Cz 452 17 hmr accuracy issue

[rsrjerry]

Hi all

Mate of mine is having problems with his cz 17 hmr, can not get a zero, we have cleaned barrel well, changed scopes, tried different ammo, checked things are tight, shot with and without moderator.

it will put a hole say on target then will throw next 3 or 4 inch high then next is 2 or 3 inch low and so on, basically cant put a hole in same area of target? its all over the place

my thinking is could be the barrel is knackered ? maybe crown or the like ?

any pointers would be great

cheers

[NickB65]

Has he/she had the gun long, has it ever held a zero, is it second hand... some background to the gun may help.

[kent]

From your description I should look at two /three things.

First switch the scope out for a proven one (exact symptom of a broken optic that wont hold)

 

Second look for stock to action issues (especially in the bedding of the action ) doubtful

 

lastly connecting screws not being centred in the holes

 

I should take odds on the scope BTW

[Redgum]

run a piece of paper down the length of the barrel to see if its free floatin, some of the 452's have a action screw half way down the barrel and some have both at action end. The CZ's are usually pretty bomb proof but don't expect every rifle to do neat little clover leaves as it takes some skill as well as the rifle but yours does sound a bit way ward, has it been cleaned with a good copper solvent? have you looked down the barrel with the bolt out from the bolt end, how does the rifling look.

Edited April 30, 2014 by Redgum

[rsrjerry]

Has he/she had the gun long, has it ever held a zero, is it second hand... some background to the gun may help.

yes mate was totally spot on mate has had it since 2008 has put a load of rounds through it mind you ,cause like me is employed in pest control , but dont know if it takes a lot to shoot out an hmr barrel?

From your description I should look at two /three things.

First switch the scope out for a proven one (exact symptom of a broken optic that wont hold)

 

Second look for stock to action issues (especially in the bedding of the action ) doubtful

 

lastly connecting screws not being centred in the holes

 

I should take odds on the scope BTW

Have tried 3 x scopes now that are fine on other rifles , so cant be that

stock to action and barrel is all fine etc

run a piece of paper down the length of the barrel to see if its free floatin, some of the 452's have a action screw half way down the barrel and some have both at action end. The CZ's are usually pretty bomb proof but don't expect every rifle to do neat little clover leaves as it takes some skill as well as the rifle but yours does sound a bit way ward, has it been cleaned with a good copper solvent? have you looked down the barrel with the bolt out from the bolt end, how does the rifling look.

Has had a really good clean out , rifling looks ok IMO ? it was a real top rifle very good groups but has just gone all over the place with no chance of a zero

[welshwarrior]

Has he got a moderator on? If so have you tried it with out the mod on?

Have you tried a different batch of ammo had it with my 22 when Winchester changed the sub x

[dadioles]

Maybe people who post here should read the original post before they keep suggesting what has already been tried!

 

"...we have cleaned barrel well, changed scopes, tried different ammo, checked things are tight, shot with and without moderator..."

 

What you did not tell us is the distance you were trying to zero. What you are effectively saying is that you are shooting a group about the size of a 6 inch circle. As it is an hmr I guess you are zeroing at about 100 yards.

 

If those two assumptions are correct it does, at least, put things into perspective.

 

Please confirm.

[rsrjerry]

Maybe people who post here should read the original post before they keep suggesting what has already been tried!

 

"...we have cleaned barrel well, changed scopes, tried different ammo, checked things are tight, shot with and without moderator..."

 

What you did not tell us is the distance you were trying to zero. What you are effectively saying is that you are shooting a group about the size of a 6 inch circle. As it is an hmr I guess you are zeroing at about 100 yards.

 

If those two assumptions are correct it does, at least, put things into perspective.

 

Please confirm.

due to the issues we tried to zero at 50yds , basically and for example we shot at circle in middle of card and one would go 3 inch high then say 3 inch low left then 4 or 5 inch off to left basically anywhere and no chance of putting 2 holes anywhere clise, and this rifle has always been bang on and real tight groups

[Blunderbust]

I don't know how the barrel is attached to the action on a 452 but I had the exact same problem with my 455, did as your friend and checked the usual. I eventually stripped it down and found that the locking nuts holding the barrel on had come loose. Tightened them up and bingo, it was back on.

