model 70 stock options

[theCZ]

Okay folks, here's my situation:
About a month ago I bought a model 70 .270 winchester with a nikon monarch 3-9x scope. It had a cheap factory synthetic stock on it that was basically hollow. At the range I was getting nothing larger than 3/4" groups of 5 with factory super-x 150 grain ammunition. I was pretty excited about this, being a beginning hangloader and all. So I bought a McMillan stock for a winchester model 70 long action. I swapped the stocks, went out and shot it, and then free floated the barrel. Group size is now 1.25" at 100 yards at best with the same ammunition. The 3/4" groups had no vertical shift, were only shifted horizontally. The 1.25" groups have vertical stringing.

Anybody know any obvious reason for this to be happening? I do about one shot a minute every time I'm shooting for groups. I'll try to answer any questions any of you might have and appreciate any suggestsion.

BTW: I still have the factory synthetic stock and I might swap it until I have time to bed it or mess with it some more.

 

[1911Tuner]

Rifle Woes

Howdy CZ,

Rule of thumb dictates that vertical stringing suggests velocity variation,
while horizontal stringing is usually caused by the bedding. I would
take it a step further and say that since you were using the same lot of ammo, it's not likely that the velocity variation would make that much
difference at 100 yards.

Try sliding a business card between the fore end and the barrel to see if
a little tension makes a difference. Winchester M-70s with sporter-weight
barrels seem to respond to that sometimes when all else fails. Try sliding
the card to different points on the rifle to find a sweet spot, and when you
find it, mark it and use some Brownells Acra-Glas Gel to make a pad at
that point. Since the stock is synthetic, there shouldn't be any problem
with moisture causing a shift in POI.

If it doesn't make a difference, or gets worse, check the new stock to see
if there's any barrel contact that wasn't there on the original. The other
bug in vertical stringing is the barrel contacting anything, hard or soft.
The barrel vibrates, bounces off the point of contact and "twangs"
upward...throwing the shot high.

You may want to play with the action screws a little. Sometimes a little more or less torque can make a difference. The center screw seems
to be the one most sensitive to over-tightening. Try locking the bedding
screw down tight, and about half as much on the rear screw...then snug
the center screw a quarter-turn past finger-tight and see if it makes a difference.

Hope this gets you back on track...

Tuner

 

[theCZ]

Tuner,
Thanks for the advice, I'm heading out to the range today to try adjusting the screws and placing a card at the forend. I'll try my best to report back here with the results.
Blair

 

[theCZ]

Ok, I went shooting today, but I did not get a chance to shoot the 270. My roomate and I were doing IPSC style "shoot the clay pigeons stationed at different places with our 22 pistols." And I have to say, that my CZ Kadet Kit for my CZ-75BD is awesome! I've put about 400 rounds of 22lr since this weekend.

 

[theCZ]

Ok, so I took 1911Tuner's advice about the action screws. First thing I did today at the range was give it a thorough cleaning with Shooter's choice. I did 5 groups of 3, it being a hunting rifle and all. All of the groups measured .748" (outside edges minus .277). Here are a few pictures of the rifle I took today at the frosty East Missoula range.

 

[theCZ]

and a close of my "homemade" target. Going for group size, not precision.

 

[1911Tuner]

RifleTuner

Ahhhh...Another satisfied customer!

Quick! Before anything moves...Make witness marks on those screw heads!

Cheers!..and happy huntin'...

Tuner