CZ 527 is very fussy

[Ralpharama]

My CZ.223 using 69gr TMKs was super accurate for a cheap gun. As TMKs I pretty much all calibres have dried up, I bought 500 Nosler 69gr bullets following recommendations on here. I made up some test loads yesterday and fired them at 100yards in Monmouth tunnel, but the results were a tad disappointing. Previously I was achieving an average, in the 100yard tunnel, of half MOA with the TMKs, which I thought wasn’t bad. 

I really love the rifle, particularly as it came in a green Form Rifle stock. I vaguely remember someone saying to me that he had rebarrelled his CZ527 which made it very much less fussy about ammo. A few weeks ago one of my much wealthier than me friends, was shooting some bargain factory ammo he had come by. His Sako wasn’t mad about it, but his AI was achieving V bull after V bull with the same ammo. His view was that the “cheap” Sako wouldn’t shoot just any old ammo, whereas his proper “quality” AI would achieve accuracy with anything it chambered. This got me thinking and  whilst I can only dream of an AI rifle, I wondered whether if it would be possible to upgrade my poor persons gun with a quality barrel?

[Richiew]

My AI 308 likes hornady and Berger but not lapua or TMKs and defo not ppu  but a mates AI rifle I sold the TMKs to loves them .Tikka 223 shoots most ammo very well but Berger and hornady again are the best  in the 70-75 grain range . It’s a matter of playing about to find the best or just settle on something that works for you . Have fun 

[Shuggy]

I believe that the CZ527 is a basic Mauser action, so any decent ‘smith should be able to improve its accuracy by fitting a stainless match barrel instead of the hammer forged one that it comes with. May as well get it glass bedded while you are at it. 

[Ralpharama]

28 minutes ago, Shuggy said:

I believe that the CZ527 is a basic Mauser action, so any decent ‘smith should be able to improve its accuracy by fitting a stainless match barrel instead of the hammer forged one that it comes with. May as well get it glass bedded while you are at it. 

Hmm sounds tempting, then I could get a 1 in 8 twist for heavier projectiles. Do stainless barrels last as long as the hammer forged ones? I don't compete and were I to spend money I don't really have on a new barrel it would need to last a very long time 🤣  

[Shuggy]

A hammer forged, chrome-lined barrel, such as you will find on an SA80 will typically last 10-20,000 rounds. A non-chrome lined barrel would probably last a bit less. But there is a big difference between service rifle accuracy standards and civilian ‘match’ accuracy. I am guessing that a stainless 0.223 match barrel would probably give good accuracy for 5-6,000 rounds? Good barrel life is one of the joys of using standard ‘underbore’ cartridges such as 0.223 and 0.308.

[snakeman]

 

Your 527 will in all likelihood print 'one-atop-the-other' assuming you have worked up a load and fed it what is most preferable. From personal experience I had the 1:9 twist varmint variant that shot the standard 69g SMK with exceptional accuracy, and yes, this was with the 'factory barrel' - never had any reason to even consider rebarreling, as it held its accuracy to-a-pinpoint throughout the time I had it.

No reason to alter the load of 24.4g of N140 seated at Sierra's book length of 2.260....

Incidentally, in the kindest possible way, your 'wealthy friend' might be a decent chap and good mate, but is talking cock

Practice, and practice more, to get your 527 into that one-hole-group you strive to achieve and it will surely achieve it - it was by far THE most accurate 'factory' rifle I have ever had the pleasure of shooting, and I've shot quite a few. Indeed it was so reliable, and the only rifle I've had that could consistently reproduce a 0.5" cold-bore shot to pick-up from where I left off on my previous outing - a remarkable little gun

ATB

[Popsbengo]

25 minutes ago, snakeman said:

Incidentally, in the kindest possible way, your 'wealthy friend' might be a decent chap and good mate, but is talking cock...

