How Does Barrel Length on a Shotgun Affect Velocity?

I did a test last week where we shot an old Marlin Goose Gun with a 36 inch barrel and compared it to other shotguns with shorter barrels but with the same chokes. We wanted to see if the extra barrel length would cause the patterns to “tighten up”.

The results were kind of surprising, as they indicated that barrel length had nothing to do with pattern size. Only the choke mattered.

You can read about it here: Does a Long Barrel Tighten Up Patterns

Some folks wondered if the extra barrel length would add velocity to the shotgun loads. We had some discussion and some of had heard in the past the shotgun shells (usually loaded with pistol powders) would burn all their powder in the first 12 to 18 inches of barrel. It was believed that barrels that were extra long would not benefit from the extra length and might even have lower velocity due to the powder being burned up and the extra length would only result on more friction on the payload. That might even result in lower velocity.

Well, this morning I had my good bubby doc540 meet me at the range and asked him to bring his chronograph so we could test the velocity on different shotgun barrel lengths.

Here’s his chrono.


He said it was inexpensive, but it seems to work well, as we have tested rifle and pistol ammo in it before.

Today I shot three different kinds of ammo in three different shotguns.

The first shotgun is my Mossberg Maverick with a 20 inch barrel.

The next is a Browning Gold Hunter with a 26 inch barrel.

The third is Jason’s Marlin Goose Gun with a 36 inch barrel.


The ammo was these three different types.

First some Sellier and Bellot 12 gauge Heavy Field Load #6 birdshot.

The second is some Federal Premium 00 Buckshot with Flight Control Wad.

The third load was some Quix-Shox Magnum Sabot Slugs.

Well, long story short, here are the results.

20 inch barrel:

Load #1 – 1103 fps
Load #2 – 1242
Load #3 – 1465

26 inch barrel:

Load #1 – 1165
Load #2 – 1300
Load #3 – 1527

36 inch barrel:

Load #1 – 1203
Load #2 – 1375
Load #3 – 1602

You will notice that in each case, the longer the barrel, the higher the velocity.

Honestly, I was surprised with these results. But there they are.

Conclusions:

1. The test was limited to three different shotguns with three different barrel lengths.

2. In each case, the longer the barrel, the higher the velocity for each load.

3. Maybe this is why those old Long Tom shotguns could “reach way up and hit the geese”. The longer barrel resulted in higher velocity.

4. You never know until you do some shooting. And “old wives tales” are not always accurate.

5. It’s fun to shoot stuff

 

1 Comment on How Does Barrel Length on a Shotgun Affect Velocity?

  1. Thanks a bunch for this article and the one just before it. This is good stuff!

Leave a comment

Your email address will not be published.


*