Underside of the XTR Signature Ring:



This is a great feature: Square recoil stop integral to ring bottom.

The "NUTS" side of the base clamps:

The "WASHERS" side of the base clamps:

Ring insert instructions page 1

Page 2

Six of the 8x40 T-15 screws in each ring top is appealing.
Two of the 10x32 T-20 screws in each ring bottom, with integral ALUMINUM recoil stop ... well ... OK ...
I'll give it a try and see if I can bust'em.



Page 96!

Rip ...

I just noticed that Burris is headquartered in Greeley, Colorado.
This is not good news.
I am suspect of anything coming out of Colorado nowadays.
Potheads.

Rip ...

I checked Burris website; appears they do have steel Weaver/Picatinny bases for the M70 with .33" spacing and the bases will fit the rings noted above that have inserts to accommodate a 25MOA tilt for the scope. So I may have a solution to the range problem on the 375RUM. No such problem for the 458 as it is used for areas where the maximum distance is about 150 yards. I'll see if I can get an e-mail for customer service for Zeiss, seeking cut-away drawings of their scopes insides- or if like the Bozo at Leupold, they are Proprietary property. Ha, see if I buy another Leupold proprietary property scope!!

This is a damned-good project, RIP and Ray B. And, if we can't convince any of the mainstream scope makers to make a model without image-movement, a more robust version of Burris's Posi-Lock, perhaps just with a stout screw surrounded by a helical spring (as per my update), might be the way to go.

Yes!


I've got a set of those on a .416 Rem.Mag. M70 that I was thinking of having re-barreled to .458 WIN with 3.6" mag box.
Good steel.
But they come with 6x48 screws and ought to be changed to 8x40.

https://www.midwayusa.com/prod...icatinny-style-matte

Rip ...

Only one cross-slot on my Burris rear base, maybe an older version?
Same concave upper surface on rear base.
Flat upper surface on front base.

The above are Burris Xtreme Tactical bases with 0.330" hole spacing for rear base as on Winchester M70 Classic Safari Express, .416 Rem.Mag.
Same base works on the Pre-'64 .375 H&H action.

Rip ...

The Burris XTR Signature Rings "Customizable Cant -- 5 to 40 MOA, No Lapping Required":



These fit the Xtreme Tactical bases which also work with Xtreme Tactical rings.
These are the 1-inch rings that are 1.00" height from bottom of ring to centerline of scope,
equivalent to "Medium" height Xtreme Tactical height of 0.5".
The Xtreme-Tactical is also available in 0.25" "Low" height,
but "Medium" is as low as the XTR Signature rings go, in either 30mm diameter or 1-inch diameter scope-tube size.

The 1-4x20mm Nikon above is utilizing the middle of three cross-slots on the front base.
The 5-MOA insert is in the rear ring, and the 0-MOA insert is in the front ring,
and the ring screws are only "fingertip tight" no white knuckle stuff.
No torque is specified on ringtop screws by Burris in the latest instructions,
but the old Xtreme Tactical rings specified 20 inch pounds maximum,
and used same screws in ringtops.

The front base is reversible to eliminate the tiny bit of overhang of the ejection port at front,
but it will not be as good with very short scopes if reversed, since it moves the cross-slots muzzleward at front.
The little bit of Seyfried Schtick over the rear of the ejection port is no problem.
Even Ross Seyfried liked that, in the extreme, on his "Professional's Rifle."

If Leupold QRW rings, or other less wide rings, are used, even a SlugHunter can be mounted with these bases.
Unfortunately, since the Xtreme tactical and XTR Signature rings are so wide, they just barely miss fitting with the SlugHunter.

This is a great set of bases for "Ultima" the Ultimate .458 WIN on an M70 LA with 3.6" mag box length ...
if the 6x48 base screws are replaced with 8x40 screws and J-B Welded.

BTW, the pair of main mounting "Clamp" screws on the bottom of each XTR Signature ring can be torqued to "40-70 inch pounds" according to Burris.
I think 55 inch pounds would be just right.
I won't hurt my hand doing that with a Fat Wrench.

Rip ...

