CZ455 .17HMR not holding zero very well... I don't think?

[oxfordshirestalker]

Hi All,

My CZ455 HMR normally shoots perfectly, 1 inch at 100 yards type accuracy with Hornady 17grn V-Max, all I can ask.
It has a Nikko-Stirling 4-12 x 50 on the front, I know it's not the best by any means but I was buying on a budget and the scope was easier to update in the future than the rifle.

This evening I went up and sat in a highseat, overlooking a cover-crop and fallow field with the view to shooting a few crows that have been kicking around and a short-range fox if it decided to show.

Anyway, to cut a long story short I had some accuracy issues the other day when I took it out for a bit of practice at a cardboard box (initially way off, brought it back on point and I put 15 shots in a 2 inch circle at 100 yards).
This evening, I got a bit bored and cold so shot at a few of the sunflower dead seed heads in the wild bird mix crop. Probably at 40-50 yards and probably 1.5-2 inches in diameter. I had a rock steady position but was missing them!!

I was a bit frustrated about this and started to think about the possible causes (below) If you can think of any others, or have any suggestions of how to remedy them then please do say!

• Action screws not tight causing wobble - everything tight.
• Scope mounts not tight? Nope, everything tight.
• Moderator? I have been taking my SAK mod on and off as it's shared with my .22RF, could that be it?
• I have definitely dinged the scope VERY lightly a few times when taking it in and out of the cabinet etc. Possible, but very light dings so seems odd...
• Ammo not being accurate. Seems odd as the rifle can shoot very straight indeed.
• Cheap Scope not holding zero properly? Always possibly but I'd like to think it can cope...
• No problem at all and it's me not pulling properly - the trigger is very 'creepy' and a trigger kit is on the cards.
• Wind - There wasn't any!
• Gun coming onto zero with a warm barrel. This is possible I suppose? But the HMR can't generate that much heat and this is probably v unlikely.
• Change in cleaning regime? I've never cleaned it and it's usually happy!

Bit of a random list, but before I go and buy a new scope or whatever I thought I'd open it up to you lot!

Thanks in advance... Happy New Year!

 

[Hereford]

Shooting down at an angle from a high seat (and at a short-ish range with a flat caliber) will probably mean you're over the top - the scope knock sounds like it was corrected previously

 

[Triggermortis]

17hmr ammo is notorious for having "bad batches" of ammo not only in terms of the bullet sticking in the barrel issue but accuracy consistancy varying between individual boxes let alone different batches, try some different makes of ammo altogether if possible just to rule the ammo out if nothing else.

 

[Muir]

17hmr ammo is notorious for having "bad batches" of ammo not only in terms of the bullet sticking in the barrel issue but accuracy consistancy varying between individual boxes let alone different batches, try some different makes of ammo altogether if possible just to rule the ammo out if nothing else.

There are always degrees of 'bad', right?~Muir

 

[Techcoat]

I say give it a real good clean and try again.

 

[paulnix]

As above, try cleaning it first, is the easiest thing to tick off the list.

 

[The Singing Stalker]

Your last point says it all. HMR does need cleaning.

 

[nun_hunter]

My HMR shot perfectly without cleaning for well over 500 rounds however it started shooting much bigger groups. I tried everything, different ammo, got it recrowned (did have a bad crown job anyway) in the end I gave it a really through clean including using a mop with bore Polish on it and the groups dropped back to 0.75moa.

 

[User00035]

I bought a pair of HW60s from Sportsman a few years ago, one in .22lr and one HMR. They came with NS 4-12 X 50 scopes on them as part of a package deal. The HMR scope went haywire within 12 months. It was properly erratic with no consistency at all. I was missing absolute sitters for no logical reason. Tried all the usual measures first with no joy then took the Hawke scope off my air rifle an immediately the rifle was a tack driver again.
Took the Nikko back. Didn't want a replacement so they gave me the list price in store credits. I was happy with that.

In my experience a poor cleaning routine will cause HMR groups to steadily open up but if its properly wild there's something mechanically wrong. (I clean mine with Butche's Boreshine every 100 rounds. I keep going until the patches come out spotless then wipe out with a hint of meths and I don't even have to check the zero. It'll shoot straight back in - my scope is a Meopta R1).

Its a simple enough rig with no recoil, there's not much to go wrong. Give it a good clean, check everything is tight and re-zero. If it won't shoot you've probably got a duff scope. Easy to check by fitting another scope which you know is a good un. You don't even need to zero the substitute. Get them on the paper and empty a mag into the same spot. If it shoots a nice neat group, wherever it is on the paper, your old scope is knackered.

 

[J111]

It almost 100% won't be the rifle as long as the action screws are done up tight and the barrel is properly free floating and presumably your'e not taking it in and out of the stock in between sessions?. Could be moderator clipping (unlikely), dodgy mounts, dodgy scope I'd say.

 

[The deer man]

Had a Nikko-Stirling 4-12x50 on a .22rf years ago and it was great until one day it just went loopy! Wouldn't hold a group at all and I suspect, but cannot confirm this, that unlike high end scopes the internal mechanisms are made of plastic not steel and once they wear or strip that's it.

However a thorough de-copper bore clean first would be my recommendation. If no luck change scopes. 17HMR ammunition has been bad in the past but not that bad, so just check if it's new production ammo or old. Moderator should be ok if it's worked before unless it's taken a hard knock and moved it off centre. Sounds like scope to me.

 

[paultap]

I would agree with the posts regarding cleaning the rifle. I went to the Orkneys in 2015 on a 3 day goose shooting trip to one of the outer Islands, in between goose flights we went rabbit shooting every day and shot hundreds of rabbits over the 3 days. My shooting companions were both using .17hmr's (one was a CZ and the other was a sako quad) after several hundred rounds both rifles started experiencing accuracy problems due to barrel fouling issues... a thorough cleaning would be my first recommendation.

 

[joe soapy]

Found with my hmr that it works best if put away clean, Think the powder residue hardens over a few hours, sending the
first shot a bit wild. Also noticed that a boresnake is difficult to pull through 24 hrs after the last shot, whilst slipping through
easily straight after the last shot

 

[The deer man]

Found with my hmr that it works best if put away clean, Think the powder residue hardens over a few hours, sending the
first shot a bit wild. Also noticed that a boresnake is difficult to pull through 24 hrs after the last shot, whilst slipping through
easily straight after the last shot

Agree, find the same.

 

[Fursty Ferret]

Clean it.....then be prepared for a number of fouling shots to be needed before acuraccy comes back

 

[satellite buck]

I too own a cz 455, have you checked the barrel retention screws...(the two grub screws)..I too have never cleaned my hmr with a rod at least but always use a bore snake and clean the crown at the end of shooting and it still shoots as when I bought new some 1200 rounds ago. I use a wheeler fat wrench to torque screws up again if the stock gets changed from one to other.

 

[barbel]

I to got a 455 t/h clean it before putting away, very accurate, been lucky no problems with ammo, love it.

 

[oxfordshirestalker]

Thank you everyone! Was out last night and it was absolutely spot on after pulling a pull through through it. Thanks for all of your ideas and thoughts!

 

[Techcoat]

Glad to hear it.

 

[Tikkat3xl]

Clean it.....then be prepared for a number of fouling shots to be needed before acuraccy comes back

Sorry to resurrect an old thread but we get told off these days if we don’t use the search tool how many fouling rounds would you say it needs? I foolishly cleaned my .17hmr a couple weeks ago and have now put about 30 rounds through it but still can’t get any accuracy back, wondering if it needs a lot more to foul the barrel?