New Barrel, .300 WM or .300 PRC

[Overkill338]

I've been talking to Mcgowen about rebarreling my Ruger M77 MkII. I went through the barrel builder, and a Sendero contour, 28" 1:8 will be $350. I have a couple questions.

One, I have all this .300 Win Mag brass. What kind of performance could I get out of the Win Mag with 4 extra inches of barrel? Is the Sendero contour the best compromise between full heavy barrel and a hunting barrel? I loved my Sendero SF-II.

....or

Since I'm going to this trouble, should I step it up to a .300 PRC, or to .338 Win Mag (I do miss my .33)? Are Mcgowen's accurate generally ?

Hornady 4DOF says a 220 ELD-X is over 3 inches flatter at 500 yards, with 2850 for a 24" vs 2975 for a 28". I've read the .300 Win Mag picks up about 30 fps per inch. Decisions decisions. I've even considered a 28" .375 Ruger. The .375 bullets are starting to gain popularity and recognition, and the .30/.33 Nosler isn't out of the picture yet.

Any help, insight, critique, or criticism is welcome. Thanks guys.

 

[WildRose]

I've been talking to Mcgowen about rebarreling my Ruger M77 MkII. I went through the barrel builder, and a Sendero contour, 28" 1:8 will be $350. I have a couple questions.

One, I have all this .300 Win Mag brass. What kind of performance could I get out of the Win Mag with 4 extra inches of barrel? Is the Sendero contour the best compromise between full heavy barrel and a hunting barrel? I loved my Sendero SF-II.

....or

Since I'm going to this trouble, should I step it up to a .300 PRC, or to .338 Win Mag (I do miss my .33)? Are Mcgowen's accurate generally ?

Hornady 4DOF says a 220 ELD-X is over 3 inches flatter at 500 yards, with 2850 for a 24" vs 2975 for a 28". I've read the .300 Win Mag picks up about 30 fps per inch. Decisions decisions. I've even considered a 28" .375 Ruger. The .375 bullets are starting to gain popularity and recognition, and the .30/.33 Nosler isn't out of the picture yet.

Any help, insight, critique, or criticism is welcome. Thanks guys.

You'd certainly be money ahead sticking with the 300wm since you already have the dies, components, experience etc.

Performance wise you'd not gain anything with the .300prc.

You definitely would not be gaining performance wise with the .338wm.

The .375 Ruger is one of my all time favorites but it is not intended to be a long range round.

I've toyed with taking one of my 300's and rebarreling with a 28" in .375 Ruger just to see how much I could extend it's range.

I've shot it quite a bit to 400yds and a litttle on to 500yds with very good results out of my custom but haven't pushed it any further.

It is absolutely a monster killer within that 500yd range though.

 

[Bravo 4]

You'd certainly be money ahead sticking with the 300wm since you already have the dies, components, experience etc.

Performance wise you'd not gain anything with the .300prc.

You definitely would not be gaining performance wise with the .338wm.

What he said. The .375 may be fun with some of the higher BC bullets (as too would the .338 WM), but would probably be about equivalent to a .308 Winchester shooting the high BC heavies (with a lot more oomph upon arrival). Personally I would stick to the .300 WinMag unless I wanted to step it up a notch, then I'd go with one of the .338's on a RUM case or maybe .300 RUM.
Big questions I would ask myself is
1. Distance
2. Intended purpose
3. Economics...well, sometimes

 

[johnnyk]

I would, and did, stay with the .300WinMag with 28" barrel. I recently (Mar '19) rebarreled mine with a Pac-Nor, 28", 9t, Varmint Contour and it is a LR hammer. I ran a Ryan Mantha finishing reamer through it after I got it from PN and it loves the 215gn Bergers and allows me to seat them out to just over 3.7". It is a single shot but with that payload you'll seldom need a follow up.
I ran out of the Bergers and have a few boxes of the 212gn ELD-X and the numbers (ES/SD) are 12/6.3 w/velocity averaging 3076fps (using RL26 and BR2's).


Here's a 1009yd group from yesterday, temp here was 50* with 4-4.5mph NNW wind. That's a 3" sticker.
This rifle was good before with factory barrel but with the Pac-Nor, RM reamer combo it is absolutely amazing! (I know PN recently had a fire but their website says they expect to be back up soon)

 

[Overkill338]

I would, and did, stay with the .300WinMag with 28" barrel. I recently (Mar '19) rebarreled mine with a Pac-Nor, 28", 9t, Varmint Contour and it is a LR hammer. I ran a Ryan Mantha finishing reamer through it after I got it from PN and it loves the 215gn Bergers and allows me to seat them out to just over 3.7". It is a single shot but with that payload you'll seldom need a follow up.
I ran out of the Bergers and have a few boxes of the 212gn ELD-X and the numbers (ES/SD) are 12/6.3 w/velocity averaging 3076fps (using RL26 and BR2's).
View attachment 161930

Here's a 1009yd group from yesterday, temp here was 50* with 4-4.5mph NNW wind. That's a 3" sticker.
This rifle was good before with factory barrel but with the Pac-Nor, RM reamer combo it is absolutely amazing! (I know PN recently had a fire but their website says they expect to be back up soon)

That is impressive! Also exactly what I wanted to hear! That is mooooving for a 212!