Here comes the saga of a .375 RUM.
It is applicable to THE MISSION in showing what profund effects throat can have,
and incidentally it tells the tale of my first Chimera WinCZechster, a .375 RUM,
sort of a tight-throated converse of the .458 WIN Chimera WinCZechster:


Back in the first two years of this century, when the .375 RUM was young, and so was my gunsmith, before he quit gunsmithing and went to medical school,
I had him cobble together a .375 RUM using a CZ 550 Magnum action, and a take-off Winchester M70 Classic barrel.
He cut off the M70 threads and re-threaded the barrel for the CZ, and chambered it as .375 RUM, and an engraver made the "H&H" disappear, replaced by "RUM."
Cerakote refinished, it looked great.
Barrel ended up 23" long.

I shot a nice, mature, basket-rack, whitetail buck with it, from a tree stand, at 50 yards, with a 300-grain Swift A-Frame.
It did little meat damage. Just blew a hole right through his rib cage.









The CZ 550 Magnum action has a serial number of AHR 50001.
All the action marking is below woodline.
It was rescued from Great Northern Guns, Anchorage, AK in the latter part of last century.

The throat was very tight, as the earliest reamers available for the .375 RUM were sometimes not SAAMI-throated.
Anyway, the 23"-barreled "Custom" .375 RUM gave a muzzle velocity with factory ammo, that was neck&neck with that of my factory M700 LSS with 26" barrel.
The 23" barreled one also pierced a primer or two with the factory ammo, before I realized I needed to handload for the tight throat.
This was my earliest "Chimera WinCZechster,"
Winchester barrel on CZ action, for the .375 RUM (converse of the one with CZ barrel on the Pre-'64 M70 action, for my .458 WIN "Chimera").
That 23" .375 RUM action was later re-barreled to .375/404 JI with a C.I.P. .375 Weatherby throat using a 26" Dan Lilja barrel, and a CZ Kevlar stock, Lapour safety and Timney trigger.

I still have the take-off Winchester barrel that looks like a factory .375 RUM from Winchester.
The "custom" CZ stock is also still in the "parts is parts" state of storage.
I need to dig that barrel out and have another look at it for aulde lang zyne.
The "Triple Magnum" Pachmayr pad would work better for me with a slip-on Galco leather pad covering,
both for LOP and to cover the ugly of that pad.
Maybe it could then be called a "Quadruple Magnum XXXX pad."

The only .375 RUM I have now is a Remington factory M700 LSS. I kept it because it is so accurate, though so was the WinCZechster.
What was wrong with that WinCZechster?

Rip ...

[/QUOTE]

So why did I re-barrel such an accurate rifle as the .375 RUM WinCZechster?
Aside from pressure signs with factory ammo due to the tight throat, which could be handloaded to correct,
it was perfect except it had a tendency to overide the rebated rim in feeding.
I could end up closing the bolt on an empty chamber with a fast reload.
Bummer!
That was in 2001, my first experience with the .375 RUM.
I kept the pushfeed M700 LSS.
What does dependable feeding matter in a rifle like that?
It was THE formative experience in my disdain of rebated rims.
I did not want to bother with that kind of feed job.
The .375/404 Jeffery Improved is a much better design.

Rip ...

What about the fact that a 23"-long Winchester take-off barrel shot faster than a 26" Remington factory barrel?
Both were chambered for .375 RUM and the same factory ammo was used in both, and the ambient temperature was only 5*F different.

23", 65*F: 2798 fps MV average for 13 shots
26", 70*F: 2794 fps MV average for 14 shots

The one extra shot with the 26" made no significant difference in the averages.

But the throat was tighter on the 23" barrel.
This was another formative experience.
It explains why the .458 WIN can be loaded long, with more powder, and beats the .458 Lott with some long and heavy bullets.

This material has been recycled from the .375 RUM thread of Mike McGuire, in order to ring THE MISSION bell.

Rip ...

Did I mention that Bobbarrela will have a Picatinny rail on top?
The stilts on the bottom the rail will be milled to make a recoil stop against the rear of the front receiver ring.
The remainder of those stilts can be milled away artfully, and disappear completely at the rear bridge.
Top of the Picatinny should be only 0.295" above the flats of the CZ action top ...



... just like the height of the Burris Xtreme Tactical 2-piece bases for the Tikka T3X,
which would make a dandy 2-piece base for the CZ:



Rip ...

The Burris Xtreme Tactical M70, 2-piece Picatinny bases also fit the 0.330"-spaced holes on the rear of my Pre-'64 .30-06.
That is where my other set of those went!

Rip ...

