7mm/short barrel/ fast powder????

[Brianma65]

I was just curious about a short barrel (18 1/2 inch) on a 7 mm rem mag. I've read that there are three issues with this. First being loudness, second being kick and third being that all the powder won't burn off , due to it being a slow burning powder. The first two are easily solved but what about the third issue? Can you use a fast burning powder such as 4227? Just curious is all, not saying I'm gonna try this

 

[stubblejumper]

There is no powder that you can use that would burn fully in a 7mmremmag with an 18-1/2" barrel, that would produce a velocity that would make it worth having a 7mmremmag. A 7mmremmag makes absolutely no sense with an 18-1/2" barrel. If you really want an 18-1/2" barrel , consider a 7mm-08, as the muzzle blast will be much less, the muzzle rise with be much less, the recoil will be much less, and in such a short barrel, you won't give up very much velocity. And if you go with a model 7 action, you can actually have a longer barrel, and still have a rifle that is the same overall length, which closes the gap in velocity even more.

 

[Brianma65]

I was reading some info on it and I think you would lose about 120 fps depending on the projectile. But the powder is the biggest hurdle. Would the 7-08 push out the same velocity? 2800+ fps

 

[jeff270]

In same length barrels the 7 mag will always be more powerful than a 7-08.
The fastest loads in a long barrel will be the fastest loads in a short barrel too.
So there is not much point in loading fast powders in magnum cases.

 

[Brianma65]

I was just curious if a faster burning powder would burn off in a shorter barrel. There's been a few experiments done and the powder not burning off was the problem.

 

[jeff270]

If the goal is to burn all the powder in the barrel ,then yes a fast powder will work.
But then you will have really low velocity .

 

[stubblejumper]

I was just curious if a faster burning powder would burn off in a shorter barrel. There's been a few experiments done and the powder not burning off was the problem.

You won't find a powder that works well in a 7mmremmag that will completely burn in an 18-1/2" barrel. The 7mmremmag will always produce more velocity than a smaller capacity cartridge like the 7mm-08, but as the barrels get shorter, the gap closes more and more. And if you were to do something stupid like add a brake to the 7mmremmag, you end up with a longer rifle which defeats the purpose of shortening the barrel.. A braked model 700 in 7mmremmag will be about 3" longer than a model 7 in 7mm-08, so you could have a 21-1/2" barrel on the model 7, and have the same overall length. That extra 3" of barrel closes the gap between the 7mm-08, and the 7mmremmag. With a 7mm-08, with a 21-1/2" barrel, 2800fps is possible with a 140gr bullet.

 

[Prairie Plinker]

FWIW, I've used faster burning powders in my 7mm-08 as it has an 18.5" barrel. With a few of the slower powders I found I got a lot of flash. I've had a couple times in the past where you take a shot on an animal in the opening or closing minutes of the day, and it takes a few seconds to get your "normal" vision back, there can be that much flash! A 7mm Magnum would blind you!

 

[billdick]

Try some imr 4064 I've used it a 257 weatherby with a 24" with good results. If you look through some old speer loading manuals from the 60's there is load data for faster powders in magnum cartridges. The purpose was to get the powder completely burnt in a shorter barrel. I was getting slightly higher velocities with 4064 then 4831 and 7828 in my 257 24", or at least thats what my chronograph said.

 

[farshot]

I found it is always a trade off. I use a faster powder in my carbine length barrels, but as was stated, the faster powders max out at a slower velocity than slower powders with all things being equal. A study of a reloading manual (Nosler's shows it very clearly with their bar graphs for velocities) will show how the fast powders can only get it going so fast...you cant get enough in to remain safe or have the room.

BUT, sometimes I find a happier balance, such as H4350 with 180 gr in a 30-06 with a 19 inch bbl, I find that I don't loose enough to worry about compared to a 22 inch bbl with a slower powder.

The magnums makes things more difficult as they usually take an overbore load to begin with and a faster powder in a shorter bbl will generally give slow velocities.

You can try different parameters such as lighter bullets with the faster powders, but you may not be satisfied. However, you may find some happy compromise with experimentation.