THROUTING A 7MM REMINTON MAGNUM

[maddysdad]

can you throut a chamber to push bullet further out of case neck and then gain powder caacity .also given a magnum bolt face on the 700 long action can it be altered to use .473 cases rather then the magnumcase

 

[hoz53]

can you throut a chamber to push bullet further out of case neck and then gain powder caacity .also given a magnum bolt face on the 700 long action can it be altered to use .473 cases rather then the magnumcase

yes on both of them but thats all i know

 

[shortgrass]

If you have the magnum bolt have bushed and then bored for .473 cartridges you no longer have or can use the Remington extractor. The bolt would have to be machined to use mini-16 or M-16 extractors. If I wanted a bolt for .473, I'd buy one instead of altering the magnum. As for throating a chamber, any chambers' throat can be lengthened with a throating reamer (and someone who knows how to use it!). If you want more velocity, I'd opt for a different 7mm cartridge. Take a look at www.hodgdonreloading.com , and look at peak pressures. That should explain why.......... (Norma makes regular runs of 7mm Weatherby brass, 7STW brass can be hard to come by). An increase from a 24" barrel to 26" can help, too. Would I re-chamber a Remington barrel? No!

 

[Will Henry]

Are we thinking that a headstamp makes a particular case more capable of handling higher pressures?
As for the throating, yes, that's easy.
The boltface? Yes, but more difficult. WH

 

[shortgrass]

Are we thinking that a headstamp makes a particular case more capable of handling higher pressures?
As for the throating, yes, that's easy.
The boltface? Yes, but more difficult. WH

The strength of the action will determine what max pressure is possible., what steel it is made of and how much bolt thrust it can stand. I heavily rely on a sound safety factor. I adhere to published load data. Change to 7mm Wby, and max published pressure increases, as does the velocity. Even the starting load for the Wby creates more pressure (and velocity) than max 7RM max load. Can the Rem 700 safely handle that? Certainly it can and will. By just lengthening a 7mm Rem Mag throat can you reach Wby velocities? Maybe, but it won't be top Wby velocity. My comparison is with 24" barrels on both, using the ever popular magnum powder H1000 and Nosler Partition 150g bullets. Even throated, the 7RM probably wouldn't hold the minimum charge of H1000 for the Wby. (I chose the Wby as an example because cases are more available than STW). If someone out there wants to lengthen the throat on their 7RM and exceed max published load data because it gave room for more propellant, have at it! I doubt anyone here has the equipment to accurately measure pressures as the propellant and bullet makers do. Sometimes it takes a very small increase in propellant to be over pressured.

 

[WSnyder]

If you convert to a .473" boltface or swap bolts to .473" it likely won't feed properly out of a box magazine with the magnum feed rails. You'd have to go to some sort of DBM.

 

[Edd]

The strength of the action will determine what max pressure is possible., what steel it is made of and how much bolt thrust it can stand. I heavily rely on a sound safety factor. I adhere to published load data. Change to 7mm Wby, and max published pressure increases, as does the velocity. Even the starting load for the Wby creates more pressure (and velocity) than max 7RM max load. Can the Rem 700 safely handle that? Certainly it can and will. By just lengthening a 7mm Rem Mag can you reach Wby velocities? Maybe, but it won't be top Wby velocity. My comparison is with 24" barrels on both, using the ever popular magnum powder H1000 and Nosler Partition 150g bullets. Even throated, the 7RM probably wouldn't hold the minimum charge of H1000 for the Wby. (I chose the Wby as an example because cases are more available than STW). If someone out there wants to lengthen the throat on their 7RM and exceed max published load data because it gave room for more propellant, have at it! I doubt anyone here has the equipment to accurately measure pressures as the propellant and bullet makers do. Sometimes it takes a very small increase in propellant to be over pressured.

I once made some brass for my 7mm Remington Mag by fire forming 7mm Weatherby cases. I shortened the necks on the Weatherby Brass about .040". and loaded and fired them in my 7mm Remington. The capacity increased after fire forming.

Fire forming is not exactly what I did. I loaded them with a full powder charge and some Barnes 120 gr bullets and used them for hunting. I think I still have some that haven't been fired.

 

[Enosiophobia]

Throat

 

[426nut]

Why not simply chamber for a 284 Winchester? E.

 

[Will Henry]

Brass is brass. If the brass is of the same make and head design, it will handle the same pressure. Different makes of brass may handle more or less pressure but the headstamp means nothing. I suppose I have extended the throat on a few dozen 7 Remingtons. Just how much change this makes is really hard to say, but everyone seemed happy with it. Interestingly, I've usually been called upon to make Weatherbys with shorter throats.
Back in the late-70's when I was chambering 7mm Rem Mags in match rifles, I was usually expected to throat to accept the 168 Sierra, seated just ahead of the neck/shoulder juncture. I chambered a couple for a long necked Rem (using 300 win mag brass) just to allow a little more latitude in bullet choice. Throated for the same OAL, but shorter bullets could be seated out closer to the lands, if that was what the shooter wanted.
Now, the 7mm Remington became known for unusual pressure spikes. Lengthening the throat did seem to help with this. I never really understood why Remington throated the 7mm so short. They had a long action, with a long mag box and could have made the cartridge longer. WH

 

[10XSHOOTER]

.280 ACK IMP!