I would like to learn a little more about bolt thrust and how it applies to common actions.

Here is a note that Rob wrote on another thread:

quote:

416 Tanzan- You should look up the early history of Weatherby who initially chambered 300 wby magnums in M98's of dubious age , lineage and heat treatment. The bolt thrust set the receiver locking lugs back to the point the actions could not be opened.Bad JuJU for old Roy WBY. Headspace issues anyone? Only fix is a new action!

Thus, the Wby multi-locking lug action was born. Many .585 Nyati's made on M98's and even FN Mauser actions did the same thing. Just stick a .500A2 in a Rem 700 and shoot full power loads till she stops opening! I've seen that one before! Every once in a while someone on this board creates a masterpiece on a old Mauser without paying attention to its heat treatment and wahlah a horror story is reborn! RIP feel free to add your experiences too.

Big cases generate a lot of bolt thrust and in general actions designed for 45KPSI just can't handle it. Thats why the CZ550, Montana PH and GMA reign supreme for really Big Bores. We know they can take it within reason.-Rob

First of all, thanks Rob. that helps put a little perspective on the question.

My question is whether a 65kPSI load on a .590" casehead needs more steel lug than a 65kPSI load on a .532" casehead. If so, how much?

What does it take to set-back a bolt in many of our common actions, say a Win M70 or a Ruger M77 or a CZ550?

The Ruger M77 Hawkeye seem pretty solid, though probably not on a par with the CZ, yes? The M77 are at least designed for 416Rem levels (416Ruger).

By comparison, although Tikka makes an accurate, inexpensive small and medium bore rifle, I've never considered it for a build beyond its own 338WM level. While it handles that, it is a lightweight, slick action that probably should not be considered for a Rigby casehead. But how do we know where the lines are drawn or should be drawn?

Or put another way, how hot can a Gibbs case be loaded before a particular action gives out and lengthens the headspace or seizes up?

Hi 416Tanzan, and Robgunbuilder:

This came up on the .510/.505 Gibbs wildcat related thread, now has it's own thread.
Good to have a spot to call its own, this bolt thrust thing.

Rob has added some good history and his practical experiences, I can only add some generalities. I am sure Ed Hubel could add some more.

Pressure against the inside of the cartridge case generates force that thrusts the case rearward against the bolt face in the action.
This is resisted by the locking lugs.
Same pressure in a bigger case generates more thrust against the bolt lugs that prevent rearward movement of the bolt.
Shear strength of the bolt lugs, and the lug recesses, have to be sufficient to prevent failure.

A real mechanical engineer and gunsmith like Rusty McGee might be able to do the measurements and math, not me.

As Rob pointed out, metallurgical properties, heat treat, etc. of the action are involved, besides the physical measurements of the lugs,
and the pressure inside the case head,
and the surface area inside the case.

I thought about doing a sporting .408 Chey-Tac just for kicks.
I read the roll stamping on the CZ 550 Magnum action of my .505 Gibbs.
Stated pressure limit is 3800 bar, 55,100 psi.
The .408 Chey-Tac max pressure is 63,800 psi,
using the same case head as the .505 Gibbs.

Some would guess that the CZ 550 Magnum action is engineered to handle 1.5 times the engineer-lawyer recommended pressure limit.

I have not done all the measurements and math.
But, the area inside the case rear face should be roughly proportional (by pi-are-squared) to the diameters of various cases.

If they are rimless, beltless, non-rebated cases,
like a .505 Gibbs and a .416 Rigby,
that rough comparison may be made based on base diameter just ahead of the extractor groove.

.505 Gibbs: about .640" diameter, area = 0.7854 D^2 = 0.322 Sq.In.
.416 Rigby: about .590" diameter, area = 0.7854 D^2 = 0.273 Sq.In.

Thrust: Pressure x area

Max thrust allowed for CZ .505 Gibbs = 55,100 psi x .322 Sq.In. = 17,742 pounds force

So for a CZ .416 Rigby, max thrust should be same (same locking lugs, same action except bolt face).
Max pressure allowed then would be roughly:
55,100 psi X (.322/.273) = 64,990 psi
rounded to three significant digits = 65,000 psi

So I better keep my .338 Lapua based wildcats down to 65,000 psi even if the brass is spec-ed to 68,000 psi?

