Perazzi Back Boring

[timps]

The US and British army have done extensive research papers with defence spending budgets on it and  having read some of the papers on it and seen the patents issued to try and deal with the problem I am 100% confident on the 2nd recoil.

Regarding the choke the physics is quite simple, 28g slowing down a little might at that moment in time reduce the primary recoil however you would have to work out the momentum change being offset by the increase in pressure overcoming the increase in friction.

But one thing is for certain the increase in pressure and the difference between the diameter of the barrel and the reduced diameter of the tighter choke increase the acceleration of the gas considerably once it is exposed to atmospheric pressure therefore increasing the second recoil. Giovanni Battista Venturi wrote a law about choke on gas flow, the gas will accelerate more hence more force.

Whether anyone can feel this increase on a shotgun is a whole other matter that I can neither prove or disprove but then again I never claim otherwise.

 

[CharlesP]

I'm still hugely enjoying the concept of "Hogwarts Physics", and I rejoice that it is alive and well on this forum.

Can we do the one about barrel length next?

 

[FlyingTrotter]

My Perazzi MX12’s are both stamped 18.5 and that wasn’t because I specified non-standard so if Mauro feels 18.6 are best and he felt that 3 years ago I’m a little confused as to why mine are 18.5 unless this is all a lot more random than the marketing suggests 

anyway 30 inch barrels fixed choke 3/8 and 5/8 - fitted for me and no issues with felt recoil even with 34g HpE in #4 so it’s not a concern just a point of interest 

A  poster earlier suggested MX12’s are out there on the used market from 18.4 to 18.7 so maybe it is more random?

 

[Wonko the Sane]

The US and British army have done extensive research papers with defence spending budgets on it and  having read some of the papers on it and seen the patents issued to try and deal with the problem I am 100% confident on the 2nd recoil.

Regarding the choke the physics is quite simple, 28g slowing down a little might at that moment in time reduce the primary recoil however you would have to work out the momentum change being offset by the increase in pressure overcoming the increase in friction.

But one thing is for certain the increase in pressure and the difference between the diameter of the barrel and the reduced diameter of the tighter choke increase the acceleration of the gas considerably once it is exposed to atmospheric pressure therefore increasing the second recoil. Giovanni Battista Venturi wrote a law about choke on gas flow, the gas will accelerate more hence more force.

Whether anyone can feel this increase on a shotgun is a whole other matter that I can neither prove or disprove but then again I never claim otherwise.

Post ejecta pressure falloff is so precipitous in a shotgun that the "second is recoil" is likely so miniscule as to be non-existent.  Cannons are different.

And JIC it was not noticed, the shot column/wad thing is not a gas.  It is particulate and I suspect that it will slow in response to an impediment.  Again, the likelihood of any significant difference in v would be probably be difficult to document what with the rather large range in v's from a single box of carts.

 

[Westward]

My Perazzi MX12’s are both stamped 18.5 and that wasn’t because I specified non-standard so if Mauro feels 18.6 are best and he felt that 3 years ago I’m a little confused as to why mine are 18.5 unless this is all a lot more random than the marketing suggests 

anyway 30 inch barrels fixed choke 3/8 and 5/8 - fitted for me and no issues with felt recoil even with 34g HpE in #4 so it’s not a concern just a point of interest 

A  poster earlier suggested MX12’s are out there on the used market from 18.4 to 18.7 so maybe it is more random?

18.5 is 0.1mm less than the nominal and the barrelset wouldn't be released for sale unless within tolerance. I doubt if anyone, not even Neil Winston, would be able to detect any difference in performance from 18.6.

 

[Will Hewland]

Here’s a idea. Let’s remove the words Perazzi and Back from the title of this thread. 

 

[timps]

Post ejecta pressure falloff is so precipitous in a shotgun that the "second is recoil" is likely so miniscule as to be non-existent.  Cannons are different.

