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Lateral stringing of groups

Posted: Wed Apr 18, 2012 8:45 pm
by Bangflop
I seem to be getting some left/right stringing of groups, not extreme but enough to make me wonder what the most common reason why this occurs. The wind was calm. My two theories are: #1-pulling the shot #2 uneven setup between the rear bag and front rest causing uneven recoil reaction. I am shooting a CZ 527 varmint/target with set trigger set to well less than 1lb.(I had to readjust it today because when I got home from shooting it would fail to set). Seems it would be hard to pull a shot with such a light trigger. Could it be parallax? I am using a VXIII 4.5X14 LR with side adjust, and shooting 100yds.. Any thoughts? Can bullet seating depth cause this or correct the horizontal grouping? Barrel harmonics???HELP

Re: Lateral stringing of groups

Posted: Wed Apr 18, 2012 11:51 pm
by Sth Oz Dan
I'm curious to hear some opinions here too.
I recently shot some groups that were less than .2" variation vertically, but spread almost an inch wide

Re: Lateral stringing of groups

Posted: Thu Apr 19, 2012 2:04 am
by 247sniper
Hand position and trigger control can cause this. Has you Cz had a trigger job ?


Steve.

Re: Lateral stringing of groups

Posted: Thu Apr 19, 2012 2:07 am
by 247sniper
What distances do you notice a diffrrance, and what range are you shooting at. Try different ranges to see if it changes etc.

Steve.

Re: Lateral stringing of groups

Posted: Thu Apr 19, 2012 3:37 am
by Bangflop
The trigger is a single set and although I don't have a scale it had to be less than a pound and crisp. Per my first post I had to readjust it would not set. I have only shot at 100yds. Dan, that is the same group size I have. Still looking for advice... will check for consistent hand position next time at the range. Weather is now going to turn bad for a while.

Re: Lateral stringing of groups

Posted: Thu Apr 19, 2012 3:51 am
by 247sniper
Have you cleaned the barrel and tried it ?

Re: Lateral stringing of groups

Posted: Thu Apr 19, 2012 8:03 am
by Bangflop
Yes the barrel has been broken in and maintained by cleaning after practice. I have shot 3 shot groups that were impressive....less than a quarter inch but average around the threes. It is probably me or the set up. I am using a Wichita front rest and a Protekor 3 front, 13B rear both in cordura. The #3 front rest is wider than I need and have a #2 coming. The rifle has shot well and the variable is the rest set up and the nut behind the rifle. There is probably no quick fix....practice to become more consistent is probably the answer. Thanks ...other input?

Re: Lateral stringing of groups

Posted: Thu Apr 19, 2012 8:09 am
by Bill K
I would say, if you are that regular with the groups, that it is probably just you and/or rest allowing the rifle to move ever so slightly left/right and this causing the consistance lateral movement. Make sense ? Bill K

Re: Lateral stringing of groups

Posted: Thu Apr 19, 2012 9:07 am
by Bangflop
Sure does Bill. I was able to put 3 shots in less than .2 once but other groups were .3 to .4 (these shot with a different front and rear rest). I was trying to settle on a powder charge and the groups I shot didn't tell me much because of the horizontal spread. I should have started with the auddette ladder. It seems 24-25.2 grains of rel10 under a 39SBK, win brass and Fed205M primers work well. How do you choose a charge weight. Should I load the middle of the range or the top if all groups are sub .5? Thanks again

Re: Lateral stringing of groups

Posted: Thu Apr 19, 2012 2:14 pm
by Bill K
If you do not mind a few extra bullets, etc. I would load from the start 24 gr up to the 25.2 gr, in 2/10ths, about five each round and see what one seems to be best, then make slight adjustments from there with 1/10ths and bullet seating depth/off lands. Bill K

Re: Lateral stringing of groups

Posted: Thu Apr 19, 2012 6:18 pm
by Boisblancboy
I agree with Bill, that's pretty much what I did when searching for a load with my 35 bergers. Started at the bottom and working up .2 at a time with 3 shot groups. You should discover an accuracy node or two. From those nodes load above and below(as long as your not at max load) .1. This should give you your load. Now one thing I did once I found my load I then shot a few groups out to 200 and 300 yards to make sure it stayed consistent.

Re: Lateral stringing of groups

Posted: Thu Apr 19, 2012 6:36 pm
by Bangflop
Thanks Bill, it seems to shoot any charge between that range equally as well. I loaded 25 grains tonight and at 2.310 OAL. The previous loads were all at 2.300 OAL. The max for the magazine would be around 2.330. I do have a single shot follower from James Calhoon but would hope to find a load that fits the magazine. Thanks for all the help. I will let you guys know what I come up with. This is still fun...not frustrated yet. The rifle shoots better than me I think...lol. I did load 3 rounds each from 23.3 to 25.1 in .3 grain increments. Those from 24 to 25.1 seemed to shoot equally well. I shot one 3 shot group of .160 with 24.5 grains at an OAL of 2.3. I shot a five shot group with same load yesterday and strung them horizontally almost an inch. Vertical was about .2 inches. If the 25 grain loads don't work out I will start near 24.5 and work up .1 grains. and shoot them at 200yds.

Re: Lateral stringing of groups

Posted: Fri Apr 20, 2012 12:21 pm
by Bangflop
I found that the bullets seated to 2.312OAL strung out laterally at the range today. I had the same load seated to 2.325OAL and that brought them together to a half inch! These were 24.5 grains of Reloader10. The 25 grain loads performed well at 2.312OAL sub 4's! ....go figure. Looks like I will stay at 25 grains and play with seating depth for now. I was thinking of trying IMR8208 but that reloader10 really works. Thanks for all.

Re: Lateral stringing of groups

Posted: Sun Apr 22, 2012 10:43 am
by Paul
I'm going to throw my 2 cents worth as my opinion: Hand, Cheek, and shoulder preasure.

Re: Lateral stringing of groups

Posted: Mon Apr 23, 2012 3:56 am
by Sth Oz Dan
Paul wrote:I'm going to throw my 2 cents worth as my opinion: Hand, Cheek, and shoulder preasure.
That's where I figured I'd gone wrong. Not quite consistent enough there.
More practice won't hurt