Vertical stringing at 100 yards with a .22? Possible causes?

[Joe L]

I claim to be a pretty good pistol shooter.  I don't claim to be much of a rifle shooter.  Even so, I have posted some pretty good results with centerfire rifles, but my little Savage Mk 2 .22 rifle has always been a challenge.  I've never been able to shoot 1 moa groups with the rifle and I don't think it is me.

This morning I mounted a new Vortex Diamondback 4-16x scope to my little Savage and went to the range, primarily to test the scope, not the rifle.  I got it dialed in very quickly and was very happy with the clarity and reticle of the new scope.  So the scope test was a success, and I ordered another one for my AR-15 when I got home, I liked it so much. 

The problem was the groups.  Now, since I was testing the sight, I was just loading and shooting pretty rapidly, 10 rounds at a time.  I shot 100 rounds.  The first group, when the barrel was cool, was good, at about an inch.  But from there on, the group would be 3" tall and 1" wide, in other words "vertical stringing" that seemed to coincide with the barrel warming up.  This is a heavy barrel, by the way, so it never got AR-15 warm, just warmer than ambient.  I ran out of range time before I could cool the barrel down completely, so I went home.   

When I got home, I checked the action bolts and they were both over 30 in-lbs, way too tight according to my Savage forum buddies.  I removed the stock, reinstalled the stock, and went 8 in-lbs on the rear and 15 in-lbs on the front bolt.  Then I checked to make sure the barrel was still free floating.  It was. 

If the vertical stringing is reduced when I go back to the range and shoot much slower and more deliberately, I won't know initially if it is because of the reduced action bolt torque or because of slowing down.  I'll have to shoot 30 rounds rapidly to see if the vertical stringing returns, I suppose.  If it is the action screw torque, then the stringing won't be affected by the rate of fire.  All I would need to do is tighten the bolts down to 30 in-lbs again and shoot off two 10 shot groups and see if the stringing returns.  Then back the screws off to 8 and 15 and see if the stringing goes away. 

If anyone has any ideas or suggestions, I would sure like to hear them.  If anyone can explain to me how action bolt torque produces vertical stringing, I'd like to hear that, too.  I'm thinking harmonics change, not angles or stresses in the action.  If I can fix it with JB-Weld or Sugru, I'm on it.   

Joe

[eastman]

have you tried an exorcism? 

[Joe L]

have you tried an exorcism? 

I exorcize regularly!!

Actually, I came close to just buying a CZ with the match chamber but it ticks me off that I don't yet understand why this rifle is such a challenge.  My background troubleshooting the pistols leads me to believe it is something simple but as yet undiscovered, like a little thermal stress or movement after the barrel warms slightly or unrepeatable harmonics due to strange loads on the action due to the stock bedding/contact points.  Something like that.  I know how to pull the trigger without moving the gun and how to line up the sight on the same spot shot after shot.  The bullet just doesn't hit where the gun was aimed all the time. 

Joe

[SerenityNetworks]

Vertical stringing is usually a sign of breathing control.  In short, pulling the trigger at different points during exhalation.  You need to pull the trigger at the bottom of your natural expiratory pause.

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[MadDuner]

I’ve seen vertical stringing with my .22 rifles, and once I started shooting over the chronograph the picture became abundantly clear.  Of course it was bulk/cheap .22LR, but it had a 300fps spread on velocity! 

I would look there.

[SerenityNetworks]

...once I started shooting over the chronograph the picture became abundantly clear.  Of course it was bulk/cheap .22LR, but it had a 300fps spread on velocity!

My experience with cheap ammo is that I get more than just vertical stringing. It shoots wider groups.

If the groups are primarily vertical and good ammo is used (CCI or better) then my money is on breathing. 

When I get home next week, I'll post back with some common group patterns and their causes.  The material is from the Appleseed Project (appleseedinfo.org).  It's a fantastic program for both experienced and novice rifle shooters.  If you haven't been to one, go!

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[Joe L]

I am pretty confident that the ammo and breathing are OK, based on what I've done at 100 yards with other firearms.  What I find on the rimfire specific forums, especially with the Savages, is the action screw torque and bedding issues.  I'll experiment there next week.  Maybe I can fix it with some JB-Weld afterall. 

Joe

[SerenityNetworks]

I don't have a Savage, but my Marlins are very sensitive to torque.  Generally, around 15 pounds is perfect (plus or minus a tiny amount, depending on the rifle).  I forgot last weekend and torqued one to 22#, like one of my other rifles.  The groups blew up.  No vertical stringing, but group size more than doubled.  Whoops! 

Bedding &/or pillars are great, but also check to make sure the barrel is free floating.  Could something be touching.  That could indeed be an issue, especially as it warms.  But my money is still on breathing.  :-)

Final note:  Consider using Devcon instead of JB Weld.  It's easier to pour, parts seem to free easier, and it's harder.  It's great stuff.

