A year ago you all helped me in beefing up my stock on a CZ 550 in 416 Rigby (thanks again). [Used it elk hunting this year, it was highly amusing!] Now I've just picked up my first true Big Bore, a CZ 550 in 458WinMag and I want to convert it to 458 Lott. Unlike the stock reinforcing project, IMHO I am going to have to get a smith to do this work for me. What are the do's (specs), don'ts, and watch out for's? Some obvious questions on my part....

** Does the barrel have to be removed to do this properly?

** Is there a "right or wrong" reamer and method? [I've gathered "no hand reamers" from earlier discussions.... anything else

Ray, I saw you recommend 600/1000ths of "freebore" for a 458 Lott one time. The smith asked me, "measured from where?" (choice of bullet, olgive, and bullet seat depth all seemed to play a factor). However, for me it is kind of a "chicken and egg" game... don't have a shooting Lott yet, so haven't shot/settled on favorite bullets yet, and it might even change if I leave for Africa or Alaska or Russia then I might adopt a bullet different from my choice for "continental USA consumption."

Do you have a measurement from the case "mouth"/neck rim that is the "ticket" for the Lotts you've had that in your experience allows them to shoot about "any ammo set up you want" and still have the freebore you desire? [I would suppose there is a trade off in there somewhere.]

** One fellow indicated that as part of the job he would want to verify/correct that the main lugs were bearing the load evenly before doing the Lott conversion, which I understand especially from a strength standpoint; however, could that start an unintended "money snowball" by throwing other items out of whack, say, headspacing?

Rob, Jeff, (others) .... any insights you may have for this "simple-no big deal" operation would be appreciated. I just don't want anyone butchering my "baby" because I don't know enough to say "no" and go somewhere else.

Yes! My first true big bore! I know compared to some of the others out there it is somewhat "junior" but from what I've experienced with the Rigby with "full house" loads, I'm thinking it will be about all the fun I (or my shoulder joint and retinas)want!

EKM

Call Dave Kiff at http://www.pacifictoolandgauge.com/index.asp
and tell him what you are doing. He will sell you the reamer that you need for +/- $148.00. Your gunsmith can cut the new chamber in less than 30 minutes.

Have fun.

JCN

check around a bit, there are lots of smiths out there with lott reamers. mine charges me $35 for the job. It's one of the easist ones out there. If your smith doesn't have a lott reamer he can rent one for about $50 - - cheaper than buying one and never using it again.

You got me mixed up with someone else on that 600/1000 number....

I'd just have the smith re chamber the gun to a standard 458 Lott deminsion and if the magazine has room give it a long throat accordingly. I think all guns should have a chamber and magazine that work together, but few actually do and thats the smiths fault... and you can normally pick up some added velocity with a long throat because it will take more powder, as you just increased its powder space.....It does not take a lot of velocity to pep up a 500 gr. bullet, thats allready capable of 2350 FPS with a good dose of IMR-4320.....

Elk,
do the same reinforcements you did on the 416...

there should be some folks out there with a "conversion" reamer,... essentially, the belt ring is DULL and will not cut past headspace...


anyone can make that one for you

best of luck
jeffe

I would pull the barrel and ream on a Lathe. Some will opt to do it by hand. Either way you will most likely end up with a chamber good enough for a 458 Lott. I doubt even a egg shaped chamber actually matters on a 75 yrd max gun designed for stopping charges! Some may claim it's actually beneficial. I'd throat separately for whatever the longest bullet is you intend to use. .100 to .200 freebore will not hurt anything. Dye-chem works wonders in making sure you don't change the headspace should you use a std .458 Lott reamer.-Rob

Ray,
Regarding the 600/1000ths freebore in a 458 Lott, now that we have the new forum software and the ability to search, I managed to find your reference to this from last July....

quote:

---

posted 25 July 2004 07:29
Re: 458 Lott Pressure

ASS CLOWN,
Somewhere in your pressure figuring there is a difference of opinnion with mine, and it pops up now and then...

This 79 gr. or IMR-4320 load could not possibly be above 50,000 PSI and more likly below 49,000 PSI....I had the pressure data at one time from Whites Lab. and it was in the high 40's somewhere, I don't recall the exact numbers....

