Custom reamer for 7 Rem Mag and 195 Berger, any thoughts? 5/28 Chamber drawing added

Jeffrthehunter

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Nov 27, 2016
Messages
149
Location
Portland Oregon
I have chambered two barrels but have never ordered a custom reamer. In the picture I have a dummy round loaded so bearing surface is just forward of neck junction. I want to send this to Dave Manson and have them grind a finish reamer for a .010" jump to a 1.5 degree throat. This will still give me .030" clearance in mag box, this is a hunting rifle. Also looks like the 175-180 grain bullets will still be possible having a jump of .030" to .050" if loaded to neck shoulder junction (I want to have a backup round if the 195 is not shooting). I will be ordering the barrel soon, it will be a Proof Carbon Sendero 26" 1 in 8.2". I have never ordered a custom reamer and just want to make sure I am not overlooking something that will bite me!!!!

Thanks for looking, Jeff

195 Berger.jpg
 

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J E Custom

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Jul 29, 2004
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10,298
Location
Texas
I would recommend talking to Ray At Manson reamers and explain what you want. He will be lots of help and make recommendations for your needs. He will then submit a reamer drawing for your approval. When that happens I will be happy to review the drawing and make any recommendations that are needed if any.

You only have one shot at the reamer and you want it right.

J E CUSTOM
 

Jeffrthehunter

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Joined
Nov 27, 2016
Messages
149
Location
Portland Oregon
I would recommend talking to Ray At Manson reamers and explain what you want. He will be lots of help and make recommendations for your needs. He will then submit a reamer drawing for your approval. When that happens I will be happy to review the drawing and make any recommendations that are needed if any.

You only have one shot at the reamer and you want it right.

J E CUSTOM
Just attached the drawing
 

Canhunter35

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Jun 13, 2017
Messages
2,774
I had a 7rem mag built and throated for the 180eldm, it works pretty well for the 197smk...not sure I’d go quite so deep, I don’t think you will need it for the 195s you will have the case room and pressure out even for a 7rem mag throated for the 180s. I’ve had a lot of fun with mine, it’s a proof 28”. 1:8 twist
E47DA1C5-AC9D-4BD2-B54A-1A4C8912F319.jpeg
 

Jeffrthehunter

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Joined
Nov 27, 2016
Messages
149
Location
Portland Oregon
I had a 7rem mag built and throated for the 180eldm, it works pretty well for the 197smk...not sure I’d go quite so deep, I don’t think you will need it for the 195s you will have the case room and pressure out even for a 7rem mag throated for the 180s. I’ve had a lot of fun with mine, it’s a proof 28”. 1:8 twist View attachment 196670
What velocity are you seeing with the 180? Do you remember what your throat dimension was?
Thanks Jeff
 

Canhunter35

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Jun 13, 2017
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2,774
What velocity are you seeing with the 180? Do you remember what your throat dimension was?
Thanks Jeff
Not sure on throat dimensions, he ran a reamer in and throated it based off my dummy case set at 3.55” length, my dummy case was set at 3.57” but thought I should have a little more room to chase the lands. This is with the 180eldm. I wasn’t able to get that bullet to shoot but it does very well with the 180hybrid at 3050fps and 197smk at 2940fps. I used h1000 with the 180 and with the 197s I switched to retumbo as I pressured out as I was coming into the node with the 197. With retumbo and the based off of sierras load data I’m a whole grain under max pressure and it shoots great.
 

Jeffrthehunter

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Joined
Nov 27, 2016
Messages
149
Location
Portland Oregon
Not sure on throat dimensions, he ran a reamer in and throated it based off my dummy case set at 3.55” length, my dummy case was set at 3.57” but thought I should have a little more room to chase the lands. This is with the 180eldm. I wasn’t able to get that bullet to shoot but it does very well with the 180hybrid at 3050fps and 197smk at 2940fps. I used h1000 with the 180 and with the 197s I switched to retumbo as I pressured out as I was coming into the node with the 197. With retumbo and the based off of sierras load data I’m a whole grain under max pressure and it shoots great.
Wow, that's some great info, I am hoping to get 2900 with the 195's
 

keithcandler

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Jan 30, 2005
Messages
632
Things to remember on reamer design:

A. neck clearance, take into account the skim cut on the neck if you want to clean it up. You want a minimum of .004 clearance in the neck of a loaded round.