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[Boris_LA]

Joe L,
I don't own the Savage and a few I have seen and shot, I was not too impressed with. But I own a few CZs in 22LR and they all MOA or better. I don't own a torque wrench and have never paid much attention to torque on the screws. I think in 22, the whole concept of the barrel floating and bedding is way overrated. Many of mine have a barrel lug and not truly "Free Floated". Even my little CZ455FS (Full Stock) with barrel band is a subMOA gun, although its too light to shoot offhand in competition.
The only gun I have with vertical stringing is Marlin Lever Action in 357MAG, that starts shooting high if shot without enough cooling and gets hot. The full power Magnum loads to knock down heavy metallic targets at 200M is way hotter that lowly 22LR rounds. Its well know issue and can be compensated for.
22 will shoot different POI in different ambient temp and zero needs to be checked, but once set its on. I don't use too expensive ammo either. Normally SK Standard Plus, or RWS Rifle match (the same as Norma TAC 22).
If you looking towards CZ rimfire, just do it. Its hard to find unhappy CZ owners on the RimfireCentral and I know why. Its right in the Anshutz' accuracy territory for less than third of the cost
Many American shooters are still oblivious enough about CZ, but ones who tried and own, can't shut up about them.
Oops! Just like i did above

[Joe L]

Boris and SerenityNetworks--thanks a bunch for the replies and suggestions. 

The ammo is Norma Match 40 gr that I use for bullseye at 50 yards so I expect it to be pretty consistent velocity wise.  I went back and checked my old notes and targets.  I don't shoot this gun very often because I am usually not happy with it.  I had not shot it for maybe a year or two before I took it out recently, so I had checked all the scope screws and action screws and I had snugged everything down.  The action screws were way too tight, say 30 in-lbs.  On previous targets, before I overtightened the screws, I had 1.5"-2" groups but not the vertical stringing.  I had never seen vertical stringing before, only large round groups.  So something changed.  I also have a much larger and stiffer scope on the gun now than I had before.  That is also a change.  So I will start with the action screws, which I have already reset to 8 in-lbs in the rear and 15 in the front.  I don't recall ever seeing any target changes as dramatic as what I saw on Thursday from this rifle, so I goofed something up, most likely.  Another possibility is the new scope itself, but the groups were too consistent for it to be something loose in the scope, I think. 

So my plan right now for next week is:

1.  Same ammo and scope, try with much lower action screw torque.  If no change, then
2.  Try different ammo (I have many to choose from) and slow down shooting pace to minimize warm barrel effects, if any.
3.  Don't be so bullheaded and change breathing sequence while holding everything else the same as on Thursday.
4.  Swap out the scope, although the new Vortex Diamondback seemed rock solid and behaved perfectly when zeroing.
5.  Buy a CZ.  Cut up the Savage so my sons and grandsons never have to deal with it, save the scope and rings and bipod for the CZ.

Of these, 80% probability that door number 5 is the winner.  I've messed with this rifle several times over the last 8 years and have never made much progress on getting it down to 1 moa consistently.  It is the only firearm I own that I haven't at least understood where the limitation was.  With the pistols, I am able to modify my technique, the grip shape, trigger reach, sights, and trigger pull feel to get to where I want to be accuracy wise.   

I apologize for sounding a little hard headed about the breathing, but after many years of bullseye training shooting standing single hand, I have learned to be very much aware of sight and breathing and calling shots based on what I saw when the gun went off.  I'm using a bag at the rear, and I don't see any vertical in the scope with breathing, like I would be looking for off the bench, just a little horizontal wiggle with pulse rate.  After I shot the rifle on Thursday, I got out the Kadet and put a B-8C target up at 25 yards and put about 50 rounds in the x ring from a rest (10 rounds in 20 seconds, reload, repeat 4 times) just to see if there was anything wrong with my vision or control.  I was OK.  Yes, the rifle is different physically, mentally it is similar. 

Here is the other thing.  IF my latest problem is the action screw torque, and IF all the Savage guys say "the gun is very sensitive to action bolt torque", why is it so sensitive?  Flimsy actions?  Poor placement of the action screw bosses?  In other words...poor mechanical design?  If so, step 5 is the answer and it isn't anything I want to deal with.  Cut it up. 

Joe

[M1A4ME]

Never gave it a lot of thought, before, but torque on the screws that hold the receiver in the rifle can be a "funny" thing.

Ever see the old single shot bolt action .22's our grandparents put food on the table with?  A single screw through the bottom of the stock into the receiver.  A big headed thing with a small coin/screw driver slot with knurled sides.  Knurled.  To make it easy to tighten/loosen with your fingers up to a certain point.  I suppose the coin slots were there in case someone didn't have the finger/hand strength to adequately tighten/loosen the screw enough to get it tight enough or start loosening it.

Not sure how much torque you can put on one of those screws with a penny (quarter could be a lot of money for some people in those days when a days work might be worth 50 cents in many jobs.)

