Perrazi boring

[Geordieboy]

So then,

a discussion amongst shooting buddies raised a point about the bores on Perazzis.  Std boring is 18.4, but a couple of chaps I know had theirs bored out to 18.5 and 18.6, as this had the effect of reducing recoil.  Now as an engineer, either it means that the friction down the bore is reduced, or the fact that some gas is allowed to escape (reducing muzzle velocity perhaps), and thereby reducing the felt recoil.  I shoot a Miroku mk38 trap and haven't a clue what the bore is on that gun.  What are peoples opinions and experiences with this 'Overboreing' on their own guns?

Cheers

 

[Hamster]

So then,

a discussion amongst shooting buddies raised a point about the bores on Perazzis.  Std boring is 18.4, but a couple of chaps I know had theirs bored out to 18.5 and 18.6, as this had the effect of reducing recoil.  Now as an engineer, either it means that the friction down the bore is reduced, or the fact that some gas is allowed to escape (reducing muzzle velocity perhaps), and thereby reducing the felt recoil.  I shoot a Miroku mk38 trap and haven't a clue what the bore is on that gun.  What are peoples opinions and experiences with this 'Overboreing' on their own guns?

Cheers

Ask your friends whether they'd be willing to put money on a blind test. 

There may just be some mileage in arguing that one bore size or another is more conducive of better patterns  , but of course we first have to establish what better means and whether it's quantifiable in practice. Over in the US they have done before and after tests on barrels and the answer is nocando difference, same with recoil. 

Remember also that comparisons have to be carried out on guns that are identical in every aspect except bore size, this is extremely difficult to do unless you have the time and resources. In practice I simply do not for one minute believe that there is a person alive that can detect bore size differences on paper or visual breaks. 

 

[Les53]

My MX8 has 18.4 tubes, recoil is quite low. I've had overbored tubes on other guns and to be honest I've never believed that they reduce recoil. I reckon it's more of a marketing ploy than anything else to be honest. 

 

[Wonko the Sane]

Please do not do this to a perfectly good gun!

There is no, as in NO, empirical evidence of ANY kind to support the claims of anything relating to the supposed advantages of bigger bores.  And as well I've not seen any claims that were not in violation of Newton's Laws of Motion which seem to held in some regard by the scientific community.

A properly fitted gun is the path to minimum recoil, not bigger holes in the barrels.

a simple fact, not JMO and YM will not V

 

[schmokinn]

My MX8 has 18.4 tubes, recoil is quite low. I've had overbored tubes on other guns and to be honest I've never believed that they reduce recoil. I reckon it's more of a marketing ploy than anything else to be honest. 

Much as i hate to disagree with you Les i was told when enquiring about the Perazzi MX8/MX12 that bore was one of the customizable options you choose.

No choice with the MXS it is 18.5 ...+/- a thou or 2 

So then,

a discussion amongst shooting buddies raised a point about the bores on Perazzis.  Std boring is 18.4, but a couple of chaps I know had theirs bored out to 18.5 and 18.6, as this had the effect of reducing recoil.  Now as an engineer, either it means that the friction down the bore is reduced, or the fact that some gas is allowed to escape (reducing muzzle velocity perhaps), and thereby reducing the felt recoil.  I shoot a Miroku mk38 trap and haven't a clue what the bore is on that gun.  What are peoples opinions and experiences with this 'Overboreing' on their own guns?

Cheers

if its the newer type mk38 with back bored barrels it should be 18.6

 

[jwpzx9r]

Purely theoretical but if the barrels were the same weight at the out set and you then removed metal to make them 18.6mm the recoil, felt, is actually going to increase because of the increased acceleration of the gun rearward. The laws of motion dictate the movement of the gun. I have heard people say they can tell what choke they have in their gun by the recoil it makes... I really do not believe that.

Les is absolutely correct the standard bore dimension for an MX8 is 18.4mm if someone wants to deliberately ruin a tried and tested perfect barrel then I have no sympathy for them!

 

[chippy]

I was just about to like this thread, then I realized it was about barrel dimensions.

 

[Les53]

Much as i hate to disagree with you Les i was told when enquiring about the Perazzi MX8/MX12 that bore was one of the customizable options you choose.

No choice with the MXS it is 18.5 ...+/- a thou or 2 

if its the newer type mk38 with back bored barrels it should be 18.6

Mark, I've no idea if the bore size on an mx8 is open to customisation on order. I've never heard of that mate.

 

[Geordieboy]

Mark, I've no idea if the bore size on an mx8 is open to customisation on order. I've never heard of that mate.

In order to support Mark, I can confirm that if you order a Perazzi,  on the order form you can specify the bore size.  

 

[Cosmicblue]

You can even specify having a different bore size in each of the barrels if you wish!   Perazzi, unlike Browning and Miroku, don't use 'back boring' either.  When I bought my HPX John Jeffries indicated that the larger bore sizes are sometimes favoured by those that predominately shoot game with heavy shot loads.

 

[schmokinn]

Mark, I've no idea if the bore size on an mx8 is open to customisation on order. I've never heard of that mate.

When i was in Greenfeilds he ran through the whole customisation process i think he fully expected me to shell out 12 grand there and then

if you look on there site they list the bore sizes of all the Perazzi's they have in and they vary from 18.4-18.8 i was actually quite surprised myself.

 

[maddmatt]

Oh dear - can of worms time...

