.338 Imperial Magnum Chassis fun project

[Pirate]

Gert, if your project is to build the chassis, why not do that, and drop the off-the-shelf 338WM and shoot it as a 338WM initially?

When the time comes you can rebarrel to ye olde Imperial chambering, but then at least you've got easier-accessable trigger time behind the gun.

I get the idea the Howa's 24" barrel may be too short for than mini cannon cartridge. Rather shoot it as a WM first, stick a nice silencer on the end...

[Gert Odendaal]

Gert, if your project is to build the chassis, why not do that, and drop the off-the-shelf 338WM and shoot it as a 338WM initially?

When the time comes you can rebarrel to ye olde Imperial chambering, but then at least you've got easier-accessable trigger time behind the gun.

I get the idea the Howa's 24" barrel may be too short for than mini cannon cartridge. Rather shoot it as a WM first, stick a nice silencer on the end...

Pirate, thank you kindly for your suggestion, it is much appreciated. I am looking at your suggestion as well, and it surely is making real sense for sure.
Pirate, here is a Long action HOWA chassis that I am sure I can base the 338 Imperial Magnum on it.

I did discuss the conversion from the HOWA .338 WM to the .338 Imperial Magnum in regards to the psi pressure levels. The 404 Jeffery case has one great advantage , the low chamber pressures in the Mauser actions.

Another advantage is the exceptional steel/quality build into the HOWA rifles since it is a Japanese product.

It will handle the .338 Imperial Magnum on every specification.

Here is a photo of the Long action chassis the HOWA company manufacture. I will focus on the butt stock to mill from /cast from an aluminum aircraft grade 30mm /40mm bar stock.

If I can buy a chassis like this in a .338 Win Mag configuration and use the magazine /action part it will be great since I want to cast or mill out the perforated front barrel cover as well.

[Gert Odendaal]

Discussion:
Members on previous discussions it was pointed out that I am wasting my time to even discuss a long range rifle build if I do not first choose the bullet, then I have to choose the type/profile/twist of the barrel in conjunction with the specifications of the bullet I want to use.

I did listen to your members since the long range shooting environment is not an environment I am familiar with at all, hence I prefer hunting methods like a large bore calibers like a 404 Jeffery at short distances like 30 to 80 meters . Making use of walk /stalk /bush-craft skills to get very close tot he game like we hunt on our 1885 Era Black powder hunts.

Here is my choice of bullets:
what is your opinion in regards to the Perigrine Range Masters.
290 GN Perigrine Range Master bullets
BC = 0. 952

Rationale of this bullet choice:

These bullets are available in a practice bullet as well and affordable.
These bullets are design for high velocities at long dictances.
It is always available
The manufacturer really gives excellent after sale service , one to one communication with manufacturers .

I really would like our member`s opinions in this regards.

[Messor]

On the question of bullets, are the BC's of said manufacturer calculated or actually measured?

On the topic of rifle build, one thing I dont have much experience in.

But, what I do have, and seems like the only one here in this thread, is an actual Howa 338 Winmag :)

[Gert Odendaal]

On the question of bullets, are the BC's of said manufacturer calculated or actually measured?

On the topic of rifle build, one thing I dont have much experience in.

But, what I do have, and seems like the only one here in this thread, is an actual Howa 338 Winmag :)

Great Messor , so you are informing me the Howa .338 is for sale???


Some interesting information of the HOWA rifle concepts :
Howa How-To_ Basics of Howa Rifles and Barrel-Swapping Tips « Daily Bulletin.pdf

[Messor]

Gert, what I would do is buy the 338 Howa now and start building the chassis.
Then when completed, I would start shooting it, but having a major BC means nothing if one does not have the skill to use it, and I say this with the utmost respect.
First work on the long range skill part, only then improve on the equip.

Select one of the lighter bullet options first, like the 245 or 260 gr bullets and start shooting long range, they have more than enough BC to reach out far, and they will have much less recoil than that 290gr beast which requires a 1 in 9 twist, something the factory Howa does not have.

Later on you can swop the barrel, the last change to the project.