And JIC it was not noticed, the shot column/wad thing is not a gas.  It is particulate and I suspect that it will slow in response to an impediment.  Again, the likelihood of any significant difference in v would be probably be difficult to document what with the rather large range in v's from a single box of carts.

[SIZE=11pt]Hence why in every post I write on the subject I say the same thing that I doubt anyone can feel it with shotgun pressures. [/SIZE]

[SIZE=11pt]But it doesn’t alter the physics involved, that is sound, if it works for a cannon and it works for a high powered sniper rifles which the army  research has proven  then it also works for a shot gun. [/SIZE]

[SIZE=11pt]The only difference which I have said in my opening post and every post I’ve ever written on the subject is with shotgun pressures it doesn’t really matter as it’s insignificant  but the difference in recoil however small still exists. [/SIZE]

[SIZE=11pt]Like I have always said it’s a marketing tool based on half truths but the physics backs it up, the op was asking why someone would try and claim it works so I answered. [/SIZE]

[SIZE=11pt]The only reason I comment is I spent too much of my young life In Salford University physics lectures and now run a laboratory. Heck it was boring hence why I boxed and raced motorcycles for fun but now I’m older I appreciate the science more so have fun debating it.  [/SIZE]

[SIZE=11pt]Simple fact Physics proves it works but seriously save your money it isn’t going to make a difference at shotgun pressures. [/SIZE]

[SIZE=11pt]But it’s sure fun to debate showing my age now [/SIZE]

[SIZE=11pt] [/SIZE]

 

[Salopian]

Timps , I didn't realise you were a Boxer ! I'd got you down as being a Laboratorydor.

Yes I'm bored too.

So should we be saying that a Beretta DT11 is really just an expensive experiment without any significant benefit?

 

[Jonny English]

There is no doubt the dt11 can be smooth to shoot, many people have noted it.

So we could add to the argument other factors, other than cartridge strength that can affect perceived recoil, such as shotgun fit, pitch, gun weight, horizontal line of force compared to butt pad etc etc that can probably all have a greater effect.

 

[Finners]

There is no doubt the dt11 can be smooth to shoot, many people have noted it.

So we could add to the argument other factors, other than cartridge strength that can affect perceived recoil, such as shotgun fit, pitch, gun weight, horizontal line of force compared to butt pad etc etc that can probably all have a greater effect.

In my experience, absolutely yes. 

 

[Will Hewland]

My DT11 exhibited incredibly low recoil, but I just put that down to it weighing 17lbs. 

 

[Geordieboy]

I've opened the can again haven't I??? 

 

[squimp]

If a full fat (as in nearly 9lb) DT11 recoils (make that 'appears' to recoil) less than a 'normal'  gun, then what happens when you take a DT11 barrel and build a gun that only weighs 8lb - 8lb 4oz ?

Such a gun exists and is called a DT11 Black Edition.....Has anybody who is recoil sensitive shot one and if so, how did it perform/feel...….?

 

[Hamster]

If a full fat (as in nearly 9lb) DT11 recoils (make that 'appears' to recoil) less than a 'normal'  gun, then what happens when you take a DT11 barrel and build a gun that only weighs 8lb - 8lb 4oz ?

Such a gun exists and is called a DT11 Black Edition.....Has anybody who is recoil sensitive shot one and if so, how did it perform/feel...….?

That's a little like asking what's your favourite diet cola, it's all subjective. Absolute recoil is measurable, you can make a jig that provides solid data as to how much a gun with a given weight moves backwards (and its barrels upwards) with a given shell and shot load  - it can even be made sophisticated enough to either fire the gun with an electric pulse or at least take the trigger poundage into account as well. 

What you can't do is to then assume that that translates into "felt" or perceived recoil for everyone, fast recoil pulse cartridges for instance can "feel" soft even if in absolute terms a slower shell registers lower actual recoil on a jig. 

 

[Jonny English]

I have just gone in to a dt11L 32 inch sporter, which was supposed to weigh a metric tonnes.

