Questions about reamers

[odoylerules]

Hey guys, I have some questions that might seem basic to some of you so please bare with me.
I am in the process of acquiring the parts for my first "from scratch" custom rifle. It'll be a defiant hunter action, with a 28" 1/8 twist proof barrel chambered in 7-300wm. I've already ordered the parts and am committed. I want to run the 195 Bergers because this is a mostly long range hunting rifle and terminal energy is a high priority. "I like big bullets and I cannot lie!"
So...reamers.
It's obvious I've jumped into the deep end of the pool. I want to make sure I have a solid understanding of some concepts and don't make any mistakes. I'm in the process of making up some dummy rounds to potentially get a custom reamer. I have read many people say it is dangerous to set up a chamber for just one bullet in case your rifle doesn't like it. I find that strange a little. With good load development I'm sure I can get it shooting well can't I?
If I make a dummy round, what should I tell the reamer maker? I don't know where to set it up? I have asked people where they have set up their rounds for this cartridge and have gotten answers like "20 thou off the lands", and .168-.260 freebore. When someone says .260 freebore, does that mean it's that far from the ogive to the lands? Seems like a hell of a jump.
My other question about the type of reamer. Should I get HSS, Carbide, one piece or separate throater? I've heard some guys say the separate throater invites problems with concentricity and other issues. When someone says they have a reamer that is set with .168 free bore, Does that mean it is that dimension for a specific bullet? How is freebore measured? From the end of the case or what? Some bullets are way longer than others so I want to understand this concept.
Should I go the custom reamer route or just find a gunsmith, let them run with it and trust them to provide the end product?

 

[shortgrass]

If you will go to the SAAMI web site, you will find drawings of cartridges and chambers. Industry standards. You can see the free bore in the cartridge drawing. The free bore is the cylindrical section that lies between the end of the chamber where the brass sits and the throat, which is the "funnel" at the beginning of the rifling. The very best way to establish your 'custom' free bore is to send 2 dummy rounds to your reamer maker (Dave Manson or JGS). Include a note telling him you want the bullet to touch the rifling using your dummys. From there, you can set up your reloads to be .005-.020" or wherever the best accuracy is. There are no hard and fast rules. The only rule there is, is that the throat will wear with every fired bullet that crosses it!

 

[J E Custom]

Hey guys, I have some questions that might seem basic to some of you so please bare with me.
I am in the process of acquiring the parts for my first "from scratch" custom rifle. It'll be a defiant hunter action, with a 28" 1/8 twist proof barrel chambered in 7-300wm. I've already ordered the parts and am committed. I want to run the 195 Bergers because this is a mostly long range hunting rifle and terminal energy is a high priority. "I like big bullets and I cannot lie!"
So...reamers.
It's obvious I've jumped into the deep end of the pool. I want to make sure I have a solid understanding of some concepts and don't make any mistakes. I'm in the process of making up some dummy rounds to potentially get a custom reamer. I have read many people say it is dangerous to set up a chamber for just one bullet in case your rifle doesn't like it. I find that strange a little. With good load development I'm sure I can get it shooting well can't I?
If I make a dummy round, what should I tell the reamer maker? I don't know where to set it up? I have asked people where they have set up their rounds for this cartridge and have gotten answers like "20 thou off the lands", and .168-.260 freebore. When someone says .260 freebore, does that mean it's that far from the ogive to the lands? Seems like a hell of a jump.
My other question about the type of reamer. Should I get HSS, Carbide, one piece or separate throater? I've heard some guys say the separate throater invites problems with concentricity and other issues. When someone says they have a reamer that is set with .168 free bore, Does that mean it is that dimension for a specific bullet? How is freebore measured? From the end of the case or what? Some bullets are way longer than others so I want to understand this concept.
Should I go the custom reamer route or just find a gunsmith, let them run with it and trust them to provide the end product?

Designing a chamber/cartridge is not for the inexperienced because there are many variables that have to be taken into account depending on the intended use.

There is a lot of misinformation that Is available and can be misleading and depending on your needs, "Disastrous" . Wild cats are even more
critical to dimensional differences and take great care and understanding when designing.

My recommendation would be to contact Manson reamers or JGS and talk to them about what you want. They can advise you of what to do and make recommendations on certain dimensions to keep you out of trouble. you can also use the SAMME 300 win mag chamber drawing, and simply change the neck diameter, leaving the shoulder datum line the same. (This would be the safe way to go and eliminate many problems).