I didn't like to say 😂

I'm sure AI makes good rifles (I've shot a few), can't say they're anything special in accuracy terms and like any rifle, benefit from good load development.

[snakeman]

13 minutes ago, Popsbengo said:

I didn't like to say 😂

 

Made me think why-oh-why didn't the 'wealthy friend' purchase some pucker ammo?...or, perhaps by "coming by the bargain fodder" that's how he became rich in the first place 😄

Whilst to some people the AI might be aesthetically pleasing, it's only as accurate as the person shooting it

[Ralpharama]

That’s cheered me up 😃 My CZ has been a wonderful gun and with it’s favourite TMKs was averaging 1/2MOA at 100yards in Monmouth tunnel in groups of five. But now unicorn dung is more plentiful, my initial dalliance with the more expensive, but less visually appealing Noslers, the groups have opened up. I wouldn’t be even thinking about changing anything were it not that the 527s favourite food had become unavailable.

I still have some TMKs so she will get an outing next Saturday at Bulford, assuming the Army don’t pull rank and push us plebs off 🤣 

I’ll also take the No4 which happily eats and spits out the very affordable PPU bullets, though with RS52 in short supply future loads will be with some cheaper and more readily available powder 🤣 The rifle accuracy matters very little when I can barely see the target through the Singer sight hole 🤣

[Catch-22]

Ralph, have you actually done any load development with the new bullets?

Id suggested doing a full OCW load Dev, plus tuning the accuracy by adjusting seating depth.

If you’re not testing these different combinations, you won’t get the best from the rifle and those bullets. You can’t just load some rounds with different charges, pop a bullet on top at some arbitrary seating depth, and hope it’ll produce 1/2 MOA groups.

However, IF you’ve done a thorough load development and found the bullets still won’t group, then you may just need to accept the barrel doesn’t like those particular bullets for whatever reason (bearing surface length, bullet shape - secant vs tangent - bullet to bore dimension etc etc), and you may need to consider trying different bullets. Or primers. Or powder.

Sometimes the same components may not work well in the same rifle if you change just one of the key ingredients. A change in bullet may necessitate a change in primer, or powder to get that particular bullet to shoot well.

[Ralpharama]

2 hours ago, Catch-22 said:

Ralph, have you actually done any load development with the new bullets?

Id suggested doing a full OCW load Dev, plus tuning the accuracy by adjusting seating depth.

If you’re not testing these different combinations, you won’t get the best from the rifle and those bullets. You can’t just load some rounds with different charges, pop a bullet on top at some arbitrary seating depth, and hope it’ll produce 1/2 MOA groups.

However, IF you’ve done a thorough load development and found the bullets still won’t group, then you may just need to accept the barrel doesn’t like those particular bullets for whatever reason (bearing surface length, bullet shape - secant vs tangent - bullet to bore dimension etc etc), and you may need to consider trying different bullets. Or primers. Or powder.

Sometimes the same components may not work well in the same rifle if you change just one of the key ingredients. A change in bullet may necessitate a change in primer, or powder to get that particular bullet to shoot well.

I did some test loads and the best was around the same weight as before. I haven't adjusted the seating depth, just left the seating die where it was before. I guess I'll just have to play with the seating depths. I don't have any measuring gear currently so I'll have to beg, borrow or buy some. In the past I have just slit an old case, inserted a bullet and pushed it in to find the lands and then set the press up just slight less. A bit less than scientific I suppose. 

[Scrumbag]

3 hours ago, Ralpharama said:

I did some test loads and the best was around the same weight as before. I haven't adjusted the seating depth, just left the seating die where it was before. I guess I'll just have to play with the seating depths. I don't have any measuring gear currently so I'll have to beg, borrow or buy some. In the past I have just slit an old case, inserted a bullet and pushed it in to find the lands and then set the press up just slight less. A bit less than scientific I suppose. 

You need a micrometer to check lengths.

Also I would say with 69gr pointy bullets you are approaching the limit of what your 1:9 twist barrel will stabilise.