Joe, you've got the video equipment.  Set up your camera so you can watch the group as you shoot it.  If it's a heat/stress issue then you should see the bullet holes climbing upwards as you shoot.  My experience with centerfire rifles has always been the group starts where you want it and then the bullet holes move away (left/up, up, right/up) as the barel heats up.  I've not seen one (that was affected by the barrel heating up) that just tossed bullets around in a big round/oblong group.  We could see the bullet holes "travel" across the paper.

Only other idea I have relates to the scope and your eye placement behind the scope.  Do you feel good that your cheek weld/eye placement is the same after working the bolt after every shot?  Shooting off the bench isn't all that easy.  It's a weird feeling position for me and I can do better with a sling shooting prone.

[SerenityNetworks]

That sounds like a good plan.  I like Joe L's suggestion to buy a CZ. I've had four.  Selling the Trainer was my worst sale mistake ever.  I still have a Scout, an Ultra Lux, and a 527 Varmint in .204 Ruger.  The 527 is the only one I have bedded.  I can't say it made any improvement in accuracy, but it did make it all but perfectly consistent from before disassembly/reassembly to after.  Re-zeroing is very rarely needed - and it is the most accurate rifle I own.

Yeah; I wouldn't expect vertical stringing with a rear bag, but with a bipod and at 100 yards I just don't know.  Maybe consider replacing the bipod with a bag.  It's doubtful, but even then it could be breathing. You've got me really curious now.

I believe my Marlin 795s are torque sensitive because they have a barrel contact point ahead of the receiver.  I have fiddled with my favorite one enough that with Eley Sportit is a sub-POA gun.  (Not bad for a $125 semi-automatic.)  I've considered removing the contact point.  But the gun shoot sway  beyond my expectations, so why risk it.  I don't know if the Savage has such a contact or not.  If so and it's close to the receiver, then that could be the reason for torque sensitivity.

If you've never bedded anything before, then you might consider using the Savage as a practice run.  Just a thought.

Drew

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[Joe L]

M1A4ME and SN--
Thank you both for the suggestions.  Winds were rough today at 15-25 mph so I didn't have high expectations, but I went to the 100 yard range with the Savage 22 anyway.  All total, I put 170 rounds downrange.  Here is what I concluded. 

1.  Vertical stringing is less at 10 in-lbs front, 8 back torque on the action screws than 30 for both.  Almost gone.
2.  Norma Match 22 may be a poor choice for this rifle.  I had less vertical with CCI SV and even CCI AR Tactical, which was the most consistent of the three I tried today. 
3.  With the AR Tactical, I was shooting 1.8-2.5" 10 shot groups in terrible winds.  Gun even sounded like a rifle.   

I love the new scope but still need to work with it some to get the eye relief, cant, and parallax perfect.  I will work on that and on groups again on a calm day.  I might actually be able to shoot this rifle fairly well some time.  The problem is not all with the rifle.  I am going to try a few more HV rounds that I have in the closet while I'm learning the scope and perfecting my bench technique.  There are a lot of variables here.  You guys who shoot these outrageously long barrelled contraptions know that. 

I would still rather shoot a P-10F at 100 yards than a finicky unpredictable .22 rifle.

OK.  I'll admit it.  This is fun.  This is not easy.

Joe

[SerenityNetworks]

Glad you figured it out.  For me, those would be pretty decent groups in any wind.  At least with my little Marlin 795.

And I'll say it, "I was wrong."  It wasn't the breathing.   :-)

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[Joe L]

This morning I tried the CCI AR Tact again, just as a control, then Aguila Super Extra, then Federal HV Match, at 100 yards.  Still had some wind, but not as bad as Tuesday.  Best results were from the Aguila Super Extra, worst were with the Federal.  Just to complicate things and to check on another possible vision detail, I changed the shape of my target from a cross to a circle with a small rectangle in the center.  With the super fine cross hairs of the Vortex scope, I was getting some double vision and confusion with the cross target.  So, the best combination seemed to be to use the 2" circle target with a 3/8" dot in the center, no cross lines, the Aquila Super Extra ammo. 

With that combination, I was able to shoot 6 "good" 10 shoot groups out of 12, with some vertical stringing indicated on only 2 of the 12 ten shot groups, with the last 4 groups pretty good, as in 2" or better.  So I will stick with the Aguila Super Extra while I figure out my technique and learn the scope. 

So, there is still some improvement to be made on the shooter side of the gun.  I am also going to check the bedding again and see if the epoxy job extends too far in front of the action.  I don't know how much of the stringing to attribute to my eyesight versus the gun and ammo. 

One of my shooting buddies at this range just ordered a CZ 557 MTR after watching me curse my Savage for a week.  I'm making progress with the Savage now.  We'll see.  Still ticks me off that I don't understand cause and effect on the action screw torque.

Joe