.338 win mag "hot rod"

P

Petey

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Hi everyone, I'm new to this forum and new to shooting. I would like to become a better long range shooter. And I think customizing my Howa M-1500 .338 Win Mag will help with that. When I bought it the 338 Lapuas were out of my price range (still are). However, the two cartridges are very similar and I think I can modify my current rifle to better imitate the performance of a Lapua. First, I plan on loading the Lapua .338 250gr Scenar bullets into the .338 Win Mag cartridges, to get a higher BC. Then get a custom barrel that is basically a .338 Lapua barrel made to fit my receiver. Here's where things get interesting, the Lapua has a max pressure of 60,000 psi while the Win Mag has a max pressure of 64,000 psi. Is there any reason why with the same barrel, same bullets, and a higher pressure I shouldn't be able to outperform far more expensive .338 Lapua Magnum rifles? I could see the case capacity being a problem if you could not get fast enough burning powder. Anyone with more experience have any insight?
 
Pressure over time, there is well over 28gr more powder in a .338 Lapua than a .338 Win Mag. You could go simple .300 Win Mag which will push 208gr amax at 3000 and that will duplicate or beat the .338 Lapua with 250gr bullets.
 
I see from your bio that you like powerful guns and fast cars.

Whether or not you get an answer on this forum -- at least, one from somebody with experience -- depends on what you want to do with the rifle.

This is a benchrest forum. In 1,000 yard benchreast competition, trophies are awarded for the best group and the highest score. Oddly enough, performance that achieves these is what we have experience with. There are no trophies for "most powerful gun," highest bullet BC," "highest pressure achieved," etc.

While match reports are somewhat unreliable as to equipment specifics, they are not all that unreliable. You can assume the competitors have a reason for the chamberings they choose, and you will not find a .338 Win Mag used, even with actions that will take rather more pressure than your Howa. And as far as that goes, you won't find all that many .338s, period.
 
my two cents...

New to shooting...punishing yourself with bigger bullets and more powder is the fastest way to NOT become a better long range shooter. Do not fall for the "bigger bullet more powder will make me a better shooter" myth. I have shot my 300 WM out to a mile and they will stay with the 338 Lapua out to 1500 yards or more with the right load/round. But, even the 300 WM is not good for a new shooter unless you have the right rig to make it shootable. My old 30-416 was supersonic to 2200 yards but it would ruin a new shooter in my opinion (and some old ones). Point is, if you are new to both shooting and long range get something that is easy to load for, and is easy on you then shoot and shoot and shoot some more and you will learn more and flinch less!

If you don't believe me try to learn Latin with a mule kicking you! I promise you will not remember the Latin!:D
 
"perform"

I guess by "perform" I meant having similar velocities, energies, and precision out at range. I don't want this to be just a target gun, I still want it to be an elk gun like it was intended to be. So, power is important. But thanks for all the input. By the way, I put a muzzle break on it and it kicks like an AK.
 
OK, the short answer to your question in No.

Pressure ratings are simply a standard. BTW, if you check European MPA pressure ratings, you might find them reversed for .338 Win Mag and .338 Lapua, I don't know.

Pressure ratings take into consideration the SAAMI (in the States) dimensions of the case and the chamber. That's not the whole story, of course, as both brass and steel expand under firing, so barrel tenon diameter comes into play, as does the robustnes of the locking system.

Short range benchrest uses the .220 Russian case, necked up to 6mm, and blown out. Whatever the rating of the parent .220 case, many run pressures in excess of 70,000 psi. These are in custom chambers, where the chamber is *about* .002 to .003 over the size of the virgin case (all dimensions in inches). The case is .440 in diameter, and used with barrel tenons at least 1.00, usually 1.125. Take the same tenon diameter and use a case with .540 diameter, and a whole different story would emerge.

Think it through. Pressure ratings are primarily to specify the life of the brass case, and moving up, the safety of the whole system. And it is a whole system.

Changing course, The difference between the .338 Lapua and the .338 Win Mag is that you use different powders. The ideal powder for a chambering is one where the case is full of powder, the pressures developed at the peak are safe, and the pressure drops to the level of bullet friction as the bullet exists the barrel. Unobtainable, with the powders we have today, and a reasonable barrel length.

If you could have a powder tailored for you rifle, which would include multiple factors, you might approach the .338 Lapua performance, esp. if it the Lapua had to rely on available powders. But you can't get such a powder.

* * *

No hunting rifle can compete with a full-blown benchrest rifle. Pick one.

* * *
They shoot 1,000 yard benchrest matches in Pella, Iowa. Take a trip down there, watch a match, and talk to people. You will get some opinions regurgitated from the "what some guy said" channel, but you will also get a lot of useful information on long-range accuracy performance, and see what benchrest is about.

FWIW
 
Great Response

Thanks Charles E,
That was exactly the kind of answer I was looking for. So, if there was a powder that burned fast enough and I got a new action, then it would be the same? But if that's the case I might as well buy a whole new rifle. Thanks again for your excellent answer!
 
Petey said:
So, if there was a powder that burned fast enough and I got a new action, then it would be the same?
Click to expand...
Well, yes and no. You need the powder to almost completely burn while the bullet is in the barrel. Otherwise, the energy from the powder just contributes to global warming.

A fast powder, on the other hand, burns too quickly, so the maximum pressure peak occurs with less than a full case of powder. Maximum peak pressure limits the total amount of powder you can have, but says nothing about total energy available from using powders with a different "burn" rate.
In simple terms, a slower powder lets you burn more powder, hence greater total energy. But slower powder is useful only as long as the bullet is still in the barrel when it nears zero pressure -- about 5,000 to 6,000 psi as a practical matter.

BTW, 2,000 psi you originally referred to is nothing. You can get that variance with changing primers, or even with the "same" load. Moreover, 2,000 psi doesn't translate directly into velocity; it depends on where peak pressure occurs.

Finally, highest velocity doesn't translate directly into accuracy.

Take it as an engineering problem, but make sure you get all the variables -- or as many as are known, which likely aren't quite all.
 
I put a lot of this badly, trying to cover too much ground.

If you plot a pressure curve, the area under the curve is what is available to do work.

The axes of the plot are time on the x axis, and pressure on the y axis. The constraint on the x axis is barrel length (when the bullet clears the barrel, pressure rapidly drops to zero). The constraint on the y axis is maximum safe pressure.

OK, the more powder you can burn withing these constraints, the "higher" the performance.

Given gunpowders, the slope of the max pressure curve has a large bearing in this. The faster the slope, the smaller the area under the curve. Powders that have a slower slope have a greater area, constrained by (1) how much you can get in the case, and (2) how much will burn in the barrel length available.

Peak pressure alone is not the interesting phenomena you've taken it for.
 
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