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CZ 17 Hornet Varmint: Gunsmith says to support barrel for accuracy

13K views 36 replies 19 participants last post by  carbonbased 
#1 ·
I have a brand new CZ 17 Hornet Varmint. It's shooting 1.25" to 2.25" groups. Place I bought it from has a lifetime warranty on guns, which is why I go there. My CZ 204 varmint and 455 Ultra Lux .22 are very accurate.

Anyway, the old gunsmith there (nice guy) looked at my groups and said, for whatever reason, my gun/barrel needs some support between the barrel and stock, right before the barrel leaves the stock. He says the groups suggest a barrel harmonics issue, and the support will reduce the amplitude of the barrel. In the groups (5 shot), there will be a couple shots close together.

Neither he or I had any 17 Hornet bullets. Just got some in tonight, and will drop off tomorrow.

What say you? I thought sporter barrels often merit such support, but not varmint barrels. Although CZ 527 varmint barrels are not real heavy…
 
#2 · (Edited)
Shot mine for the first time today and had similar results. Horrible groups. 20 Grain Hornady Superperformance ammo. Sigh. Beautiful rifle, but another project. I was going to try a torque test first, followed by rubber pressure pads at action and at the end of the forearm. Also a new scope, you know, just in case.
 
#4 · (Edited)
I was going to try a torque test first, followed by rubber pressure pads at action and at the end of the forearm. Also a new scope, you know, just in case.
Torque test? I'm no gunsmith, so I'm guessing you mean making sure the barrel is tight to the receiver? It's oddly reassuring that someone else out there has a similar problem.

I used both the 20g Hornady and the discontinued Hornady 25g. Same results.

I bought three rifles for this prairie dog trip, and none of them are ready. Started in January. Two brand new Leupold scopes had to be sent back for problems. Picatinny bases machined unsquare. Etc. Sigh.
 
#3 ·
Listen to the gunsmith. Free floating is often a solution for bad stock inletting. The Winchester model 70s actually had a screw that went into a knob on the barrel at the midway point.dampning the barrel harmonics can produce excellent accuracy. Plus he likes to do it right where I like to , right at the front where the action climbs out.
 
#5 · (Edited)
No, I think his gunsmith is suggesting a pressure point at the end of the stock, right before the barrel leaves.
What you are describing with the Winchester, is similar to something that was known as the bughole tuner. Basically, it is a set screw that is inside an escutcheon set into the forearm of a rifle so that it can be screwed onto and upon the barrel.
I do not know if this is made anymore.

EDIT: I read that incorrectly.
T.S.
 
#6 ·
I'm curious, did he say that without even looking at the rifle?
Anyway that is an easy thing to check, you can cut some foam or rubber into little pads and put them under the barrel at different thicknesses and locations. Its simple to do just takes time. If you don't see the groups tighten up then I would start looking at other things.
 
#9 ·
I'm curious, did he say that without even looking at the rifle?
He did look at the rifle. It's currently free-floated all the way, from the factory. And he was talking about support right at the end of the forend.

Dropping rounds off today, so we'll see. Thanks for the input guys. I'll keep you posted. It's a little disappointing to have this happen with a CZ, as this sort of thing is why I didn't go with the 17 Hornet Ruger.
 
#10 ·
Fwiw, general info not specific to your model but has worked for me:
Try a strip of bicycle inner tube (or something firm of about the same thickness)about 1/3 the barrel channel and 1.5" long placed 1.5" back from the tip of the stock. Make sure the amount of free float relief isnt keeping the shim from actually putting up pressure on the barrel. Some rifles require a dbl. up of shim.
Torque the action screws to 20 in.# and try. If not good enough up the screw torque by 2 in.# increments until satisfied. I dont like to go past 28 in.#, at some point more torque is just abusing the thread contacts, especially if it has pillars.
 
#11 ·
As was already mentioned, I'd start with setting the action screws around 20-25in.lbs first and most importantly, use an in.lb torque wrench because you'll be surprised how little force is required to tighten them to that range.

I have two CZ 527 Varmint 17 Hornets, both came from the factory with Gorilla strength torque on the action screws. Also, un- bedded actions are generally more sensitive to action screw torque than those that have the actions fully bed. CZ does kind of a half azzed recoil lug bedding from the factory. I've had some CZ 527's where this factory recoil lug bedding was so bad the barreled action would rock back and forth like a teeter totter because the recoil lug bedding was so poorly done.

If you like the gun and don't mind taking a chance and spending a little money on it, have the action fully bed by a professional and maybe even consider having pillars installed. I have everything bed and always have pillars installed with wood stocks.

Not trying to offend, but if the gunsmith you use is suggesting a pressure point, do yourself a favor and find a different gunsmith. Pressure points can, sometimes, work but they are only a crutch and temporary fix to a different problem. If you are only shooting this a shot here or there and will never build any heat in the gun or barrel, it's possible you could luck out and find a pressure point that'll, maybe, make it shoot better, but it'll only be a temporary fix and as soon as you get any heat in the gun, everything starts changing and it's likely it will shoot worse.

Also, factory ammo is just that, so if you haven't already done so, buy a different box of ammo with a different Lot# and give that a go.

If you plan to reload, give 12-12.2gr of AA1680 w/20gr Vmax a try. That load always seems to shoot pretty well in the CZ 527 17 Hornets.
 
#15 ·
Ironically, I just had someone look at one of my CZs and said the same thing. I found this odd being that I thought the whole purpose of a free float barrel was to keep it off the stock. This gun already shoots pretty well but when I was showing it off to him, he mentioned squeezing some additional accuracy out of it by doing the same thing you've mentioned. Had it done on his 452 varmint. Said bike tire inner tube works well. It's very cheap and harmless to try so I'll give it a shot this weekend. Pun intended...

