Gunsmithing .260 match reamer question

[wb00757]

Hey,
I chambered a brux barrel in 2016 with a .260rem floating pilot match reamer. This was my 5th chamber but first "match". The project got set aside until today when I finally got some brass. My issue is that with 140gr noslers at an OAL of 2.70" I'm right on the lands.
I feel like these should be seated much longer or I am going to be compressing my loads with that much of the bullet in the case. Are match reamers meant to be followed with a throating reamer so you can get everything "just right"?

Here is the print of the reamer I used.

Thank you!!!

 

[Mordamer]

Post a picture of a loaded round. Which 140 nosler? They make a few different 140 grain bullets. That sounds pretty short for a .260. Your reamer print looks good to me and if you are running a short action I would not run a throating reamer at all. I suspect your measurement to the lands might be wrong. How did you find the lands?

 

[Supersubes]

Agreed, the print looks good. About ideal for a long nosed bullet like the Berger 140 hybrid or similar.


Edit: That is a seriously tight neck. Don’t forget to neck turn your brass.

 

[Deleted member 10043]

http://www.snipershide.com/shooting/threads/140gr-nosler-custom-comp.6893508/#post-7127291

 

[wb00757]

Here is one that has been pushed about .005" into the lands next to a bullet for reference. They are Nosler Custom competition 140gr. Its several years old, I just have a lot of it That I shoot in my 6.5x55.

 

[Supersubes]

You’re fine. Just work up charges normally. If you ever decide to use a newer bullet, you’ll be just about ideal.

 

[wb00757]

I found the lands by sizing a case and loading a bullet long and trying it, then seating it another couple of thou until the bolt would finally lock up with practically no force. I use sharpie on the bullet when I start getting close and can see when it is in contact with the lands from the marks they leave. I am using full length sized 7mm-08 brass (chambers easily by its self) that I have neck turned. I have cleaned the chamber and bore very thoroughly to eliminate any chance of debris.

 

[wb00757]

Thank you Supersubes!
It makes my life easier not having to mess with this. It just was freaking me out a little since I am used to having to seat really long to get to the lands in my .300wm and 6.5x55. I try to be very cautious since I do all of my own work and know what can happen if I don't get something right.

 

[Supersubes]

My personal reamer is .080 freebore. With a 140 hybrid loaded to touching, it’s 2.97 if I recall. Much too long for an AICS magazine (I use AW mags) without significant jump.

 

[Mordamer]

Your loaded round looks exactly how I would expect for a freebore of that length. I think you picked a good reamer and you are good to go. Shoot up those garbage bullets. Haha. Some of the new 140 class bullets are around a .650 G1 B.C. and you should be able to load them mag length with good results.

 

[Rubicon Precision]

Out of curiosity, what is your loaded neck diameter? Did you spec .297/.291 neck on your reamer?

 

[wb00757]

.2915/.2895 is what I am reading on this resized Hornady 7mm-08 brass. I did not spec anything on this reamer, I just decided click "match" when I ordered it elk ridge. I didnt know quite as much back when I did this barrel (aside from how to properly setup and indicate a barrel for lathe work).

 

[Rubicon Precision]

That chamber neck diameter scares me. Also, I look at your FB as .048. I have 2 popular 260 reamers. One is .2975 neck/.060 freebore and the other is .298 neck/.090 freebore (I have a brand new JGS carbide reamer for sale in this spec, if anyone is interested). The .298 neck will run any brass. The .090 FB works good with the 140s in the longer mags. The .060 gives room to chase the throat as it moves.
My personal opinion is that reamer is too small all over, if not dangerous in the neck.

 

[wb00757]

Thanks Rubicon. I'll cast the chamber as soon as I get a chance and see what actual neck dimensions are. What would a good neck dimension be on my loaded cases with my .297/.291? Looking at other reamer prints I don't understand why there is so much taper on the neck of this one.

 

[Rubicon Precision]

Thanks Rubicon. I'll cast the chamber as soon as I get a chance and see what actual neck dimensions are. What would a good neck dimension be on my loaded cases with my .297/.291? Looking at other reamer prints I don't understand why there is so much taper on the neck of this one.

I couldn't answer that. I have not seen a neck with that much taper. I am sure there was a reason for it, and maybe it was a common thing, I just haven't seen it. What I do see is the dimensions are all small, so you could run a more common reamer in it and not need to neck turn and get the freebore lengthened, if you chose.

 

[Edds]

There is a misprint on the reamer spec sheet. The numbers, length and diameter, don't compute.

 

[wb00757]

So I (poorly) slugged the neck area today and the dimensions came out .293/.2925. It some dirty, pure lead so the results weren't great...

 

[wb00757]

Thank you everybody for the input. I carefully worked up to 44gr of H4350 without pressure signs with a 140gr BTHP. I guessed at a good load of 42.6gr amd ran it out to 600yds. I think I can improve the load when I get out my chrono, but this is looking promising!