Kimber Montana 6.5/300 WSM .300 Neck

[longrangehunter]

So I just got back my rifle from Shilen Rifles yesterday and mounted the scope back on. It has a 25" 4 grove Select Match Ratchet Barrel in a #4 Taper w/ a 1:8 Twist. I should have the barrel broke in this weekend while doing some preliminary load data. I'll post the progress when I have a load developed that works at extreme conditions, and that is super accurate at long range.

When I got It back I realized I should have had it threaded, Duh! Oh well, forgot about that one!

 

[DrMike]

Very neat. It is something like Christmas to have the opportunity to work up a load on a new rifle. Congratulations.

 

[Desert Fox]

Nice rifle LR hunter. She will be a hammer. I presume 140 Berger VLD is in the menu.

 

[SJB358]

Nice rifle! What are you planning on shooting out of it? Scotty

 

[longrangehunter]

I'll start w/ whatever I think will work in the 130-140 gr. bullets, but in the end it will be the gun that decides what I'll shoot. I did purchase a box of the 130 hunting VLD's from Burger, I've had better luck with other bullets, but we'll see...... you never know?

It just has to do three things: shoot were I aim (at 1/2" MOA or less), hold together, and make it thru to its destination! Right? Or did I forget something?

 

[SJB358]

Sounds good to me. I am working with a 264WM right now, with 130gr AB's and Retumbo. Seems like a pretty decent combo. Next up is the 140gr AB or PT! Scotty

 

[JD338]

longrangehunter,

Welcome to the forum.

Nice Kimber! The 6.5 WSM is picking up interest here. Keep us posted with your load development.

JD338

 

[257 Ackley]

That is a beauty...hope to have mine soon :roll:. Mine is coming with a 8.5 twist to handle the longer 130 and 140 grain bullets. Starting with AB's and Sirroccos in 130 and some 140 VLD's.

What powders are you going to use?

 

[Ridge_Runner]

holding togather and berger do not jive, at least from my experience, using 140 gr. 6.5's.
RR

 

[257 Ackley]

holding togather and berger do not jive, at least from my experience, using 140 gr. 6.5's.
RR

Only thing I see those VLD's for is punching paper at long distance . That is why I'm trying both AB's and Sirrocco's to see which hunting bullet it likes best.

 

[SJB358]

holding togather and berger do not jive, at least from my experience, using 140 gr. 6.5's.
RR

That sounds about right RR!

I did buy some Nosler 140gr CC's to try out in the 264. Not sure if I will ever get around to using them, but I will be getting some 140gr AB's or PT's shortly. Can't wait to see how they work out. Scotty

 

[woods]

Couple of questions:

You posted in your thread title ".300 Neck". Is that stamped on the outside of the barrel, did the gunsmith tell you that or is that the dimension you told him to ream it? The reason I ask is that my 2 customs have a .293" and a .296" neck. The .293" neck is pretty tight and I have to outside neck turn my brass down to .013" in order to have the customary neck clearance of .003". If you have a .300" neck then you would have to find thick brass of .0165" in order to have a "custom tight fitting neck" of .003" or you will have a loose fitting neck like a factory reamed gun.

When you say you should have had it "threaded", do you mean for a muzzle brake?

 

[longrangehunter]

Couple of questions:

You posted in your thread title ".300 Neck". Is that stamped on the outside of the barrel, did the gunsmith tell you that or is that the dimension you told him to ream it? The reason I ask is that my 2 customs have a .293" and a .296" neck. The .293" neck is pretty tight and I have to outside neck turn my brass down to .013" in order to have the customary neck clearance of .003". If you have a .300" neck then you would have to find thick brass of .0165" in order to have a "custom tight fitting neck" of .003" or you will have a loose fitting neck like a factory reamed gun.

When you say you should have had it "threaded", do you mean for a muzzle brake?


