.300 win mag barrel length and twist...

With all the factories producing eld ammunition at very competitive prices, I just can't justify the reloading portion of the long range shooting game. My $800 Tikka is a .5moa rifle, and my $8,000 AI is a .25moa rifle both with Hornady match. It sounds like you made a good choice, and I would suggest sinking some money into classes first. Be sure to post pics when it's all wrapped up.

Why guess ?
The current science is to minimally stabilize the bullet so it maintains tractability and goes nose down as velocity slows and it enters the transonic zone. if you have a good gunsmith who can center the chamber exactly to the bore and bed the rifle so as to maintain exact axial alignment then the bullet will maintain stable flight through transonic deceleration.- if the twist to velocity is just right and you do your marksmanship fundamentals part

Think no more seating off the lands run out control etc. You can shoot really good match ammo tailored to a crappy gun or you can shoot avg factory AMMO in an excellent gun and still get good results.

BTW. If your gunsmith is good ur looking at more like .25moa accuracy. (I can't shoot that well -lol )

If youre not shooting precision to extreme ranges of the cartridge then none of this matters. But it is an addicting skill set to learn w big magnums. Think 2200-2500 yards accuracy

Go to applied ballistics ap and plug in your desired bullet weight and velocity and look for the twist rate that keeps you above 1.3. That's where weird stuff starts to happen.

To learn more. Sign up for a REX Defnese or applied ballistics seminar. Well worth the money saved buying stuff that don't work.

PS Brad Stair (sp?) does excellent work. I have shot his 6.5 Creedmoor consistently to 1 MILE ( yes you read that right -1 mile) And I am a new newbie newbie first time shooting to that distance. Hit within 3 rounds then 3 in a row just to prove it wasn't a fluke. Great Smith avg to below avg shooter

(Me shooter. Not Brad lol)

Docx said:

Why guess ?
The current science is to minimally stabilize the bullet so it maintains tractability and goes nose down as velocity slows and it enters the transonic zone. if you have a good gunsmith who can center the chamber exactly to the bore and bed the rifle so as to maintain exact axial alignment then the bullet will maintain stable flight through transonic deceleration.- if the twist to velocity is just right and you do your marksmanship fundamentals part

Think no more seating off the lands run out control etc. You can shoot really good match ammo tailored to a crappy gun or you can shoot avg factory AMMO in an excellent gun and still get good results.

BTW. If your gunsmith is good ur looking at more like .25moa accuracy. (I can't shoot that well -lol )

If youre not shooting precision to extreme ranges of the cartridge then none of this matters. But it is an addicting skill set to learn w big magnums. Think 2200-2500 yards accuracy

Go to applied ballistics ap and plug in your desired bullet weight and velocity and look for the twist rate that keeps you above 1.3. That's where weird stuff starts to happen.

To learn more. Sign up for a REX Defnese or applied ballistics seminar. Well worth the money saved buying stuff that don't work.

Click to expand...

I thought the new thing was to spin the bullet faster than needed to maximize the bullet's BC potential.

Vandy321 said:

I went ahead and ordered, based on ya'll inputs. Went with 1:9, 26", sendero, .30 cal blank. Next step is to find a quality smith. Planning on an A191 for the chamber. Seems like it would allow me to shoot 215 VLDs as well as just off the shelf 208 ELD-X. I havent gotten into reloading yet, but have a manual on the way, to begin to get familiar, and that's the plan for the future. I'm leaning towards Robert Gradous as I've owned a rifle of his in the past and it was .5moa with factory match ammo, better than I will ever need.

Click to expand...

Great choice.

Let me give you some advice on a smith. I choose the bullet I want to shoot and then I make a dummy round with that bullet at the OAL I want to run it at and then I send that dummy round with the barrel and action to my smith. The best smiths do the chambering in two steps with the throating reamer being used second to match your dummy rounds dimensions. If a smith does not know this process I would not use them. Anybody with a little training can learn to chamber a barrel so beware. Robert Gradous built my 330 Dakota and it is an absolute hammer and he will ask for a dummy round for the build. Robert and Greg at Gre-Tan Rifles are the best in the business.

If you choose to go the reamer route research the A191 reamer first and see what bullet it was designed for before just choosing it. There may be a better choice. If you have a chance call Dave Kiff at Pacific Tool and Gauge and tell him what bullet or bullets you plan to shoot and he will recommend a good reamer. I like minimum spec reamers when going this route - smithing it myself. Most reamers have too much freebore IMO.

I am absolutely not claiming to be an expert, but I remember few years ago to come around an article (by one of ballistics experts) where the author published results and table of extensive testing what is optimal for which caliber. Since one of my rifles is 300WM I remember that optimal was barrel 1:9 and length of 26" to 28". Optimal bullet grain 210. Unfortunately I cannot find it anymore. I as looking for it for awhile because it listed cool tables and graphs to figure out optimal combination for any caliber. Now I am just guessing for my other rifles what is optimum, and painstakingly testing at the range. Just for a kick of it 7mm RM is 1:9.25 and 168 grain.

coyotezapper said:

Great choice.

Let me give you some advice on a smith. I choose the bullet I want to shoot and then I make a dummy round with that bullet at the OAL I want to run it at and then I send that dummy round with the barrel and action to my smith. The best smiths do the chambering in two steps with the throating reamer being used second to match your dummy rounds dimensions. If a smith does not know this process I would not use them. Anybody with a little training can learn to chamber a barrel so beware. Robert Gradous built my 330 Dakota and it is an absolute hammer and he will ask for a dummy round for the build. Robert and Greg at Gre-Tan Rifles are the best in the business.