Now I will stipulate that all of my guns had .600 inch free bore as I have found that necessary with any 458 Lott to get enhanced velocity or to reach the goal of 500 grs. at 2350 FPS with 84 grs. of IMR-4320, a max load in most of the 458 Lotts that I have played with except two that would handle even more, but then recoil became a deciding factor, at least with me......

I would assume that any good smith would know the advantage or .600 in the 458 Lott and use that criteria in chambering.

For more information on the 458 Lott and its history and loading, I suggest one Read "THE 458 LOTT" by G. Sitton, Rifle No. 136, May-June 1991....Very informative. I read it in 1991 and that was my introduction to the Lott and the reason I built my first rifle, and 2nd and 3rd and even a 4th..sold them all eventually....

Lots of recoil was my only complaint with them...and in certain field positions they hammered me a couple of times a little too much...I settled on the 416 and 404 for that reason..a personal choice.

---

Ray, if I may ask, did you mean .600 inch freebore (measured from the olgive of say a 500 grain straight-sided round nose) or .600 inch throat (measured from the rim of the case mouth)?

I want very much to do proper due diligence on this project and make sure my new Lott will readily attain 2350 fps with reasonable pressures and I value your opinion and experience in this matter.

Thanks In Advance,
EKM

Does anyone have a copy of the article that Ray alluded to in post just above?

"THE 458 LOTT" by G. Sitton, Rifle No. 136, May-June 1991

Thanks,
EKM

I know Ray is on his way to Dallas at the moment, hence no reply---

I'd like to see that article also--chris

Elkampmaster, I would like a copy of this article too, if you get hold of it, eould you do me the famour of making a copy for me? Thanks, Bent

For my wildcatting I like to use separate
throater. I throat long so as to seat bullet out for more powder space.Most everything I do is single shot, so mag restrictions don't apply.On my 458HE wildcat,my 510HE wildcat
I throated .800 freebore measured from chamber end.After using chamber reamer,I take throater and from where it starts cutting(up against the
rifling) go in the
length I want.For the Lott .600 is fine.If you want to set bullets way out go .800, like if you were a #1 owner or doing major magazine lenthening on bolt action.Now as to actual
freebore you have when your chambering is done, it still
depends partly on bullet seating debth and shape of the bullet, as well a what you reamed out; IE a long sloping point more freebore than a blunt bullet of same weight, seated the same debth in case..Ed.

Hubel458,

Thanks for your input and specifics (".... measured from the chamber end...."). I've watched you post over the last couple years and I value your opinion.

csutton and just,
If I acquire a copy of the article I will forward it to both of you. Even if it is a paper version I have a flat bed scanner. Thanks for your interest.

EKM

EKM--thanks--I've been searching the net, but have come up empty--may have to call Rifle to see if they have a back issue, as it's not listed on their site--only goes back a couple of years for back issues---chris

I have the article.
Anyone who wants it just send me your snail mail address and I'll send you a copy.
noak@direcway.com

lawndart

sent you an email--chris

JCN,

I'd like the article, too. Sent you an e-mail.

Steve

God bless ya lawndart. I sent you an email with address --- I look forward to the article.

What a great resource AR is!

Thanks

EKM

Bump to top --- Ray A's back!
Check post #7 for the follow up please.
----------------------

Lawndart:
Haven't got the article yet.

EKM

EKm,
Im back from Dallas, the .1000 is what threw me off.....The .600 is a generality and lets just say a half inch of free bore is fine, but the thing I like to do is match the chamber to the max length of the magazine at about .500 or .600, that figure is not critical as long as it serves its purpose of matching everything up...

Getting 2350 FPS is not hard to do in the Lott but it has to be done with IMR-4320 as far as I can tell in my shooting of several lots..I have done a good deal of experimenting with the Lott and have come near 2600 with that powder but things were near sticky at that and I definately got some extractor marks on the case head, but I had one gun that maxed out safely at 87 grs. of IMR-4320, the other three would not come close soooo, one has to realize that guns are individuals or rather barrels vari a great deal....Most lotts settle at around 83 to 85 grs. of IMR-4320 and at 2300 to 2350 FPS in my experience with them....84 grs. has always been my working load with the Lott....

Reaming it out is the easy part. The rails will need to be widened up front and the ramp ground down some. I lucked out with that and the new CZ's look exactly like what I did. If you screw it up there is no going back! Best to get somebody's CZ Lott and copy what CZ did.