And standard .408 Chey-Tac loads are about 8000 psi too hot for a "sporting featherweight" CZ 550 Magnum so chambered?

Yet CZ chambers their 550 Magnum for .338 Lapua Magnum, with a CIP pressure spec of 4700 bar, 68,150 psi?
Close enough to 65,000 psi to be acceptable with a 1.5X safety factor for over-engineering-and-over-lawyering?

I have no idea what the MRC PH action (0.800" or greater bolt diameter?), or GMA Magnum Mauser action with 0.750" bolt diameter, can handle.

CZ 550 Magnum, Ruger M77, Winchester M70, standard Mauser M98: all have similar .700" bolt diameter, and similar locking lugs.
No comment on Remington M700, or Weatherby MkV from me ...

Sumbuddy who know please feel free to point me in the right direction on any of this.

BTW, Rusty McGee has added a "porch" to the front of Hilltop Gun Shop, and a small building for "powder magazine" out beyond the porch.
That ought to keep his powder dry.

quote:

I thought about doing a sporting .408 Chey-Tac just for kicks.
I read the roll stamping on the CZ 550 Magnum action of my .505 Gibbs.
Stated pressure limit is 3800 bar, 55,100 psi.
The .408 Chey-Tac max pressure is 63,800 psi,
using the same case head as the .505 Gibbs.

so the Cheyenne Tactical needs 16% more shear strength than the stamp on your 505.

That stamping may be giving the SAAMI recommendation rather than the CZ550 capability. Still, it is a start for calculations. Rigby caseheads would be good for 65kPSI in a CZ, at least. I would hope that the action/lugs are good over 100kPSI. Proofing houses usually fire something up at 80-90k in typical sporting rifles, don't they?

Anyway, the Rigby calculation above will be nice to know next month when letting off a 2850fps 350gn round under an African sun. There have been no pressure signs before on the brass/primer and I suspect that the the brass/primer is the weak link in the chain, not the bolt lugs. Hopefully.

So where does that leave those with AccRel builds on a Ruger M77?

quote:

CZ 550 Magnum, Ruger M77, Winchester M70, standard Mauser M98: all have similar .700" bolt diameter, and similar locking lugs.

"Similar" can be measured. Shear strength is a function of the area of the lug connection to the bolt and the hardness of the steel. If the Rockwell hardness of the above actions was the same one could measure the length and radial width of the lugs in order to get a comparison.

The CIP pressure standard for the .505 Gibbs is only 2700 bar, 39,150 psi.
There is no SAAMI standard for the .505 Gibbs.
The fact that the pressure limit on the .505 Gibbs CZ action is stated as "3800 bar" suggests that it is a roll stamp placed on the action in Czechoslovakia.

That is a long term "safe" working pressure for the action with the large .505 Gibbs case head.

Proof loads are only about 1.25X cartridge max-average pressure limits.
The max working pressure for a rifle is probably a lot less than what it can do short term, yep,
but how many times could it go +100,000 psi before it started to fail, set back, kaboom?
Brass won't go that high without a kaboom of some sorts.

My feeling is that the Ruger Hawkeye and M77 MkII and RSM,
Winchester M70, or standard Mauser M98 of modern steel, are all just as strong as a CZ.
Ruger is good at heat treating.
No worries for a 500 AccRel, 49-10, or 50-12 aka 500 Mbogo Short.

quote:

Originally posted by 416Tanzan:

quote:

CZ 550 Magnum, Ruger M77, Winchester M70, standard Mauser M98: all have similar .700" bolt diameter, and similar locking lugs.

"Similar" can be measured. Shear strength is a function of the area of the lug connection to the bolt and the hardness of the steel. If the Rockwell hardness of the above actions was the same one could measure the length and radial width of the lugs in order to get a comparison.

