Accuracy problems with CZ550 in .375 H&H

BRICKBURN said:

This contradiction begs a question.

You shot 3 round groups sub-MOA. So, how did you do it? Details.

Before you blame the gun, have someone watch you or video tape yourself shooting. (or both)

It has taken me some time to learn how to shoot my CZ500 .375 at targets to get tight groups. It has to be held differently than my other calibers.
When I am consistent, the rifle shoots very well.

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Hi Brickburn

I wish I knew why not all the shot end up in the same spot. I own several guns and shoot quite a lot (+- 5000 rounds a year). I use a sturdy Caldwell front rest with stock stop block to ensure the weapon is placed on the exact same position for every shot. A leather bean/sand bag under the rear end of the stock. My trigger pull is very consistent and I don't flinch (shot several dummy rounds to test). I am pretty confident that I am able to repeat the same routine consistently for each shot and I am used to shooting big calibre rifles as accurate as my normal ones. All my rifles group sub-MOA, except the 375.

Sometimes the first 2 shots are 2" plus and the next would land in less than an inch, or 1,3 and 4 would be sub MOA, absolutely no consistent result, so I am really convinced the gun has some funny trick or nick that must be sorted... I am still trying any possible solution short of re barreling the gun.

ornery said:

Speaking professionally, with all of the above work completed, Brick is correct on the next step. One of the most difficult ponds I have had to dive into is operator error. There are rifles that some of us shoot well and others do not. Is it a "hogback" stock or a straight one? I shoot the dropped comb style much better that the straight, myself.

Optics mounting and attendant problems should be studied carefully. You did not mention the optic itself. The iron sight test is a good option.

You're getting good advice here. I would check all of these things were you to bring it by the shop. How did it shoot before you bedded it?

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Hi
I used Burris mounts and rings (have already changed from other brand to test) and a Zeis Duralyt 3-12 x 50 scope. I have re fitted all to ensure no funny stuff wrong with the optics or mounting of the scope. Tested the scope on another rifle and functions perfectly.
I had the same issue before bedding the rifle. I have now removed all bedding and the only contact on the barrel is the lug shaped like a F and the barrel lug welded to the barrel. My next option is to remove the F lug, put a cross bolt in behind the receiver lug and have the complete barrel free floating. Sounds extreme for a big bore rifle, but then I know I have eliminated all barrel contact with the stock.

Hi, is this the largest caliber rifle you own? Not questioning your shooting ability at all, but when I bought my first 375 H&H, also a CZ 550, I would shoot it from the bench like I do my 270 and 300 mag (no grip on the forearm, my off hand on the sand bag right only on the trigger, rifle snug into my shoulder). Shot all over the place. I then changed to having a very firm grip pulling backward and down on the forearm of the rifle, and voila everything was fine. Bear in mind my 270 shoots nickel sized groups with classic bench rest technique, not so for my 375 and 500 Jeffery. Hope this helps

Have you checked your brass (if using reloaded ammo) for neck concentricity? Sometimes the way the neck of the case "grips" the bullet varies. Can lead to accuracy issues. Any tight spots in the barrel, throat erosion, etc? Is the firing pin strike in basically the same place on the primer after each round is fired. If not it could be the bolt face may have a problem (sorry can't think of the proper name).

I was talking to a bench rest shooter the other day about shooting techniques etc. He was telling me that one of the mistakes people commonly make is placing their front rest directly on the bench flat top or table top. He said that if it is made out of concrete or similar hard surfaced material it can affect accuracy (not all the time but does play a role in the occasional "flyer"). He said to put the rest on a piece of wood, or shooting mat that would support the rest and then try shooting from that.

When you shoot from the rest how are you holding the stock forearm (if you do that)? Some people will pull down on the forearm but inadvertently pull slightly to the side which will cause a different impact point that where you think your aiming.
It could be barrel harmonics. Did you try shooting your rounds in another rifle? Did you have someone else shoot your rifle?
I apologize if some of these points were already covered buy I'm typing them as I think of them.

