Gents:
I have been studying the pertinent comments on this super forum and learned a lot-at least to the extent that I can now a lot of stupid/smart questions.I am in the process to "build" a new long range hunting rifle
starting c a stock Rem BDL SS in .300 UMag
slapping on a barrell to shoot straight.

Questions,what is the best configuration for the chamber and throat,slightly "sloppy" to accomodate all ammo or finetuned to turned
privately owned cartridges ,so nobody else can shoot the gun ,including myself when the batch of cartridges is worn out.
Some happy medium must be the answer to this question,so what do the experts recommend
for the chamber and throat to allow more then 1 bullet type.
thank you

sheephunter

Brass lasts longer in a tight chamber, but some degree of sloppyness don�t hurt that bad if you neck size. A case stays straight in a tight chamber when it does not bulge in any direction when fired for the first time. There is always the danger that you will have to get custom dies if standard dies don�t squeese the brass enough (Present smallish problem with my new Lapua and RCBS dies).

The throat should be short enough to let you put the shortest of the preferred bullets into the lands, if the beauty happens to like them that way. FWIW, AKI

If you are going to spend the money on a good barrel and a gunsmith to Thread and chamber it, then believe me you don't want a "sloppy" chamber if you want a gun for serious long range shooting. Big Mistake! Talk to JGS or PPC and find out what reamers they have that their customers are pleased with. Then talk to your gunsmith. Make sure he really knows how to ream a precision chamber and doesn't do this just now and then. A Match chamber ususally isn't a problem if you reload and usually standard reloading dies work just fine. Find someone who does lots of chambering work and whose customers are happy. Pac-Nor for example know what they are doing. I used to check references before I deceided to do this work myself. JGS and PPC ususally will be happy to discuss their standard reamers with you and depending on what bullet or bullets you want to shoot will make a reccomendation. Ask your gunsmith or pay him to use one of their reamers or one with equivalent dimensions. Don't just necessarily settle for whatever he has rattling around in the toolchest. Remember the best barrel in the world with a poor chamber is just an expensive tent peg-Rob

I will now tell you some of the things that I have found to be mostly true after over 20 years of chambering and shooting BR, Target, and hunting rifles and seeing them shot by customers.
From an accuracy standpoint concentricity and alignment are more important than chamber dimensions exclusive of the throat.
If cartridges are not perfectly straight a standard chamber will often shoot better than a tight one also full length sized cartridges will shoot better than neck sized.
Throat diameter is important. Probably more important than length. It is best to throat to accomodate the weight and type of bullet you are likely to be using. For your 300 Win there is no point in throating for 155 Palma bullets since it is unlikely you will use them.
It is no problem to make a 1/2 minute rifle that will accept and fire factory ammunition though it won't fire it into 1/2! When I speak of a 1/2 minute rifle that is one that on any day if the wind isn't blowing you can say "watch this" and be able to shoot a 1/2" group or slightly better. This with suitable ammunition of course.
Short range BR rifles are another thing entirely and though a .250 capable rifle is possible with standard chamber dimension the truth is that a .250" rifle won't win much and to get down to the requisite .150" rifle the minimum neck dimensions and tailored brass are accepted as being necessary. I can't disagree with this.
If you wish to obsess about chamber dimensions to the point that the neck must be .334 and not .336 be willing to pay extra so your gunsmith can rent or buy the reqired reamer. Regards, Bill.

sheephunt

You mentioned a long range hunting rifle and not an all out target rifle.

In my experience if you have a match grade barrel of around number 5 contour chambered in 300 Winchester with say a stanard JGS reamer and that barreled action is correctly bedded and the scope, mounts and loads are OK, you will achieve most of the accuracy potential from that barrel.

In other words if you tested that combination and the rechambered the same barrel with a neck turned chamber and had the action "trued", you would not see a real big improvement.

Mike

A tight neck requireing that the brass be neck turned isn't very practical in a hunting rifle, especially if you run out of ammo or loose the ammo.

A good. straight and coeccentric chamber job is by far more important. One thing you might want to do is load up a couple of dummy rounds of what you plan on shooting and have the barrel throated for that configuration. It's best to use a live pilot throating tool also.