Makers of a No.4 sporter contour .458 barrel:

Shilen no, #5 is as low as they go.

McGowen? Surely. They make a No. 4 sporter equivalent for CZ's .458 WIN and .458 Lott, same contour used also on .416 Rigby and .375 H&H.

Pac-Nor? Yes. I have a stainless #4 Pac-Nor on the 19.75"-barreled .458 B&M midget rifle.

Douglas? Probably.

The Prechtl-actioned SIGARMS Magnum Mauser 98, Mauser Banner .450 Dakota uses a 25"-long No. 4 sporter contour for Pete's sake!

Rip ...

https://youtu.be/h27qVNUvaNk
Try this in a 458 WM? Maybe it will need some tinfoil

boom stick,

Thanks for seeing that THE MISSION bell tolled yesterday.
That is all I have to say about shooting foam ear plugs out of a .458 WIN.
Oh, yeah. Tin foil? Do you mean the kind you use to make your hat to shield your brain waves from interference.

Rip ...

Meanwhile back on Memory Lane, GUNS Magazine, January 1968:

And from the July 1968 GUNS Magazine, a joking reference to the .458 WIN as a woodchuck rifle:



Les Bowman was more O'Connor than Keith.

Rip ...

I have tried a few .458-caliber rifles along the route to arriving at selection of the .458 WIN as most perfect.
Some .458-caliber rifle weights are listed here for consideration of where the .458 WIN sorts out.
I have owned a Japanese .460 Wby Mk V Deluxe. It would have been the heaviest (and longest) of all, at 10.5 lbs bare,
but it was traded off and will not be considered here except as overweight baggage limit.

The following are for rifle and scope bases only,
either with the integral bases on some rifles, or,
(for those rifles with no integral bases)
with an addition of 2 ounces as an "equalizer," for a generic, steel, 2-piece, cross-slot-type set of scope bases.
Weights include no ammo, no scope, no scope rings:

0. .460 Wby, Mk V, straight factory of 1984, no iron sights: ................................................................... 10.6250 #

1. .450 Barnes Supreme, Whitworth Mk X, 22" heavy barrel of 0.860" muzzle diam., plus brake, express sights, B&C Carbelite stock: 9.8750 #

2. .450 Dakota, Magnum Mauser 98, 24.5" barrel of 0.670" muzzle diam., Express sights, walnut stock: ... 9.6250 #

3. .458/.338 Lapua Mag, CZ 550 Magnum, 23" barrel of 0.745" muzzle diam., walnut stock, Wisner and NECG sights, walnut stock: .... 9.5000 #

4. .450 NE, Ruger No.1-H SS, re-chambered .458 Lott factory rifle, 24" barrel of 0.810" muzzle diam., laminated wood stock: ...... 9.1875 #

5. .458 WIN, Winchester M70 Super Grade Safari Rifle, 24" barrel of 0.730" muzzle diam., express sights, walnut stock: ........... 9.1250 #

6. .458 WinRuger, Whitworth Mk X, 24" barrel of 0.670" muzzle diam., factory rifle re-chambered, express sights, walnut stock .... 8.6250 #

7. .458 WIN, Ruger M77 Mk II SS, 25" barrel of 0.760" muzzle diam., Wisner and NECG sights, Zytel stock .......................... 8.5625 #

8. .458 WIN, Winchester Pre-'64 M70 action & CZ barrel, 24-7/8" barrel of 0.670" muzzle diam., express sights, synthetic stock ... 8.1250 #

9. .458 Lott, Whitworth Mk X, barreled action re-chambered, 24" barrel of 0.670" muzzle diam., express sights, BrownPre. stock ... 8.0000 #

10. .45-70 Govt, Ruger No.1-S SS, 22" barrel of 0.670" muzzle diameter, laminated stock .......................................... 7.2500 #

11. .458 B&M, Winchester M70 Classic St. Short Action, 19.75" barrel of 0.715" muzzle diameter, NECG sights, synthetic stock ..... 7.1875 #

12. .458 WIN, CZ 550 Magnum, 25" barrel of 0.730" muzzle diameter, no iron sights, B&C Medalist stock ............................ Maybe 8.5 #


That 22"-barreled Ruger No.1-S .45-70 Govt will be an easy conversion to .458 WIN,
just an extractor conversion and re-chamber.
It is bound to be less than 7.25 # after reaming the excess steel out of the breech end of the barrel.
Having 1:20" twist, it would be interesting for cast bullet use, and ought to be adequate for most other bullets.