Is the action inletted/bedded properly? I had a 550 where the action was so poorly bedded at the factory (American stock, not Czech) that the tang was a couple of millimeters away from the stock when the screws under the lugs were pulled.

colorado said:

Hi, is this the largest caliber rifle you own? Not questioning your shooting ability at all, but when I bought my first 375 H&H, also a CZ 550, I would shoot it from the bench like I do my 270 and 300 mag (no grip on the forearm, my off hand on the sand bag right only on the trigger, rifle snug into my shoulder). Shot all over the place. I then changed to having a very firm grip pulling backward and down on the forearm of the rifle, and voila everything was fine. Bear in mind my 270 shoots nickel sized groups with classic bench rest technique, not so for my 375 and 500 Jeffery. Hope this helps

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Hi

Yes it is, but I have and shoot regularly other big bores. I do shoot with my off-hand on the sand bag, etc...
I will try holding on to the front of the rifle. I might have found another possible problem. Directly behind the front lug screw on the barrel, it is touching the F shaped lug and might create a high spot. I have machined a hollow on the lug so the barrel is not touching anywhere (suppose I could have taken some wood out the stock and dropped the lug couple of thou, but don't like taking wood away, not so easy to replace...)
I hope this solves the problem, but will also apply all the other advice as well...

My CZ's have always shot well...

I did have a cousin (amanita safaris Erik Terblanche) that purchased a Ruger 223 he could not get it to group under 2.5" at 110 yards.

Long story short, rugers reply after months of work was:
A die makes a barrel, dies make batches of barrels before they are replaced, as it dies the die wears,..... so....... If you get a barrel early in the batch it'll be tight on the range....
If you get a barrel at the end of the batch it'll be "looser" although it still falls within their (producers) specs...

Jaco Strauss said:

My CZ's have always shot well...

I did have a cousin (amanita safaris Erik Terblanche) that purchased a Ruger 223 he could not get it to group under 2.5" at 110 yards.

Long story short, rugers reply after months of work was:
A die makes a barrel, dies make batches of barrels before they are replaced, as it dies the die wears,..... so....... If you get a barrel early in the batch it'll be tight on the range....
If you get a barrel at the end of the batch it'll be "looser" although it still falls within their (producers) specs...

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Hi Jaco
I agree with your statement, but then the barrel would shoot consistently larger groups, not shoot sub-MOA and suddenly a flyer or two. this looks like a disturbance somewhere on the barrel. I hope changing the lug will sort this out, waiting to get time to go to the range and test again....

Nic7-300wsm said:

Hi Jaco
I agree with your statement, but then the barrel would shoot consistently larger groups, not shoot sub-MOA and suddenly a flyer or two. this looks like a disturbance somewhere on the barrel. I hope changing the lug will sort this out, waiting to get time to go to the range and test again....

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True

Nic7-300wsm said:

Hi Jaco
I agree with your statement, but then the barrel would shoot consistently larger groups, not shoot sub-MOA and suddenly a flyer or two. this looks like a disturbance somewhere on the barrel. I hope changing the lug will sort this out, waiting to get time to go to the range and test again....

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If you haven't changed the lug yet, I'd go back to the range put a soft towel on top of the sandbag sand try holding the forearm with pressure firmly down and back into your shoulder. Your right hand gently on the pistol grip. Dry fire until your sight picture is the same both before and after pulling the trigger when dry firing. Shoot a three shot group. Wait a minute, dry fire some more and repeat.

There's a reason why a 454 Casull revolver shoots higher with lower velocity heavier bullets than with faster lighter ones in general. This is true to a smaller extent with big bore rifles.

If that doesn't work, it's definitely the rifle.

