Groups Stringing Vertical


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roc1
December 28, 2009, 10:59 PM
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What is the main cause of a veritcal stringing group? My CZ 550 243 is still doing that some even after I cleaned it very well. I changed scopes and got the group size consisent. I tightened up action screws. I will try a different load this load has always shot well in the past? The crown is ok and the scope rings are tight does not have bases it is like a Ruger.
Thanks
roc1

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dispatch55126
December 28, 2009, 11:08 PM
The barrel is heating up. I'm not familiar with the 550 but take 3 shots, let the barrel cool for about 5-10 minutes then take another 3 shots. If it vertical strings with 3 rounds, you should have close to double holes as the POI raises.

wayne in boca
December 29, 2009, 05:02 AM
Could be stock fit.Possibly when the barrel heats,it is touching the stock and putting vertical pressure on it.Sometimes it is necessary to remove some wood in the barrel channel to make the barrel free float.

rangerruck
December 29, 2009, 11:12 AM
bbl heats up, touches bottom or end wood in stock channel. either sand it out some more, and reseal, or put a little pressure pad up front, under the bbl.

Heck
December 29, 2009, 11:52 AM
I would say stock it is the stock fit. I believe the 550 is already fre floated from the factory. I would see if you can run a dollar bill between the barrel and the stock all the way back to the action. If it won't make there may be and issue with the stock and putting pressure on the barrel. If it were my rifle I would checkthat first then i would take it to a smith and have them glass bed the action.

Pokyman
December 29, 2009, 11:57 AM
I have a model 527 that did the very same thing. Tried all of the above suggestions- they did not help.
What it turned out to be was a stock that had been machined in the action area so that when the screws were tightened to hold the action tight in the stock, the action could/ would still move.
I glass bedded action and the rifle now shoots well.

oneounceload
December 29, 2009, 12:40 PM
Glass bedding the action and recoil lug area and free-floating the barrel should help I would suspect

Offfhand
December 29, 2009, 05:27 PM
I suppose you are shooting from a rest. What are you resting the forend on? Verticle stringing can often be traced to a rest that is too soft or too hard. Same with bipods. The FIRST place to look for accuracy problems is with the basic shooting setup and marksmanship.

Winston_Smith
December 29, 2009, 06:13 PM
The FIRST place to look for accuracy problems is with the basic shooting setup and marksmanship.

How consistent is your respiratory pause?

Walkalong
December 29, 2009, 06:18 PM
Inconsistent shoulder pressure. Inconsistent velocities. Wind either directly in your face or blowing away, but changing without you noticing.

knights_armorer
December 29, 2009, 06:30 PM
the first place to look for accuracy issues is at your ammo.

Uncle Mike
December 29, 2009, 08:29 PM
Post a couple pix. of your targets...let's see what's going on.

StretchNM
December 30, 2009, 12:16 AM
I have been told that, when a rfile is toherwise shooting well, and new ammo or a new load is tried, seating depth will cause vertical stringing. After all the other suggestions are taken care of, or anytime in-between (as long as you only do one thing at a time between shooting sets), start building your loads with the bullet closer to the lands, in .010" increments maybe.

Art Eatman
December 30, 2009, 01:31 PM
I think we've covered the subject fairly well at

http://www.thefiringline.com/forums/showthread.php?t=390883

bbrownie
December 30, 2009, 02:41 PM
the benchrest shooters at our club say if your action is bedded properly and the barrel free floated and the rifle strings the groups vertical, then you need to add more powder to your load.

roc1
December 30, 2009, 03:31 PM
Thanks for the help. What is the proper breathing methods? Three breathes then exhale and shoot?
Thanks
roc1

Boris Barowski
December 30, 2009, 06:43 PM
Someone mentioned running a dollar bill to check free float. Having just the space to get a bill trough isn't enough to float the barrel when it's resting on the stock. try tapping the end of the stock and hear if it's hitting the barrel.

If you benchrest the rifle, make sure it rests every time in about the same place on the stock

as mentioned, inconsistent velocities could also be the problem. do you have access to a chrono ?

roc1
December 30, 2009, 08:09 PM
No chrony. I think that I need to get a better rest.
Thanks
roc1

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