Have fun with some load development!

[Catch-22]

4 hours ago, Ralpharama said:

I did some test loads and the best was around the same weight as before. I haven't adjusted the seating depth, just left the seating die where it was before. I guess I'll just have to play with the seating depths. I don't have any measuring gear currently so I'll have to beg, borrow or buy some. In the past I have just slit an old case, inserted a bullet and pushed it in to find the lands and then set the press up just slight less. A bit less than scientific I suppose. 

You definitely need a caliper - and I’d recommend the Hornady Lock N Load Ogive inserts to measure the length to ogive.

Forget that draconian voodoo magic of splitting a case, it’s not a great or accurate method. Do yourself a favour and follow these excellent and simple steps (see video). costs you nothing - no dummy case needed, and you use a loaded round - safe because you’re using a stripped bolt.

https://youtu.be/tYZu7RG28ow

With your bolt stripped and minus ejector (not extractor claw) you will actually feel the lands very accurately. Then simply set the die accordingly to a 0.000” touch, backing off whatever increments you want to jump the bullet by. Load a bunch of test loads with different seating depths to fine tune the most stable charge weight (as first determined by the OCW test I’ve spoken of previously).

[Scrumbag]

My further question is, how do you know your die hasn't moved...?

[snakeman]

 

6 hours ago, Scrumbag said:

My further question is, how do you know your die hasn't moved...?

 

Insert the die in your press and tighten the lock ring. The die in itself will not move, or it shouldn't move. If it does move, buy new lock rings, if it still moves after installing new lock rings, buy a new die, then if the die still moves, buy a new press. If you then meticulously repeat the aforementioned and the die still moves, buy some factory ammo and be satisfied that at least you've given it a bloody good go! 👌

[Ralpharama]

I’ve invested more money I don’t have in a Hornady bullet seating measuring device and a comparator to attach to one of my lovely Mitutoyo calipers. I did look at making the seat depth gauge but it looked to be a right pain in the bollix to save £45 posted. The comparator whilst easy to make, for those of us blessed with a small machine shop, but was so cheap it really wasn’t worth the time. I will however be making my own test cases because it’s better to work with cases fireformed by one’s own gun and they seem quite expensive for what they are, particularly as I need three …, I don’t think I’ll bother with the Lee Enfield 🤣 Looks like I’ll be spending more time in the Monmouth tunnel 🤣

[Catch-22]

Ralph, don’t bother with the hornady case comparator (you know, the dummy case with the head machined out with threads for the ‘rod’ to screw into so you can push the bullet out of the neck and into the lands) - they’re not massively accurate and they’re expensive.

Do use the lock n load bushing inserts to measure the base to ogive of your bullets with your calipers.

Then simply make up a loaded round, seating your bullet long. Then strip your bolt,  follow the steps in the video and you’ll easily find where your lands start. Simply seat your bullet progressively deeper into the case until you barely have any resistance when closing the bolt. There’s your lands.

[snakeman]

 

34 minutes ago, Catch-22 said:

Then strip your bolt,  follow the steps in the video and you’ll easily find where your lands start

You're throwing cash away buying something that really is a waste of money 🙄

Ralph, if you feel wary or doubtful of your ability to disassemble your bolt, set your mobile to video your procedure. Then, reverse your procedure to reassemble your bolt after you've completed your measuring.

When you've done this once you will gain the confidence to use this method every time (which is by far the most accurate) to measure every bullet you use, should you wish to do so - it really is straightforward

Believe me, moons ago I tried it your way with the cut case method, and the Stoney Point gauge - once gained confidence to strip the bolt method I never looked back. It also gives you the opportunity to check your firing pin and springs

ATB

 

 

[Popsbengo]

I disagree slightly;  I use the Hornady gauge with a Sinclair insert (steel not ali like Hornady). It works fine once you develop a feel.  I take a series of readings using the modified case (I make my own) with a new bullet from the same batch every time, average and done.  I use a long wooden dowel down the barrel to just feel the bullet onto the lands.