Just an update. I have read through all your advice and tested everything, from removing and re-fitting the optics, to changing and holding the rifle differently. Still the same result. And it's not consistently shooting the first 3 rounds sub MOA, out of any 5 shot group, 3 would be close (MOA or better) and 2 shots would be 1,5" to 2" further away. Sometimes the 2nd shot is the flyer, sometimes the 4th shot....
I have taken the rifle to a gunsmith and requested to remove the F lug, install an additional cross bolt directly behind the receiver recoil lug (same as older versions, don't know why they changed that) and ensure the whole barrel in free floating, then I know nothing impacts on the barrel movement. I will have the rifle back during the course of this week and then the next test.

I actually have the same challenge with everything I shoot. Turns out it's me. It's the way I shoulder the rifle on the bench. I have a tendency to push my rifle shoulder forward as I'm about to shoot which changes the position of the muzzle ever so slightly which affects accuracy. I don't do it all the time though. When I don't do that I shoot well.
I use a Caldwell Leadsled DFT when I shoot. I have upper back and neck issues so it reduces the abuse somewhat. Still when I know the "bang" is coming I still have the tendency to try and "protect" my upper body (when one experiences recoil from a rifle your neck receives a form of "whiplash" so I'm told). I found that instead of resting my arm (I'm a righty so my right side) on the bench I raise my right elbow up as if I were shooting off hand. This seems to work for me.
One thought: Do you reload your rounds?

8x68 said:

I actually have the same challenge with everything I shoot. Turns out it's me. It's the way I shoulder the rifle on the bench. I have a tendency to push my rifle shoulder forward as I'm about to shoot which changes the position of the muzzle ever so slightly which affects accuracy. I don't do it all the time though. When I don't do that I shoot well.
I use a Caldwell Leadsled DFT when I shoot. I have upper back and neck issues so it reduces the abuse somewhat. Still when I know the "bang" is coming I still have the tendency to try and "protect" my upper body (when one experiences recoil from a rifle your neck receives a form of "whiplash" so I'm told). I found that instead of resting my arm (I'm a righty so my right side) on the bench I raise my right elbow up as if I were shooting off hand. This seems to work for me.
One thought: Do you reload your rounds?

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Yes I reload everything. I have tried various factory ammo, but same results. My reloads seem very accurate over the chrony with extreme spread of only 10 fps and std deviation of 6 fps (5 shot groups). On paper this should be as accurate as you can get....
as far as myself, I don't flinch at all when shooting, not even heavy big bores. I have tried some of the advice from members by holding the front down and steady, I have had the rifle "free-recoil" but still there are these unexplained flyers, thus my diagnostics that something is affecting barrel vibrations.
I will have my rifle back next week and will take it to the range and see if the cross bolt modification worked. if it doesn't then I know not to accept better than 2" or re-barrel the rifle (most probably will do just that because I don't like rifles that don't group at least MOA. As Col Townsend Whelen said: "Only accurate guns are interesting!")

I wish you the best! My CZ 550 in 375 H&H shot 1.25" groups or better with factory Remington ammo with no tweaking. I've only shot handloads through my 500 Jeffery (can't afford factory) but it shoots better .5 MOA. If this fix doesn't work I'd call the CZ custom shop (if you're in the U.S) and see if they won't give you a new barrel and fit it for free. Jason and Harlan are great guys.

Too late now but I would not have taken that other lug out, its likely not the problem but oh well. Sure sounds like a barrel bedding issue to me. When the barrel heats up they sometimes wander around a little or "land" in a slightly different spot after each round, then launch a little differently. I imagine your smith will sort it out though, good luck. Let us know what he finds too.

After trying everything suggested here and getting the sam results, I'll be interested to see what happens after the Smith's modifications.
I'm hoping for your success.

Status update, I received my rifle back but was unable yet to shoot it. Cant wait to see if we solved the problem. Most likely will go to the range during next week and push couple of rounds through it....keep your fingers crossed!

hi Nick

please keep me posted

bassasdaindia said:

hi Nick

please keep me posted

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Will do...

Nick how was the CZ shooting?