7mm Rem Mag - Barrel Length Question

[gtriple]

I've inherited a Winchester Model 70 Classic Stainless in 7mm Rem Mag. I can't really get rid of it due to where I got it from, but I need to figure out what to do with it.

Right now, it has an awful barrel porting that doesn't help at all with the recoil, but makes it loud as hell. See below.

First question:
The barrel measures 23" from end of receiver to end of barrel. I believe that means it is actually a 24" barrel. Is that about correct?

Second question:
If I keep it in 7RM and don't rebarrel, I want to cut off the porting and thread it for a TBAC 7 or 9. It'll be about 2" off, which will make the barrel 22" before the suppressor. Does anybody have experience with a shortened 7RM when running a can?

Third question:
If I do want to rebarrel/rechamber it... should I redo it in 7RM with a carbon barrel? Or since it is already a magnum length action, would it be better to step it up to 300 PRC? I've never rebarreled a gun, so I'm not sure what all you'd have to change. I'd have a gunsmith do all of the work.

I appreciate the help!

 

[IrkedCitizen]

Chop it, thread it, shoot it, be happy. People get too wrapped up in velocity. A 22" 7RM is going to be plenty fast enough for anything within 600+ yards.

Changing to 300prc will likely require modification to the mag box as it is significantly longer than a 7RM.

 

[Wapiti1]

First Answer: Yes, barrel length is measured from the breech to the muzzle.

Second Answer: So the porting is a Magnaport, and they work great on handguns. Rifles, not as much. A can on a 22" 7 mag will be fine. You'll get roughly 50-100fps slower velocity than leaving it 24". Add the can, and you might see 25-75fps. Just make sure the can is capable dealing with that pressure. Most are.

Third Answer: I would go with a steel barrel if I rebarreled it. I don't see the point of carbon in the vast majority of applications. Big heavy, long range rifle? Yes, carbon can help with weight. 22-26" sporter weight? I wouldn't bother with the expense to save a little weight. If you are adding a can anyway, you will probably be at the best length verse performance combo after cutting it to 22" regardless of cartridge (if sticking to magnum). 24" plus a can is a long setup. 22 isn't short. The question on a rebarrel is "do you want or need more than a 7mm RM"?

Rebarreling to a different cartridge is not complicated. It would be a simple rebarrel to go to any other belted mag that is 3.4" COAL like .300 Win, .338 Win, .458 Win. 3.6" on that action is not hard, but it would take a little more work. Going to a PRC, or other .404 Jeff based cartridge (RUM) will require some feeding work in addition to the barrel. Those are fatter, and won't feed correctly out of a belted mag magazine.

All possible. Depends on need, want, and if you are willing to part with the cash.

I'd cut it, thread it, and see how I liked it. Then decide.

Jeremy

 

[gtriple]

First Answer: Yes, barrel length is measured from the breech to the muzzle.

Second Answer: So the porting is a Magnaport, and they work great on handguns. Rifles, not as much. A can on a 22" 7 mag will be fine. You'll get roughly 50-100fps slower velocity than leaving it 24". Add the can, and you might see 25-75fps. Just make sure the can is capable dealing with that pressure. Most are.

Third Answer: I would go with a steel barrel if I rebarreled it. I don't see the point of carbon in the vast majority of applications. Big heavy, long range rifle? Yes, carbon can help with weight. 22-26" sporter weight? I wouldn't bother with the expense to save a little weight. If you are adding a can anyway, you will probably be at the best length verse performance combo after cutting it to 22" regardless of cartridge (if sticking to magnum). 24" plus a can is a long setup. 22 isn't short. The question on a rebarrel is "do you want or need more than a 7mm RM"?

Rebarreling to a different cartridge is not complicated. It would be a simple rebarrel to go to any other belted mag that is 3.4" COAL like .300 Win, .338 Win, .458 Win. 3.6" on that action is not hard, but it would take a little more work. Going to a PRC, or other .404 Jeff based cartridge (RUM) will require some feeding work in addition to the barrel. Those are fatter, and won't feed correctly out of a belted mag magazine.

All possible. Depends on need, want, and if you are willing to part with the cash.

I'd cut it, thread it, and see how I liked it. Then decide.

Jeremy

Thanks for all of the info. Cut and thread is exactly what I'm going to do. I don't really need it to be a different cartridge, but wanted to consider something more modern.

 

[RedBeard22]

Let is us know how it goes. I have an old Savage 7mm Rem Mag that I'm strongly considering cutting down from 24" to 22"or 20".

 

[IrkedCitizen]

Let is us know how it goes. I have an old Savage 7mm Rem Mag that I'm strongly considering cutting down from 24" to 22"or 20".

Just do it. Nike.

 

[RedBeard22]

Just do it. Nike.

But which length???

 

[IrkedCitizen]

But which length???

20"
It'll be faster than a 24" 7mm-08 with same bullet weights.

 

[zion zig zag]

20"
It'll be faster than a 24" 7mm-08 with same bullet weights.

What do figure effective range would be for elk with a 20" 7mm RM shooting 160 Accubonds? Just curious of people's opinions.

 

[IrkedCitizen]

Effective range comes down to the shooter's ability.