Yes, yes, and yes, but no.
First off every barrel that's is a Wildcat, and/or a tight neck chamber should have that written on the barrel. Then when it ends up in someone else's hands they don't do something really dumb. That and you wont forget the conversation between yourself and the person who did the chamber work.
Norma's brass is thicker then the Winchester stuff, so that's one of the reason for the .300 neck. The other reason is I only remove enough of the brass to make it uniform, ( clean it up) not ream it down, that and I don't care for spending my time neck turning.
The other reason is the unforeseen chance that sand, dirt, grit, or water that turns to ice in places it shouldn't be?
I have not yet measured a fired Norma case yet, because I haven't had the time too even shoot the dam thing yet (I could be if I wasn't writing this though). But the once fired Winchester case that was sent w/the gun measures .2960"...... which only leaves 0.004". So I don't believe that leaves a lot of slop to align the bullet in the bore.... but then again it's a hunting gun, so I don't get too fussy about it. The Norma brass will be even less, which means it will already be a tight neck.
And Yes, l space out about having the bbl threaded. But for a suppressor, and no I'm not a nut. Once you use one you'll wont believe your "eyes", because you'll still be looking through the scope, and your "ears" will thank you even more. But then again so will your Guide/PH so he can hear the big stuff charging you!

 

[woods]

OK, beginning to understand. So the .300 is stamped on the barrel but a once fired case measures .296". Not wanting to nit-pick but this kind of stuff interests me. Allowing for .002" springback on fresh brass that would put your chamber neck at .298" or so. I know I have a 280AI that Hart did that has .313" stamped on it and once fired is .311"

Several times fired will get to .312" but it will never mic .313", even though I believe the chamber is .313" or very close.

The real question is what is the OD of the neck on a loaded round. If your brass is .014" thick (which is about average IME) then it would be .264"+.014"+.014"=.292" loaded OD. That would leave .006" to .008" clearance around the neck which is just fine. Tight necks are not all they are cracked up to be.

One thing to watch out for is the formation of a do-nut which can be a problem in necked down cases with steep shoulders.

So you're going to put a "can" on it. Yes that does interest me but I thought you needed a permit to use one or is that only in my state? Also does it add much weight to the end of the barrel? Does it suppress recoil also or just noise?

BTW, nice rifle. A Kimber Montana with an aftermarket barrel is a good idea. Controlled round feeding in a light platform.

 

[longrangehunter]

Woody,

Yes .002" is what I use for spring back too, that's why I use a bushing die if possible. But like I said the Norma 300 WSM brass that I have is anywhere from .004-.006 thicker then the Winchester stuff. And I haven't yet had the chance to measure a fired case yet. But if I've done my math correct it should be perfect for what is in my own opinion..... correct?

And yes I use a carbide cutter to remove the donut if there is one when I outside turn the necks.

Speaking of cans..... mine is calling me so I gotta run!

 

[longrangehunter]

OK, beginning to understand. So the .300 is stamped on the barrel but a once fired case measures .296". Not wanting to nit-pick but this kind of stuff interests me. Allowing for .002" springback on fresh brass that would put your chamber neck at .298" or so. I know I have a 280AI that Hart did that has .313" stamped on it and once fired is .311"

Several times fired will get to .312" but it will never mic .313", even though I believe the chamber is .313" or very close.

The real question is what is the OD of the neck on a loaded round. If your brass is .014" thick (which is about average IME) then it would be .264"+.014"+.014"=.292" loaded OD. That would leave .006" to .008" clearance around the neck which is just fine. Tight necks are not all they are cracked up to be.

One thing to watch out for is the formation of a do-nut which can be a problem in necked down cases with steep shoulders.

So you're going to put a "can" on it. Yes that does interest me but I thought you needed a permit to use one or is that only in my state? Also does it add much weight to the end of the barrel? Does it suppress recoil also or just noise?

BTW, nice rifle. A Kimber Montana with an aftermarket barrel is a good idea. Controlled round feeding in a light platform.

