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cz 527 vertical stringing
varian
Member Posts: 2,260 ✭✭✭✭
mine in 22 hornet after the barrel gets a little warm will start stringing shots in an almost perfect vertical line about 2 inches from top to bottom. about a minute between shots so barrel is not hot.shooting from a rest with handloads. 12.5 grs lil gun using 40, 45, and 50 grain bullets. barrel is free floating, action screws are tight, scope screws are tight. any ideas about what may be causing this. first few shots from a cold barrel shoot a respectable group center of aim. 100 yds.
Comments
1. before shooting thoroughly clean chamber/bore/bolt face and locking lugs and recesses
2. make certain all receiver/scope screws/bolts are tight
3. use a dollar bill and see if it slips freely down the barrel channel without contacting barrel before shooting and after each shot
If the rifle isn't returning to the same battery after each shot, you get all kinds of inaccuracy problems. You might then consider glass bedding the stock and receiver and about 2 1/2 inches of the barrel chamber area.
Then again you say it shoots accurately on a cold/cool barrel - so depending on the conditions under which you plan to use the rifle (e.g., I used mine for turkey hunting and the occasional hog that pops up gets a bullet middle of the ear - eye) this would be acceptable.
I got very good accuracy with Speer 45 semi spitzer soft point and IMR 4227 and it worked well in the Ruger 77/22Hornet too.
A minute between shots might be sufficient if you remove the bolt & blow cold air into the chamber. Give it a little longer to replicate a cold barrel.
You might try this and it takes little bit of practice without a helper.
Check your action screws and make sure they are snug, then place a dial caliper jaws over the top of the barrel and under the stock at the fore end as far out as you can get, I use plastic jawed caliper so as to not marr the wood or barrel and watch the dial caliper as you loosen and tighten the front recoil lug screw. If the dial caliper moves any at all the action is warping in the stock as the screws are tightened. (the dial caliper reading should not move any at all) Keep in mind that a movement of .001 can be approx 1 inch at 100 yards. Get a helper at first to loosen and tighten the front stock screw (with the tang screw tight) and the other guy holding the caliper in place while the gun is laying on a pad and if using steel jawed dial caliper take precautions to not marr the wood or barrel. After some practice you will get to where you can do this by yourself. (take several test runs and it will be obvious if the action is warping in the stock as the screw is tightened and loosened as you are gently holding the caliper jaws between your thumb and forefinger with light pressure. When the gun is properly bedded you can completely remove and re-install the stock and the gun will still shoot to same POA (point of impact) or real close at 100 yards if you properly re-torque the action screws BECAUSE THE ACTION is not warping into the stock. If it is then vertical stringing after the action is PROPERLY bedded you need to thourghly clean the barrel, checking for copper fouling, then change to different powder and or bullet weight and so on and on.
Summary: You have to start FIRST with a properly bedded action if you expect any precise repeatable accuracy out of a rifle.
While it is important to check the action screws for barrel deflection and making sure that the action is bedded stress-free, I think the real problem is the barrel itself.
"Barrel Cold Hammer Forged "
This is the highest form of stress induced manufacturing that a barrel maker can use. Several hammers beat a tube of steel over a negative image mandrel. Here is a video of a Ruger barrel being hammer forged:
https://www.youtube.com/watch?v=8pzL5h2cl80
Best.
varian,
While it is important to check the action screws for barrel deflection and making sure that the action is bedded stress-free, I think the real problem is the barrel itself.
"Barrel Cold Hammer Forged "
This is the highest form of stress induced manufacturing that a barrel maker can use. Several hammers beat a tube of steel over a negative image mandrel. Here is a video of a Ruger barrel being hammer forged:
https://www.youtube.com/watch?v=8pzL5h2cl80
Best.
Correct about HUNTING rifle barrels.
My point was/is if he is really that critical for accuracy out of a HUNTING rifle barrel at very least glass bed it PROPERLY first. I don't trust any un-bedded rifle to shoot the same accuracy on target from one day to the next even if it has a real good group on day one.
It appears that the Hornet is shooting a 2 inch group cold to warm or hot barrel.
I've never played with a Hornet and have heard rumors of some that are really fineky about reload accuracy, but I have glass bedded and worked up loads for several other BOLT ACTION calibers that had the vertical stringing issues and have NEVER failed to correct vertical stringing issues in hunting rifles and get them to shoot a good respectable 1 1/4 inch HUNTING group.
I've seen few hammer forged barrels that were really bench rest accurate, with reloads but not very often.
You are correct in that if the shooter wants bench rest accuracy the gun should have a bench rest barrel, but a bench rest barrel can be like putting lipstick on a pig if the action/bedding itself is poor.
For a hunting rifle my final test is to see what kind of a group the gun will shoot WITH A COLD BARREL first shot over several days. (make the first shot count) If it's not printing a COLD BORE group it's
not a hunting rifle for me. I've seen quite a few rifles that would shoot a real good group after the barrel got warmed up, but not shoot a good first shot cold bore group as the temp of the weather changed and the cold temp of the barrel. Most animals in my neck of the woods don't wait around while I take practice shots getting the barrel warmed up.
I'm not real sure what he means in HIS OPINION of a RESPECTIFUL group from his Hornet? I could not accept a 2 inch group from a hunting rifle, but I can live with a consistent 1 1/4 inch group max. I've seen others that can live with a 4-6 inch hunting rifle group at 50 yards with old Betsy and a Bushnell Banner $35 sportview scope.[;)]