I also don't recommend a special chamber for a specific bullet because if the barrel doesn't like it you may be screwed if you try a different bullet. (Load ammo to suite the chamber, don't cut a chamber to suite a bullet). There are plenty of different long range(heavy) bullets to chose from.

I also believe that a HSS reamer does the best job and recommend the freebore and throat be built into the reamer. (You can always throat later if needed). SAAME chamber designs are the safest and most trouble free if they are used and with good loading practices can be just as accurate without getting tricky. Only real experienced smiths can wade off into special chamber dimensions without getting in trouble and even sometimes they also experience problems but they know what to do to correct the problem.

This is just my opinion and I hope it helps.

J E CUSTOM

 

[Rich Coyle]

As much as I like https://mansonreamers.com/ I feel the opposite toward JGS. JGS messed up two reamers so I don't do business with them anymore. Fortunately my gunsmith noticed the reamer was not going to cut the chamber I told him about. Dave Manson made at least six or eight reamers for me and all are exactly like we discussed.

 

[shortgrass]

I have never had that experience with JGS, and I own at least 8 of their chambering reamers. Now, PT&G is another story! They can't seem to make even a standard, SAAMI spec reamer that cuts on more than one flute!

 

[Rich Coyle]

I have never had that experience with JGS, and I own at least 8 of their chambering reamers. Now, PT&G is another story! They can't seem to make even a standard, SAAMI spec reamer that cuts on more than one flute!

Their worst offence was when I called and asked if they had a modern digital scanner that can send information from the scanner to the CNC machine to make the reamer. The guy told me "Yes." I sent JGS a drawing. A few weeks later I get a reamer than would make a Weatherby double radius shoulder. The drawing didn't have Weatherby type radii at all. The 'smith told me so I returned it to JGS. I called and asked about the problem with the communication between the scanner and the CNC machine. This phone person told me they don't have anything like that.

I met Dave Kiff of PT&G at a store one time and figured I would give him a try. After giving him a try I discovered he is a liar and a thief.

On the other hand Dave Manson of Precision Reamers has never made a mistake and never attempted to deceive me.

 

[shortgrass]

AHHHH! But Mansons shop has made mistakes, at least one mistake! I ordered a 6mm neck reamer and Dara sent me a 6mm throating reamer. I called and talked to her and returned the throating reamer for the neck reamer. She was very apologetic! No problem. I did NOT get upset about a simple mistake. Every person has at one time or another 'made a mistake', even you Rich! I, for one, will continue to order tooling from JGS as well as Dave Manson in the future. Not everyone who answers the phone at these places has all of the answers you might want or knows everything about the shops' capabilities. Many times I have been referred to Dave (Manson) himself, or transferred to the engineer at JGS to clarify or define/refine a tooling order or for help fixing a problem I was having.

 

[Edd]

Is Clymer still in Business? Does anyone buy anything from them?

 

[shortgrass]

I have a few Clymer reamers in my tool box, but they were purchased years ago. I think Brownells still stocks SAAMI speced reamers made by Clymer. But I prefer to deal directly with the maker of the tools/parts I may be buying.

 

[Rich Coyle]

Is Clymer still in Business? Does anyone buy anything from them?

Manson used to work for Clymer. That's where I started working with him.

 

[Georgiashooter]

Dave Manson runs a top notch company. I sent a reamer back to be inspected because a chamber I cut had .006 runout and the reamer seemed dull. I suspected the barrel might have been annealed incorrectly,and daves inspection of reamer confirmed that was problem. He didn't charge me a dime. Next chamber I cut with said reamer was effortless and perfect.

 

[Kevin Cram]

Are you wanting to build a 7 x 300 Weatherby Mag or 7 x 300 Winchester Mag? I have a 7mm Practical reamer here which is the 7 x 300 Winchester Mag. I can e-mail you the print to see if it's something your looking for.

 

[odoylerules]

I wanted to do a 7-300 win mag. Isn't the "practical" the design with the shoulder angle being changed?

 

[Kevin Cram]

There are a couple 7mm " Practical " reamer designs out there depending on who you talk to. Nathan Fosters article in Terminal Ballistics Research shows his 7mm Practical, Manson reamer design with a 30* shoulder angle where the standard 300 Winchester Mag. has a 25*. I have a JGS 7mm " Pactical " ( 7 x 300 Winchester Mag ) with a 25* shoulder. Here's my JGS 7x 300 Winchester Mag print vs my PTG 300 Winchester Mag Tactical Match reamer print.