CZ 457 PRS Build

Leuchtkafer said:
Some pleasing results with a few of the ammo types, R-100 delivered 3 sub 1-inch groups, something that I think in another thread very few rifles without a tuner have posted such a result.
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Nicely done. Three consecutive sub-one inch 100 yard ten-shot groups on the same target without a tuner is a very good achievement. (Given that ammo unpredictability increases with distance, it can be tough with a tuner, too.)

In the 100 yard challenge for 2023 only about three different shooters of all 20 entries shot three consecutive sub-one inch groups without a tuner, with averages of .681", 719" and .828". (For the record, I submitted no entries in 2023.)

How much of a difference a tuner will make is not simple to determine because of the inevitable variation of group sizes. Of course, while it's hard to prove a tuner works at longer distances, it's also hard to prove that they don't. It's possible that one way to assess tuner efficacy is by the number of consecutively shot sub-one inch groups at 100.
 
good shooting
reads like you don't have a ballistic app on your phone to figure out drops
Like me, I still don't rely on an app, prefer to use d.o.p.e.
at a bare minimum though, maybe look at Shooters Calculator
you can alter atmospherics details to see how much or how little they truly matter

In a game with generous target sizes you are obsessing over best ammo when really most all your targets are good enuff
My budget rifle and ammo still are not what holds me back, the stages and shooting positions are the challenge for me
 
Thanks. No I don't use an app, I like hard data. Since I've been having matches on very windy days lately, it might be worthwhile to look into something for wind adjustments, I know I am weak on wind management at distance (100y+). I wouldn't say I'm obsessing over best ammo, I've only done some casual testing so far. Did I shoot any Tenex, Midas+ or R-50? :p Look at how I assessed things, SK HV wasn't shooting anywhere near as good as I initially thought, Lapua LR showed me it's not worth using for benchrest shooting thus giving it a use case in this rifle for ORPS. R-100 looked a little too good to use, for one me not (yet) being able to take full advantage of it and I'm torn on saving it for benchrest shooting. Center-x (not tested) runs what, $22.50 a box these days? R-100 about the same. RWS Special Match I got as low as $16/box, and it's hitting that sweet spot of price/performance, much less likely to have nasty surprises in it like the SK has or the lower grades, orange and yellow box RWS. I've had Center-x that shoots poorly before so the current price of it is uninspiring compared to what I'm seeing with RWS Special Match. I prefer to get reliable feedback knowing that my equipment is putting shots where I send them. Misses are me, I don't have to scratch my head and wonder what's going on with the gear.

Speaking of the gear, I feel pretty settled into a final setup and all the accessories I'll need for some time. From here on in, nothing major will change so I will start building that necessary familiarity with everything. I'll talk about some of the things I did to get to the final setup. A pair of exterior weights was needed to get the balance where it needs to be, the full set of internal weights was not enough. I got by with a quick and dirty weight while I worked on this. First I made some T-nuts. Yeah, I could just buy some M-lok nuts, but where's the fun in that? T-nuts are a basic machinist's project and good practice. I had to shim the parallels to give the cutter a C-hair of clearance from the vice jaws. Clearance is clearance. Straightforward stuff, move to coordinate, centre drill, drill, tap, chamfer. If my machine had a DRO I'd do all the holes with one tool rather than changing tools for each hole before moving to the next, but with analog it's easier for me to just finish one hole 100% before moving coordinates.



With them all done it's time to slice my nuts off. :eek::oops: Git yer mind outta da gutter! Not those nuts, jeez! :rolleyes:



Gave them a cold blue treatment



There's something so satisfying about a precision fit :cool:





I had an 11 hour work day today so I'll continue the post about the weights proper another day and leave it there. I'll briefly recap match 5 I shot on the weekend. Mental game is something that can really affect your shooting. I had attended two venues previously and was going to a third new one. Directions/address weren't really clear so I ended up first arriving at the location they used to hold the matches at, then drove around for a half hour trying to find the actual location. It wasn't far from the original spot but there were two other addresses given and no clear signage. I did find it but I had now missed the orientation and sight in period. I scrambled to get my rifle unpacked and bang out 5 sighter shots which I just finished then I was up for my turn at the first stage. My brain was frazzled, I took my first shot, miss. WTH? That was a good shot... I look up over my scope and I was on the wrong target of this multi-distance stage... D'oh! I made 5/8 hits, 62.5%. I go and get the rest of my gear for the day out of my truck.

