doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Shotgun Recoil Questions

I'm a banker, and not a scientist. I did make it through college physics - but just barely...

My questions are:

1. Does a full choke shotgun hae more "felt recoil" than the same shotgun and load, with a cylinder choke? Does the squeezing down process increase felt recoil?

2. Using the same shotgun and load, would the muzzle velocity be different between a full choke vs. a cylinder choke? Is there an effect due to the squuezing down?

3. Similarly, would a new overbore shotgun (.740") have less felt recoil than an older tight bore (.727")? Any velocity difference?

THANKS.

Jerry

1. No
2. Not much, lost in the numbers of statistics
3. A. Some , B. A tad bit less

Remember the volumn of the void as the wad leaves the hull and travels down the barrel is larger in a overbored shotgun, but not much by percentage.

I've a slightly different view than skeetex - as follows:

1 & 2. In the '20's of '30's, as I recall and have not been able to relocate the report, Remington determined that choke increased velocity at about 1 fps per 0.001" of constriction. So, a choke of 0.040" (real full) should increase MV by 40 fps over a cyl bore with all other variables held constant. If you were sensitive to recoil, you might feel a velocity increase of that amount. The "squeezing down," which seems to imply increasing pressure within the shot swarm, isn't actually a squeeze, rather the the shot accelerates as it enters the choke so as to maintain mass flow rate in the reducing area of the constricting choke. The increase in velocity is at the expense of reducing internal pressure within the shot swarm.

3. Any change in felt recoil would be due to changes in acceleration or muzzle velocity of the shot swarm. The increase in bore diameter will reduce the gas pressure on the wad base and allow the wad base skirt to flare slightly to a larger diameter, increasing its area. If the reduction of pressure and increase of area are equal by percentage, there will be no velocity change.

Post back if any of this is not clear.

DDA

What Rocketman recalls may be true for felt wads - no way to tell.

For plastic wads in identical loads in identical guns the answers would be: no, no, and no. Shotguns don't duplicate data very well anyway. The slop in the average load would overwhelm whatever diff there may be from the gun, if there was any.

And for a person to perceive the difference, of which there is none, it would require a nervous system so advanced beyond the current model that it won't be a problem for some considerable time, if ever. Of course that doesn't mean that there will not be people that will swear to the converse of any or all of the above. There are also people who attest to the tonal difference if the phase is reversed in a single speaker. I'm sure they also ride their flying pig to work.


HTH

have a day

Dr.WtS

Wanker, what difference do you attribute to felt vs plastic wads?

DDA

I suspect that your V increase is adjunct to a pressure spike as the felt wad hits a full choke and seals better increasing the net V even w/ the presumed frictional increases.

The plastic would have sealed completely, at least better, the entire bbl time (so we are told by marketing), and there consequently would be no end game pressure spike and V increase.

Absolutely none of that has any basis in empirical data and is simply my presumption. But it's prolly as right as any other BS explanation and at least not in obvious conflict w/ physics I know.

And you may address me as Dr. Your rudeness is uncalled for and unappreciated

have a day

Dr.WtS

Pretty sure he is implying that the contact areas of plastic wads go from a solid to a liquid in the presence of combustion gases and pressure that occurs in a barrel at the moment of firing. My bronze brushes and old T shirt patches give me some indication of the same.
That liquid would offer up less resistance to being blown out the end of the barrel than felt wads. Less resistance would further nullify very subtle differences that exist only theoretically to begin with.
Or, not.

Best,
Ted

I was quite good at physics. It's probably as well at this point to distinguish between the measurable recoil and "felt" recoil. This first can be calculated from velocity/ mass equations and measured in accelerometers, the latter is highly subjective and has umpteen variables.

There will be a slight increase of velocity through a tight choke over a cylinder bore, but its effect on any recoil would be I think negligible; the greatest acceleration of the shot load is accomplished in the first couple of inches of travel and that's what initiates and determines the recoil of the gun. By the time the load reaches the choke, its all over.

A bit, as above.

Not much. Again the velocity of the load is developed in the first couple of inches of travel; I don't think the downstream bore size will have any influence.

The only influence a wad could have is in its weight; the heavier it is the greater its contribution to the mass component of the equation. The difference in obturation between a felt wad and a plastic one (should it exist, which I doubt) again would not appreciably influence recoil since it would not affect the initial acceleration.

Eug

IF full choke increases velocity over cylinder bore . . . then yes, there would have to be an increase in measureable recoil. Some people might notice the difference if that increase is as much as 40 fps, as Rocketman suggests.

Re overbore, I have a 1930's Sauer 20 that weighs about 5 3/4#. It's actually a 19 from the factory, so significant overbore. To me at least, it recoils less using the same loads than other, heavier 20's I shoot. Of course there are a lot of other variables at work there: different fit, good recoil pad on the Sauer, etc.

Use KISS principle and like good Ole' Englishman buy lighter loads with less muzzle velocity (which for 12 is 1oz to 1&1/8oz at 1100 to 1200fps). The problem should go away.