I have had this conversation with a very well respected and highly skilled barrel maker. You need to look at the whole picture when it comes to any advantages or disadvantages of bore size etc. Recoil is a reaction to the cartridge being fired, the cause is the build up of pressure which propels the shot down the barrel. Several factors all contribute to this pressure build up, cartridge (obvious I know), type of powder used and burn speed, crimping, this is designed to allow the powder to reach a full burn and therefore pressure, forcing cones - barrel bore and chokes all have an effect on this pressure build up and also how the reaction is felt by the shooter.

So, does over boring reduce felt recoil, probably not on its own, you need to look at the combination of cartridge, forcing cone length, barrel length and bore and choke.

 

[jwpzx9r]

To be fair there are several manufacturers who claim that back boring the barrels of a shotgun reduce the felt recoil ... personally I think its smoke and mirrors. The placebo effect can be a very powerful thing... if someone tells you it is going to be more or less some people have the ability to actually believe and notice something that does not exist... you don't have to believe me  but you can ask drug companies as well as other market research companies who are obliged to carry out studies.

With respect to back boring shotgun barrels at what point do the sporting governing bodies  say stop doing that that gun is not a twelve bore? Just because a gun uses a 12 bore cartridge and chamber dimensions are right does not make it a twelve bore by the definition of the original concept. I think all these back bored guns should be banned as oversize... perhaps its time for an absolute on the definition of what actually constitutes an acceptable shotgun bore diameter for clay target shooting... they have a stipulation for every other conceivable thing... why not bore size. A competitor can be chucked out for having a cartridge which is 100mg over mass load but another can be shooting and eleven bore? Or do I have this all wrong an the fact is bore size is irrelevant and it is only the cartridge used that defines the legality of the gun.. ie If the gun is chambered for a standard  70mm 12 bore shell its fine.. never thought about it that way.

 

[squimp]

My RSR  (MX8) has 18.4 barrels -  out of choice as it will be used regularly with fibre game loads.

My second hand MX12 has 18.7.

 

[Cosmicblue]

Wasn't the term '12 bore' based on the principle of 12 spherical lead balls that exactly fitted in the muzzle weighing 1 pound?  One of those wonderfully quaint concepts...

 

[Hamster]

To be fair there are several manufacturers who claim that back boring the barrels of a shotgun reduce the felt recoil ... personally I think its smoke and mirrors. The placebo effect can be a very powerful thing... if someone tells you it is going to be more or less some people have the ability to actually believe and notice something that does not exist... you don't have to believe me  but you can ask drug companies as well as other market research companies who are obliged to carry out studies.

With respect to back boring shotgun barrels at what point do the sporting governing bodies  say stop doing that that gun is not a twelve bore? Just because a gun uses a 12 bore cartridge and chamber dimensions are right does not make it a twelve bore by the definition of the original concept. I think all these back bored guns should be banned as oversize... perhaps its time for an absolute on the definition of what actually constitutes an acceptable shotgun bore diameter for clay target shooting... they have a stipulation for every other conceivable thing... why not bore size. A competitor can be chucked out for having a cartridge which is 100mg over mass load but another can be shooting and eleven bore? Or do I have this all wrong an the fact is bore size is irrelevant and it is only the cartridge used that defines the legality of the gun.. ie If the gun is chambered for a standard  70mm 12 bore shell its fine.. never thought about it that way.

I think as long as you use 12 gauge shells then it's a 12 bore, unless one day someone re-invents the wheel and can alter the interior profile of the barrel to give measurably better/unfair results and I don't think that's ever going to happen.

 

[Wonko the Sane]

Oh dear - can of worms time...

I have had this conversation with a very well respected and highly skilled barrel maker. You need to look at the whole picture when it comes to any advantages or disadvantages of bore size etc. Recoil is a reaction to the cartridge being fired, the cause is the build up of pressure which propels the shot down the barrel. Several factors all contribute to this pressure build up, cartridge (obvious I know), type of powder used and burn speed, crimping, this is designed to allow the powder to reach a full burn and therefore pressure, forcing cones - barrel bore and chokes all have an effect on this pressure build up and also how the reaction is felt by the shooter.

So, does over boring reduce felt recoil, probably not on its own, you need to look at the combination of cartridge, forcing cone length, barrel length and bore and choke.

All BS no matter who tells about the mythical advantages.  Ask any of the proponents for documented evidence in the form of scientifically obtained and analysed data and you will get ZIP!  That's cuz there ain't any.  From anyone.  Anywhere.

here is an actual researcher with no vested interest in a concept or product.  You'll perhaps find the recoil and bore tests illuminating

http://www.claytargettesting.com/index.html

Mr. Winston is my hero

 

[Les53]

When i was in Greenfeilds he ran through the whole customisation process i think he fully expected me to shell out 12 grand there and then

if you look on there site they list the bore sizes of all the Perazzi's they have in and they vary from 18.4-18.8 i was actually quite surprised myself.

£12k is nothing to a man of your means Mark! ???

 

[Geordieboy]

So then, as an engineer by profession I have to work with facts to come to a solution to a particular problem.  A Lack of facts means I have to source them via practical and educated means and prove out the end result.  This, has already been done for us by the articles provided by Wonko the Sane.  I didn't really think that bore size would have played a major part in recoil considering the differences were between 18.4mm and 18.6mm on a typical Perazzi.  If bores were to blame then Cylinder choke would have less recoil than full!  The explosion within the cartridge will force the walls of a plastic and fibre wad forward and outboard due to the pressure anyway so a good gas seal is attained.  Recoil it appears is down to physics and shot velocity.  The faster and heavier the shell....the larger the recoil.  Using different powders produce dynamically similar results.

So if you want a "Lightening cartridge" to reduce your lead and guarantee a smash of a clay and break it 200 yds out...use 42 gram 3's and feel the pain!!!!  Simples!