7x300

[MudRunner2005]

How could a case that is longer, with similar basic dimensions, have a shorter base-to-neck- length?

Unless you're measuring from the base of the .300WM neck, to the top of the 7mmRM case...

And if that's the case, then I see what you're saying... But yall have been saying that for both cases measuring from the base to the neck was shorter for the .300WM.

 

[IdahoCTD]

Look at your picture. See where the 7RM neck stops and where that is on the 300wm? It's a little over half way up the neck of the case. Now if the 7-300wm reamers neck is larger than a 7RM in a factory chamber then you'd be fine. If not then from where the 7RM ends to the end of the 7-300wm chamber you'd have a smaller neck dimension which would give you a stepped neck. My reamer has a .314" neck which is less than 7RM SAAMI specs so I'd have a stepped neck on a simple rechamber. The cool thing about a Remington is they thread pretty close to the shoulder and they have a separate recoil lug that doesn't need threads under it. So you can just cut the shoulder forward without trying to rethread anything.

 

[bigngreen]

Look at your picture. See where the 7RM neck stops and where that is on the 300wm? It's a little over half way up the neck of the case. Now if the 7-300wm reamers neck is larger than a 7RM in a factory chamber then you'd be fine. If not then from where the 7RM ends to the end of the 7-300wm chamber you'd have a smaller neck dimension which would give you a stepped neck. My reamer has a .314" neck which is less than 7RM SAAMI specs so I'd have a stepped neck on a simple rechamber. The cool thing about a Remington is they thread pretty close to the shoulder and they have a separate recoil lug that doesn't need threads under it. So you can just cut the shoulder forward without trying to rethread anything.

Appreciate you posting that little but important fact, I never put the case next to each other and thought it all the way through before but was planning on do the 7mm-300 to the next 7 mag I buy, the devils in the details!!!

 

[MudRunner2005]

I understand what you're saying 100%, but everyone kept saying the base of the neck to the base of the case was shorter on the .300WM. I was just trying to clarify, since I knew that had to be wrong or a type-o. I do understand 100% that the .300WM case is shorter from the base of the neck to the base of the case, than the OAL of the 7mmRM case. Any person with eyes can look at that and tell.

Also, if he ordered a standard 7x300 reamer (no-turn), he should be ok. According to ANSI dimensions, the .300WM brass has a .0317" neck thickness, and the 7mmRM has a .0310" neck thickness. So since the .300WM brass is .0007" thicker, in theory, he SHOULD be ok, if the reamer has a standard neck thickness for the .300WM brass, and doesn't require turning.

In a perfect world...But as we all know, we don't live in one of those.

 

[IdahoCTD]

The only real way to know would be to cast the chamber to see what the factory neck dimension is and make sure the reamer he is going to use is larger then that by at least .001". BTW there is no SAAMI spec for a 7-300wm. It's a wildcat and doesn't follow a standard.

 

[IdahoCTD]

Appreciate you posting that little but important fact, I never put the case next to each other and thought it all the way through before but was planning on do the 7mm-300 to the next 7 mag I buy, the devils in the details!!!

Your welcome. I've been down this road a few times with rechambers. I hate to admit it but I've been down the road with a unsupported case or too short of a tenon too. That causes brass issues just like the guy was having with his 26 Nosler. It's amazing how easy it is to cut a tenon .100" short when your tired. That's how you learn when your self taught and thankfully all my F-ups have been on my own stuff. I've got a few knocks from the school of hard knocks but thankfully most of my stupid stuff is behind me after 23 years of rolling my own (knocking on wood here). It sure would have been nice to have the internet for help when I started. I'm sure those 180.00 Hart barrels (yes they were 180.00 at the time with a quantity discount) would have shot better. I sure set back a bunch of them in the beginning.

 

[MudRunner2005]

The only real way to know would be to cast the chamber to see what the factory neck dimension is and make sure the reamer he is going to use is larger then that by at least .001". BTW there is no SAAMI spec for a 7-300wm. It's a wildcat and doesn't follow a standard.

I know, I was referencing the .300WM and 7mmRM neck dimensions by subtracting the bullet diameters from the OA neck diameters according to ANSI dimensions, not the 7x300. I know it's a wildcat.