That said a 20" 7RM shooting a 160gr bullet should be doing ~2725fps at the muzzle. Look at some ballistic charts and see when it reaches the minimum requirement for expansion for that bullet.

 

[RedBeard22]

Effective range comes down to the shooter's ability.

That said a 20" 7RM shooting a 160gr bullet should be doing ~2725fps at the muzzle. Look at some ballistic charts and see when it reaches the minimum requirement for expansion for that bullet.

Do you know of a good ballistic calculator that does kinetic energy?

 

[IrkedCitizen]

Do you know of a good ballistic calculator that does kinetic energy?

Do a search on this forum and you will find the answers.

 

[zion zig zag]

Effective range comes down to the shooter's ability.

That said a 20" 7RM shooting a 160gr bullet should be doing ~2725fps at the muzzle. Look at some ballistic charts and see when it reaches the minimum requirement for expansion for that bullet.

I was curious about what other people think. But if I assume:
-velocity of 2900 fps w/24" barrel
-loss of 200 fps w/20" barrel
-needed velocity of 2000 fps at impact

then going from 24 inches to 20 inches you lose about 150 yards, from 700 to 550. Which would still be plenty for me.

Ultimately, I have a Tikka t3x 7mm rem mag that I want to cut down to run with a suppressor. What I keep going back and forth on is do I want to convert it to a 7 saum at that point for a more efficient short barreled cartridge, or does the convenience of available factory ammo make me want to stay with the rem mag?

 

[IrkedCitizen]

I was curious about what other people think. But if I assume:
-velocity of 2900 fps w/24" barrel
-loss of 200 fps w/20" barrel
-needed velocity of 2000 fps at impact

then going from 24 inches to 20 inches you lose about 150 yards, from 700 to 550. Which would still be plenty for me.

Ultimately, I have a Tikka t3x 7mm rem mag that I want to cut down to run with a suppressor. What I keep going back and forth on is do I want to convert it to a 7 saum at that point for a more efficient short barreled cartridge, or does the convenience of available factory ammo make me want to stay with the rem mag?

For you I would recommend a new barrel since you want to run a can. Your Tikka barrel might not have enough meat to properly support that endeavor. You can stay with 7RM with the new barrel thus keeping factory ammo options.

Hornady is supposedly releasing a 7 prc which will likely be based off the 6.5 case. The 6.5 and 300 prc are not going anywhere so the 7mm will likely stay as well. So there will be more 7prc options than 7saum. It'll obviously take time though. I think a 7prc loaded factory with 162gr ELD-M would be a winner. The ELD-M is a deadly bullet it's what I shoot in my 7RM handloads.

 

[RSC12]

I'm curious if

I've inherited a Winchester Model 70 Classic Stainless in 7mm Rem Mag. I can't really get rid of it due to where I got it from, but I need to figure out what to do with it.

Right now, it has an awful barrel porting that doesn't help at all with the recoil, but makes it loud as hell. See below. View attachment 394840

First question:
The barrel measures 23" from end of receiver to end of barrel. I believe that means it is actually a 24" barrel. Is that about correct?

Second question:
If I keep it in 7RM and don't rebarrel, I want to cut off the porting and thread it for a TBAC 7 or 9. It'll be about 2" off, which will make the barrel 22" before the suppressor. Does anybody have experience with a shortened 7RM when running a can?

Third question:
If I do want to rebarrel/rechamber it... should I redo it in 7RM with a carbon barrel? Or since it is already a magnum length action, would it be better to step it up to 300 PRC? I've never rebarreled a gun, so I'm not sure what all you'd have to change. I'd have a gunsmith do all of the work.

I appreciate the help!

I'm curious as to what ended up happening with this rifle. Did you cut it down and if so how did it perform?

I have a tikka 7RM that I'm seriously debating cutting down to 20 or 21". One issue for me is I live in BC so suppressors are not in the question. I'm not worried about the velocity loss but more the increased muzzle flash and noise if that would be an issue and make the rifle a pain to shoot. I know 22" seems perfectly fine but something about 20" is speaking to me

 

[gtriple]

I'm curious if

I'm curious as to what ended up happening with this rifle. Did you cut it down and if so how did it perform?

I have a tikka 7RM that I'm seriously debating cutting down to 20 or 21". One issue for me is I live in BC so suppressors are not in the question. I'm not worried about the velocity loss but more the increased muzzle flash and noise if that would be an issue and make the rifle a pain to shoot. I know 22" seems perfectly fine but something about 20" is speaking to me

I did end up doing it. It's a backup rifle, so it doesn't get a lot of range time. We are gna do a little whitetail hunting with it come mid October, so I'll let you know how it goes.

I haven't regretted going as short as possible on any rifle yet. 16" 6.5CM, 16" 308, an 18" 7PRC is on it's way too.

 

[Chris_in_Idaho]

I did end up doing it. It's a backup rifle, so it doesn't get a lot of range time. We are gna do a little whitetail hunting with it come mid October, so I'll let you know how it goes.

I haven't regretted going as short as possible on any rifle yet. 16" 6.5CM, 16" 308, an 18" 7PRC is on it's way too.

How did your October whitetail hunt go? And what length did you end up with on your 7?