Rifle (re) build: Going full F-class

Thiking about re-building this rifle:



The Lilja bbl has been good getting 0.30" groups (measure c-to-c) But I'm told the bbl mounting system (grub screws) is less than ideal.

I want to stick with the CZ 457 action and MPA chassis - just re-barrel, add a tuner etc for max accuracy.

Doable? Barrel / tuner recommends?

Thanx.

 

You're at 0.300" 50 yard groups? For how many rounds?

So you want to thread it, or you want to glue-in?

For the barrel, Shilen Ratchet, Benchmark, and do NOT reprofile a larger contour. Custom order if you need to, but do NOT cut a whole bunch off the diameter anywhere.

 

My 50 yd 5-shot avg group is right at 0.30" c-t-c. I've repeated this group at least a half dozen times. With Eley Tenex. Occasionally larger, occasionally smaller, but I would say the 0.30" c-t-c group is repeatable when I do my part.

The action is for a straight shank barrel with no threads. I'm OK with glue in, unless it can somehow be modified with threads.

 

Paint job came out nice.

 

Also will neeed a 'smith recommend...somebody who specializes in 22 rf F-class, to install the barrel.

 

That's factory paint on an MPA . Upcoming paint job is for an XLR chassis.

 

Righto.

So I'd call Mark Penrod in Manchester, IN to see if he'd be interested. Don't jump in on a bunch of details about F-class and whatever it is you know... just ask him, and let him lead the conversation. He's one of the "knowers" in the industry, I assure you.

Being a repeater, you will of course want a chamber that will extract loaded ammunition, so make sure to discuss that with him. I would assume that he has several reamers.

Personally, I would not go with anything NEAR as loose as a Bentz because this is an accuracy-minded bolt action that can be manually extracted...not a blowback that can only rely on extractor tension to get it done.

On the flip side of that, you DO probably want to use a reamer that has at last a small amount of taper. Judging from your posts and photos, and simply the choice of action and rifle, you are not the type of BR50 shooter that is going to maintain a spotless (and I MEAN spotless) dust-free chamber.

It TAKES that kind of maintenance to assure that a zero-taper chamber like a Calfee 1 will work out okay.

So stick to one with a little (0.0005"-0.001") taper, keep the freebore to the MODERATE end of things, and go reasonably tight on the "freebore" dimension to match that Eley. (NOT super short, and NOT super tight, or it won't extract without dumping powder all over your action).

Glue-in is totally bueno, provided it is a tight fit, and preferably, that the barrel's glue is allowed to cure in a vertical position.

It seems that the action could also be threaded 3/4-16 or whatever. Either way, with this much work, probably good to face the action.

It will take a barrel shoulder of about 0.900, if I recall correctly, but I don't personally think you need it, PARTICULARLY if you aren't threading.

-Nate

 

@natdscott ... thanx !

 

Go with this reamer

 

I disagree. I think that's too short, and way too tight for what this gentleman has in mind. The Nevius is tighter than a 52D, and at 600, almost as short...pretty close to a Freeland.

The EPS chamber itself is 0.617....and that's plen'y short.

Don't get me wrong, I like Kevin, and I trust his judgement on chambers for precision rimfire...I just don't think a rifle that is supposed to REPEAT 100% has any business being that tight.

 

Help me understand... what WOULD be an appropriate use for that chamber? I keep my guns pretty clean (even if I've argued devils advocate elsewhere) What would be ANY use for a chamber that won't "repeat"?

 

that chamber is specific to Lapua.. from what i gather and you know.. that smallbore shooters at Perry or at Bristol have to be able to unload a round on command

 

F-Class is slow fire one round.. at a time, so he won't have to use that mag, just have a dummy with an insert to place the rounds

 

CZ sells a single feed "mag" for the 457.

 

I can understand removing material near the muzzle /crown area, but why nowhere else? I had barrels turned down at the chamber end and both shoots really good sort of inducing choke

Lee

 

If you shoot Lapua this is the chamber to use. this chamber is exactly like the Myers 1.5 but without the stop.

Lee

 

Can you explain by what is meant by repeat 100% and how the chamber being tight has an effect

Lee

 

I MAYYY be reading between the lines too much, but if I get things assessed right, I would bet that this young man would like to be able to run 5 rounds from magazine if he so chooses, in addition to F-class, one-at-a-time stuff.

As for that chamber, I do not have direct experience with it. I do have experience with others, but like the OP, I use Eley EPS, and prefer it.

I compared that reamer to the spreadsheet list of reamers I have, and made judgement about it based on knowledge of very similar chambers..

...maybe that was too much extrapolation.

 

Simple: If the chamber is tight enough in diameter, short enough in length, and/or is installed in a barrel with a tight enough bore or heavy land/groove ratio...the barrel has more purchase on a chambered bullet than does the casing itself.

So, a guy tries to remove the unfired round, and it simply UNseats the bullet from the casing and extracts the casing only.

Long closing cam actions that can be chambered really short can see the worst of it, if the smith sets them up that way with a reamer like the Nevius that does not cut the rim.

-Nate

 

Benchrest, indoor, even dedicated Prone rifles if they are kept really clean. If it's a REALLY tight chamber for the barrel and ammo dimensions, accuracy can go to hell in less than a box of ammo.

Really, those chambers are good for any type of precision shooting where you don't have to expect a "cease fire and make safe", and where you can be assured of time to carefully maintain chamber conditions, and refoul when necessary.

IE: if you can always just fire the unexpended round to clear the rifle, then a parallel chamber, even if it isn't kept clean, isn't a SAFETY issue.

...but parallel chambers also SHOOT much better if they are A) cut large enough for the barrel/ammo in the first place, and (B) kept reasonably clean.