouled. You might try shooting it and not cleaning it. Just an idea. I don't ever clean mine unless accuracy degrades, or if I get mud or something in it.
Could it possibly be firing pin drag from grease gunked in the bolt? When the grease heats up dragging could lessen. Not saying it is plausible possible, but who knows.
Yes, clean and fouled barrel is of no consequence. After a couple shots, can shoot 80+ rounds without group size changing.
The bolt has ben disassembled and cleaned. No issues there.
I still believe Mr. Barsness assesment is the most plausable culprit. All barrels can't be perfect.
I have had several barrels/actions cryoed and it made no difference in their performance. However, they did clean easier after treatment.Rick.
Read an account here at the 'fire (don't recall which forum), where the owner of new model 70 -- it may have been an FN -- was having accuracy inconsistancy, and sent the rifle to a 'smith. It was determined the threads of the receiver, and barrel were poorly fitted (loose), and actually allowed the barrel to move.
Not saying that's the case, but those tolerances would certainly "tighten", once the barrel heated up. I'd at least consider that possibility.
Good luck.
I have a 700 in 204 that came from the factory with a plastic stock. Couldn't get it to shoot in the factory stock or a boyds laminate.Finally exerted pressure on the barrel till it shot little bitty groups. I glassed a pad out near the tip of the stock to maintaine that pressure.
Later on, I read that mis matched threads on the barrel/action allows the barrel to move. The pressure on the forend tightens that fit. I would consider putting more pressure on the barrel to see if that would make a change for the better.
Fred, the OP plainly states that the rifle had been pressure-bedded during the search for accuracy.
It's been interesting to come back to this thread. None of the last three possible problems suggested display the symptoms described in the original post. I know this because I've owned rifles with all three problems.
On the other hand, barrels with some internal stress often do shoot better and to a different place when they heat up during firing. Such stress is usually caused either during manufacture (especially with button-rifled barrels) or when a barrel is straightened after rifling.
Cryo won't cure it, but heat-treating might. But why bother? Instead replace the barrel that's been made right.
Such stress is usually caused either during manufacture (especially with button-rifled barrels) or when a barrel is straightened after rifling.
Cryo won't cure it, but heat-treating might. But why bother? Instead replace the barrel that's been made right.
I agree replacement with a quality barrel is the best way to go
Replacing the barrel on a rifle that won't shoot is starting to sound more interesting to me. I have a deep-seated mistrust for rifles on the 4 sale rack that have nonstandard barrels because you never know where the barrel came from, who installed it, or if they had a clue how to do such work correctly. Also didn't know a local "gunsmith" that I would trust replacing a lightbulb. But I have recently met the acquaintence of a couple 'smiths that do have a good reputation. I also have recently acquired a rifle assembled by a reputable firm of old from top notch parts, including a Douglas barrel, that shoots waaay better than I can. So the rebarrel option is sounding a bit more interesting now.
Any chance that the action might be stressed? I suggest installing a bore sighter, noting ones cross hair coordinates, loosening the screws with the sighter installed, and see if there is any movement. If so, the action is stressed and needs to be rebedded in a fully relaxed state.
If you want to check your bedding, it's best done with a dial indicator. I have a fixture that clamps on the barrel and allows a dial indicator to rest on the bottom of the stock at the tip. To check the bedding start with about 20 inch pounds on both screws. Increase the torque on the front screw to 30 then 40 and 50 to finally 60 inch pounds. If the dial indicator moves more than .002 or .003 you have a bedding issue. A good well bedded rifle will have <.001 movement.