That is obvious.
Please do so and report back.
Surely someone has done that before ... search function?

quote:

Originally posted by RIP:

quote:

Originally posted by 416Tanzan:

quote:

CZ 550 Magnum, Ruger M77, Winchester M70, standard Mauser M98: all have similar .700" bolt diameter, and similar locking lugs.

"Similar" can be measured. Shear strength is a function of the area of the lug connection to the bolt and the hardness of the steel. If the Rockwell hardness of the above actions was the same one could measure the length and radial width of the lugs in order to get a comparison.

That is obvious.
Please do so and report back.
Surely someone has done that before ... search function?

I would if I could. I will have no access to any actions except the CZ550 during the next couple of months, and nothing at the moment.

quote:

The max working pressure for a rifle is probably a lot less than what it can do short term, yep,
but how many times could it go +100,000 psi before it started to fail, set back, kaboom?
Brass won't go that high without a kaboom of some sorts.

Well, I don't want it to go over 100k even once. It is just good to know that the action is stronger than tested.

The most obvious to the naked eye is the pressure on the base of case and the shear area of the bolt lugs. It may look simple, but it is far from it.

First lets look at the case, where the inner diameter at critical point is the governning factor. This critical point is located somewhere near the base where the thickness of the brass is able to withstand the the pressure and won't expand enough to adhere to the chamber past this point. If there is any meassurable head space and the pressure is higher than the yield stress of brass case cross section the case will fill the gap (headspace) by stretching. If the pressure is bellow the yield stress of the brass only the primer will move out to fill the gap. The brass Yield tensile strength cross section of the case at this critical point works to the bolt thrust advantage and is taking the load of the bolt itself by the particular ammount of YTS applicable.

The bolt lug calculated shear area is another factor that is not so simple either. If we don't know the exact material but we know the hardness HRC we know what the approximate ultimate strength UTS would be. As a rule of thumb the Yield strength YTS 0.2% is 80% of UTS and using the same rule of thumb the Shear strength is 60% of UTS. We can confidently confirm the load of the firing is dynamic and the rule of thumb is 50% of the Shear stress all in all it is about 30% total of UTS.

This doesn't apply to carburizing steels where the hardness of the surface may be 60HRC and the core 35-45HRC. At any case the where carburizing steel is used only the CORE hardness, strength value is applicable for any calculations.

I've never seen a single bolt where the lugs would shear along the body, but were rather ripped out and the bolt would have a chissel like appearence, just to put an edge to it an use it.

The next to consider is the line of Stress Accumulation, The sharp cornes of the locking lugs, the hight of the lugs, the seats etc. Weatherby 9 lugs design may be the topic of critisism but in reality if everything else is equal it is superior to the two lug bolt . Just like a 32 teeth spline will out do 28-20-10 spline because of the stress accumulation factor.

The set back is the matter of contact area, the supporting backing area and the hardness just like in any mechanical device. As a toomaker I have the skills and the knowledge but I would never reharden any action as the risk of cracking is far above my comfort zone. Let alone not knowing the exact type of steel used.

Receiver and bolt are like any mechanical devices will give way with time. The Mauser 98 was designed for .470" case head and the same size lugs are being used for .590", even .640" case heads the only what is different today is the steel.

In some German manual the carburized steel used in the original 98 Mauser bolt had core of UTS 78 100PSI in the hardened condition, todays action bolts are made between 42-48 HRC and of UTS between 170-210 000PSI. These days even the carburizing special purpose steels used in the motor racing industry can have the surface at 58-60 HRC and the core well over 220 000PSI UTS, what is even more astounding is that the toughness and ductility is better than the gun commonly used 4140-4340 steels. Unfortunately no one is using these super steels in the gun industry.

The CZ or any of todays actions can and will most likely take probably + 120 000PSI BLUE PILLS but the question is for how long. The set back, the stretching the microscopic cracks along the stress lines is not comforting to me, but generally it is fully ignored by everybody.

Tanzan to answer your question the difference is about 20% and that still is within the action safe capability.