The bolt strip method is very good, however I found with care the Hornady system works as well (by comparison I achieved the same results within ±1 thou.)

The slotted case is crude and a waste of time IMHO.

I would also point out that an error of 1 or 2 thou is hardly relevant once you've started to fine adjust seating.

[VarmLR]

I have a 527 which I had barrelled in a 26" LW 1/8 twist.  Can't comment on the factory barrel because it was well and truly toasted when I bought it.  I've found that TMKs can be fussy and if anything, prefer a long jump which is unusual for a secant ogive bullet but after all, they were developed for semi-autos in the USA using a long jump.  I prefer the sierra matchkings or gamekings which are much easier to find a decent load with.  Currently, I'm using #1390 gamekings for muntjac and they are a very accurate load.  Back to the TMKs, batch consistency can vary so I batch mine by B to O measurements, and powder choice favours RS50 or N140. Barrel wise, you're probably close to the dge of stabilising them in a 1/9 twist as they prefer a 1/7 or 1/8 ideally.

I do use a Hornady B to O comparator and seating gauge but it does take some practice to get consistent results, either with the dummy case or with a split case.

[Ralpharama]

I have measured the bullet seat on the TMK shod rounds and they are 0.107" back, which is a hell of jump, but they are consistently averaging 0.5MOA with 22 grs of RS40 so I'll leave them as they are. They were shooting superbly last Saturday at Bulford.

I do need to tune the jump for the Noslers though. The powder load is pretty much the same for best group, but they're not in the same ball park as the TMKs currently, but hopefully I can improve that with messing about with bullets seating.

 

[VarmLR]

Just out of interest, have you tried other powders?   I found that between 23.2 and 23.6gr RS50 was a better match (tighter grouping in mine) with a similar jump to yours (slightly less actually to avoid over compressing the rounds)

[Ralpharama]

When I first got the gun I fed it RS52 as some folk said this was good. I then looked at Swiss Powders web site and they suggested RS40, so I tried it, enjoyed the small economy and found accuracy with the TMKs to be far better than I ever expected, even out to 600metres.

interestingly I watched a YouTube video on bullets seating and a guy (American) said that TMKs were developed with semi-autos in mind and they like the jump. He also said that Berger, which I have never used, like to start with pretty much no gap, but are pretty much unique in this respect. 

I have now bought a Forster micrometer die for seating and set it up in a single stage press my friend donated to me for the purpose.  I am told to start at 0.009” from the lands and go back in 0.003” increments until the node it found.

should be fun 😃

[VarmLR]

General rule of thumb (if there is one) is that tangent ogive profiles tend to be more jump tolerant whilst secant ogive fare batter closer up.  TMKs in various calibres are a strange breed, some being classic VLD (secant) designs such as the .308 and others tending towards tangent profiles.  I've found the .223 tmks don't have many sweet spots but generally just varying the jump for a range of loads finds at least 1 if not 2 nodes.  They can be fussy, and whilst after a house move, I haven't unpacked my Litz reference on these, I think they tend to a vld profile, and as my barrel has worn, so I've had to alter seating depth for the same load (23.5gr RS50) to maintain precision.  Just a jump too little or too much by 10 though seems to affect them.  This does seem a little at odds for the long jump semi autos that they were developed for but a precision bolt action rifle is a different animal, "precision" being the objective. When I can find my Litz book, I'll check the Rt/R ratio for these as it may shed some further light.  However, I don't think it's your CZ barrel that is fussy.  The 69TMKs are notoriously fussy to find that consistent sweet spot for IME.

[Ralpharama]

Praps I've just been lucky. I did not make any seating adjustment. I only started down this route after the problems with getting TMKs and having to try different projectiles. It's all good - I love learning new skills 😀