Reamer question

[haisardao]

So what goes into ordering a custom reamer, what I mean it's let's say I want a 30 Nosler or a 7 Saum but I don't want to go SAAMi, do I just increase free bore to seat the bullets where they belong? Do you guys change something else?
I've ordered reamers in the past and that's the only change I've made, happy for any input, thanks

 

[Justice1327]

I have about 30 reamers made and 10 reamers made in the last year. Nathan at JGS is really smart and can articulate the nuiances of designing a reamer. Most of mine were for AI cartridges, but some were modifications to SAAMI cartridges like my 284 or 6mm Rem. Some things to consider and your GS probably need to weigh in on what they prefer based on what their equipment is and experience is:
Pilot: Floating or Solid
Fluting Geometry
Freebore, as you mention, should be based on cartridge dummies you send in if possible. I have several 7-08 and 22-243 AI that I shoot on an XM+ action for this purpose due to the length of where I preferred the bullet to be.
Leade angel: should be considered as well. Again dummy round and discuss with reamer designer
Material the reamer is made from: HSS or Crbide

 

[haisardao]

I have about 30 reamers made and 10 reamers made in the last year. Nathan at JGS is really smart and can articulate the nuiances of designing a reamer. Most of mine were for AI cartridges, but some were modifications to SAAMI cartridges like my 284 or 6mm Rem. Some things to consider and your GS probably need to weigh in on what they prefer based on what their equipment is and experience is:
Pilot: Floating or Solid
Fluting Geometry
Freebore, as you mention, should be based on cartridge dummies you send in if possible. I have several 7-08 and 22-243 AI that I shoot on an XM+ action for this purpose due to the length of where I preferred the bullet to be.
Leade angel: should be considered as well. Again dummy round and discuss with reamer designer
Material the reamer is made from: HSS or Crbide

Thanks!
I knew it was more complex than just adding freebore

 

[FEENIX]

I knew it was more complex than just adding freebore

It can be complex, but it depends highly on what kind of improvement you are trying to accomplish with the parent case. IIRC, it was @Alex Wheeler who said, very little is gained with modern cartridges, and 7MM SAUM is one of those cartridges. I have 7MM SAUM, but it's not worth my time, effort, and investment. But do not take my word for it; you must make your own assessment of whether it is worth it for you. If you are unsure, work closely with a reputable GS who will build your rig.

My last build was a .338 Thor (NMI). I have sizing and chamber reamers made. With the sizing reamer, my GS made me a custom hydraulic forming and sizing die using blank dies, COAL/CBTO gauges, and seating dies.

Below are the improvements.

Good luck!

 

[haisardao]

It can be complex, but it depends highly on what kind of improvement you are trying to accomplish with the parent case. IIRC, it was @Alex Wheeler who said, very little is gained with modern cartridges, and 7MM SAUM is one of those cartridges. I have 7MM SAUM, but it's not worth my time, effort, and investment. But do not take my word for it; you must make your own assessment of whether it is worth it for you. If you are unsure, work closely with a reputable GS who will build your rig.

My last build was a .338 Thor (NMI). I have sizing and chamber reamers made. With the sizing reamer, my GS made me a custom hydraulic forming and sizing die using blank dies, COAL/CBTO gauges, and seating dies.
View attachment 740568
Below are the improvements.
View attachment 740569

Good luck!

Thank you, for me it is more about maximizing case use with heavies and not handicapping the cartridge. Perhaps for my use is as simple as more freebore? I was just curious how people go about making their reamer designs etc.
Appreciate your input.

 

[haisardao]

It can be complex, but it depends highly on what kind of improvement you are trying to accomplish with the parent case. IIRC, it was @Alex Wheeler who said, very little is gained with modern cartridges, and 7MM SAUM is one of those cartridges. I have 7MM SAUM, but it's not worth my time, effort, and investment. But do not take my word for it; you must make your own assessment of whether it is worth it for you. If you are unsure, work closely with a reputable GS who will build your rig.

My last build was a .338 Thor (NMI). I have sizing and chamber reamers made. With the sizing reamer, my GS made me a custom hydraulic forming and sizing die using blank dies, COAL/CBTO gauges, and seating dies.
View attachment 740568
Below are the improvements.
View attachment 740569

Good luck!

How fast and with what barrel
Length are you pushing bullets out of that beauty?

 

[FEENIX]

How fast and with what barrel
Length are you pushing bullets out of that beauty?

Check your DM.

 

[AZShooter]

haisardao:

You said you didn't want to use SAMMI specs. Here are two more specifications to consider:

Specify the neck diameter of the chamber. Using the intended brass, measure the OD of a loaded round and subtract .004" to 006". A lengthy search will generally show a consensus of .004"-.006" total clearance for highpower, hunting, and long-range. Benchrest is typically tighter with many shooters turning the necks.

You might want to use a 1 degree 30 min (1 1/2 degree) throat angle. I believe the cartridge designers realized this angle makes some of the high BC bullets easier to tune, like the VLDs. If you check you will find many of the newer cartridges use it. All the Creedmoors, the PRCs, the WSMs, Ruger RCMs, 338 RPM, 338 Norma mag, 338 Nosler, 7 backcountry, and 300 Blackout, plus many more, employ this throat angle.

You can look for others here:
https://www.theballisticassistant.com/saami-rifle-cartridge-catalog/

I ordered the 1 1/2 throat for my 257 Weatherby reamer along with less freebore. The reamer has made a dozen chambers and all of them shot the 115 Berger VLD accurately.

 

[haisardao]

haisardao:

You said you didn't want to use SAMMI specs. Here are two more specifications to consider:

Specify the neck diameter of the chamber. Using the intended brass, measure the OD of a loaded round and subtract .004" to 006". A lengthy search will generally show a consensus of .004"-.006" total clearance for highpower, hunting, and long-range. Benchrest is typically tighter with many shooters turning the necks.

You might want to use a 1 degree 30 min (1 1/2 degree) throat angle. I believe the cartridge designers realized this angle makes some of the high BC bullets easier to tune, like the VLDs. If you check you will find many of the newer cartridges use it. All the Creedmoors, the PRCs, the WSMs, Ruger RCMs, 338 RPM, 338 Norma mag, 338 Nosler, 7 backcountry, and 300 Blackout, plus many more, employ this throat angle.

You can look for others here:
https://www.theballisticassistant.com/saami-rifle-cartridge-catalog/

I ordered the 1 1/2 throat for my 257 Weatherby reamer along with less freebore. The reamer has made a dozen chambers and all of them shot the 115 Berger VLD accurately.

Thanks!!

 

[FEENIX]

Thank you, for me it is more about maximizing case use with heavies and not handicapping the cartridge. Perhaps for my use is as simple as more freebore? I was just curious how people go about making their reamer designs etc.
Appreciate your input.

Haisar,

I considered the same concern with my .338 Thor over LMI. BTW, good luck on your .338 NMI build, I am sure she'll be a shooter.

Here's a nice visual for you on improving a cartridge.

I have .30-06 and .30 Gibbs.

Ed