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13-04-2021, 12:38 #31
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Re: .338 Imperial Magnum Chassis fun project
The specifics would really depend a lot on your purpose with the rifle, your experience and skill levels and lastly your taste and your budget.
So, if you are going to enter it in the King of 2 Miles match, then there will be certain requirements. If you want to pop a few baboons off a cliff across the valley, then the requirements may differ.
My choice would be:
Barrel: 1:9,5" twist. This allows you to stabilize the longest and most slippery bullets, especially the better mono-copper bullets. Over-stabilization is an old wives tale IMHO. But choose the bullet first, then see what barrel specs you need.
Action: I have a dislike for the Rem 700 action. I know the 'Muricans just love it, but that's their problem. It can be made to work, but I would prefer a stronger action. Most of these are custom made, but maybe you can find a shot-out Sako TRG or similar big action for a decent price. Even a good P14 might do the trick. This is not a project to build on a normal action. You want strength (to keep the pressure in) and rigidity to keep the heavy barrel from bending the action. The Howa action has an open top and will not carry a heavy, long barrel without flexing. For a cheap action, the old RSA may be a viable option. Not sure how well it will hold the extra bolt trust of such a big case. A Brno ZKK602 or CZ550 Magnum might do the job. The breech face is the right size already and the tread is slightly thicker (I think?). You will have to mount it properly in order to not flex it with a long, heavy barrel, as the action top is open as well. Another option to consider is a Weatherby MkV action. Most were made by Howa, they are pretty strong as required for the 460Wby and 378Wby mags. With the typical barrel-eating calibers they come out with, there should be many shot-out Weatherbys sitting somewhere. Just the action top is open as well, so flex may be an issue and needs to be prevented. Choices, choices.
Bullet: Long and heavy with a high BC. I would aim towards the better lathe-turned bullets, as these can be made in some slippery shapes that a die just can't swage a copper tube into. So see what is available. Fortunately we have a variety of local makers who can produce these, and they compare to the best in the world. Do some proper research, as the bullet is actually the primary component that everything should be built around. You want the bullet to do a certain job on a certain target way out there. The rest of the parts should all work their magic to get the bullet there. Then choose the barrel, as you said. A higher BC gives you more legs than an extra few grains of powder or extra fps down there at distances over 1000m.
Powder: In the old days, I would use the Somchem powder performance as a guideline to choose a caliber/load combo, since that was what was available. This has changed. Almost anything can be had now, or maybe not. Powder availability is problematic. If you find what you need, make a plan and reserve enough of it to last you about the lifetime of the barrel.
Scope: There are many available and only your budget will limit you. I would like something like a Vortex Razor or better, with "christmas tree" reticule and locking turrets calibrated in milliradians. Also consider the base angle, fixed or adjustable, or maybe a Charlie TARAC or similar device for when your turret runs against the stop, but your bullet has not.
Other considerations: Stock design to fit the primary purpose. Bipod? Muzzle brake, supressor or both? I like a fixed brake (not a break!) with external thread that I can screw a supressor over when desired.
Sub-caliber practise rifle. Shooting at long range requires lots of practice. This burns money quite fast. A lot of the long-range skills can be learned on a much cheaper (per shot) rifle. So do consider building a similar practise rifle in a smaller caliber for developing your skills.
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13-04-2021, 13:40 #32
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Re: .338 Imperial Magnum Chassis fun project
A-R thank you kindly it is much appreciated, you really add a lot of knowledge to this thread . Yes, I need to find the bullet first.
Question: Will it be possible to work with a system like Perigrine bullets where they offer you the choice of a very high BC in a paper/steel /varmint premiun grade bullet and a copy of that same bullet about 6grains heavier for practice shooting?
..I really think that is my answer..keep in mind..this rifle will be a fun shooting rifle...I will use it at our club shooting days for fellow members to shoot with it as well out to 600meters ..that is the long range we have .
Action: RSA action will not work..there is not enough thread to fit a long heavy barrel at all, it is 26 years old technology..so I will not consider the RSA action at all.
Remington action : a lot of long range rifles has been build on it...I just need to find a complete rifle or barrel action to apply for a license for it making the paper work easy.
Howa .338 barreled action is still the top contender. Financially and license wise.
The Sako TRG will be a brilliant option if I can find a complete rifle standing in someone`s rifle safe that he do not need it or use it at all.
Telescope : I already have a first focal plain/red dot illumination 5-25 x 50 rifle scope to fit .( will use it since I bought it for such a project)
The powder now I am looking at is the S12.7 or the old MR5 ( Sonchem powder manufactred for the 505 Browing machine gun..it is really cheap and a lot of product is still available..R300 a tin of S12.7 /MR5 ..really affordable .
