Barrel length and smooth-bore slug accuracy

[Quiet]

Internet lore says that barrel length does not affect rifle accuracy (I'm not here to argue about that), but what about in a smooth bore?

For instance, is slug accuracy in an old school cylinder bore slug barrel affected by a barrel length difference such as an 18.5" security barrel compared a 24" deer barrel?

I can see that sight radius is affected, but have my doubts that sight alignment is much of a factor for a good shot at those distances, compared to the limitations of smooth bore accuracy in general.

- Does increased barrel length improve flight stability?
- Is the velocity drop enough to significantly limit the effective accurate range of one versus the other?
- Are there slug designs that are more affected by barrel length than others?

 

[0faustus0]

What kind of accuracy are we talking about?

 

[Quiet]

What kind of accuracy are we talking about?

I was hoping that people with experience shooting slugs out of different barrel lengths would tell me, but for the sake of argument I'd say practical accuracy is the maximum distance you can always keep a group within a 10" circle.

 

[0faustus0]

If we are talking 14" to 30" barrels ... then according to my experience ... barrel length is not as important as the right choke and slug combination.

With the right choke and slug combination and a good sighting system you should be good out to 100 meters ....14" barrel or 30" barrel.

 

[tiriaq]

Could you give an example of a particular choke/slug combination that gives that level of accuracy?

 

[0faustus0]

870 Police with 18"barrel, IC choke, Ghost Ring sight, and Federal Truball slugs at 100 meters.

With that setup I can consistently shoot 4" to 5" groups at that distance, given that I clean the barrel of all the leading after every 20 to 30 shots.

 

[Butcherbill]

My experience with slugs and different barrel lengths tells me it doesn’t affect accuracy, last time I tested new slugs I shot them out of 20”,14”,12.5” smooth bore barrels @ 50y accuracy was similar between all three barrels. What made more of an impact on accuracy was what choke I shot them through, mod (20” & 12.5”) and full (14”) were the winners.

 

[Falconflyer]

Lol, I like how you managed to get your window sticker in the pic!

 

[mosinmaster]

Shotguns where the barrel attaches securely via interrupted threads like the M37 and M12 or are fixed are more accurate compared to slip fit attachments i.e. 870/500/BPS etc.

 

[todigy]

Shotguns where the barrel attaches securely via interrupted threads like the M37 and M12 or are fixed are more accurate compared to slip fit attachments i.e. 870/500/BPS etc.

This is very true.

I haven't seen a decrease in accuracy short vs long barrel. However I would think you may see higher MV out of a longer barrel?

 

[Butcherbill]

Lol, I like how you managed to get your window sticker in the pic!

I will also note that the brand of slug will also add to your level of accuracy in your particular shotgun, some will shoot better in one gun than another.

 

[0faustus0]

Shotguns where the barrel attaches securely via interrupted threads like the M37 and M12 or are fixed are more accurate compared to slip fit attachments i.e. 870/500/BPS etc.

I would agree with this statement .... but only for guns where the sight (sighting system) or a portion of the sights are fixed to the receiver.

If your sights or sighting system is fixed to the barrel .... then this is a moot point ....

Here are examples of where the sighting system is fixed to the barrel .... both are 870 Police shotguns ....

 

[Quiet]

Interesting observations. It's looking like a lot of experimenting with different chokes (for those guns that have them) and different ammo is the only way to go. If only slugs were cheaper and sold in bigger boxes!

 

[tiriaq]

Ganderite posted a system for economical production of slug loads.
Use a Lee mold to cast slugs. Cut out the crimp of a trap load, leaving the rolled edge. Dump the shot and pop in the slug. It works.

I have a Noble/S&W pump gun that I acquired with a damaged barrel. Cut and trimmed the barrel, and installed one of Brownells' adapters that allows screw-in choke tubes to be used. Have a couple of tubes including a rifled one. Drilled and tapped the receiver for a Weaver base.

 

[mosinmaster]

I've had good luck with Federal Tru-Ball slugs. That plastic ball design seems to work really well in smoothbores. I've also used some Fixed-wad (Brenneke) type slugs from Fiocchi Aero Slugs. They seem decent as well and should have good penetration due to the solid slug design. However, for the $ the Federal Tru-balls are good for light skinned game.