Shorter rifle barrels... taking a cue from silhouette pistols

[clm2112]

Was watching a podcast this afternoon from Vortex and got to thinking "why not?"

Ep. 293 | Barrel Length – Does Size Really Matter?

If you don't need the absolute maximum in velocity for the purpose of range, why carry the extra barrel weight around? Moreover, why not use load data from a silhouette pistol that works with a short barrel and apply it on a slightly longer rifle barrel?

I paused a project and took a spare 243 Win Remington 700 take-off barrel over to the lathe. Bobbed the thing to 16.5" and threaded the muzzle 1/2-28tpi. Carved down the shank and threaded it for a Remage barrel nut. I still need to crown the muzzle before use, but at some point I want to see just how well this shorty barrel works.

Anybody else have these heretical thoughts?

 

[Bongo Lewi]

Was watching a podcast this afternoon from Vortex and got to thinking "why not?"

Ep. 293 | Barrel Length – Does Size Really Matter?

If you don't need the absolute maximum in velocity for the purpose of range, why carry the extra barrel weight around? Moreover, why not use load data from a silhouette pistol that works with a short barrel and apply it on a slightly longer rifle barrel?

I paused a project and took a spare 243 Win Remington 700 take-off barrel over to the lathe. Bobbed the thing to 16.5" and threaded the muzzle 1/2-28tpi. Carved down the shank and threaded it for a Remage barrel nut. I still need to crown the muzzle before use, but at some point I want to see just how well this shorty barrel works.

Anybody else have these heretical thoughts?

Depends on the ammo. The .223 AR with a 7.5 or 10 inch barrel is a flamethrower. But 300 Blackout works great. Just for yuks, I chopped a few inches off a cheap Rossi 22 WMR I keep handy for varmints and it made no measurable difference at all in terms of accuracy. The shorter barrel makes it easier to quickly grab and shoot from my SxS.

I have a non-rifled AR with a 10 inch barrel in .223. It being non-rifled, the rounds start tumbling end over end after about 20 yards, putting keyholes in the target. That may seem cringe-worthy but I say so what. It's a short-distance weapon that makes large, elongated holes in whatever it hits and you never have to worry about over-penetration.

 

[clm2112]

I agree, the formula inside the ammunition is going to be a major factor.

I think if I were to shoot some of the 243 Win loads I have would generate some impressive fireballs out the muzzle. But those loads are based on recommended loads for a 24" long barrel. Looking at published load data for a silhouette pistol (15" barrel) you see different propellant choices...faster burning powders that get consumed within the shorter barrel length.

You see that showing up comparing a 223 rifle load against a 300 Blackout. The 223 loads are tailored for a 20" barrel (M16 rifle length) using traditional rifle powders like IMR 4895, but a 300 Blackout runs a fast burning large bore pistol powder, like H110.

Aside from thinking the Remington XP-100 looked kinda neat, I mostly ignored Silhouette shooting. It didn't have an application I was interested in. But, now I kinda regret not taking interest... it is handy having less barrel out there. I can't go shorter than 16" because I'm not paying for a damn tax stamp, but I can go down to a little over 16" on a bolt rifle.

243 Win was the easy choice to see what happens... they are the most made, and least loved, barrels out there. You can buy $50 take-off barrels all day long from people who bought a 243 and now want something bigger.

The lathe is already humming this morning, making a bushing to run the barrel in a steady rest so I can put a crown on it. Coffee break is over, back to work

 

[clm2112]

As a humorous aside... the fellows who seemed so smart in the Vortex podcast yesterday, demonstrated a high degree of ignorance today when talking about a reproduction Charleville musket.

#10MinuteTalk - The 1766 Charleville – America’s Original Battle Rifle

Couple of groan moments... like every time it gets called a rifle and their basic lack of understanding of 18th century battle tactics.

Even so, good topic for this Independence Day. Fills me with the urge to take out the Brown Bess and my paper cartridges, and see if I can ventilate an over-ripe cantelope (the chickens were going to feast on it anyways. )

 

[Bongo Lewi]

I didn't crown the Rossi. Just filed the cut flat and smooth. I don't have the tool for cutting a crown and couldn't find one anywhere. I have a small vertical mill but not a lathe.

