.300 win mag barrel length and twist...

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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.

Explain "specialty only" comment please.
 
I would go with the 1:8 barrel 28" you will have no regrets it will handle the light as well as the heavy bullets, and the extra velocity is nice when you go long range. A good brake and you will be able to shoot all day without a sore shoulder. Keep in mind that the added rifle weight will help with the recoil. I have a tikka t3 with a pac nor ss custom barrel and 28" with 1: 8 and 11 lbs with scope. it is almost 3 shots in the same hole at 100 yds. As technology evolves so will better bullets and heavier wts, and 1:8 or faster will be the norm of the day. Twenty years ago 225 gr. were rare or unheard of.
 
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.
I'm shooting on a Remington 700 platform in .300 win mag. I built it with a 5R 1:10 twist and a magpul LA stock with a detachable mag. I also went with an M-16/Sako extractor and a .250 recoil lug. I've worked up a 165gn Hornady sst. At 500yrds and a fair wind I can cut .750" groups. It's a bit heavy at 11#'s but not all that hard to carry. It's also set up with a 3.5# timney trigger and a brake. Felt recoil is super light, so my follow thru is much better without the muzzle jump. Last Saturday I took a head shot on a Doe at 375ish yards in a cut corn field. The bean field right next to it hasn't been cut yet so it was out of bounds. I just figured on a solid hit or a clean miss cause I didn't want to drag her out of the beans. I hit her right where I was looking just below and behind the ear. I picked out the hair I wanted and sent it. She dropped like a rock! Super cool except for dragging her out. Anyway, this rig took me 3yrs to put together, I'm disabled and moneys tight. But it's been an awesome build for me. Maybe it'll give you some ideas towards what you're looking for. I didn't know it unti after I started, but it's close to the Remington 700 Sendero. Good Hunting
 
Awesome Info and thank you for including reasoning behind your thinking along with the suggestions. I emailed Proof today with my wish-list and asked them for inputs. I'll post what I get in response.

Initially I asked for sendero, 26", 1:9...will be sure to check weight difference between 26 and 28. I'm trying to stay under 10lb with this rifle. I have a TBAC on my wishlist as well, and if I go that route, I think 28" and a TBAC Ultra 7 is pretty dang long
Why wast time and money on a custom build when you can get a Christensen arms rife line fo 1600. I have one and it will shoot .5 mos all the way out to 1000yd . I shoot the ELD-X in 178 gr. at 2978. Most rifles will shoot better than the shooter. I live in the west and hunt deer to Elk with it any where from 200yd to 1000yd. There is no need for any bigger than 180 to hunt or steal with. Optics will make the difference.
 
Building rifles is always a fun time, and they seem to hold value a little better than an off the shelf gun, given, they cost more initially too though.
 
I built and shoot a .308 Norma Magnum (very similar to .300WM) and I went with a 28" Bartlein 1-9 5R Sendero contour. I shoot the 208gr ELD-M with excellent accuracy. I chose the 9 twist over a 10 so I could shoot just about any 200+ grain bullet available. People say too fast twist won't shoot as well, but if you stay to heavy for caliber bullets you won't have a problem. Now with 150-180gr bullets the 1-9 is probably too much, but I believe it's smart to go with if you are building a magnum and intend to use heavy, high BC bullets.

I always say I would rather be a little over stabilized than be under stabilized and have to jump down to a ballistically inferior bullet. You can go too extreme with too fast of a twist and you'll potentially blow up bullets or distort them. A 9 twist in a .300 with heavy bullets is perfectly fine.
 
The best smiths do the chambering in two steps with the throating reamer being used second to match your dummy rounds dimensions.
If you have the reamer with the correct freebore it's best to do it in one shot. Less chance of anything going wrong that is why people send dummy rounds to reamer makers like JGS or Mansons.
Yes throaters done properly are the next best option.
 
If you have the reamer with the correct freebore it's best to do it in one shot. Less chance of anything going wrong that is why people send dummy rounds to reamer makers like JGS or Mansons.
Yes throaters done properly are the next best option.
I agree with L.Sherm. Why do something in two steps when you can do it in one with the same results. There's nothing wrong with throating a chamber longer if you already have a reamer on hand. If you're going to order a reamer though from the ground up, make a few dummy rounds with the bullets you intend to shoot at the O.A.L. you want them at and send them to the reamer maker.
 
I agree with L.Sherm. Why do something in two steps when you can do it in one with the same results. There's nothing wrong with throating a chamber longer if you already have a reamer on hand. If you're going to order a reamer though from the ground up, make a few dummy rounds with the bullets you intend to shoot at the O.A.L. you want them at and send them to the reamer maker.

The smiths listed above don't make those mistakes.

The concept of too fast a twist is a myth.
 
I thought the new thing was to spin the bullet faster than needed to maximize the bullet's BC potential.
It was - but spinning it too fast makes it stay angled nose up as it descends creating an awful angle of attack /yawl that is not aerodynamic so starts to tumble. What you want is a "gracefully thrown football" remember how the perfect spiral noses down as it heads into the receivers arms. But bullets are not football shaped - yet. And yes it is the newer science in extr long range shooting
 
I would steer clear of SAAMI reamers and order a 'A191' reamer.
You will thank me later, trust me.
As to barrel length and twist, I prefer 26"-28" with a 1-10" twist. I shoot 230's in 28/30/32" 1:10" twist barrels every other week with ZERO issues regarding twist rate.
Sure, a 1:9" twist will give some margin for error, but a 1:10" twist IS actually fast already in 30 cal.

Cheers.
:)
OK, ya really got me wondering, what is the diff. between the sami reamer and the A191?? Thanks in advance.
 
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