Next up Ladder stage, I did a little better, 7/10. I need to practice on ladders, wasn't steady enough. Now, when your mind is in a tizzy, you make bad decisions. It's funny how it works... you KNOW your setup isn't good, you're going "gosh, I'm not stable, I should adjust", but you don't. You try to force it, and that usually doesn't work out well. You miss and tell yourself "that was stupid, I knew I shouldn't have shot!" But you did it anyway. Isn't it better to take the time to fix the setup and make your hits, even if you time out? 8/10 and a timeout is better than 6 or 7/10 rushed shots from a bad position. You'd think so, tell that to your frazzled brain and get it to listen :cautious:

Pile of tires next, I did a little better, 9/12 = 75%. Now the nerves were settling and this was just a challenging stage, tires are bouncy and it's difficult to stabilize on them. Next stage, 5/9 = 55.5%. I don't know, I had a bad stage, it happens. To finish, I cleaned the tank trap, 100%. Always satisfying to finish strong. Overall, 79.55%. Now I'm at a point where my rifle is setup the way I want it, and performing the way I want it, so I'm getting a good read on the things that I need to work on for my shooting. I had a good run up the learning curve and have hit that point where gains will be incremental and commensurate with the amount of practice I put into it. I know I have it in me to perform at a high level, I just need to put in the work to get there. I'd like to take a spot on the podium before the season is out, don't care if it's 1st, 2nd, or 3rd, I know competition is stiff at the top of the leaderboard. It's good to have goals, even if you don't meet them, in trying you will improve upon where you currently are at, and that's what really matters.
 
Next time your at a match and on a pile of tires, think about whats the stiffest part of a tire? Its where the tread meets the sidewall> But almost everyone puts their bag on the middle of the sidewall which is the most Spongy Bouncy Part. If you havent aquired a Sticky Gamechanger Well Ill let you figure that one out. No dropped bags, super shapeable and can do things no other bag can. Trust me, its one of the ONLY bags youll need. I like that youve been bitten bye the bug
 
Yeah, there's a couple different ways the tires have been setup. A neat stack with them laying flat on each other I've been fine off of, it's when they lean them at an angle in a row against each other and you have to do 3 unique positions off them, that's where it's been more difficult for me. My range has two tires, not quite enough to replicate the setup and practice off of. Thanks for the tip on the bag.

OK, back to making the weights. I had some stainless steel stock that suited this project well, I just needed to split it in half. Some requirements of this task would be to preserve as much material as possible and make an accurate cut. Hacksaw? HAH! I'm not suicidal. Angle grinder? Fast but too much waste and not accurate. Band saw? That would be a good choice, but I don't have one. OK then... what else? I do have a slitting saw, that would be very accurate and the thin blade would waste very little material. One problem, with a max depth of cut being 0.030" in this material, and 1.250" of material to cut.... do the math. Many slow passes 0.030" at a time, this took a little over 10 hours of machine time to do. Man. I could only cut halfway through before bottoming out on the blade arbor then had to flip it around. When I finally saw daylight break through, I went and poured a fine Scotch to celebrate :LOL: I cut them to length with a hacksaw then did a light facing cut on all the sides to clean it up.



