Lever popping open on shooting

[rockrat]

On the rifle I had JES rebore/rechamber to 356Win, for me, he had included a note that the lever was opening on firing on factory rounds and one of his handloads. Lever would open about 1/2"

Been working with it at the range, and same thing, along with poor accuracy. Been frustrating. Lever won't open with midrange loads, only about when the 35-200 rcbs boolit approaches 1800fps or so. Headspace is fine. Suspect the poor accuracy is due to the lever opening.

Last night I took the bolt out of the rifle and put in the bolt from my 444. Fit fine and headspaced well. Took it out to the boonies a few miles from the house and fired off three rounds, one of which was a factory 250gr.

Everything was fine. Lever never tried to open up a bit, even with the factory round. Going to have to compare the bolts to see if there has been a problem in the machining of the locking area and take a look at the locking lug.

Will make it back to the range next week, hopefully I will have a good range report.

[missionary5155]

Good morning
Sounds like by changing levers you may have discovered a clue. Every rifle is a system unto itself. Maybe the locking area of your bolt is worn also. Or just the simple combination of parts as they fell into your rifle causes a "loose" that has finally made it's appearance with a "higher pressure" cartride.
That is just another aspect in this firearms hobby. Turn up the heat and pressure in a system that has happily gone along for years as a plodder and you may just encounter the weak link. That is one reason as I started loading for my caliber 414 Supermag Marlin 336 conversion this year I took things easy working up slowly. Any drag racer can tell you the story of the block,or rod,or crank or head that suddenly let loose under to much stress.
If every part could be made to the microscopic particle equal them we could expect that my Max load in my caliber .736 "Toyota Crusher" could also be safely fired in any other Crusher double bore. But alas even CNC machines have a fudge factor although they sure do a great job unheard of 60 years ago as individuals labored sided by side assembling Fox B 12 bores.
I know a feller that must have a box of 50 1903 bolts. He carefully fits his bolts to all target rifles he builds lapping happily for hours knowing he will end up with that perfect fit for a specific 600 yard goal. He even ends up with a rifle that will not shoot his pet load but requires endless hours or reloading to finally discover it will never hold up to his standard.
Well anyway.. I hear the deer calling and my recurve awaits to be bent again.
Mike in ILL

[rockrat]

Suspect the bolt fittment was probably the reason the rifle was on the rack at Cabelas. I know when I took it to the range while it was still a 30-30, it shot the worst groups I have ever had with a levergun

[fouronesix]

Sure sounds like worn/sprung parts to me. When the lever is pulled up and all the contact parts go into full battery, there is usually a small amount of "break over" tension with these actions. Some causes for this premature wear can be hot loads and/or insufficient resizing of reloads. And nothing lasts forever so this gun may simply have had a LOT of rounds fired through it with little or no maintenance or lubrication. Another possibility is that the gun has had some "shade tree" gunsmithing in the past. May need to identify the parts affected and rebuild/replace. It is not right as is.

[Beerd]

a recent thread on Marlin Owners:

http://www.marlinowners.com/forum/reloading/100361-handloads-kick-my-336-action-open-today.html
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