pls help me identify this?

[Stockrex]

I permanently borrowed a barrel from my buddy.

The barrel has the following:

6br norma
272 N\L

S/S
S7
8T

So this is a shilen?

[thomae]

If your buddy reads this forum, you are in trouble!:p

But Seriously, if you can take some photos of the various marks, it will likely help others ID the barrel.

[82boy]

Sounds like one. Is it engraved on the chamber end of the barrel? The s7 Is a "Savage varminter" contour. (This is the main reason I believe it is a Shilen."

[Stockrex]

shhhhhh! don't tell plssssss.
http://imgur.com/0ZncdlW.jpg

here you go, posted the pic.

http://imgur.com/0ZncdlW

[82boy]

Yup that's a Shilen

[Stockrex]

what does
"272 N\L" mean?

[northlander]

The 272 N/L that you are asking about is actually .272NK referring to this chamber having a .272 no turn neck. The (S/S) marking indicates that this barrel is a Stainless Match and not a (SM) Stainless Select Match barrel.

Jim Briggs
NSS

[Stockrex]

Jim et Patrick, Thanks bunch!


One more question:

1. So this chamber spec is good for Lapua brass?

[northlander]

You can measure the OD on some of your loaded brass and see how much clearance you will have in the neck area with your loaded Lapua cases and the .272 chamber neck. I do remember that the older Lapua was a real tight fit in some chambers. Make sure you measure so that you know just what you have for brass expansion.

Jim Briggs
NSS

[82boy]

A .272 neck will be fine, it is a bit on the big side of things. The older gold cardboard box Lapua brass would measure out to .269 to .2695 The newer blue plastic box will measure out to .268. According the Lapua the "Thinner neck is here to stay." generally you want around .002 to .003 neck clearance, for your loaded rounds. Your going to be around .004 with the new brass. Nothing to worry about.

[Stockrex]

I have the new blue box of lapua brass, yeaaaaah.
Thanks again guys!

[barrel-nut]

A .272 neck will be fine, it is a bit on the big side of things. The older gold cardboard box Lapua brass would measure out to .269 to .2695 The newer blue plastic box will measure out to .268. According the Lapua the "Thinner neck is here to stay." generally you want around .002 to .003 neck clearance, for your loaded rounds. Your going to be around .004 with the new brass. Nothing to worry about.

If this should be a new thread, feel free to move it and start one. I would have but my phone app won't allow me to copy 82's quote and then use it to start a new thread. Sorry

I also have new blue box Lapua brass, and a new 6BRX McGowen barrel that I believe has a .272 neck. I have not yet loaded anything, or fired anything in the new barrel. I ordered a set of Whidden full-length bushing dies. My question is what size bushing would be a good starting point? I ordered .269 and .270. Did I mess up?

[82boy]

I also have new blue box Lapua brass, and a new 6BRX McGowen barrel that I believe has a .272 neck. I have not yet loaded anything, or fired anything in the new barrel. I ordered a set of Whidden full-length bushing dies. My question is what size bushing would be a good starting point? I ordered .269 and .270. Did I mess up?

Generally speaking you want about .002 neck tension on a loaded round. With that said you need to measure a loaded round to see for sure. Most times a 6BR with the new blue box Lapua will load out to .268, so with that said an appropriate bushing may be .266. Now when you fire form your new brass and blow the shoulder out, you may see a slight difference in neck thickness, especially is you anneal the brass at some point before or after. Even with that said I would say that with a .269 or .270 bushing you will not have enough neck tension to hold a bullet. You need to know for sure what your chamber neck diameter is, you may want to ask McGowan for the reamer specks.

Too add to this the Blue Box Lapua is just as good if not better than the original gold box Lapua. Don't be ashamed of it. The slightly thinner necks is fine, and from my understanding the original design was to use the specks now being used, Lapua had a control problem in the past causing the thicker necks.

[82boy]

A way to get a rough idea what neck bushings to buy before you load any ammo, is to start out with the thickness of your brass, take that number and multiply it by 2, then add the bullet thickness.

Example if your neck thickness is .014, and your bullet diameter is .243, then subtract .003 from that. The math looks like this.
.014 x 2 = .028 + .243 = .271 Now subtract .003 off from that and get .268

This method is a bit flawed as it is hard to measure exact neck thickness. This figures was taken from a round that loads at .269 to .2695. When I measured the neck thickness with a standard set of calibers I got .014. Now using a ball mic I got a measurement of .0137. The problem is with a ball mic, unless you use one all the time they can be a bit hard to manipulate, and get a true reading. Now if we re-do the match going off the ball mic you get .2704 and you would get .2674 with .003 neck tension. Still a bit off from the original loaded round .002 neck tension figure, but close enough to get you a good start.

[barrel-nut]

Just looked at the McGowen Outlet site and clicked on "reamer specs" for 6BRX. It shows the chamber as being .271, and in the chart it shows "Resize N.D. .268". Also "Basic Brass: Lapua 6MM BR". So I guess I shoulda started with a .268 bushing. And I shoulda checked this chart before ordering. DOH!!! Thanks 82.
Sorry about the hijack!

[Davidw3625]

Seems to me a 272 is set up as a no turn neck...