My 527 .204 came out of the box at <1/2" accuracy so hadn't even thought about messing with it. His 527, the same. But I may try it on that just to see what it does.
 
#16 ·
Also what B23 is saying. Factory ammo isn’t always the best. Some guns shoot it better than others. And different lots of ammo will also shoot differently. I still think that gun should shoot better than that right out of the box.

If you have taken the gun apart or done anything to it, I would make sure everything is reassembled back to factory specs,
 
#17 · (Edited)
What say you? I thought sporter barrels often merit such support, but not varmint barrels. Although CZ 527 varmint barrels are not real heavy…
A quality, correctly and concentrically fitted barrel should not need the dampening effect of a pressure pad. That said some rifles whose groups are best described as "patterns" rather than groups will do better when dampened. I agree that sounds like a harmonic issue, the source of which might be the bedding of the receiver (allowing movement), the quality of the barrel's steel, the bore's path, or a combination of these and perhaps more factors.
Before I spent much on "fixing" anything I'd vet every component/factor:
scope/mounts, bore cleanliness/coppering condition, receiver bedding/screw torque, ammo quality (handloads), bag/rest set up, and (no offense) your technique on the bench.
None of the above cost much. Once they've been eliminated as possible source of your inaccuracy then it's much more palatable to accept permanent changes to your rifle. If it were me and some pressure supplied by a few layers of business cards (near the tip of the fore end) doesn't help, I would be much more inclined to look at a major change, ie...sell, trade, or rebarrel.

Good luck.
 
#18 ·
I had my CZ 527 in .17 Hornet out at the range yesterday. I had replied above saying that my first groups were horrible, and they were. But it turned out, in my case, to be a scope/ring problem. I swapped the scope and yesterday did this with Hornady 20 grain factory ammo at 100 yards:



The barrel is free floated to the action on this rifle. My "bad" groups were like the ones you reported. The above target doesn't "prove" anything with respect to your rifle, of course. But I was glad that I took another look at the scope issue before sending it back to CZ.

BTW: I think your rifle might be outside CZ's own accuracy standard. I had a .222 like that that had some gaps in the chamber metal and was shooting at over 2 inches at 100. I sent it back to CZ-USA and they replaced it with a rifle that can actually do well. Have you called them yet?

By "torque test" above I meant the action screws. You can go up in 5 inch/lb increments and see what the effect is on your groups.
 
#20 ·
Better! That three shot group labeled "Mike" is how I wish I shot all day long. ;)

You know, my first centerfire rifle was a CZ 527 in .223 and it didn't start coming into its own until I had a certain number of rounds down the barrel. With a round count around a thousand now, the barrel looks like it was lapped.

[Lifting a glass of imaginary beverage] . . . here's to many more small groups.
 
#22 ·
I recently started to shoot my 527 varmint 17HH with a factory threaded barrel. I sighted it in with hornady 20 gr factory rounds. It was shooting between 1 and 2". Then I started shooting reloads. 12 gr of 1680 with hornady 20 gr bullets were .5" 12.2 gr went to .56" 12.4 went .7" the faster It went the bigger the group's got. My next secession I am going to reduce loads a bit and test them.
The biggest issue with group testing is wind. Southern Idaho has wind every day.
 
#23 ·
Give the bore a good clean and repeat the test using the same ladder steps but this time start at the 12.4 and come down.
I chased my tail when I first got my 527A. There appeared to be no rhyme or reason until I considered how few shots it took before precision dropped off. I'm seeing more copper than I expected and considering trying to re break the barrel in to see if I can get a layer of carbon between the steel and that screaming little pill of destruction.
 
#27 ·
Only two of my 10 CZ527's have not pleased me when I first got them, first is a .204 that came to me used, they're known not to shoot 40gr Vmaxs very well and this one doesn't, just really haven't tried much else so far. My 6.5 Grendel was the other, 1 1/4" groups at 100 yards didn't warm my heart. Took it to my gunsmith and he said lets bed it as there's a lot of room around that action, a good bedding job did the trick. 1/2-3/4 inch groups with Black 123's is now the norm. I don't think needing bedding is a unusual thing with the 527's though only one of mine has had to have it to make me happy.
 
#28 ·
I'm just starting to load for my CZ 17 Hornet, varmint barrel. I found that the Federal ammo shoots well in mine, not so much the Hornady Superformance. But I am interested in finding out more about the details on loading for this round. I use an RCBS Chargemaster 1500 for everything so far, except with these small loads I'm finding a .1 grain difference makes 60fps difference in speed in my 17 Hornet. And the Chargemaster has a load accuracy of +/- .1 grain.

I just got a more accurate scale to check the Chargemaster loads, and found my loads varied about +/- .07 grains, so possible .14 difference from loads what were supposedly the same! I think that is contributing to variations in my test loads, and larger and smaller groups with my tests.

So, I'm curious what method people are using in measuring the powder to create their test loads for their 17 Hornet? Or in producing accurate final ammo? Any help appreciated, on tweaking this load, making it more accurate.

Also, any primers seen to be better than others?

Factory Federal and Hornady
 
#30 ·
I'm trying to get my charge loads more consistent, then will tackle seating depth and primers as other options soon I'm hoping, before the winter hits and messes up further load development.

I'm curious what you found helpful in regards to seating depth, closer to lands or seated deeper? Have an OAL or base to ogive that worked best? Sounds like you have a CZ 527 also.

Also, so far powders I'm testing are CFE BLK and Accurate 1680 right now, and V-max 20's. Any particular loads you're finding your rifle favors? I've got some IMR 4227 and A2200, but not tried those as of yet, heard V110 and H4198 are other possible.
Thanks!
 
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