Pyzda

FWIW I did BLUE PILL a CZ550 Action when I first developed the .600OK. Three shots were fired with loads that were designed for 85KPSI. The locking lugs on the bolt and receiver surfaces were Miked and showed no differences. I have never tried to go beyond that and as we say that experiment was N=1. I'm not really in the action testing business. The .600OK was designed for 65KPSI maximum to reach its max velocity of 2400fps with a 900 Gr bullet and I felt 85KPSI was adequate. However, as PYZDA has pointed out, the issue is not necessarily peak pressure survival, but rather how long will it survive at high, but less than peak pressures. That actually was a major concern with the CZ550 and the .600OK and since most folks never even get close to its max power level, and we have no known examples of action failures,we can conclude its safe. Luckily, I have seen very few really catastrophic failures of modern actions such as sheared bolt lugs except where people do really stupid things like converting Garands to .300 win mags and M96 Mausers to .375 H&H's. Generally they just push back the receiver lugs till the bolt won't open along with concomitant headspace issues.-Rob

Just got off the phone with Will at MRC. I specifically asked about bolt thrust and action strength with regards to cases such as the 408 and 375 CheyTac. He said they have not yet sent out the PH for destructive testing. He went on to say the PH is significantly stronger than their standard long or short actions and they have been tested to exceed 130KPSI.

How many times do they test fire the action at +130,000 psi?
How do they get the action open after each shot?
How do they get the brass fragments out of the action after each shot?

In his book, "The Bolt Action" Stuart Otteson discusses back thrust in actions. Among the facts he mentions is that back thrust is dependant not on the outside diameter of a case or the base of the case, but on the maximum inside diameter, since that is where the force is being exerted. Therefore, also the head diameter of the .378 Weatherby is .587 and the rim diameter .605, the important dimension is the maximum inside diameter of the case, which is .515, reflecting an area in square inches of .208 and a maximum back thrust of 10,425 pounds.

Otteson also discusses a number of the most popular bolt actions and gives lug shear area, lug bearing area bolt diameter and lug heights on each of the actions discussed.

He remarks, "P.O. Ackley's book "Handbook for Shooters and Reloaders" describes specific tests considering the effects of case design and lubridation, and showing that surprisingly little stress is sometimes transferred to the bolt.

A couple of conclusions can be drawn on locking-lug design, noting, however, that we are not considering a ruptured case head and the effect of uncontained gas. First the cartridge diameter as a factor in chamber pressure. Big cartridges create heavy back thrust. Second, the percentage of this stress transferred to the lugs can vary widely. A dry chamber and case puts less strain on the locking system. So does a minimum body-taper case."

My friend and gunsmith, the late George Fullmer had a policy of hardness testing every Mauser action brought in to him for barrel work. His opinion of wartime produced Mausers was very low on the basis of their inferior heat treatment and hardness. He refused to work on any action which did not meet his exaction standards.

The benefits of a multi-lug system are questionable when one considers the fact that many bolt actions with only two locking-lugs have only one lug contacting. One of the first steps in "blueprinting" and action for benchrest work is assuring that both locking-lugs are contacting their recesses. If it is difficult to insure that two out of two lugs are contacting, how much more difficult is it to insure that all the lugs of a multi lug system, such as the Weatherby, are contacting?

I have experimented with a series of wildcat cartridges, ranging in size from .510 caliber to .416 to .375, all based on the .460 Weatherby case shortened to 2.500". The test vehicle in each case was the P-14 Enfield action. I was able to obtain performance identical to the larger sized British rimmed cases intended for single shots and double rifles with no difficulty and with no signs of excessive pressure using IMR powders.

The same holds true of another experimental cartridge based on the .577 Nitro Express, with the rim removed and an extracting groove cut into the case head. Although it too was reduced in length to 2.500", I had no trouble driving a 750 grain bullet at 2050 fps to duplicate the performance of the .577 NE. Again, the test vehicle was a P-14 Enfield action.

When it comes to figuring bolt thrust, can get accurate enough figure plus up to about 10%,
without sectioning cases to get an inside measure to figure cross section.

