What cartridge characteristics lend themselves to shorter barrels?

[oldnewguy]

Total newbie here. I just bought my first non-AR rifle and in the process of purchasing my first magnified optic.

I've been reading here, articles online, reloading manuals, and the Brian Litz books on Amazon Unlimited, but still have some questions.

I've been reloading pistol for years, and plan to do the same for rifle rounds. I'm also planning to do most of my shooting suppressed.

So, I'm trying to understand the concept that certain cartridges work better in shorter barrels. Whether it's a matter of case geometry, or powder speed, etc. Just trying to learn a little at a time.

 

[nn8734]

Generally speaking (ie all things equal), cartridges with less overbore produce less pressures and are better fits for short barrels. This applies to both short and long action cartridges. You can run 6.5 creeds in shorter barrels (16”-20” is considered short for the 6.5CM) but you will have higher pressures than 308 with same barrel length.

308, as an example, burns most of its powder inside of 18” with most bullet weights used so a variety of powder and bullet combinations are available that work nicely in barrels <20” but generally greater than or equal to 14.5”.

Also, magnums can be run in shorter barrels but not as short as the non-magnums (in the case of magnums it’s the sheer volume of powder being burned that requires longer minimum recommend barrel lengths).

I’m sure others will chime in with more but that’s a very high level run down.

 

[spife7980]

I dont know of any cartridge that lends itself better to a short barrel.
What happens in a short barrel is exactly what happens in a long barrel, it just ends sooner.

Now, if youre talking about blast and port pressure for considerations of a silencer etc, its purely the amount of powder and pressure.

 

[1911hombre]

12 gauge buckshot.

 

[memtb]

Total newbie here. I just bought my first non-AR rifle and in the process of purchasing my first magnified optic.

I've been reading here, articles online, reloading manuals, and the Brian Litz books on Amazon Unlimited, but still have some questions.

I've been reloading pistol for years, and plan to do the same for rifle rounds. I'm also planning to do most of my shooting suppressed.

So, I'm trying to understand the concept that certain cartridges work better in shorter barrels. Whether it's a matter of case geometry, or powder speed, etc. Just trying to learn a little at a time.

I won’t suggest that there are rifle cartridges that work “better” with shorter barrels, but there are certainly some cartridges that are minimally affected with shorter barrels than generally seen in factory rifles! A .375 H&H immediately comes to mind....it’s generally found with 24” barrels, but can be cut back to 20” without a great reduction in muzzle velocity.

Just as a general statement, cartridges that are of fairly small case capacity for the caliber are affected less than say an “overbore” cartridge such as many of the Weatherby cartridges! memtb

 

[OlsenG_360]

Generally speaking (ie all things equal), cartridges with less overbore produce less pressures and are better fits for short barrels. This applies to both short and long action cartridges. You can run 6.5 creeds in shorter barrels (16”-20” is considered short for the 6.5CM) but you will have higher pressures than 308 with same barrel length.

308, as an example, burns most of its powder inside of 18” with most bullet weights used so a variety of powder and bullet combinations are available that work nicely in barrels <20” but generally greater than or equal to 14.5”.

Also, magnums can be run in shorter barrels but not as short as the non-magnums (in the case of magnums it’s the sheer volume of powder being burned that requires longer minimum recommend barrel lengths).

I’m sure others will chime in with more but that’s a very high level run down.

308 win is a good example of this. I only gave up about 100fps with 168gr FGMM cutting my barrel from 26" to 18". If it was a 243 or 22-250 I could be giving up 300+fps.

 

[6.5SH]

6.5 Grendel is another that works well in short barrels.

 

[oldnewguy]

I think that's what I was asking, but better phrased. There are some cartridges that cutting off 4" of barrel would cost you 3% of muzzle velocity, others might be 6% or more, etc.

As far as what length of barrel it take for a particular load to burn all of its powder, where you find that information?

 

[308pirate]

I dont know of any cartridge that lends itself better to a short barrel.
What happens in a short barrel is exactly what happens in a long barrel, it just ends sooner.

Now, if youre talking about blast and port pressure for considerations of a silencer etc, its purely the amount of powder and pressure.

+1,000,000

People need to stop overthinking every little thing they can come up with.

 

[308pirate]

I think that's what I was asking, but better phrased. There are some cartridges that cutting off 4" of barrel would cost you 3% of muzzle velocity, others might be 6% or more, etc.

As far as what length of barrel it take for a particular load to burn all of its powder, where you find that information?

Why don't you just tell us some more details on the intended use of the rifle and we'll go from there with recommendations?

All these open ended questions, many of which have no easy answer because they matter little to none at all, will just create paralysis by analysis

 

[oldnewguy]

I do have a project in mind, but at this point I'm mostly curious. Just in general, why are .308 or 6.5CM recommended for shorter barrels, versus 6XC, etc.

 

[spife7980]

They aren’t by anyone that’s not ignorant of the facts?

If someone has to make the argument it would be that, all else equal to make the specific argument case work, a 150 gr 308 will accelerate faster than a 150gr 6.5 will. And a 110 gr 6.5 will accelerate faster than a 110 gr 6mm. So it gets a larger bore to an equivalent speed sooner.
That takes zero consideration into external ballistics such as bc or internal ballistics such as powder choice. It’s just a larger surface area of an equal weight will go relatively quicker sooner.

If you want to shoot long range go with a longer barrel with a heavy for caliber bullet of high ballistic coefficient and chose a proper powder.
If you don’t want to shoot long range then it doesn’t matter.