Chamber/ammo questions

[Lardbutt]

First off I am kinda new to shooting and certainly new to upgradeing a gun, so please bear with me while I struggle to overcome my ignorance. I have a CZ 457 that I want to replace the barrel on. I have had great luck with Lapua Center X and Lapua in general has been good for me. I know the maxim that your gun chooses it's ammo but is there a certain chamber that likes Lapua?

 

[Booner1334]

It seems to me that someone a few months ago here on this forum published a chart of various .22lr chamber types, and their dimensional size. You might try a forum search or perhaps someone will be kind enough to repost it for you. I'm thinking it was a our forum member @littlepod who posted the chart but not willing to put money on that.

I would also think that in addition to the proper chamber, you'd want the proper headspace for the Lapua brand too.

 

[SanginSpecial]

Like Booner said... Headspace is also an important consideration. In my experience, headspace should match your chosen ammo's rim thickness for best, consistent, accuracy.

I don't have any hands on experience to draw upon for this particular chamber, but word on the street is that it was designed specifically for the Lapua family of ammo. It's called the "Nevius" chamber. I've included a drawing of it's published dimensions.

 

[Lardbutt]

Thank you Booner. Sometimes I wonder if I am knowledgeable enough to ask the right questions. I will search for chamber discussion. The headspace discussion is at this point left for another day.

 

[Lardbutt]

Thank you SanginSpecial. I think I will start comparing chamber drawings, not that I will be able to tell their effect on a bullet. I am thiking about a Bartlein Barrel and they generally put a Bentz chamber in. My funds are not unlimited so I want to do it right the first time.

 

[Booner1334]

Thank you Booner. Sometimes I wonder if I am knowledgeable enough to ask the right questions. I will search for chamber discussion. The headspace discussion is at this point left for another day.

LB,
I appreciate your thanks,
Here is a chart of probably the most common chamber dimensions:

Your CZ 457 (and my CZ455) probably has an "LR Sporting" chamber. Notice the "sporting" has the largest chamber dimensions fitting a general purpose rimfire, meaning it'll shoot all the various .22 ammo produce with "acceptable accuracy," (whatever that means). You mentioned a Bentz chamber. It's my understanding that that chamber was developed to improve the accuracy for semi auto rimfires, while still being large enough to allow for reliable functioning. The rest of the chamberings listed are what I would consider to be "match chambers" for bolt action rifles. I have a Winchester model 52 and I assume it's chamber matches the dimensions of the Win 52 D Match as listed. Notice this has the shortest chamber of those listed. When I chamber a round, the rifling lightly engraves pretty much all of the driving bands of the bullet. This centers and supports the bullet in the chamber, and to me, that's what what I'm looking for in a match chamber.

You said you were new to shooting and rimfires. Might I suggest the book "The Art of Rimfire Accuracy" by Bill Calfee. The book is somewhat out dated now, but it will provide you with a good foundation to build upon as you learn more about rimfires. The book is available on Amazon.

 

[Lardbutt]

Thanks Booner,

I was looking at that book but was concerned about it's age. I guess I will buy the Kindle edition. I first picked up a gun 2 1/2 years ago and have kinda settled into BR 22LR as what I enjoy the most, and no I probably won't ever be "good". If I ever get so I think I have mastered it I willl take up golf to increase my frustration level.

Is your 455 modified? I am planning on taking my CZ 457 17hmr and upgrading with a barrel (leaning toward Bartlein) and putting it in a KBR Bravo chassis.

 

[Booner1334]

Thanks Booner,

I was looking at that book but was concerned about it's age. I guess I will buy the Kindle edition. I first picked up a gun 2 1/2 years ago and have kinda settled into BR 22LR as what I enjoy the most, and no I probably won't ever be "good". If I ever get so I think I have mastered it I willl take up golf to increase my frustration level.

Is your 455 modified? I am planning on taking my CZ 457 17hmr and upgrading with a barrel (leaning toward Bartlein) and putting it in a KBR Bravo chassis.

You're welcome again, LB.
It's not so much as a book as it is a collection of essays by Calfee regarding his building of rimfire bench rest guns. and his writing style can be a little tedious as I can best describe it as "good ol' boy," but he provides a huge amount of information that I still refer to. I have the kindle version too, but I wish I had purchased the book as I tend to mark up my reference material, and he does provide a lot of information. Like I said, it may be dated, but it was a huge information source.

When you say you're interested in BR 22LR I'm assuming you mean bench rest 22 lr? If that's true, you really jumped in deep, didn't you? I've been shooting for 60 years, (I'm 67 & retired now), and like most, I started with a .22 and now, all these years later, I've returned to it, and am toying with the idea of getting into .22 bench rest. I'm essentially a target shooter, and enjoy tweaking my guns to try improve their accuracy.

My 455 is essentially stock, although I've done a little work on it to try and improve it's accuracy, but I didn't win the barrel lottery on it, as it's the least accurate of all the .22's I have. It looks like CZ had a dull reamer when the chambered it, so maybe a new barrel would help.

I'm not a big fan of the .17hmr. I purchased one right after they first came out, and it was a rather decent shooter, but I've been pretty disappointed with the quality of ammo produced in the last few years. I seem to get a lot of split necks with the ammo I've purchased recently; I never had that problem 10 years ago. So if QC improves, or if someone puts out a match grade ammo, I'll take another look at it, but until then, I'll continue playing with .22rf.

 

[Lardbutt]

Well Booner I went to download the book and I had it in my tablet already. I started it and some of the early essays were pretty general and not terribly interesting to me and set it aside. I continued reading and I got to the meaty sections and continued reading. Read a couple of hours last night.

I was 58 the 1st time I picked up a gun, with exception of BB guns as a kid and trying to win a toy for a girl at a carnival. I am 61 now and retired. I will probably never be a serious bench rest competitor. I just enjoy trying to make small holes with multiple bullets.

I agree with you on the 17hmr. I have gotten cracked cases too it is kinda anonoying, plus, of course, the ammo is meant to hunt and doesn't need the accuracy for target . Best groups I routinely get with it are about 2 MOA, maybe I got the dull reamer that day too.

Well thank you again.

 

[Sgeorge]

Calfee takes a lot of getting used to

 

[Lardbutt]

I would concur. I do some writting for a model magazine. My writting would be as informal (little more northern) but my editor makes sure it doesn't print like that.

 

[1813Benny]

Like Booner said... Headspace is also an important consideration. In my experience, headspace should match your chosen ammo's rim thickness for best, consistent, accuracy.

I don't have any hands on experience to draw upon for this particular chamber, but word on the street is that it was designed specifically for the Lapua family of ammo. It's called the "Nevius" chamber. I've included a drawing of it's published dimensions.View attachment 7372641

FYI, the chamber was developed by Kevin Nevius who is a sponsored Lspua shooter for both centerfire and rimfire disciplines. It is an excellent chamber for Lapua products.

Regards
Ken

 

[Lardbutt]

Ken,

Thank you. At this point I may wind up with a Bartlein Match chamber. Bartlein has reamers for a Bentz, SAAMI Match and their own match reamer. It seems like the Bartlein will be the tightest and closest to the Nevius.