Range Report When will I need to change my load?

[ykrvak]

I've got a 7mmRM with a 26" and am thinking of cutting it down. I currently reload for this rifle with 65gr of RL22 behind 168gr VLDs. I'm thinking of cutting back to 20" and putting a can on it. Will I still be ok, or will I need to switch to a faster burning powder? I just don't want to end up with a flame thrower, where a third of my powder is burning up after the bullet has already left the barrel. Thanks.

 

[7mmRM]

Re: When will I need to change my load?

Honestly, youre wasting your time with a 20" bbled 7mmRM. For that short, pick a lesser 7mm.

 

[ykrvak]

Re: When will I need to change my load?

Thanks.

 

[Greg Langelius *]

Re: When will I need to change my load?

I agree, overbore chamberings typically benefit more from longer barrels, and might be the worst choices for serious chop jobs.

For a can, and limiting flash signatures, you'd almost definitely need to use a much faster powder, and download the charges to a fraction of case capacity. Just seems like such a waste with an otherwise very nice magnum cartridge. Noise and light signatures cripple the cartridge's potential.

The best way to envision subsonics is to see them as pistol loads built into rifle cartridge cases. Smaller cases waste less capacity, and magnums need not apply

 

[ykrvak]

Re: When will I need to change my load?

Thanks guys, I certainly appreciate the input. What would you consider the minimum length for this round? 22"? 24"? Not looking to go subsonic just take away a bunch of the racket while shooting is all.

 

[UKDslayer]

Re: When will I need to change my load?

What velocities were you at before? I was shooting factory BH 175's and my velocities went from 2650 w/26" barrel to 2450 w/20" + can. some have said the BH velocities have gone down too but that is just my personal experience if it helps.

 

[Greg Langelius *]

Re: When will I need to change my load?

I just inherited an M77 Sporter 7mm Rem Mag and will undoubtedly be dealng with the caliber sometime in the not too distant future. Taking a SWAG, I'd guess the length at 22". Its a common enough length in factory chamberings that I'm taking another SWAG that many of the published loads should be compatible. So that's where I'd be pointing you. My best guess is that loads involving faster powders may complement your can maybe somewhat better.

Greg

 

[ykrvak]

Re: When will I need to change my load?

Honestly, I haven't yet run it through a chrono yet. I just picked it up this past winter. I've just been shooting it and getting true statements for a dope card. I then ran it through a ballistic program and it seems to be fitting right in the 2950fps range. That's with the 168 VLDs and 65gr RL22. I know it's not the most efficient way, but I did get some shooting in and that's why we're all doing this I suppose.

Greg, Thanks for the thoughts. I'm really trying to avoid changing my load for this. So, I'm going to leave it as long as I have to in order to avoid that. I'm relatively new to this caliber though I'm really started to like the 7mm performance. Up until now (for the most part) my main carry/hunting rifle was always a 300WM which I've been getting a little tired of feeding. Powder wise anyway.
The main reason for cutting this thing down is to make it a little less unwieldy once I put a can on it. Though I obviously don't wish to take too much away from the performance of the round by doing it.

 

[Greg Langelius *]

Re: When will I need to change my load?

In my view, cans could be redesigned to nearly eliminate additional length, at the cost of some O/O the box thinking.

The muzzle might be configured as something somewhat like a Garand Gas Trap (initial Garand version, only somewhat elongated, to provide some time delay), being ducted into a can which is underslung rearward beneath the barrel, routing the gasses rearward through the can, and then forward again to re-exit through the same trap once the projectile is clear. Taking this a stop further, this can could also serve as somewhat of a barrel support/stiffener, something like a barrel sleeve, but underslung, and could also serve as a bipod/accessory mounting foundation. And the underslung configuration would not intrude into the optical axis. With proper heat insulation, it could become a substitute for/with the same ergonomic purpose, as a stock forend.

But my ideas seldom catch hold...

Greg