First the sides of a case takes some of the thrust and 2nd the base inside is
of course smaller than the outside, which is the easy part to measure.

So a simple formula I use, using the OD of the base(not rim or a belt) is--

Base cross section X peak pressure x 2/3 = bolt thrust in lbs....
Something you can compute in a few seconds..

Examples for 3 sizes of big cases at say 60,000 psi....

The Gibbs cases/Cheytac cases/my 585HE cases, all at the base measure .634" OD.
Cross section is .321 sg in, times 60,000 psi, times 2/3 = 12,800 lbs thrust.

Next major group down Weatherby/Rigby size bases are .582" OD bases.
Cross section is .270 sq in, times 60,000 psi, times 2/3 = 10,800 lbs thrust.

Next is 404 Jeffrey and all the variants based on it with base OD od .543".
Cross section is .235 sq in, times 60,000 psi, times 2/3 = 9,400 lbs thrust.

The reason simple formula is safe is that gun/case designers(including me), try to design in
2.5 to 3 times a safety factor for the operating bolt thrust of the cartridge.
Example is the trusty ole Enfield. With bolt lug cross section of .47 sq in
and metal strength of around 140,000 psi. Engineers for shock loads take the metals strength
and divide it by two, giving 70,000 psi, times .47 sq in = 33,000 lbs shear rating for lugs.
Most other bolt guns are similiar and as long as lugs are not soft they work.
Now in our 12ga FH I put in the Savage 210 3 lug bolt gun, the lug rating was 39,000.
In the Enfields that I put much bigger cases in I added a rear bearing lug using big bolt handle
base to give the Enfield a shear rating of about 53,000 lbs. So that say my 700HE has a
bolt thrust of 20,000 lbs, that gives me over a 2.5 safety factor...Ed

I have to say I would be rather skeptical of a +130K PSI claim without written proof/ certification for the Montana PH action. Did the action open due to the case having VAPORIZED rather than having simply brazed and/or plasma torched itself to the bolt? A catastrophic case failure is real bad JUJU in my opinion.-Rob

Thanks to all y'all.
It is good to review the fundamentals now and then. I will get out both volumes of Otteson, Ackley, and Hatcher too.
The latter two authors are not well indexed, but there are some pearls in all of them.

Seems that most of us mere mortals playing with case heads no bigger than .416 Rigby have nothing to worry about in modern actions.
Especially if our wildcats have little case taper, and the brass and chambers are not lubricated regularly between shots.

I revert to Viking Law of "Bolt Back Thrust": It all depends, there are no absolutes, everything is relative.

I don't think that anybody in todays gun business is game enough to use BLUE PILL loads much above 85000 PSI as a regular proof test to every gun they sell. The main issue is the strength of brass rather than the strength of the action. At this pressure the chance of brass to burst out and destroy the action is very high. Even at the best they would need a mullet to open the action.

The Brits used oiled Blue Pills to deliberately generate more bolt thrust.

The multi lug, multi plane actions such as the Weatherby etc. can be made (lapped) to bear evenly on all lugs, but it takes much more effort and much more time. If one has a CNC or special purpose machinery and the final machining is done after the final heat treatment there is no more BEARING ISSUE.

The other factor is the END OF THE BREECH. Straight face, conned face and the nose three rings of steel face. Which is stronger in the even of catastrophic case head rupture??? In my personal opinion if the case was sitting .08" bellow the face of the barrel and it was closed with three rings of steel I would feel far more comfortable than if the case was above the flat face of the barrel and half of the case left unsupported. But that is just my personal view on the matter.

My logic RATIONALE is and how I look at it is to calculate WHAT MY SMALLEST SAFETY MARGIN FOR THE PARTICULAR ACTION/CASE IS rather than to get over zealous by HOW FAR I CAN PUSH THE MAXIMUM CALCULATED SAFETY LIMIT.

I like to squeeze the last SAFE fps/fp from any cartridge I own. I would like to have 600ok, but somehow the large base of the case is my concern How long the CZ action will last WITH THE 65K PSI MAX. LOADS. As I know myself well enough I know I would push the limit until the 2400fps would be achieved.