The high grade Aluminum chassis is what this whole project is based on..that is what I want to mill from a bar stock of Aluminum.
As you pointed out..there are a lot of choices and options to make it a great fun project.
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13-04-2021, 17:33 #33
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- Apr 2019
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Re: .338 Imperial Magnum Chassis fun project
"Action: RSA action will not work..there is not enough thread to fit a long heavy barrel at all, it is 26 years old technology..so I will not consider the RSA action at all."
Not quite sure why you think that. Bisley and F-class shooters have been mounting heavy palma profile barrels of 30+ inches for decades with no problem. Seems to me the only stronger commercial actions that I have seen is the Tikka T3, Ruger and Barnard-P.
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13-04-2021, 21:14 #34
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Re: .338 Imperial Magnum Chassis fun project
Look Gert, I don't want to dampen your enthusiasm, but 600m is still 308 Winchester territory. What you are building should have 1600m abilities at least. The cost per shot does not justify such short range shooting, unless what you are shooting there requires a big and heavy bullet. Steel and paper does not. Do build it alright, but start looking for a 1 mile range somewhere on a farm. All it needs is a proper koppie or mountain as a backstop.
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13-04-2021, 21:22 #35
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Re: .338 Imperial Magnum Chassis fun project
I have seen a 338LM built on an RSA action. It seemed to last and that was when the SABS still proof-tested rifles. The threaded section is longer than on most sporting actions, just the diameter is not known to me, but I suspect the thread to be similar to a Mauser 98. I have seen 416 Rigbys built on a K98 action. The RSA would need less of the bottom recoil lug recess cut away as feeding from a mag is not all that important. Action stiffness is better than most and lock time is pretty decent too. You would have to open the loading/ejection port a little for the fatter cartridge.
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13-04-2021, 21:57 #36
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Re: .338 Imperial Magnum Chassis fun project
Janfred, what is your opinion in regards to the Howa .338 Win Mag barreled action as a long range fun shooting platform>??? The OAL =84.5 the .338 Imperial Magnum is 91mm.
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14-04-2021, 09:22 #37
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Re: .338 Imperial Magnum Chassis fun project
I do not have nearly as much experience with rifle building as you. The closest I ever got to a Howa was at the gunshop and the range. Also never seen a .338 Howa except in photos.
That said, I have doubts that the action would work well with a long heavy barrel if you free-float it. The open top of the action make it great for easy loading and ejecting, but you also lose a lot of strength (rigidity). You would need to see it in your hands.
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14-04-2021, 13:05 #38
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Re: .338 Imperial Magnum Chassis fun project
Jan, I agree...I will see if it will be a aluminum pillar block bedding, or a full epoxy bedding or a free float bedding...only if I have the donor action /barreled action in my hands. My first priority is to mill the butt stock from solid high grade aluminum sheet 30mm thick..incorporate the weights in the design as well..the weights will be fitted in the butt stock , at the belly of the forearm and in the chassis .
I am currently still working on what action I am in need of and where to source it...so far the .338 Howa barreled action is available at a good price as a donor component.
If there are a member who wants to buy a .338 cal barrel, it will be a good option to buy the Howa .338Win Mag Barrel from me since I will only use the Howa action if I choose the Howa route..I will be fitting my own Brux barrel or the Bartlein barrel.
It might be just a bargain to buy the Howa barrel since it will be around R4500 for the barrel if we share the cost of the Howa .338 Win Mag barrel...it depends on what I will be able to purchase the Howa .338 Win Mag barreled action for .
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14-04-2021, 13:19 #39
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Re: .338 Imperial Magnum Chassis fun project
I got a quote on the .338 Win Mag barreled action = R9000
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14-04-2021, 17:35 #40
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Re: .338 Imperial Magnum Chassis fun project
ARI agree, this will be a long range shooting rifle ...it will be able to shoot out to 2000 meters for sure...the fact is this rifle will be shooting steel plates the whole day long , it will do so much, much better than I ever will be able to do..so I do not question the capabilities or performance of this .338 Imperial Magnum build on the aluminum chassis ..only the shooter behind the rifle..that will be me ...
I will shoot it as far out as possible , as far out as what the bullet can travel..or at least I will try do so it...I know the rifle will do it for sure..
I am sure other shooters shooting with it will be shooting it quite well...as long as I have fun with it and I learn some long distance shooting techniques the whole project will be worthwhile ...
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