Drilled and counterbored for the mounting screws, you can see my analog readout setup in that pic. Now, they say if you want to do good work, you should never cut corners. Well, I don't follow the rules, I cut all the corners :p



These might just be weights, a utilitarian device, but when they're mounted on a fine rifle, they should look good too. I gave them a brushed finish then heat colourized them. I applied a vinyl sticker with an Imperial-ish Firefly logo on it. With a razor I cut out the design so I could then scratch off the colour finish down to bare metal again within the perimeter of the sticker.



I'll let the pictures do the talking :cool:





I went out to my range on Tuesday after work for some practice and had a productive session. For one example, I figured out a good way to approach a certain bucket stage. Start prone on one side of the bucket using the bipod, place bag on the bucket before getting into the first prone position. I leave enough space between the barricade stop and bipod so that I can transition to sitting in front of the bucket and just drop the rifle down onto the bag, leaving the bipod deployed. Then it's as simple as going back to prone on the other side of the bucket using the bipod again. Very efficient and stable.



Match 6 coming up this weekend, I know where to go and won't get lost this time though :ROFLMAO:
 
Well this summer sure went by in a flash, I didn't have much time for machining projects with everything else going on. That was the point, I hardly went shooting last year since I was working hard to be able to do my build so I promised myself I'd focus on shooting this year. I got several 4th place finishes, last month being just 2 hits behind the winner. Not bad for a first season up against the seasoned veterans while I worked out all the bugs with my build, learning the ropes of this sport as I went.

I did get one more project done, I made knobs for the cheek riser to make adjustment/removal tool-less. I have to remove the cheek riser for cleaning so this is very convenient. I made the knobs out of aluminum and some threaded brass inserts that would be loctited in place after I anodized the knobs.



Shown here after anodizing and dyeing in a liquid nickel acetate bath for sealing.



Finished product, I'm happy with the result. This was my first time anodizing anything.



Not sure if I mentioned it but RWS ammo was giving me extraction issues. I might've figured out why. You'll have to zoom right in on the pic, Lapua on the left, RWS in the middle, Eley on the right. You can see the RWS has more of a flare at the base where the straight wall transitions to the rim.



0.001" is all it takes to turn free movement into an interference fit. A few months ago I tried a dual extractor mod, replacing the shell holder with another extractor claw. This was an improvement, but I would still get a stuck casing or two during a match. I remembered I had chamfered the chamber mouth, with the borescope it looked like that operation left a very slight burr at the chamber mouth. So here's the only thing that makes sense; tight chamber + slight burr + flared case at base junction = interference fit, thus, stuck casings. I chucked the barrelled action back up in the lathe and polished the chamber with 600 grit to remove the burr, problem solved, so far so good. No more stuck casings in my last two sessions with RWS.
 
CZ457 can struggle with extracting some types of ammo. I experienced it myself on my new custom cut barrel.
I am considering to get the aftermarket extractor to address this issue
 
EugeneM said:
CZ457 can struggle with extracting some types of ammo. I experienced it myself on my new custom cut barrel.
I am considering to get the aftermarket extractor to address this issue
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Live rounds are one matter, spent casings should be able to be flicked out with a fingernail. If spent cases are stuck hard in the chamber, it could be from firing pin damage where there is a nub of displaced metal biting into the casing. It could be a burr from machining that needs clean up like in my case, or it could be cheap ammo with out of spec large brass that got press fit into the chamber, an issue that you're really only going to have with a tight match chamber.

If the spent case is easy to remove but the extraction system isn't pulling it for some reason, most likely the extractor slots weren't cut deep enough and there isn't enough rim left exposed for the claw to bite on.

An aftermarket extractor doesn't solve any of these root causes of extraction issues, and honestly a little tune up of the factory extractor with a stone would have the same effect. I ditched the dual extractors and am just running the single OEM extractor. If you're able to diagnose and address the root cause, there's no need for an aftermarket extractor.
 
I found a pic of me at a match that highlights my rifle pretty well, thought I'd share. I've been thinking about what to do in the off season, still some machining projects to get back into, it's just dang cold in the garage now which limits motivation. Maybe installing a heater will be the first project :LOL:

 
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