B. .240 Freebore is very, very long. There is also another .015 at least that comes off the case mouth on that 45* angle you see. I would not go longer than .190. Stuff the bullet down in the case, and monitor for doughnuts.

C. you say you have .030 Cartridge base to ogive on a new barrel, Length of the cartridge for magazine use. Few hundred rounds and your have zero clearance in your mag box...plan for success, give yourself more clearance. Planning on .030 clearance on a new barrel, is in deed planned failure.

D. .514 dia in front of the Web. Get samples of the brass you plan on using and mic it with a good micrometer, not calipers. Give yourself .003 at a bare minimum, and you may want to buy the set of dies you are planning to use in advance, size some fired brass, and see what dimension the dies size to taking into account the spring back.

E. I like #5 contour barrels, and Brux is at the top of my list. If I were hiking in the Utah mountains, I would either have the #5 fluted or go #4 contour. The less machining on my barrel, the better I like it, chambering and threading the muzzle is all I will tolerate. I expect a custom hunting barrel to shoot at least in the very low 3's, preferably better. 1/2 MOA is border line for me, 1/4-1/3 MOA is acceptable to an old benchrest shooter/hunter, and 5/8 MOA is time to set a barrel back or put on a new tube.

F. 7 Mags have some recoil, you need some weight for controlling recoil.

G. Alex Wheeler on accurateshooter is a darn smart cookie when it comes to building long range deer and elk rifles. He knows his way around long range rifles, and will steer a guy in the right direction, first time!

H. Magazine box OAL will eventually have something to do with your barrel life, so change your expectations, and plan on eventually shooting a single shot.

I. if you want to use the magazine box for all hunting applications, then plan on 600 and MAYBE 800 rounds of useful barrel life. This short barrel life, does not leave much room for load development, thus the shorter freebore becomes more attractive.

In the past, I have gone much tighter dimensions than the ones above, and experience has a $ cost to the learning curve. For instance, .002 clearance on the .514 web dimension...really bad thinking as this was what Target shooters use. I did not check the dimension against the web of the brass nor the dimensions that the brass was sized to. I had to have RCBS make me a small base sizer, and RCBS does not offer this service anymore. Often, the most accurate load that is shooting 1/4 MOA is on the ragged edge of high pressure, plan on success giving yourself some breathing room in the web.
ON a more positive side, I have gone .110 FB using 168g Bergers with no problems, Remington & Win brass, R#22 and R#26, and Retumbo at 3100 in a 26" and one 28" that was 3200.

Two things, I don't like the cost of a carbon fiber barrel, and I do not like the way a reamer pilot rides the tops of the lands of 7mm 5 R rifling. If/when the reamer pilot falls down in the trough between the land tops, this creates reamer chatter. There are ways to "hide" & clean up chatter. Tight fitting reamer pilots can stop this problem, but they also may cause other problems. Many gunsmiths will not chamber a 5 R barrel for this reason....many. This 5R issue is controversial I know, but I don't take a chance. Give me a good 4 or 6 groove barrel any day, personal preference.

Shoot for accuracy in the extreme, don't cut corners, and GRAND success is sure to follow.
 

JLM8401

Active Member
Joined
Apr 28, 2019
Messages
35
Location
SouthAlabama
I always figure the 5R barrel chatter came from the number of Cutting flutes being out of sync with the Number of lands. Basically there will be 1 flute not cutting while the others will. This will alternate as the barrel turns. But it must not be to bad. There are a lot of gun smiths chambering 5R barrels. I learn something everyday!!!
 

keithcandler

Well-Known Member
Joined
Jan 30, 2005
Messages
632
When one does chatter, the chamber is screwed up, then set the barrel back, start over, repair, use another barrel.

I have 5 R barrels and one 3 R barrel made by X caliber in 6mm Dasher 8T.
 

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