[Messor]

And no, my 338 is nor for sale, my pig thumper stays with me :)

[Gert Odendaal]

Some feedback members:

I am fortunate to get a milled out version of the MDT chassis `s action/magazine well in a CAD drawing from a person who manufacture the complete HOWA chassis here in SA.

It seems this technical skilled HOWA chassis manufacturer is going to build a .338 Imperial Magnum caliber in his newest version of the MDT Howa Chassis for himself.

I will supply him with all the contacts /details to be able to purchase a complete .338 Imperial Magnum reamer/gauges go/no go , head-stamped .338 Imperial Magnum brass and re-loading dies.

So now I have only the buttstock and front end feature to mill from a solid piece of aluminum or cast it myself..man I like it when a plan comes together..

[Gert Odendaal]

Gert, what I would do is buy the 338 Howa now and start building the chassis.
Then when completed, I would start shooting it, but having a major BC means nothing if one does not have the skill to use it, and I say this with the utmost respect.
First work on the long range skill part, only then improve on the equip.

Select one of the lighter bullet options first, like the 245 or 260 gr bullets and start shooting long range, they have more than enough BC to reach out far, and they will have much less recoil than that 290gr beast which requires a 1 in 9 twist, something the factory Howa does not have.

Later on you can swop the barrel, the last change to the project.

Messor, thank you kindly, your opinion is much appreciated as always.. I absolutely agree with you and Pirate in regards to buying the .338 Howa first...my challenge with this is if I buy a Howa .338 WIN MAG it comes as a complete rifle, while the .338 WM HOWA barreled action only cost R9000 and the complete .338 WM rifle is about R15000, the barrel is great to use directly..the stock is another problem since I pay for an item I am not going to use and I really do not think any hunter will buy a Howa synthetic/plastic stock from me ..so I pay for a component I will only discard ...not expectable to me even if I get R100 for the discarded HOWA stock..This is why I only will buy a .338 Win Mag Howa barreled action for this future project..I have all the time in th eworld to complete this chassis build , so there is no need to get things done as fast as possible..I already made enormous progress by being abled to get hold of the milled action/magazine-well part of the chassis.

Clarification:
.338 Win Mag psi pressures = 64000 psi
404 Jeffery psi = 52339

[Gert Odendaal]

Members I would like a discussion on the following two comparisons: ( no names or calibers:

Bullet diameter	10.72 mm (0.422 in)
Neck diameter	11.48 mm (0.452 in)
Shoulder diameter	13.46 mm (0.530 in)
Base diameter	13.84 mm (0.545 in)
Rim diameter	13.79 mm (0.543 in)
Rim thickness	1.27 mm (0.050 in)
Case length	73.02 mm (2.875 in)
Overall length	89.66 mm (3.530 in)
Case capacity	7.32 cm3 (113.0 gr H2O)
Rifling twist	420 mm (1-16.53 in)
Primer type	Large rifle magnum
Maximum pressure (C.I.P.)	365.00 MPa (52,939 psi

The other one:

Case type	Beltless, rebated, bottleneck
Bullet diameter	.338 in (8.6 mm)
Neck diameter	.371 in (9.4 mm)
Shoulder diameter	.526 in (13.4 mm)
Base diameter	.550 in (14.0 mm)
Rim diameter	.534 in (13.6 mm)
Case length	2.760 in (70.1 mm)
Overall length	3.600 in (91.4 mm)
Case capacity	113 gr H2O (7.3 cm3)
Rifling twist	1-10 in (254 mm)
Primer type	Large rifle magnum
Maximum pressure	65,000

Where and why is there this big difference in psi of these two cartridges?

Please explain thoroughly?

I have a theory but will want your opinions/theories in this regards?? Messor, A-R, Gates414, Driepoot, Gamrfarmer , Pirate, and any member who would be so kind as to take part in this discussion.

Please provide suggestions about measures to be put in place to either :
Increase the lowest case`s psi level to the highest case`s psi OR

De-crease the higher psi to equal the lowest psi pressure of the case .?

What properties will you change to get these two cases to the lowest psi of the two cases in a rifle building project like this .338 Imperial Magnum chassis build ?