[turbo33]

Jerry, has a new/different magazine been used? Has the magazine been stripped for any reason? If it has, I believe that if the spring is put back in the wrong way, it will cause feed problems. If it were me, I would cycle and eject a magazine full onto the carpet, and check the bullet heads for damage. I'm pretty convinced this is what was wrong with mine..........sold it in frustration, but thinking back, I wish I'd investigated the cycling aspect for my own piece of mind.

 

The other issue is a weak spring in the firing pin. Apparently causes inconsistent burn if the strike is variable.

 

Let us know how you get on

 

[cooter]

Try stripping and cleaning the bolt as well.

A build up of crud in the bolt also causes this kind of problem (as in post #10).

 

The other ones could be that as the barrels are tapered it may require some crud to make it seal properly after cleaning (the old one about needing a number of shots to get it back on song), if that proves to be the case it means the barrel is probably worn.

It could be that the crown is pitted.

[kent]

due to the issues we tried to zero at 50yds , basically and for example we shot at circle in middle of card and one would go 3 inch high then say 3 inch low left then 4 or 5 inch off to left basically anywhere and no chance of putting 2 holes anywhere clise, and this rifle has always been bang on and real tight groups

 

To confirm the groups are shifting ie not holding MPI ? Or just plain open and unsatisfactory? If it is the former and its not the scope there is some wood to metal interaction that's just not right. I have seen this on guns that are bouncing on an action screw or have a crack in the stock, free float can effect groups but I have yet to see it keep shifting to multiple MPI normally it just opens things up.

If the barrels done it just opens up, though there is a chance of some contaminate moving periodically but one can only assume you have tried cleaning the life out of it. Bolt cleaning can better groups through consistent strike pressure but shifting MPI - never seen that but there is always a chance.

 

 

Its one of those things you just have to work through one stage at a time. Be interesting to put it on the range here and see what was / wasn't actually happening. Please conform again groups ok but shifting MPI / zero?

[rangey]

Hi all

Mate of mine is having problems with his cz 17 hmr, can not get a zero, we have cleaned barrel well, changed scopes, tried different ammo, checked things are tight, shot with and without moderator.

it will put a hole say on target then will throw next 3 or 4 inch high then next is 2 or 3 inch low and so on, basically cant put a hole in same area of target? its all over the place

my thinking is could be the barrel is knackered ? maybe crown or the like ?

any pointers would be great

cheers

mine shoots like this after a good clean,but after around 25-30 rounds its back on song.

[Luckyshot]

Hi all

Mate of mine is having problems with his cz 17 hmr, can not get a zero, we have cleaned barrel well, changed scopes, tried different ammo, checked things are tight, shot with and without moderator.

it will put a hole say on target then will throw next 3 or 4 inch high then next is 2 or 3 inch low and so on, basically cant put a hole in same area of target? its all over the place

my thinking is could be the barrel is knackered ? maybe crown or the like ?

any pointers would be great

cheers

 

My old 452 went like that after 14000 rounds, I tried everything to get it back on song but nothing worked new scope, mounts, re crown different stock etc even 2 gun smiths could not explain it as they both said the barrel wasn't in bad shape but couldn't understand why is was shooting like a shotgun, had to get rid of it in the end and bought a new 455.

[dadioles]

Thanks for the extra info.

 

Gosh, for an hmr to be that far out at 50 yards is pretty bad. A "shot pattern" 6 inches or more in diameter at 50 yards!!

 

That is not subtle.

 

As others have suggested.....

 

Back to basics, try one thing at a time. But it seems you have tried most things.

 

I would start by removing the rifle from the stock, checking the woodwork and metalwork for damage or "looseness". Clean thoroughly, oil where required then fitting it back together checking for proper fit and screw torque.

 

Slowly and methodically work through all the steps already mentioned and writing down exactly what has been tried and firing 4 or 5 shots at each stage to see what happens.

 

There has to be a logical explanation but heaven only knows what it is.

 

You can eliminate a lot of the variables by locking the action in a vice (you don't need the stock) and bore sighting (remove the bolt and look down the bore) onto the target. It is easier to do than it sounds and even a Black and Decker Workmate or something similar can be used to hold the gun. Just re-check by bore sighting that nothing has moved between shots. A good opportunity to try a couple of different brands of ammunition.

 

It is a pity you are not just around the corner from me, getting to the bottom of this one would be fun.