Barrels weigh 1543 grams

Forend 315 grams

Action and fixed stock 1822 grams

Plus 60 grams of the possible 140g of b-fast weights

Total all up weight of 3.74 kg or just about 8lb 4 oz

The recoil isn't non existent, maybe a little less than my Browning of similar weight, but the recoil impulse is definitely different.

 

[jwpzx9r]

I have just gone in to a dt11L 32 inch sporter, which was supposed to weigh a metric tonnes.

Barrels weigh 1543 grams

Forend 315 grams

Action and fixed stock 1822 grams

Plus 60 grams of the possible 140g of b-fast weights

Total all up weight of 3.74 kg or just about 8lb 4 oz

The recoil isn't non existent, maybe a little less than my Browning of similar weight, but the recoil impulse is definitely different.

Funny about the weight thing my MX8... not a gun that gets called heavy comes in at 3.950Kg

barrels 1550g

forend 436g and

 action plus stock 1964g for a total of 3.950Kg or 8lbs 11.3 ozs and I never have any problems with recoil at all

 

[squimp]

That's a little like asking what's your favourite diet cola, it's all subjective. Absolute recoil is measurable, you can make a jig that provides solid data as to how much a gun with a given weight moves backwards (and its barrels upwards) with a given shell and shot load  - it can even be made sophisticated enough to either fire the gun with an electric pulse or at least take the trigger poundage into account as well. 

What you can't do is to then assume that that translates into "felt" or perceived recoil for everyone, fast recoil pulse cartridges for instance can "feel" soft even if in absolute terms a slower shell registers lower actual recoil on a jig. 

I accept all that.

So why doesn’t some body who is independent, do the jig experiment and test whether DT11 barrels or Hi Tech actions  etc etc actually do make a difference. If us mere shooters can’t tell the difference maybe we need a machine to lead us in the right direction....remember when we used to shoot 36g Fitasc loads all day long !

Presumably mr Beretta and Mr Perazzi have done these experiments - otherwise it is all really just an exercise in marketing.

i should declare an interest here - I am very recoil sensitive and want a gun that isn’t too heavy (no more than 8lb 4 oz) but has minimal perceived (by me!) recoil. And before anybody asks; yes I have my gun fitted and yes I use good (Isis) recoil reduction systems and I shoot light cartridges.......

 

[Hamster]

I accept all that.

So why doesn’t some body who is independent, do the jig experiment and test whether DT11 barrels or Hi Tech actions  etc etc actually do make a difference. If us mere shooters can’t tell the difference maybe we need a machine to lead us in the right direction....remember when we used to shoot 36g Fitasc loads all day long !

Presumably mr Beretta and Mr Perazzi have done these experiments - otherwise it is all really just an exercise in marketing.

i should declare an interest here - I am very recoil sensitive and want a gun that isn’t too heavy (no more than 8lb 4 oz) but has minimal perceived (by me!) recoil. And before anybody asks; yes I have my gun fitted and yes I use good (Isis) recoil reduction systems and I shoot light cartridges.......

Well obviously B, P or K wouldn't bother for a start because they know it's all a load of marketing baloney and since such a contraption would probably be fairly expensive it's not going to be something that an ordinary shooter or independent body would consider. When it comes to recoil trouble the most important things (by a country mile) are gun weight, sensible shells, sensible pad or better still a mechanical reducer and of course at least moderately good "fit", the latter is often touted as THE most important factor, usually by those who don't suffer recoil I might add  , in my (also recoil sensitive) and fairly expansive experience, it's probably a solid number 4 - factors like bore diameter are probably into double digits  hence why I have always tried to hussle talk people into a bet.    

 

[Wonko the Sane]

http://www.claytargettesting.com/study2/pages/study2a.html

http://www.claytargettesting.com/Bore_Diameter/Bore_Diameter.pdf

Posting these links for the severalth time.  Perhaps someone will eventually bother to read them.

 

[squimp]

Thanks for the links. I wasn’t aware of that data source. Very interesting stuff and also somewhat chastening !