Rip ...

I recall the shortcomings of the M16 and its chambering quite well. I'm approaching the 50th anniversary of my ride on the big bird that lifted off from Danang air base on December 12, 1968, having completed my 385 days. But enough of that. I got my shipment of berry bullets: cast with full copper coating, 350 grains. I just loaded four of them into WW brass and 50 grains of IMR4198. I don't have any loading data for that light of loads, so I'm guessing as to the load that reduces the velocity to Berry's listed max of 1700 fps. the Speer manual lists a load of about 65 grains as the starting load which yields 2100 fps. So I'll need to set-up the Chrony and see where I'm at on the velocity. seated on the cannelure the OAL is 2.82" so they are considerably shorter than the hunting loads. the other loads I referenced were for the 45-70, which seems to me should be similar since they are both straight walled cases of .45" with bullets seated to about the same length.

quote:

Originally posted by RIP:

That 22"-barreled Ruger No.1-S .45-70 Govt will be an easy conversion to .458 WIN,
just an extractor conversion and re-chamber.
It is bound to be less than 7.25 # after reaming the excess steel out of the breech end of the barrel.
Having 1:20" twist, it would be interesting for cast bullet use, and ought to be adequate for most other bullets.

Rip ...

RIP:

My #1 Rugers in .45-70 have stabilized the 500gr Hornady just fine. The #3 Ruger of my son did just as well. The 600gr Barnes Original shot surprisingly well from my Ruger .45-70 LT at 1900 fps, but the bullet holes at 100 were slightly oblong.

In comparing SPEER's manuals #11 with #12, they mention what I personally discovered in differences of throat length between my first #1 Ruger in .45-70 and my second Ruger in .45-70. The second had a shorter throat (as mentioned in a recent blog). That was one reason, among others, why I had it lengthened by 0.30".

In #11 they crimped into the bottom cannelure of their 400gr allowing 62 grs of RL-7 to be used at an MV of 2178 fps at less than 35,000 cup. In #12 it's mentioned that they crimped into the top (first) cannelure because they had been informed that later #1 Rugers in .45-70 had a shorter throat -- exactly as I had experienced between my first and second. Their max load with the 400gr seated to the top cannelure was only 52 grs of RL-7 @ 1934 fps and 31,000 cup. That's 10 grs less and 244 fps less due to shortening COL from 2.76" to 2.54" !!!

I talked with Allen Jones, the head guy at the time, who said, when asked, "64 grs AA2015 would be fine" in my "new" Ruger with the long throat, under the 400gr Speer. In #12 they were showing a max load of AA2015 @ 56 grs producing 2018 fps @ 35,000 cup, and a COL of 2.54" (as mentioned). My COL for the 405gr Remington was 2.87" in the #1 Ruger LT.

This is brought into the light because the difference between the throat length of my first and second Rugers in .45-70 was only about 1/16" (0.0625") before I had the second extended by 0.30". For Speer it made a difference of 244 fps and nearly 900 ft-lbs. Of course, AA2015 had come along between those two manuals and gave better results than RL-7 anyway.

The point of this is to again stress what this thread is all about anyway -- a longer or shorter throat by just 1/16" can make a huge difference in final results. In my situation, extending the throat by 0.30" turned my 22" Ruger in .45-70 into the equivalent of a 22" .458 WM, and on the heels of a .458 Lott -- so it is proven and stated in my "old" manual on the .45-70. I didn't need the #1 Ruger Tropical in .458 WM to achieve greater ballistics than the #1 in .45-70 LT, but it was done for "health and safety" reasons, as explained in recent blogs. I really preferred the shorter and lighter (by 2 lbs) #1 in .45-70 LT. But, I'm a big fan of the #1 Rugers anyway, so the extra couple of pounds is not really unhandy when the overall length is a mere 40.25". And it holds very steady with the Mag-na-ports and 10.6 lbs (with five cartridges and scope). It's recoil for a similar load in the former .45-70 LT is reduced by about 38%. How about a 500gr at 2251 fps from my current #1 Ruger in .458 producing a recoil of only 52 ft-lbs! A similar load from the .45-70 LT at 2200 fps was about 72 ft-lbs! That's 38% more! I'll take a reduction of 20 ft-lbs recoil at the expense of two extra pounds weight. Hey, I've lost 40 lbs weight since 2013! A mere +/- 2 lbs one way or the other is about what my personal weight fluctuates per week anyway.

