Help me understand chambering (when are specific reamers needed?)

[tondar15]

I am still very new to centerfire rifles and I'm trying to learn as much as I can. I recently bought a model 16 in 7mmWSM. I'm on the list at SSS to get T&T'd. I think I'm going with a McRee Precision stock. The last decision I have to make is what barrel and what cartridge. I am definately favoring the 7mm RSAUM but I'm trying to figure out chambering. More specifically when do you need a custom reamer?

If I order a barrel chambered in 7mm RSAUM what am I getting? I know you need a specific reamer for chambering in 7mmWSM when you are planning to use 300WSM brass. Does this mean you can't ever shoot factory 7mmWSM rounds? One of the guys over at Benchrest forums used a PT&G reamer designed specifically for 7mmRSAUM based on resizing 300RSAUM brass (Nosler specifically).

Is it simply not possible to setup a chamber that can shoot factory 7mmRSAUM as well as reloads with 180 Berger's based on either remington brass or Nosler/Norma 300 RSAUM brass?

If I know the majority of my rounds will be reloads should I consider what my "usual" load will be based on and pursue a reamer that fits that combination?

Thanks for the help!!

[Artpro]

I hope you're not as confused as your post leads me to think. Firstly, you can have a reamer made to whatever specs you desire within reason. Custom reamers for a specific cartridge will usually have smaller-tighter necks and maybe shorter or longer throats, than SAAMI specs, depending on which bullets the shooter intends to use. Please also be reminded that the 7mmWSM and 7mmRSUM cartridges are factory rounds but are NOT interchangable. If you have your new barrel chambered for 7mmRSUM that is the only cartridge case you should shoot in it. Reforming brass is a separate topic.

[tondar15]

Sorry if my post is confusing. I completely understand that 7mmWSM is not interchangeable with 7mm RSAUM. I bought the rifle in 7mm WSM but I am planning to sell the factory barrel and get one chambered in 7mm RSAUM. The point of my post is do I need to order a blank and a custom reamer if I plan to shoot reloads based on 300 RSAUM brass and 180 Berger bullets. If I get a custom reamer for that load will I not be able to shoot factory rounds? What if I want to reload with 7mm RSAUM Remington brass?

[stevec]

The simple answer is yes, You can shoot factory loads.

Things that will change that answer.

1 If your reamer is a "tight neck" That would require you to turn your necks to a smaller diameter.
2 if your reamer has any deminsions that are not within SAMMI specs. something like changing the shoulder angle or body taper.

Hope this helps, Steve


P.S. I asume you will have sombody else do the barrel work for you. any good smith will be able to answer your questions probably a lot clearer than I can. He should be able to help you pick a reamer that will do what you want.

[jrmy_1]

What is the benefit of using the .300 cases versus the 7mm cases? Is it only an availability issue? Also, the WSM cases have more case capacity than the SAUM, ~7.5% based on an article I recently read. Why are you wanting the SAUM versus the WSM? I thought there was talk of the WSM taking most of the industry and the SAUM slowly being phased out.

[laportecharlie]

I'm with jrmy_1 on this one. Why would you want to go from the more popular, more powerful round to a less popular, less powerful one and spend a bunch of money to get there? I think your money would be better spent on some good optics.
Charlie

[PEI Rob]

...

Is it simply not possible to setup a chamber that can shoot factory 7mmRSAUM as well as reloads with 180 Berger's based on either remington brass or Nosler/Norma 300 RSAUM brass? ...
Forget the chamber, the issue is how to resize your 300 brass down to 7mm properly. The 7mmRSAUM and the 300RSAUM are the exact same dimensions from the base to the headspace datum line on the shoulder. I would think, haven't done it, that you could simply run the 300 brass in your 7mm die and load it up. After firing your brass would be fireformed to the proper 7mmRSAUM neck junction dimensions. If 300RSAUM brass can be run in a 7mmRSAUM die then your good to go. This is the real question you are trying to find an answer to.

The advise on going wsm is good.

[tondar15]

The WSM rounds are more popular but from what I'm reading the RSAUM is the better cartridge. There's a good article here: http://www.6mmbr.com/7mm284.html

The popularity of the WSM is tempting due to the availability of components. Remington is the only supplier of 7mmRSAUM brass but Norma and Nosler are making 300 RSAUM brass.

[jrmy_1]

The WSM rounds are more popular but from what I'm reading the RSAUM is the better cartridge. There's a good article here: http://www.6mmbr.com/7mm284.html

The popularity of the WSM is tempting due to the availability of components. Remington is the only supplier of 7mmRSAUM brass but Norma and Nosler are making 300 RSAUM brass.



Thanks for the link.....good read. Forming the 300 brass to 7mm should be easily completed in the reloading die and fire formed. The choice between WSM and SAUM sounds like it will be a harder decision......

[dcloco]

Might want to neck turn the 300 brass BEFORE you reduce the size to 7mm....will help to alleviate the dreadful "donut" that happens when forming brass down in caliber size AND help in forming the brass anyway.

[geargrinder]

I'd stick with the WSM.

Then you have way more options for good brass. I'm using 300WSM Norma brass for my 7mmWSM. All it takes is a simple fireform.

I got the quicker twist for the 180g VLD's and 200g Wildcats.

I plan on using mine for long range hunting as well as paper punching so I wanted all the fps I could get out of the short action magnums. The7mmWSM has more velocity than the 7/300wsm or 7mmRSAUM.

And I can shoot factory ammo if I get in a bind.

[Edd Panzella]

The WSM rounds are more popular but from what I'm reading the RSAUM is the better cartridge. There's a good article here: http://www.6mmbr.com/7mm284.html

The popularity of the WSM is tempting due to the availability of components. Remington is the only supplier of 7mmRSAUM brass but Norma and Nosler are making 300 RSAUM brass.


Read that whole link. I think the amount of hard fact vs personel opinion in the link would not drive me to spend money converting from 7mm WSM to 7mm RSAUM without giving the WSM every opportunity to shine FIRST. If it's a dog, by all mean go for it.

[EFBell]

The WSM rounds are more popular but from what I'm reading the RSAUM is the better cartridge. There's a good article here: http://www.6mmbr.com/7mm284.html

The popularity of the WSM is tempting due to the availability of components. Remington is the only supplier of 7mmRSAUM brass but Norma and Nosler are making 300 RSAUM brass.


Read that whole link. I think the amount of hard fact vs personel opinion in the link would not drive me to spend money converting from 7mm WSM to 7mm RSAUM without giving the WSM every opportunity to shine FIRST. If it's a dog, by all mean go for it.


Plus 1 !

[jrmy_1]

The WSM rounds are more popular but from what I'm reading the RSAUM is the better cartridge. There's a good article here: http://www.6mmbr.com/7mm284.html

The popularity of the WSM is tempting due to the availability of components. Remington is the only supplier of 7mmRSAUM brass but Norma and Nosler are making 300 RSAUM brass.


Read that whole link. I think the amount of hard fact vs personel opinion in the link would not drive me to spend money converting from 7mm WSM to 7mm RSAUM without giving the WSM every opportunity to shine FIRST. If it's a dog, by all mean go for it.


+1