So I came across an article I read awhile back about the WSM's, mainly the 7mm/300 WSM at 6mmbr.com

Here's the link:
http://www.6mmbr.com/7mm284.html

But here's the section that had me use a .300 Neck and/or not to need to turn the necks, other then clean them up a little.

Producing Better WSM Ammo
Here are some advanced reloading tips gathered from successful 7mm WSM shooters.

1. Turn the necks, particularly with Winchester brass. This will help with neck-wall uniformity and bullet release. WSM cases need adequate neck clearance in the chamber for bullet release. Total Clearance of .003"-.004" (both sides combined) will probably better than .0015" or less.
2. Make sure you have sufficient clearance between the neck and the side of the chamber. Some guys running with super-tight clearance on the necks had persistent and frustrating accuracy problems and unexplained flyers. Adding neck clearance (by turning the necks) cured the flyers. Three or four thousandths total clearance (sum of both sides) will probably work better than one-thousandth.
3. Proper case-mouth chamfering is very, very important for accuracy and optimal ES and SD. With these long bullets you want the entrance to the case mouth as perfect as possible.
4. Experiment with shooting the VLDs OFF the lands. While the 180gr VLDs, typically, work best seated .010" or more into the lands, some shooters have obtained excellent accuracy jumping their bullets .020" or more. It's worth trying. Very low ES/SD is possible
5. WSM brass really stiffens with time. For best results you may need to adjust neck tension (switch bushings) after a few reloadings. Annealing can also help after four or five reloading cycles.

Any ways, everybody has there ideas and/or opinions of what works. I wasn't comfortable having a hunting rifle that could cause me an issue in the field, only because I have had these issues arise before and it wasn't very pretty having a bolt gun that wouldn't open after a shot.

 

[Desert Fox]

Turn the necks, particularly with Winchester brass. This will help with neck-wall uniformity and bullet release. WSM cases need adequate neck clearance in the chamber for bullet release. Total Clearance of .003"-.004" (both sides combined) will probably better than .0015" or less.

Here's the SAAMI Spec for 7WSM

Neck dia: .321"
Shoulder dia: .538"
Web dia: .555"
Rim dia: .535"
Case length 2.100"

Here's Winchester Brass Measurement (at least what I have on hand)

Neck dia: .310"
Shoulder dia: .530"
Web dia: .549"
Rim dia: .532"
Case length: 2.099"

Neck diameter measurement with loaded round is .312"

Measurement of same brass after one firing (not resized) my rifle has match chamber (what ever that means) no turn neck.

WW Fired case
Neck dia: .312"
Shoulder dia: .537"
Web dia: .553"
Rim dia: .532"
Case length: 2.098"

If my rifle has the SAAMI spec. chamber, then that leaves me with .004" all around the neck chamber clearance.

I found Norma brass, at least in my position, have thinner wall... around .013" on average, but very consistent.

 

[FOTIS]

Another joins the 6.5mm club. :lol:

 

[longrangehunter]

Well my Gun is already being shipped back to Shilen, Inc. I only shot it once to check the head space, chamber length and case dimensions.

I measured the chamber length before I started working on breaking in the barrel, and found the neck was cut too deep! By .0685" over the suggested trim length of a WSM (2.090"), which is why I would suggest to every one to measure their chamber lengths so you're not trimming your cases too short for the chamber of your gun.

Since Shilen doesn't have an actual 6.5/300 WSM reamer, they use a .257 WSM reamer and cut the necks w/ a bushing neck reamer after the chamber is cut, which in the case leaves a margin of error, and was cut too long. So after my call to them, I think they'll be getting one soon from Dave Kiff at Pacific Tool And Gauge.

The SAAMI WSM's should have a max of 2.127", but most would keep that measurement to 2.105"-2.110" chamber length. Which is what I had specified.

Oh well, nothing to report other then a big fat waste of money shipping it back!

 

[SJB358]

Good luck with it LR! Hope they take care of you fast. Scotty