Speaking of barrel length

[Spinner]

What effect does barrel length have on velocity of the shot string? When does a shotgun barrel start to slow down the string of shot by a noticeable amount?

With rifles theres a rule of thumb of about 50 fps velocity drop with every inch you shorten the barrel. So does this apply to shotguns too? Or are the velocities involved slower so the effect is less noticeable?

Just curious as to whether shot is travelling significantly faster from a 30" barrel than from an 18" barrel (given the same loads, etc). Does this (or should this) have a bearing on barrel length selection?

Spinner

 

[Dave McCracken]

There's conflicting info on this, Spinner.

The Rule of Thumb for rifles doesn't apply to shotguns.

A load may travel faster from a 30" barrel than an 18" one, but slower than a 24" barrel.IMo, the difference ins't that significant.

 

[mete]

Velocity loses are proportional to the velocity so the per inch lose at 3000 fps is higher than the lose per inch at 2000 fps. When we get down to shotgun velocities lose per inch is very small.IIRC there was a test that showed that significant loses start below the legal 18" barrel length. Many shotgunners like those long barrels but the facts are that long barrels may help balance and sighting but do nothing for velocity.

 

[sm]

Well Spinner my friend

Glad Dave and mete answered...what they said and mete's example sounds good to me.

Honest - I never gave bbl length and velocity any thought.

Me being me and all Simple fella I am and the way I'm wired...

I focused on gun fit, reliabilty of firearm and ammo, gaining the skills to hit what looking at - be it flying, moving or sitting still. I shot a lot of pattern boards, media such as bldg materials, car windows, doors , hunting various critters...

Never gave shotgun velocity a thought. I did take all the above in consideration for what used for what task , like what shot for what critter, what a slug will do in this media...the way I'm wired if the gun,ammo won't run and I miss...well.

 

[Denny Hansen]

I've never done any in-depth testing so I can't speak from personal experience. What I can tell you is that U.S. Customs did some pretty involved tests years ago and came to the conclusion that shotgun shells would fully burn the powder and reach optimum velocity within the first 14 inches, and therefore anything more than 14 inches was basically just added weight, and may in fact slow the shot charge down. Keep in mind that their air units need something as short as possible getting in and out of Blackhawks, Citations, etc., and the tests were perfomed to see how short they could get their barrels without reducing performance.

It may be the loads I use (and shotguns can be very indvidual creatures), but casual tests with a chronograph with one 870 with an 18-inch tube had very slightly higher average velocities (about 15 fps on the average) than one with a 20-inch barrel, both with IC chokes. YMMV.

Like Dave and mete said, I think any difference would be insignificant for most of us.

Denny

 

[Spinner]

OK, so when I finally get to build my "Lupara" any barrel length over 18" or so (as the legal minimum, rather than a performance minimum) is going to be OK. I'm still in 2 minds as to whether I should be looking at a 20" coachgun or getting an old, cheap SxS and lop it to the required length.

Current thoughts for barrel length are around 24" ....... intended use is upland birds, rabbits in thick cover, HD (though officially that is not an option according to our laws). Something nice and handy, quick to point and swing, reasonably light .... and, of course, as cheap as possible.

If an old SxS is sourced I may have it jug choked rather than tubed ..... costs for jug choking are likely to be less though versatility might be greater with tubes.

Spinner

 

[sm]

Denny - good info, thanks!

Spinner, Dave did a pc on the "Lupara" back on TFL, might want to pull that up.

I'm thinking , legal length, with Cyl + and Light Modified would work well , tweak with loadings. Agree with handy and balance.

Jug choke *grin* you just might be onto something there. Keep us posted.

 

[Spinner]

Spotted Dave's post on the Lupara and found it very inspirational ....... it pretty much formed the basis of my crazy desire for a handy light SxS. See, Dave McCracken is responsible for more than just the proliferation of 870s

The Lupara project is simmering away on a back burner at the moment. Now is not a good time to be looking to buy shotguns (even 2nd hand guns) or to be hassling gunsmiths to make modifications. Our duck shooting season opens 1 May ..... 'smiths are very busy this time of year and gun prices climb. Prices of 2nd hand guns will drop in a month or two after the season tails off and people upgrade their equipment because they didn't bag the birds (it never occurs to most people that the best upgrade they can make is to the nut behind the butt).

Besides which, we have just put a contract out on our two cows .... the killer comes in on 19 May to despatch them and take them to the butcher. If I produce a Lupara as well the neighbours might start to think I'm part of La Cosa Nostra

Spinner (amico degli amici)

 

[Dave McCracken]

A desire for a light and handy SxS is far from crazy, Spinner. With training and practice, it's a fine weapon and tool. I'd probably go with barrels in the 23-25" range rather than the bare legal minimum for less noise and flash, and better balance.

Must haves would include good triggers, good fit, reliability, durability and long chambers (vs just 2 1/2"). With tubes or one barrel choked kinda tight, it'll cover lots of territory.