neck clearance

[Luckus]

What is considered perfect neck clearance in a match rifle?

[1jonzmith]

No exact number that I know of. min 2 thou and best at 2 to 4 thou. research the carteideg you want to shoot and the barrel you will use and "do what they did".

I can tell you that a "NO TURN NECK" is the very best way to go. Your asking the question indicates you are not in the Bench Shooter class that would get any benefit from playing with neck thickness and clearance.....1 MOA.

Use NORMA brass or you will be fighting brass that has uneven neck thickness that might cost you .5 MOA. Lapua is as good. Price the stuff and make a choice and never deviate.

HTH,

John

[Luckus]

I'm having a 6 Dasher barrel installed on my 12 FTR. My Lapua brass with bullet seated is .266-.267, Smith miked his reamer at .272. I am sure it will be accurate, just curious as to what you guys thought.

[Grit #1]

.001 for 30 cal. & 6mm .002 for 7mm Don't ask me why .002 for 7mm it just works better for it.
Best regards,
Grit

[82boy]

.002 is mimum, if you go thicker you will get flyers. (.002 to .003 is ideal.)
On a 6PPC Top Match BR shooters (Jack Neary for one.) and myself agree "thin to win," is the way to go. I cut my PPC brass to .0083 giving me .0166 thickness add the .243 bullet gives a .2596 loaded round used in a .262 chamber giving about 2 1/2 thousands clearence. Some shooters will go .0089 giving a bit over 1 1/2 thousands, that is just too tight for me. (I also find that these guys guns are a bit finicky.)

[1jonzmith]

I'll take Patrick's word on almost all of this. I read 2 to 4 thou clearance on the neck and I'll stand corrected if Patrick says .002 to .003 is the range. And thanks for the info.

Patrick,

A neck can be reamed out after the chamber is cut. Were I to say cut a chamber with .002 thou could I re cut the neck to 2.5 and then 3? How would you arrive at the optimum neck size? Seems like you go till you start loosing and then you would back up a single notch....?

Thanks,


John

[Luckus]

I will be picking up my rifle on Friday. I have to form cases and then work up loads, i'll keep you posted on its performance. Im not a benchrester just a F class shooter.

[82boy]

Patrick,
A neck can be reamed out after the chamber is cut. Were I to say cut a chamber with .002 thou could I re cut the neck to 2.5 and then 3? How would you arrive at the optimum neck size? Seems like you go till you start loosing and then you would back up a single notch....?
Thanks,
John


I dont understand what you asking. I would never fit a chamber to the brass, it is just a whole buch easier to fit the brass to the chamber. A chamber is a delicate thing, the less tooling involved the better I would say.

If you got a 22 br with a .250 neck, then make your loaded round measure at .248 or less. (I cut my brass to .0115, and it gives me a .247 loaded round. (I tried a .249 cut once, and the gun shot like crap most frustrating thing ever you would shoot 3 shots in the same hole the next one would go an inch or two out, and the fourth would go right back in the first hole, and it would do this at random.)

People put too much importance on tight chambers. I run a .262 neck PPC one because that is the reamer I have access to, and two it is monky see monky do, that is what everyone else is doing, it is easier to follow suite.(If that make sence., it is more of a confidence thing, when your dealing with wining and loosing by thousands of an inch, you do about anything.) In my long range stuff I use standard chambers, I honestly dont see where a tight neck benifits.

[Luckus]

In my instance of approx .006-.007 clearance, would jamming bullets be better. I will try both ways, but is against the lands or jammed a little generally helpfull in this situation?

[82boy]

In my instance of approx .006-.007 clearance, would jamming bullets be better. I will try both ways, but is against the lands or jammed a little generally helpfull in this situation?


No.
Find the seating depth that work the best. With .006 or .007 clearence you will be fine, you just want more than .002. In my long range guns I run about the same, and they shoot lights out.

[MrMajestic]

Im not a benchrester just a F class shooter.


A belly bencher! Good luck with the build!

[1jonzmith]

?Patrick,

I must not have been clear. "I don't understand what you asking. I would never fit a chamber to
the brass," ?? I am not interested in turning necks to pick up the .001 group sizes you refer to. I,
therefore, specify "no turn neck" to the reamer maker. I send a loaded(?) round, without the
prime or powder, to the reamer maker...Pacific Tool and Gauge..... and they make the reamer,
dimensionally, to the brass I will be using loaded with the bullet I will be using and the free-bore
is determined by the bullet profile. My reamer is built to my commercial NORMA
brass...exactly. I am not smart enuf to have figured all this out on my own. I went with what the
smart and experienced people, such as yourself, suggested.

