.272" neck for 6br?

[Hatrick]

I am having a barrel chambered in 6mm br for my 700 Rem action. I received my Lapua brass the other day, and loaded a dummy round to check some dimensions. The neck measured .266" so I called the smith to see what the neck is on their reamer.
They informed me that their only reamer has a .272" neck dimension, and it would be just fine with my loaded brass. Seems like too much slack in the neck for a custom build, more like one would get from an off the shelf rifle.

What do you guys think? Should I just settle for that .006" neck clearance, or should I try to rent, or purchase a reamer with a tighter neck for the smith to use?

 

[jkohler]

Hatrick,
.272 is what you wanted for the old card bord box brass. With the new brass .270 is the new no turn dimension. That being said I have shot the new brass in my.272 6br and see no difference in how it shoots. The brass will just see more work on the neck when resizing your brass. so it may not last as long as a .270 neck. But in the end its your new rifle and a reamer isn't that much to $ get what you realy want.

 

[Steve Blair]

Hatrick,
.272 is what you wanted for the old card bord box brass. With the new brass .270 is the new no turn dimension. That being said I have shot the new brass in my.272 6br and see no difference in how it shoots. The brass will just see more work on the neck when resizing your brass. so it may not last as long as a .270 neck. But in the end its your new rifle and a reamer isn't that much to $ get what you realy want.

+1 - A new reamer is $138 from PT&G and can be sold after to recoup most of your cost. Even a .269 neck like my Viper SS has would still work with Lapua "blue box" brass. I would not go under .002" clearance, however. My reamer is a .104" freebore and could be just a little longer, although I have no room to complain given the way it shoots Sierra 107s.

 

[fdshuster]

Hatrick: I used my .272" neck PTG 6BR reamer with the older, thicker Lapua brass with neck walls that measure .0135". Since mostly using the "new" Lapua, blue box, with the .0125" neck walls I've had that reamer reground to a .270" chamber neck diameter. Did it make any difference in case life, or anything else? I don't know, too early to tell. I just did not like having a .272" chamber neck with .266" loaded round neck diameter. With those dimensions, we're approaching a standard factory clearance.

 

[k80skeet]

I just had my chamber done .268 neck and it works perfect with the (NEW LAPUA BRASS IN BLUE PLASTIC BOX) Dave Kiff at PT&G can supply with the reamer you need. $138.00

 

[DCRYDER]

my last batch measured .2675" with a loaded round. have they changed it again?

 

[Nodak7mm]

Hatrick,

Bear in mind you really have only 0.003 clearance.

Sounds like this is your first 6BR and I'll assume your not going to shoot BR comp with it, so I suggest chamber it, learn the cartridge, (Youll love it) and have a BLAST.

At this point, you wont see the price of a new ream justified down range... Read FDSchuster's post again (he has the experience to back it up).....

Go forth, shoot it and have a great time... Trust me you will come to love the 6BR.

Rod in Fargo

 

[dreever]

I vote for a new reamer, then it will be exactly what you want. Another plus is that brass fired in that barrel can be used for any subsequent barrel chamberings. This is a plus when you have two rifles chambered with the same reamer.
I run a .269 neck and still found I had to lightly turn the new Lapua blue box brass. Like the others said a .270 would be the new no turn neck dimension.

Danny

 

[jriggs]

i'd leave it be. Jim Borden is building a 6BR for me right now and i'm keeping it at .272 and i'm running the corrected spec blue box Lapua. it's for NRA high power...and will be just fine.

this is what i was taught...so someone please correct me if i'm wrong...tight necks on BR rifles are there to control the expansion of the brass...not neccessarily to control accuracy. although by minimizing the neck stretch they are in fact helping with accuracy because there will be less work to be done to the brass which would make it easier to repeat what you had previously..and consistancy = accuracy.

on a .272 like my high power rifle the couple of thousandths of extra space will not harm accuracy...it'll just mean a little more work on the neck with it comes to resizing...and ultimitely...less life out of the brass.

am i right?