Do you pay any attention to the barrel length when you're carrying it?

 

[Overkill338]

What he said. The .375 may be fun with some of the higher BC bullets (as too would the .338 WM), but would probably be about equivalent to a .308 Winchester shooting the high BC heavies (with a lot more oomph upon arrival). Personally I would stick to the .300 WinMag unless I wanted to step it up a notch, then I'd go with one of the .338's on a RUM case or maybe .300 RUM.
Big questions I would ask myself is
1. Distance
2. Intended purpose
3. Economics...well, sometimes

The RUM wont work because of the action length.

 

[Bravo 4]

The RUM wont work because of the action length.

Sure it will, just not what you may consider ideal as you are probably looking at a single shot and/or maybe pulling the bolt on a live round. I have a buddy with a .338 Edge built on a short action Savage.
Whether you think you can, or think you can't- you're right!
Seen that Henry Ford saying in another member's posts.

 

[elkaholic]

Have you considered the 30 Sherman Magnum? You can shoot 300 prc ammo very accurately and then reload with the 30 SM dies. I run the 230's at 3050' out of a 28" barrel.
shermanwildcatcartridges.com

 

[johnnyk]

That is impressive! Also exactly what I wanted to hear! That is mooooving for a 212!

Do you pay any attention to the barrel length when you're carrying it?

Yes, that's definitely faster than the books say a WinMag will send these 200+gn bullets. The reamer that I used creates a little bit of freebore and let's me seat the bullets out farther so that the COAL is longer than SAAMI specs., giving the .300WinMag more "head room", as I've heard it referred to. Nothing new really. Guess I have a .300WinMag Creedmoor.
With this set up, pressures are lower allowing one to add more powder to reach already established pressure limits. I'm using 75.0gn of RL26 and primers aren't cratering.
Last summer, with the factory barrel, I took it up to 77gn's and that was tooo much. I'm obviously still here but my ejector didn't make it. My velocity with these loads was 3125fps and I was using Hornady brass in a SAAMI chamber. That little test toa$ted the barrel and the bra$$!
I bought the rifle lightly used in August 2008 and will say that barrel was "long in the tooth". I'm guessing close to 1200 rounds when it gave up the ghost.
I worked up this current load using Norma brass and would like to keep it around for more than two firings, hence my conservative load.

I don't have a problem with the 28" barrel. I make allowances for it, you know? I mean I have one 30" Lilja barrel and several 26" barrels, all varmint contour (or heavier). When I do hold a rifle with a 22" barrel, I think toy or BB gun.

 

[WildRose]

What he said. The .375 may be fun with some of the higher BC bullets (as too would the .338 WM), but would probably be about equivalent to a .308 Winchester shooting the high BC heavies (with a lot more oomph upon arrival). Personally I would stick to the .300 WinMag unless I wanted to step it up a notch, then I'd go with one of the .338's on a RUM case or maybe .300 RUM.
Big questions I would ask myself is
1. Distance
2. Intended purpose
3. Economics...well, sometimes

I"m averaging about 2850 with the LRX and VLR4's so the potential is there but it's never going to be a thousand yard hunting round with so many flatter shooting rounds available.

If I have a particularly good year though I've got a stainless Model 70 CRF I bought for a donor and I may just have to do the 28" version just for fun.

 

[Bravo 4]

Yep, you can "make" just about any cartridge that will launch a bullet with a decent BC at moderate velocity into a somewhat long range killer. Just takes a little more on the shooters end to get it done proper.

 

[Tiny Tim]

I agree with others recommendation to stick with the 300 WM. With the added barrel length and some of the "hotter" powders, results can be most impressive. But if something different is seducing you, the Sherman mag certainly is tempting.

 

[yorke-1]

One thing to consider is that the M77 has a very short magazine (3.400") that's not easily lengthened. A SAAMI spec PRC or a Win Mag loafed with high BC Bullets will likely have to be a single shot.

A different idea would be to go with a WSM. Using it in a long action would allow you to use any bullet you want and have it throated however you want. A WSM loaded to 3.200" gives up very little to a Win Mag/PRC loaded to 3.400".

As far as McGowen barrels go, I've had a bunch of them and they always shoot well. Most have landed somewhere around .3 MOA.

 

[Rum Man]

I dont have any experience with either cartridge but I sure do with the McGowen Barrel's

!! They shoot amazing ! One of my 338 Edges wears one of there barrels it shoots lights out . It's a Remington Sendero contour and 30 " on a Lawton action. It's almost a hole in hole rifle !

My good friend just built a Remington 375 Ultra on there barrel also its 30" too.
He is still get things finnished up on it .
Great guys to work with !
Best of luck in your choice !

Rum Man