M305 done!! now .... new problem ??

270dave

270dave

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Took me awhile but finally finished it. I have had this one for few years and just enjoyed shooting it as it was but...got the bite to do something new. Its' an older version with the slant reciever and an S&K mount. Filled the cutout, did the bedding, tried my hand at paint, popped a Bushnell 3200 10x on top and took it to the range....
Left and right it only varies an 1" but...now it's stringing them vertically 6" to 8" :( The mount has two extra screws tapped through on the left and right of the main knob and is solid as hell. The bedding is rock solid, gotta use a little brass drift to tap it out of the stock. Scope is new, tried another one I had around and results were the same. Handgaurd clearance is good. Seems like a bbl stress issue.Are there any particular points where these rifles are sensitive to that ?

Back to shooting my "stocker" till I figure it out.

http://www.hunt101.com/img/461654-big.jpg
http://www.hunt101.com/img/461652.jpg
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http://www.hunt101.com/img/460109.jpg
 
Just for shzts and giggles;

1) Were you using your bi-pod, or a bag rest (Go back without the bi-pod and try)

2) Is your gas system loose? Does the gas lock tighten up before 5 o'clock, or is it perhaps loose?
 
My el boggo nork shoots a tidy group , off a sand bag with open sights .
but found it shot a string (horizontaly?) using a bipod . so guess what i dont use a bipod .
 
Good thoughts ...but the bipod was only for the pics. Shooting was done off the bags, front and back. gas cylinder is tight. With the irons I was getting a typical 3" "circle" at 100.
 
if you tried 2 different scopes on top of that mount and the irons are giving you good groups then something must be up with the mount. just a guess, im not sure what it would be without seeing it close up, ive never used the s&k mount either only the arms 18.
 
270dave said:
Good thoughts ...but the bipod was only for the pics. Shooting was done off the bags, front and back. gas cylinder is tight. With the irons I was getting a typical 3" "circle" at 100.
Click to expand...

Were the irons used before the bedding, or after? If those groups were before the bedding then I'd try again with irons and the same ammo as before. That should clarify if it's an optics problem or the rifle itself, likely bedding.

It sounds like you are using a new fiberglass stock. Do you have the old stock to try it in? That would help determine if it's a bedding problem.
 
I would think the scope mount is more likely the problem, but there may be more than one issue after all the work that's been done on it. I was suggesting ideas of how he can narrow down what areas may have problems.

With mine that I purchased with a shortened barrel I had multiple problems including shifting reticle, scope mount not holding zero and bedding material causing several problems. All of this plus the front sight disappeared with the second bullet I fired out of the rifle. 270Dave should have a much easier time fixing his problem than I had dealing with all those at once. ;)

As far as his question regarding sensitive areas with the bedding or barrel tension, two areas come to mind. It sounds like it is snugly bedded into the stock at the receiver, but how tight does the trigger group get when latching it into place? If that is not tight the receiver could shift up and down a bit during recoil which is certainly violent in this rifle.

Second is the front ferule. Many people go by the idea that there is supposed to be a certain amount of downward tension on the front of the barrel, which is created by raising the barrel up a bit with a spacer while bedding the receiver. Not everyone feels this is necessary and I'll leave it to more experienced people to decide if that could contribute to this.
 
Cariboo_kid is right regarding the tension of the front band and front stock ferrule. Numerous experiments were done by the US AMTU and they found that : Tension vs. No tension vs. light tension vs. Free floating had NO effect. My NRA High Power High Master Classification Coach passed this on to me.

Hope this helps,
Barney
 
my guess is you're dealing with a heat expansion issue moving something as you do your strings. Some part, say from the bedding job (or whatever), is preloaded, and changing as it heats.

I think........


;)
 
Keebler750 said:
my guess is you're dealing with a heat expansion issue moving something as you do your strings. Some part, say from the bedding job (or whatever), is preloaded, and changing as it heats.

I think........


;)
Click to expand...


I would have to agree. You should find an un-bedded stock to try.
 
I know there is some downward tension on the bbl ,that may not be the issue then. I had bedded the original wood stock so it's not an option but ....I do have another 305, bone stock from the last Marstar shipment. I had not thought to swap the stocks but thats a great idea. Should sort it out between the bedding or the scope mount. We'll giver a spin and let you know. thanks for all the suggestions.
 
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