It was suggested to me by a Bench Shooter that I chamber for a light 6mm bullet. The theory was
that as I shoot more rounds the lands will retreat and I can regain accuracy by going to a heavier,
longer, bullet to allow the seating "into" the lands. PT&G suggested that I could ream the lands
further out if I decided I wanted to shoot longer bullets at a later date. Your comment "A
chamber is a delicate thing, the less tooling involved the better I would say." is unequivocally
true. I pay a handsome price to people that make the tooling I use....I pay a handsome wage to
the proven professionals that do my work....and, I listen hard and long to what these people are
telling me. You are one. But that does not mean that I correctly heard what I was told or
understood what I read. I am making statements that might sound unequivocal but look at them as questions. If you disagree with any of ths info I was given I hope you will share that with all of us.

Do you still stand by your unqualified comment? A lot of guys will be doing all of this, given
PT&G's 6-8 week backlog, and discussion will benefit all.

Thanks,

John

[1jonzmith]

I'm having a 6 Dasher barrel installed on my 12 FTR. My Lapua brass with bullet seated is .266-.267, Smith miked his reamer at .272. I am sure it will be accurate, just curious as to what you guys thought.


Are you saying you have 5 to 6 thousandths neck clearance? I think that is a lot. From what Patrick said that much clearance will lead to "flyers"...if I understood him correctly. I don't think I fully understood you the first time I read your question.

John

[Luckus]

I guess the proof will be in the results. I feel better with 82boys reply. I think range time may be more important than neck clearance.

[82boy]

Are you saying you have 5 to 6 thousandths neck clearance? I think that is a lot. From what Patrick said that much clearance will lead to "flyers"...if I understood him correctly. John


No, it is just the opsite. You can have all the clearence in the world, and the gun will shoot great, the only thing is with big chambers you will work the brass more.

Now if you DONT HAVE ENOUGH clearence, this will cause flyers. You need a mimum of .002 clearence, and less (Ie .001 or .0005) will couse havock and flyers.

[82boy]

I am not interested in turning necks to pick up the .001 group sizes you refer to. John


Turning necks has nothing to do with shooting small groups. You may want to re-read my post.



People put too much importance on tight chambers. I run a .262 neck PPC one because that is the reamer I have access to, ... In my long range stuff I use standard chambers, I honestly dont see where a tight neck benifits.

and


With .006 or .007 clearence you will be fine, you just want more than .002. In my long range guns I run about the same, and they shoot lights out.




It was suggested to me by a Bench Shooter that I chamber for a light 6mm bullet. The theory was
that as I shoot more rounds the lands will retreat and I can regain accuracy by going to a heavier,
longer, bullet to allow the seating "into" the lands. PT&G suggested that I could ream the lands
further out if I decided I wanted to shoot longer bullets at a later date. John


I would not recamend this, have the barrel chambered for what you intend to shot in it. Start out right and have the barrel chambered for what its intended use is. If you going to shoot light bullets then have it chambered for light bullets, (And use a slower twist barrel) if you plan on shooting heavier bullets have it chambered for such. If you going to have a fast twist barrel to stabilize the heavier bullets, it would be a bad idea to chamber it for a light bullet. Just have it chambered for the right bullet for the twist, and you can still shoot light bullets out of a longer chamber. Yes the lands will retreat, but why were out a barrels, and fire crack the barrel worse by doing this is beyond me, and I doubt the lands would retreat enough to change the chamber specks that much. Here is a better idea if you must have this barrel chambered for light bullets, then you deside latter you want something longer in the future, get a barrel with a thick enough profile that you can cut the chamber off, and re-chamber it to the longer bullet.

[1jonzmith]

Here is a better idea if you must have this barrel chambered for light bullets, then you deside latter you want something longer in the future, get a barrel with a thick enough profile that you can cut the chamber off, and re-chamber it to the longer bullet.


That is solid advice. I have done that. My Smith told me he could re-chamber/set back the chamber/move out the free-bore at a later date.

Thanks,

John