I'm sorry Rob, but personally I would like to have 65K PSI 600ok in larger action. For that very reason I won't go to any larger than .460 Wea. on the CZ ACTION.

I know and I've seen tools, machine parts to to exhibit catastrophic failures with force loads far less than the calculated Yield stress with repetitive dynamic use. Same batch of steel same tool part, same heat treatment same load force, same everything and one tool lasts for 20 hours and the next 100 hours. The same can be applied to the guns or any other tool/machine part for that matter.

Pyzda

This is interesting reading. Not being overly technical some of what I say may be at odss with what has been said. Please do not be backward in setting me straight.

I have read an article where the authour set up a barrel- that is no receiver and barrel and a swing firing pin from memory. Cartriges like the 30-30 had the case come flying out of the chamber on firing. Cases with minimal taper tended to stay in the chamber. He did this to show that with no headspace issues there was minimal boltface pressure. I for one still like good strong lock up of the bolt.

I do have a couple of CZ550 and when I compare the lugs with those on the Rem700 the CZ's look smaller. Am I correct in this.

RIP I am new to the forum so pm me if you like but what are your thoughts on the Rem700 and Weatherbys.

The Steyr Prohunter action is suspose to be tested to 130,000psi repeatedly-what ever that is- and still functions.

I know an organisation in Aust. that broke the locking petals-for want of a better discription-off a Blazer R93 in 338 Lapau 1 at a time. With less than half the petals left and the bolt still holding they stopped the testing.

PYZDA- Trust me you will only fire at most 1 or 2 full power .600OK rounds. Your self-preservation instincts will kick in after number 1. Considering .600Ok number 001 has fired over 1000 rds and number two about half that ( No where near full power though) and there are over 200 other ,.600OK's out there, I don't think we have anything to worry about concerning the CZ550.-Rob

Rule 303,
Any further analysis of the Remington 700 and Weatherby Mark V: Above my pay grade.
But I am not worried about any weakness in either of them.
Will leave that to the engineers, machinists, and metallurgical wizards.
Always fascinating to hear from the wizards.

Thanks RIP.

quote:

Originally posted by Robgunbuilder:
PYZDA- Trust me you will only fire at most 1 or 2 full power .600OK rounds. Your self-preservation instincts will kick in after number 1. Considering .600Ok number 001 has fired over 1000 rds and number two about half that ( No where near full power though) and there are over 200 other ,.600OK's out there, I don't think we have anything to worry about concerning the CZ550.-Rob

Rob I trust you 100% what youv'e said. BUT I still have two ace cards in my hand.

The first, I'm not recoil shy and I've yet to discover my recoil tolerance limit, however just like everybody else I'm not recoil immune. It very well may be the 600 OK where I would say enough is enough. I agree 100% that 900gr/190gr/2500fps in 13 pounds rifle can be more than handfull, but this is where I still have my second ace card.

My advantage I have over most people is I do not care about the weight of the rifle and there is nothing else better to take care of the recoil than extra weight. If 13 pounds is too light there is 20-25pounds or more pounds available if it has to be. If the rifle is well balanced I can lift 20 pouds rifle to the shoulder and fire a shot and hit dinner plate at 100 yards in less than one second with iron peep sights.
With age I've become intolerant to noise so bad that even .22 under the roof at range without muffs is irritating. I do not mind the blast of big bore if it is in the open and I like the wind to blow the blast away, but under the roof it is intolerable.

I've been looking to the .700/BMG or even the possibility of the .600/50BMG/3" but how the Gun Laws are going these days I don't know anymore. I had enough of their BRAINY bullshit. I do not want to get something good and few months later some BRAINS decide this is too much of good things and it is banned.