Thanks for all the good advice,
it pretty much reflects my concern that very accurate target ammo might be overly restrictive for hunting conditions,considering availability of ammo.
On the other hand I am willing to see what accuracy one can reasonably achieve at 400+ yards, worth a trial.
It makes a lot of sense that concentricity of the chamber/throat should be as or more important than throat diameter.As I know nothing about techniques ,I have to rely on the gunsmith in that regard.
I finally chose Greg Tannel today ,to do the chambering of the Liljan barrel,mostly because of his good reputation here and elsewhere.Despite all his expertise , I still have to tell him what I want.I get the feeling most good gunsmith BR rifles,and others do hunting rifles maybe implicitly stating that in hunting rifles accuracy isnt that important.I think that is an incorrect attitude.I'd rather go with a BR gunsmith and work with him on whats practical in the bush.
Way I understand Greg he proposes to ream the chamber 0.002" bigger than the loaded
ammo neck,using turned cartridges.
He suggest to turn the necks 0.003" smaller
then loaded diameter,suggesting thats enough
neck tension to keep a hunting bullet seated correctly and riding thru the bush.

Wonder whether anyone has same or different experience.
At this stage I dont know how long the throat will be,sampling bullets that are likely to fit.

again,thanks for all the sharing,this is a fantastic forum
sheephunter

If I read what you posted correctly, you will have a total of .002" diameter (or less) clearance. And you will have to use neck turned brass. The last part I believe you meant to say you would neck size .003" under loaded ammo size for proper bullet tension. I'll agree on the resizing, but not a tight neck in a hunting rifle.

I really see no reason to go to a tight neck and turned brass on a hunting gun. A decent tight SAMMI chamber will shoot very well and allow the use of off the shelf ammunition. Out of a decent aftermarket barrel such as a Lilja, it should easily group under an inch, even with factory ammunition (if there is a factory load the rifle likes, of course).

I personnally feel that at some point, using BR techniques for a hunting rifle reaches a point of diminishing returns. I don't think a deer would notice if the rifle were 1/4 or 3/4 moa capable and I am not a proponent of sgooting past 500 yards and would consider 500 yards to be overly long for most people and most rifles.

That said, I have tinkered, tuned and rebuilt pretty much every rifle I have, excepting a couple of classics that have more value (both price and intrinsic) in original form. I have a fair amount of money in a couple of them. Practicality wasn't an issue. So, good luck and enjoy.

[This message has been edited by Rust (edited 11-14-2001).]

Rust,
thanks for you comments.Thats why I posted the question.The tight neck accepting only turned brass was suggested by the (excellent) gun smith I use.I am new to the accuracy game,but at distance >333 y,every inch multiplies,thats math.I believe I can do without factory ammo,havent bought any in 19years,nevertheless one likes the rounds to load.Some hunters report "sticking"rounds c tight turned necks,other use them.
Maybe we can sample the forum for experiences.
sheephunter

I shot very tight groups at 600 yards using less than optimum chambers in my M1A match rifle. Most gas guns have chambers which, if you push a little, will close the bolt on a no-go guage. In spite of this I've shot plenty of 20 shot groups inside of 10 inches from the prone on a slightly windy day. Lots of bullets that group well at 100 yards are poor performers at longer ranges. Conversely, I've shot ammo that was just OK at 100 yards that flew absolutely wonderfully at 600, 700, 900 and 1,000 yards.
The dispersion factor for bullets is not linear in my experience. Some actually seem to stabilize better after 200-300 yards. The Sierra 190 gr HPBT comes to mind... In my experience the 168gr MK gets worse beyond 600 yards and is abysmal at 1,000. The only way to tell how a given bullet will print at a given range is to shoot it at that range.
As I said, guns with rather sloppy chambers can be capable of extraordinary accuracy!

Jeff, I have noticed the same thing with my M1A. Federals factory 147FMJBT groups about 1moa at 100yds but 8moa at 300yds, go figure.

On the other hand a 180gn Scirocco over 43gns of Varget on a CCI 250 at 2.850" will go under an inch all the way to 900yds with a Leopold 3x9 (2500fps). At 1000 they punch paper sideways though.

I too am contemplating the tight neck chamber and turned cases for a 338/416 Rigby Imp. for a 300gn Sierra MK.

What are the critical steps that asure concentricity I should quiz a gunsmith on to be asured he CAN acomplish this, and what is a tight neck, .001", or .002" etc. larger than the diam. with a seated bullet? Thanks.

Later
Brent