If you choose to go the reamer route research the A191 reamer first and see what bullet it was designed for before just choosing it. There may be a better choice. If you have a chance call Dave Kiff at Pacific Tool and Gauge and tell him what bullet or bullets you plan to shoot and he will recommend a good reamer. I like minimum spec reamers when going this route - smithing it myself. Most reamers have too much freebore IMO.

Click to expand...

Right now I'm hoping for something to shoot 208gr factory ELD-X, and something I can learn to reload up to 215 bergers with. I'll do some more research, if being able to shoot both decently well will open up tolerances, I'd rather just build it around one specific bullet

DeadmansPoint said:

With all the factories producing eld ammunition at very competitive prices, I just can't justify the reloading portion of the long range shooting game. My $800 Tikka is a .5moa rifle, and my $8,000 AI is a .25moa rifle both with Hornady match. It sounds like you made a good choice, and I would suggest sinking some money into classes first. Be sure to post pics when it's all wrapped up.

Click to expand...

The big question that has to be asked with factory fodder is what are your ES and SDs? I used some Hornady factory match ammo to break in a barrel on my 6.5CM and ran it through my chronograph just to see what the short barrel was capable of and I had ES of 90 fps and it grouped .5" moa. I would much rather sacrifice group size and have a lower ES. Someone may have to shoot quite a bit of factory ammo to find a good long range load but then again I may be wrong as I don't shoot factory ammo that often, actually almost never.

With all the new long range Bullets being made now, I would go with a 1:8 twist and if you're having a carbon barrel made I would go with the 28" just to keep the velocity up with 195 gr and above Bullets! The new Berger EOL shoots great out of the 300 WM above 3,100 fps makes a great long range hunter second only to the big 7 mm's like the 7 STW, 28 Nosler.

1:8 not available in CF from proof, only 1:9, 10, 11 in .30cal

Vandy321 said:

First Post on this forum, happy I found this place, seems like a wealth of info and thanks in advance for the suggestions.

I currently have a 6.5CM barrel being spun up at Proof. I ordered this when I was in Florida with intent on a mix of long range steel and deer, to replace a .308 I'd built.

Now, with Utah hunting on the mind, I've decided to cancel the 6.5 order and Proof is letting me switch my order to a .308 blank that I will have chambered for .300 win mag.

My only experience with .300wm is an old browning A-bolt I grew up shooting, but no clue on optimal barrel length (I know its debatable) and twist rate.

Can someone give me a few suggestions for specs (contour/twist/length)? This rifle will be packed in on hunts and will also spend time plinking steel.

I'm leaving towards 1:9 cut to 26" as a happy medium between weight/length and repeatable accuracy. Shooting for sub .5moa when it's back from the gunsmith.

Will eventually have to hand load to afford to shoot it at the range, but I figure it's cheaper than building both a 6.5CM and a .300wm...I cant afford both.

Click to expand...

1:9 26" should be perfect for 215 Berger Hybrid although they shoot extremely well in a 1:10 especially with a little elevation. The 1:9 would just give you a bit more margin to have them shoot just as well at sea level.

.300 Win Mag
H1000
215 Berger Hybrid OTM
They go together like bread and butter.

Vandy321 said:

Right now I'm hoping for something to shoot 208gr factory ELD-X, and something I can learn to reload up to 215 bergers with. I'll do some more research, if being able to shoot both decently well will open up tolerances, I'd rather just build it around one specific bullet

Click to expand...

If your going to hunt with the 215's do some research on the bullet prep needed for hollow point bullets. The tips need to be uniformed / opened up slightly for consistent performance. Very simple process and helps them open up and are very explosive if that is what you are wanting. The ELD-X performs more like a conventional bullet and is also deadly. Both have their strengths.

Vandy321 said:

First Post on this forum, happy I found this place, seems like a wealth of info and thanks in advance for the suggestions.

I currently have a 6.5CM barrel being spun up at Proof. I ordered this when I was in Florida with intent on a mix of long range steel and deer, to replace a .308 I'd built.

Now, with Utah hunting on the mind, I've decided to cancel the 6.5 order and Proof is letting me switch my order to a .308 blank that I will have chambered for .300 win mag.

My only experience with .300wm is an old browning A-bolt I grew up shooting, but no clue on optimal barrel length (I know its debatable) and twist rate.

Can someone give me a few suggestions for specs (contour/twist/length)? This rifle will be packed in on hunts and will also spend time plinking steel.

I'm leaving towards 1:9 cut to 26" as a happy medium between weight/length and repeatable accuracy. Shooting for sub .5moa when it's back from the gunsmith.

Will eventually have to hand load to afford to shoot it at the range, but I figure it's cheaper than building both a 6.5CM and a .300wm...I cant afford both.

Click to expand...

You need to figure out what bullets you would like to shoot first and then check out what twist rate they recommend. 1 and 10 is a great twist rate for a 300 Win Mag 1 and 9 is for specialty bullets only. A 26 inch custom barrel is nice for long-range shooting. Check-out the Berger 210-VLD and the Hornaday 212-G ELDX heaver bullets hit harder and go faster after 500 yards that the lighter bullets do and they are better to shoot long-range with in the wind.