Pyzda

I do have a .700 RLG on the full length BMG case. My version of the .700BMG as well as a .600RLG that I designed maybe 15 years ago.. Your most welcome to try it. The .700RLG will do 3100 fps with a 1000gr bullet in a 18 lb rifle. If that somehow doesn't satisfy you there are 2000 gr boreriders available at much lower velocities though. I absolutely Guarantee you'll achieve your recoil dream level. Its even , built on a Mcmillan repeater action to avoid all Bolt thrust concerns!!!.! Most enjoyable -To watch! You need to take high dose prophylatic Ibuprofen starting two days ahead of the experience.-Rob

"MacMillan repeater action to avoid all Bolt thrust concerns."

Fair enough. But some of us draw the line at what we want to carry for an impala or hartebeest that may be on the menu besides buffalo. All rifles are compromises. At least I'm hearing that Rigby case heads can be taken to 65k PSI in undamaged over the counter actions (RugerM77, Win M70, and CZ550Mag). That gives a hunter alot of actions.

So now another question--
what about a 338 Norma Magnum in a Tikka T-3 action?
In other words can those slick light T-3 actions handle a 65k PSI Rigby casehead?

Tanzan why Tikka T3 action???

You may find the single stack removable magazine is not wide and long enough to accomodate the .338 Norma. The next may be the bolt diameter and the next may be the size of ejection port. Unless you can do the necessary work yourself forget about it.

Rob, thanks for your offer, as I've said I trust you 100% once again the recoil of 1000gr/300+grains/3100fps surely would full fill everybodys recoil dreams. These figures are right up there, where I would like to go. How long is the barrel? However I know nothing about the other whatever , that I suspect may be some kind of pain relief medicine.

Pyzda

quote:

Originally posted by Robgunbuilder:
I do have a .700 RLG on the full length BMG case. My version of the .700BMG as well as a .600RLG that I designed maybe 15 years ago.. Your most welcome to try it. The .700RLG will do 3100 fps with a 1000gr bullet in a 18 lb rifle. If that somehow doesn't satisfy you there are 2000 gr boreriders available at much lower velocities though. I absolutely Guarantee you'll achieve your recoil dream level. Its even , built on a Mcmillan repeater action to avoid all Bolt thrust concerns!!!.! Most enjoyable -To watch! You need to take high dose prophylatic Ibuprofen starting two days ahead of the experience.-Rob

Yes I have had my 416 Rigby CZ550 loaded to just below Weatherby velocities. I have to admitt I like them a little slower. Case are both Hornady and Bertram.

quote:

Tanzan why Tikka T3 action???

Why? Because I have a Tikka in 338WM that has a slightly large chamber (fired cases become .516" above belt). So I can either have two loads for the rifle, new case and fired case, or else re-chamber the rifle into something.

Yes, I've wondered if the magazine could be adopted, though Tikka does offer the WSM chamberings. Even more importantly, the bolt head would need to be opened up.

so maybe it's best to leave the rifle as it is.
It's light and shoots MOA.

Tanz,

I did identify that 4D had a 30/375 Ruger finish chamber reamer and related gauges for rent.

Unfortunately nothing but standard calibers in .338 caliber. So you'd be in for a custom finish chamber reamer should you go in that direction.

Your best bet is to stay with the 338 WinMag and either keep to loadings or buy a resize die that resizes the case at the belt back to factory diameter.

Tanzan how hot are you loads? .516" diameter after firing may be just too hot. Drop 2-3 grains and see what diameter you will end up with.

Pyzda

Pyzda--standard loads by a book are about 100fps slow by the book but still produce 'wide' .516".

Tanzan just before we make final call on the .516" chamber

Personally I would not used my "standart" 100fps bellow the published data load just yet as decisive pressure indicator. Tight barrel, powder lot to lot burning rate variation, case volume variations and also the fact that some barrels never ever achieve the published velocity without excessive pressure. If the fired primers are rounded with no cratering that can be the proof beyond doubt that the chamber is too large.

My advice is if the rifle is new under warranty contact Beretta or whoever is the owner of Tikka and have the barrel replaced for free.

If that can not be done, cut the thread off and rechamber with the correct size reamer

Pyzda

For full power loads using a Rigby case I used to buy .416 Wby cases and turn off the belts. Those cases can take 65kpsi. Happy to make some for anyone who wants them.-Rob