 

[RonAKA]

I've attached the PTG reamer specs for both the old brass and the new.

I've done a bit of research recently trying to understand what happens to brass when it is fired and resized. The conclusion I came to is that with normal neck clearances the brass will never gain enough yield strength so that it stays in the elastic range. By that I mean that the expansion and contraction stress is below the yield, and there is no plastic deformation. The result of this is that the brass will get harder and harder until it is either annealed or breaks (neck split).

That said, if neck clearances were very tight -- say 0.002 max, and you only bushing sized back to the very largest size that still gives you sufficient seating tension, you may be able to get into the elastic range below yield after a few firings. Once you reach that point, any reasonable number of additional firings will not change the strength or hardness of the brass in the neck. The big up side of this is that neck tensions should become very uniform, and there is no real need to anneal.

I recall that one poster here (and I apologize for forgetting who) says they reload up to 40 times or more and never anneal. With a very tight neck, that may very well be possible, and potentially may be the very best way to gain uniform neck tension. To control a neck that tight may require neck turning, or rejection of the oversized necks though.

 

[KevinThomas]

jriggs,

You're completely right. Benchrest is Benchrest and Highpower is Highpower, and there's some definate differences between the two. Tolerances that are good for a benchrest rifle are pure poison for a highpower gun, for a whole host of reasons. Our reloading techniques are different (as they should be) as are our expectations of how ammo should chamber and function. They're very different animals, and they need to be treated as such.

 

[4xforfun]

I hate prepping and FF brass. Will more frequent annealing make the necks last any longer. My new chamber is .272 and I only have 30 rounds down the tube so far. I could always rechamber to a .270 neck if it is the only way to make my brass last.

 

[Hatrick]

Gentlemen, thank you for all the good feed back. I am concerned about brass life, and my experience with some other calibers has been the more size down on the necks, the more chance of run out. Not my first rodeo, but my first 6br for sure, and with the money I am spending I want to do all that I can for a good experience.

I checked with PTG today, and of course they do not have the 270 neck reamer in stock, and it is a 6 week wait to have one made to specs that I want. I think that I may post an ad on the site to buy, borrow, or rent a reamer that I would like to use.
If all else fails I will have a saami spec chamber that will probably shoot just fine.

 

[fdshuster]

Hatrick: Since you mentioned brass life, i will also. With my .272" chamber necks, and the old .0135" neck walled Lapua, I have several boxes of 20 each that have been loaded between 37 and 40 times, depending on which box. I keep a count on number of times reloaded for each group of 20, so I know those are true numbers. My Lapua 220 Russian/ 6ppc old lot of brass has the same number of reloads on them, in fact, the barrel was burned out at 2410 rounds, and the brass is still usable. I do believe that is one advantage of very close (.002"/.003") neck tolerances. I think I got my money's worth out of them.

 

[D.Kiff]

Hatrick, call me I have two 6mm BR Blue box reamers on my desk if you need one. I have not told the sales staff I have them. 138 bucks and out the door. Thanks Dave@PTG 541-826-5808

 

[Hatrick]

Hatrick, call me I have two 6mm BR Blue box reamers on my desk if you need one. I have not told the sales staff I have them. 138 bucks and out the door. Thanks Dave@PTG 541-826-5808

Sir, you just made my evening. ;D I will call you in the morning.

Thanks,
Jeff Y.

 

[jkohler]

hatrick
There is the answer you needed. problem solved

 

[Hatrick]

hatrick
There is the answer you needed. problem solved

No kidding! How cool is that?

 

[Steve Blair]

Very cool and typical of the way Dave does business. Attached is an image of three of my PT&G reamers, .308, .284 and 6BR, top to bottom. The quality is uniformly excellent.

 

[NorCalMikie]

Funny how things turn out when you talk to the right people. 8) And PT&G are the right people. ;D