338-300 Win Mag (338 Patriot)

[Lefty7mmstw]

tag...

sounds interesting... I've got a 300win I may want to do this too eventually...

 

[thesheepdog]

tag...

sounds interesting... I've got a 300win I may want to do this too eventually...

I posted a link for the reamer website. I think Shilen also has this reamer as well.

The guy shooting next to me was using his suppressed 338 Lapua, and I can tell you though my 338 didn't hit the 1 mile plate as hard or fast, mine was A LOT quieter suppressed-very pleasant on recoil and the ears!

 

[thesheepdog]

Here's some pics of the rifle (upgraded)

 

[AZShooter]

Interesting read. I am wondering how much more velocity you can expect with this chambering? Are you going to try hotter loads?

The reason I ask is that I have a long throated 338 RCM in a long action with a 1 in 9 twist 30" barrel that shooting the 300 gr berger target hybrid at 2525 fps. I am using 56 gr of RL-17.

I figure you should be able to get closer to 2700 but who knows?

I realize that you ARE getting some great downrange performance but I wonder what is the true potential might be.

 

[thesheepdog]

Interesting read. I am wondering how much more velocity you can expect with this chambering? Are you going to try hotter loads?

The reason I ask is that I have a long throated 338 RCM in a long action with a 1 in 9 twist 30" barrel that shooting the 300 gr berger target hybrid at 2525 fps. I am using 56 gr of RL-17.

I figure you should be able to get closer to 2700 but who knows?


I realize that you ARE getting some great downrange performance but I wonder what is the true potential might be.

I think the case has 80gr H2O capacity IIRC, so I can definitely put more powder in there. I do plan to do hotter loads down the road eventually. Maybe with some Retumbo. I think getting the velocity a little higher to work in, say 24" barrels would be cool.

2700 with a 285gr would be AWESOME. I built the load data off a 330 Dakota because it had similar case capacity. I need to revisit this.

Have you tried a slower powder for your 338 RCM? I found the slower powders work better for long barrels and heavy projectiles...even in smaller cases. I'm running RL17 for 208gr AMAX in my 308 long throat barrel, 24" at 2600.

I do want to do more prototyping down the road. Hoping some other people get on the 338-300 Win Mag bandwagon and bring even better results to the table.

 

[AZShooter]

No I haven't tried any slower powders and won't bother. The SDs are extremely low and it shoots bugholes. I seriously doubt I can gain over RL-17 which is made for short fat cartridges like the RCM.

That 300 gr bullet is something downrange. Even at the mundane velocities of my rifle or the slightly faster velocities of yours it sure performs. I have often thought that a sporter weight 338 win mag or larger but not as large as a RUM would be a useful hunting rifle.

Now that I am on this thread I will be informed with any new things you do.

Thanks for your efforts.

 

[thesheepdog]

No I haven't tried any slower powders and won't bother. The SDs are extremely low and it shoots bugholes. I seriously doubt I can gain over RL-17 which is made for short fat cartridges like the RCM.

That 300 gr bullet is something downrange. Even at the mundane velocities of my rifle or the slightly faster velocities of yours it sure performs. I have often thought that a sporter weight 338 win mag or larger but not as large as a RUM would be a useful hunting rifle.

Now that I am on this thread I will be informed with any new things you do.

Thanks for your efforts.

RL17 is amazing. It's a miracle powder for heavy bullets.

2500fps with a 300gr is nothing to dismiss. That's what I really wanted to achieve at minimum with my 338 Patriot.

I looked last night at case capacity and the 300 Win has 90gr H2O; the Dakota has 84.6gr H2O; the 340 Weatherby has 98gr.

So this is in between the two.

 

[thesheepdog]

Round 2:

I shot the 338-300 Win out to a mile again, but this time with some cheap 250gr Hornady BTHP'S.

These were clocking 2750-2800 based off my DOPE. At a mile they were subsonic for sure, but they were very accurate. When the wind was being consistent, these were hitting within 12 inches consistently. I got a couple of solid hits but the wind at 17mph gusts and holding 4 mils was really pushing it for these little 250gr bullets.

Next time I'll be using up what 300gr bullets I have left and test them at a mile too.

 

[Timber338]

RL17 is amazing. It's a miracle powder for heavy bullets.

2500fps with a 300gr is nothing to dismiss. That's what I really wanted to achieve at minimum with my 338 Patriot.

I looked last night at case capacity and the 300 Win has 90gr H2O; the Dakota has 84.6gr H2O; the 340 Weatherby has 98gr.

So this is in between the two.

Out of curiousity, where does the 33 Nosler compare with case capacity?

 

[thesheepdog]

Out of curiousity, where does the 33 Nosler compare with case capacity?

It's essentially a 330 Dakota. The 33 Nosler case is 2.460" and the Dakota is 2.540" with exact shoulder and taper dimensions.

Not sure about capacity on the 33 Nosler yet. I'd really like to get a barrel chambered in one if the brass is widely available.

 

[thesheepdog]

I have since broken the 1 mile record with the 338 Patriot and Hornady 250gr HPBTs.
I got a few hits on 1800 yards last weekend.

 

[Wild Monkey]

found some info on this similiar round called: .338 Tora Bora