 

[clm2112]

Okie-dokie, Barrel swap done. As soon as daylight comes, I can bore-sight it and try it out. It's a little goofy, being a 243Win on a Remington 700 long action, but not as weird looking as I expected. I guess it helps that the chassis has a short fore-end, so proportionally the 16.5" barrel sortta looks normal.

Muzzle crown with a temporary 1/2"-24 thread protector on it out of the parts drawer. I'll hold off making one to fit until the barrel has been shot and works. It could just end up in the scrap bin if it doesn't shoot reasonably well (i.e. suitable accuracy for a hunting rifle, which is a pretty low bar to reach for me.)

 

[no4mk1t]

I agree, the formula inside the ammunition is going to be a major factor.

I think if I were to shoot some of the 243 Win loads I have would generate some impressive fireballs out the muzzle. But those loads are based on recommended loads for a 24" long barrel. Looking at published load data for a silhouette pistol (15" barrel) you see different propellant choices...faster burning powders that get consumed within the shorter barrel length.

I have an internal ballistics program called Quick Load. If you wish to avail yourself of this resource in the quest for an efficient load, holler.

I have used in connection with finding subsonic loads, but it is equally useful for choosing components for super sonic.

It allows you to select caliber and barrel length, and then the bullet and powder combination. Plug all that in and it spits out:

• Estimated chamber pressure, including a graph to show the pressure curve.
• How many inches when the powder is fully consumed. You typically don't want a load that is blowing unburned powder out the end of the barrel or into your suppressor. This is erosive to the blast baffle.
• Estimated muzzle pressure. Useful for finding loads for a rifle using a pistol can for subsonic use. You don't want to over pressure the can.

And of course velocity.
Plus a lot of other nerdy data if you want to really get down in the weeds.

This is useful for finding the most efficient load for a particular barrel length, and for powder selection and charge weight to zero in on a specific velocity when developing subsonic loads for suppressor use. Subsonic load development is done in the opposite fashion from super sonic. You start above the target velocity to avoid sticking a bullet in the bore and work down in powder charge weight to the desired velocity. This saves guesswork and components at today's inflated prices.

Here's a sample graph of the classic 45 ACP load of 5.0gr of Bullseye with a 230gr. FMJ

On this one, I selected the chart instead of the graph to zero in on a charge weight to work down from for subsonic 44 Mag for the Marlin 1894. For subs, you typically want the chamber pressure at 20K psi or higher at the desired velocity for best results. While this powder achieved both goals, it didn't shoot as well as Bullseye and was not pursued.

 

[clm2112]

Back from a rainy session at the range. Only shot 20 rounds of my hand loads through it just to get the rifle zeroed at 100 yards. Bullets were 100 gr. Sierra Game King Boat-tail Spitzers, 32.0 gr. of H4895, WLR primer in mixed brass. Due to the rain, I just used a bucket lid as a target. First couple rounds were off the target on the top. Just kept shooting three round groups (the "X" marked holes) until I got the elevation. The "O" and Diamond marked groups of four rounds were adjusting the windage.

Group size is acceptable for a hunting rifle, so it is usable and I have a fall-back load. The load I have on hand is actually in Hodgdon's load data as a silhouette pistol load. This was just accidental coincidence, as these loads were made up as low recoil hunting loads for a friend's 100lb teenage daughter to use. Now that he is into reloading too, he got the last of my jug of H4895 to work with.

Out of a 15" barrel they should be doing 2400 to 2500 fps. I'll have to wait for the rain to stop and chronograph a few to see what they are doing out of a 16.5" barrel.

But, for now that I have some brass in the tumbler, I can start looking at some test loads geared specifically for shorter barrels. I have plenty of 100gr bullets to work with. The propellants I have are Win 748 and StaBall 6.5... same stuff I was playing around with in 6.5 Creedmoor. I may have to go shopping for a propellant like Varget.

Internal ballistics software looks interesting, though I haven't used one since Sierra's CD version. At some point I'll have to try and get it to run under Linux.