Velocity from 12-1/2" 12 Ga

P.E. Islander

P.E. Islander

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When shooting my Grizzly 870 for the first time last week it seemed to me that recoil was mild. Because of this I figured that the velocity from the 12-1/2" barrel must have been quite a bit lower compared to the usual longer barrel.

Since there is no substitute for measured data I took my chronograph along when I headed to the skeet club today. Being in a bit of a hurry I fired only five shots with one type of shell. I'll try other loads in the future as I get the chance.

Shells used were Federal "Top Gun" Target load, 2-3/4", 1-1/8 oz #8 shot, 2-3/4 dram, with an advertised velocity of 1145 FPS.

The chronograph was placed 8 feet from the muzzle and the following velocities (fps) were recorded: 1005, 1040, 1051, 1031 and 1025. This gives an average velocity of 1030 fps, 90% of the speed quoted by Federal for this load.

Those results surprised me. Thats better performance than I expected.
 
I would think that in a 12.5" barrel you should get complete or almost complete powder burn from the cartridge. Those results seem to show that you would get complete powder burn.
 
I think the lack of felt recoil is from the heavy stock. Most people who pick the gun up notice that it feels quite heavy for its size. Also those are target loads , slugs have a definite but controllable felt recoil, but the concussion with the short barrel in a covered firing line is enough to cause headaches.
 
Generally speaking... For every inch cut off a 12 gauge barrel from 30" you loose only about 6.5 feet per second of velocity with grouse/target loads.

This from a good old book I have on grouse hunting.
I have read other articles on the subject that say about the same.
 
This is where I admit that I shot a few target load 2 3/4" out of my Grizzly (first time I have ever fired a shotgun) and I was kinda stunned by how bad the recoil was. I'm downright scared to fire anything like a magnum slug, sheesh!
 
CanAm said:
Yes, fast powders, just like pistol powders.
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Yep, the federal target shells must be loaded with a fairly fast powder to get that much speed out of that short barrel. I cut apart a shell from the box tested, it had: 16.3 grains of a coarse looking flake powder and 491 grains of shot.

I expect shells loaded with slower powders will experience a larger loss of velocity in the short barrel compared to a more standard length barrel.

I loaded some Lyman slugs (1-1/4 oz) last night using with 30 grains of Winchester Super Field. Should be interesting to see how the speed of those compares when fired from an 20" and the 12-1/2".
 
Calum said:
Generally speaking... For every inch cut off a 12 gauge barrel from 30" you loose only about 6.5 feet per second of velocity with grouse/target loads.

This from a good old book I have on grouse hunting.
I have read other articles on the subject that say about the same.
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How short did they go in the book you mention? There is a fair bit of information out there on 18" and longer, but not much in the way of measured fact about the performance of these really short tubes. Old books can be a great source of information but often authors in the past had no access to chronograph equipment.
 
Mnay people tend to get confused about velocities, especially from shotguns.
the sub guage tubes offered by many companies ( colonial for one) are very short, yet do quite well in the velocity department.

I'm not too sure of the velocity losses myself, but I think I have some experiments done By Carles Askinsjr.
I'll look and see what he found out.
Cat
 
Mark_P said:
I would think that in a 12.5" barrel you should get complete or almost complete powder burn from the cartridge. Those results seem to show that you would get complete powder burn.
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Really?!? I don't follow. I thought that if we had complete burn before the wad and shot load left the barrel, we would not have a nice fireball out the muzzle. :confused:
 
Fireball or fire is just high temp gas. So it's possible powder burned but still have fireball.

NASA rockets all have fuel completely burned in chamber but you can see huge fire from behind.

Shuttlelaunch.jpg
 
I would like to hear your results for slugs from a shorter barrel, I have a 20" that I got for deer and was thinking of getting a 14" instead. It would be nice to see how much loss there would be from 6" to see if would still be good for a shotgun zone deer hunt.
 
P.E. Islander said:
How short did they go in the book you mention? There is a fair bit of information out there on 18" and longer, but not much in the way of measured fact about the performance of these really short tubes. Old books can be a great source of information but often authors in the past had no access to chronograph equipment.
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In one book They went down to 12". Which was illegal at the time in that state, so after the test they had Marlin replace the barrel.

Oh and yes they had chronograph equipment.
I'd dig it up, but the books are packed away for a move in a few weeks.

Oh wait here is some info from a previous post I made:

Shotgun digest 3rd edition (3rd edition) Edited by Jack Lewis... page 74 "The Long and short of it".
A Marlin model 55 bolt action 12 gauge was progressively tested and cut down, and re tested...from 36" to 12" Approx 464 rounds used. Cylinder bore at 33". (Any number mistakes are mine as I'm typing out of a book).

Also I'm only typing out 3 sample groups listed:

Federal 2-3/4", 00 Buck, Average velocity out of 5 shots, and fps:
36" 1234 (full choke)
33" 1276
30" 1278
27" 1224
24" 1210
21" 1207
18" 1202
15" 1274
12" 1197

Federal rifled slug, 2-3/4" : Average velocity out of 5 shots, and fps:
36" (not tested in full choke)
33" 1558
30" 1554
27" 1531
24" 1457
21" 1309
18" 1428
15" 1327
12" 1227

Winchester AA trap(7 1/2 shot), 2-3/4":Average velocity out of 5 shots, and fps:
36" 1234 (full choke)
33" 1265
30" 1293
27" 1141
24" 1326
21" 1265
18" 1207
15" 1211
12" 1209

I'd personally like to see some modern testing done, with these new shotguns, and the new ammo we have these days.

Also I'd like to know what effect different types of chokes would have on velocity.
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I'm back from the range with some more chronograph numbers.

I tried the Federal target shells in two other guns:
30" Winchester - 1183 fps
20" Remington - 1107 fps
Yesterday the 12-1/2" Grizzly gave 1031fps.

The 12-1/2" gave 87% of the speed of a 30"barrel and 93% of the speed of a 20"barrel with the Federal target shells.

Next up were slug loads. All loads consisted of compression formed Win AA Hulls (once fired) with Win 209 primers, WAAF114 wads and cast Lyman Sabot slugs 525gr. Three different powder charges were used: 30 grains Winchester Super Field; 25 grains Herco; 23 Grains Unique.

30 Grains Winchester Super Field:
20" Remington - 1340 fps
12-1/2 Grizzly - 1206 fps
For this load the short barrel gave 90% of the speed of the longer one.

25 grains Herco:
20" Remington - 1152 fps
12-1/2 Grizzly - 1047 fps
For this load the short barrel gave 91% of the speed of the longer one.

23 grains Unique:
20" Remington - 1154 fps
12-1/2 Grizzly - 1072 fps
For this load the short barrel gave 93% of the speed of the longer one.

Perhaps I'll try some factory slugs next time.
 
Thanx PE, that was good information.

I am doing some slug (actually round ball) loading right now too.
Using IMR 4756 in Rem Gun Club hulls with various wads and a .715 diameter 537g Wheel Weight (SMALLER DIAMETER THAN THE BORE!!!) round ball out of a 20" Mossberg.

28.5g of 4756 got 1060fps

31g of the same got 1170fps

I fired the 31g load into a 5" frozen poplar tree and it went through and stuck 2" into the one behind it. THe ball was not deformed at all and I reloaded it and shot it again.

I also fired it at the edge of a tree to see if the ball would deflect. It cut a straight "wound" channel 1/2 the ball diameter in the tree. I was surprised it went so straight!
 
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