Bob

www.bigbores.ca

The 458s ready for the chronograph: 500 grain Nosler Partition; 500 Grain Hornady Soft Point, 350 grain Speer Mag Tip, 405 Grain cast Oregon Trail; 350 Grain Berry Copper enveloped cast; 350 grain Lyman cast. varying loads, so we'll see how they compare with loading manual predictions.

Ray B,

Glad you handled that article by Askins so well.
I cannot resist anything that mentions the .458 WIN, and the date was special.
January 1968 was my first full month as a gun owner, after an X-mas 20G single shot shotgun, from Sears & Roebuck.
I begged for a BB gun for X-mas. Dad and Mom said those were too dangerous, said I might shoot my eye out, so I got a shotgun,
for rabbits and squirrels and such.
That shotgun nicknamed "Sweetie" was the first girl I ever slept with.
Her real name is not revealed, to protect the innocent.

Please do report on any handload results,
for THE MISSION.

Rip ...

Bob,

Thanks for the ".45/70 Long Throat" discussion. Very enlightening.

Yep, there is more than one way to skin a cat, .45/70 LT or .458 WIN on a Ruger No.1.
I will certainly be needing a scope for ballast on a 7.25-pounder.
I will take the quarter rib off and re-install it with J-B Weld before the first shot of .458 WIN.
That short ring spacing is nice for fitting any scope you want on a Ruger No.1.

So, Bob, I am following in your footsteps again, this time with a Ruger No.1,
soon as Bobbarrela Shilen-CZech (her fancy hyphenated name) the .458 WIN has been taken to the dance.

Rip ...

For the mission. Doe killed today with 458. 350 tsx 77.2 gr H4895 3.44oal. 130 yds Nikon slughunter. Home cobbled savage with E R Shaw barrel.

Imgur from a phone. Apologize in advance if to big
JRN

https://imgur.com/a/NqG5AzR

well that didn't work from the phone, lets try again.



posted 05 December 2018 06:05 Hide Post

For the mission. Doe killed today with 458. 350 tsx 77.2 gr H4895 3.44oal. 130 yds Nikon slughunter. Home cobbled savage with E R Shaw barrel.

Imgur from a phone. Apologize in advance if to big
JRN

jrn,

That is a humdinger ringer of THE MISSION bell!
Beautiful!
Buy a buy a donkey!
Ladies and gentlemen, Elvis is in the building!

That is an outstanding rig for an all-around rifle.



FWIW, my starting load with Chimera WinCZechster of 24-7/8" barrel:
350-grain TSX, 3.440" COL, F215 primer, WW brass
H4198 72.0 grains >>> 2516 fps MV

(5-yard chrono was exactly 2500 fps, so,
assuming the Barnes Manual #4 BC for this bullet = 0.272, to correct to MV add 16 fps.
Bob Mitchell, member .458 Only, thinks that BC is too low, however.
I will get a chance to re-check that load in a Shilen barrel of 25" soon.)

What primer and brass case did you use, and how long is that barrel?
Have you chronographed that load with 72.1 grains of H4198?

HBN powder tumbling of that bullet a la David Tubb and Cold Trigger Finger might help it be more HV-like.
For THE MISSION.

Rip ...

If it's not overkill, it's not interesting.

RIP
Hornady brass and Winchester large magnum primer. I used to have comprehensive velocity data but had a catastrophic computer failure and lost same(and can't remember). I will be running them through again and will report back. This load does produce .772" groups in this rifle. I do have more accurate loads for it.

24" barrel. 1 \14 twist.

Additionally, as you can imagine, no appreciable evidence of expansion and you can eat right up to the entry and exit holes. It dropped on the spot dead as a door nail - nary a twitch.

JRN

jrn;
good shot ! Good gun , great load.

With the SlugHunter reticle and the accuracy of that load. It would make a fine outfit for general big game hunting. But it will spoil a guy. You will be able to make shots that smaller guns would shy away from.

CTF,
So true. Earlier I was watching a half racked buck at 230 yds but could never see the body. Would have made an impressive story with the 458. I'm dialed now for a max point blank at approx. 230ish.

Since I have another one that needs to hunt, I will finish our general firearms with a Ruger No. 1 in 458.
JRN