280 REM & 7RM

[JiggyIi]

I've owned multiple 7mmRM's & own a 280.
Why with both does one have to go over book maximum to get good velocities?
No matter what load I've tried they lack the speed unless I go quite a bit over

 

[Bob Wright]

Data from multiple sources may show different speeds. But since I just work up slowly I can get quite faster loads without being on the margins of "too much". To me, manuals give you some info to just get started. Then you take it where you feel safe and good results.

 

[JiggyIi]

Data from multiple sources may show different speeds. But since I just work up slowly I can get quite faster loads without being on the margins of "too much". To me, manuals give you some info to just get started. Then you take it where you feel safe and good results.

Lol there was a gun writer years back that wouldn't even think of his 7RM with a 160 Gr unless it was doing 3100 plus

 

[8x68s]

As Bob said... it's all about the legal liability of publishing data. Just a place to start...

 

[cajun]

I've owned multiple 7mmRM's & own a 280.
Why with both does one have to go over book maximum to get good velocities?
No matter what load I've tried they lack the speed unless I go quite a bit over

Are you talking about charge weights or actual velocities? Charge weights can vary a good bit depending on the chamber or throat. If you have a long throat or a loose chamber it can take more powder to get the listed velocity.

 

[JiggyIi]

Are you talking about charge weights or actual velocities? Charge weights can vary a good bit depending on the chamber or throat. If you have a long throat or a loose chamber it can take more powder to get the listed velocity.

I've had multiple 7RM's, 2 Rem, 2 Mark X, Savage, & Browning. 2 280's
All the same, max charges out of book, way below book velocity. A 7RM chronographed @ 2900 with 140's at max charges as per manual is pathetic lol so are the 280's @ 2800 with 140's.

 

[cajun]

I've had multiple 7RM's, 2 Rem, 2 Mark X, Savage, & Browning. 2 280's
All the same, max charges out of book, way below book velocity. A 7RM chronographed @ 2900 with 140's at max charges as per manual is pathetic lol so are the 280's @ 2800 with 140's.

Well I've had the opposite. I never can get to Noslers max charge weights before hitting max velocity. I think people need to understand that the charge weights necessary to reach max velocity can vary. They can vary lot to lot in powders. What we should be paying attention to is the velocity. If Nosler for example lists 3200 fps with a 140 grain bullet it doesnt matter if it takes 58 or 60 grains of whatever powder. Most of the test barrels these companies use have tight chambers which will take less powder to get max.

 

[JiggyIi]

Well I've had the opposite. I never can get to Noslers max charge weights before hitting max velocity. I think people need to understand that the charge weights necessary to reach max velocity can vary. They can vary lot to lot in powders. What we should be paying attention to is the velocity. If Nosler for example lists 3200 fps with a 140 grain bullet it doesnt matter if it takes 58 or 60 grains of whatever powder. Most of the test barrels these companies use have tight chambers which will take less powder to get max.

From everything I've read over the last 40 years is that the 7RM is very notorious for variations in chamber dimensions. Not sure about the 280 & dimensions. I do know companies have tested many rifles other than the barrels listed in the manuals

 

[cajun]

From everything I've read over the last 40 years is that the 7RM is very notorious for variations in chamber dimensions. Not sure about the 280 & dimensions. I do know companies have tested many rifles other than the barrels listed in the manuals

If you look at a saami chamber print theres a .010 tolerance in chamber dimensions for headspace. Not to mention throating for different bullets. The way I've always approached reloading is pressure and velocity are closely related. With a max book charge if you have a long throat pressure and velocity will be less. So it may take more powder. The max velocity is the key number. However much powder it takes to reach that is variable.

 

[hankle]

Speaking to the 7RM, I heard some conjecture that the max chamber pressures were lowered by saami to accommodate auto loaders by some rifle manufactures. Not sure if this is true, but it seems plausible. I'm about 4gr over max on my 7RM

 

[JiggyIi]

Speaking to the 7RM, I heard some conjecture that the max chamber pressures were lowered by saami to accommodate auto loaders by some rifle manufactures. Not sure if this is true, but it seems plausible. I'm about 4gr over max on my 7RM

I've read the same before about the 280, & 7RM,, add more Powder!! So I. Asked on here. I got my first 7RM around 35 years ago, a MarkX, rt hand, I'm a lefty lol

 

[crashlanding]

+ load data for the 7 rem mag is kinda all over the place with charge weights of same powder

 

[RedRabbit]

With the 280 Rem, the pressure of max loads is consideraby less than say with the 270Win, as the 280 load data was limited by the semi-automatic rifles it was chambered in.

 

[JiggyIi]

With the 280 Rem, the pressure of max loads is consideraby less than say with the 270Win, as the 280 load data was limited by the semi-automatic rifles it was chambered in.

Which doesn't make any sense since the 06' & 270 were chambered for the same rifles