Forcing Cone Lengthening and polishing

[Davy_B]

i see Teague do this , they have it on their list of gunsmithing services . what is it ? does it make any real difference 

 

[MartynB]

I didn’t get it done in the MK 38 trap I sent to Teague Precision , I don’t personally think it makes a ha’porth of difference positively , but I’m of the opinion  ( and it’s just that  my opinion) that it might have negative impacts especially with Fibres  .

I reasoned that if Mirokus engineers  had thought that their competition gun needed longer forcing cones , they could have added it in the manufacturing process for the cost of a few pence .

On the other hand the same factory churns out Browning Pros with longer cones ... so performance benefits or marketing ? Who knows , the only thing I am certain about is that I couldn’t reverese the change if I didn’t like it. 

 

[Wonko the Sane]

The difference is the size of the Teague bank account.  

I've not seen any definitive evaluation of different length cones and personally find it beyond believing that a company like say Perazzi is so tech deficient that their guns have need of modification.  But a bewildering number of owners seem to think so and make incredible claims for the mod.  And yet Perazzi and so many other still struggle along in ignorance.  Strange, eh?

 

[schmokinn]

The difference is the size of the Teague bank account.  

I've not seen any definitive evaluation of different length cones and personally find it beyond believing that a company like say Perazzi is so tech deficient that their guns have need of modification.  But a bewildering number of owners seem to think so and make incredible claims for the mod.  And yet Perazzi and so many other still struggle along in ignorance.  Strange, eh?

A fool and his money........

 

[jwpzx9r]

The difference is the size of the Teague bank account.  

I've not seen any definitive evaluation of different length cones and personally find it beyond believing that a company like say Perazzi is so tech deficient that their guns have need of modification.  But a bewildering number of owners seem to think so and make incredible claims for the mod.  And yet Perazzi and so many other still struggle along in ignorance.  Strange, eh?

Don't know about forcing cone work BUT even Mauro is extolling how over boring is helping to reduce recoil on Perazzi's latest high tech competition gun... and if he and Perazzi say it does that is good enough for me :lol:

 

[squimp]

Nigel T doctored an old 3800 Trap for me years ago. He opened the chokes (to 12 and 16) and lengthened the forcing cones.

After that it shot really well and the recoil was fine. Whether the longer cones had anything positive to do with that, I couldn't tell you.

But the cones did used to rust on the way home from shooting -  so I got into the good habit of spraying gun cleaner down the tubes as soon as I finished shooting and then rodding the barrels as soon as I got home. 

I think more modern Miroku guns have  less rust prone barrels !

 

[MartynB]

You can have over- bored barrels and a short cone,  Miroku do that , and keep the chamber length to 2 3/4” . Where as my Lightweight receiver K80 has 3” chanbers , longer cones and “ over-bored barrels ... it makes you wonder how Lord Walshingham ever managed to shoot a squillion grouse a day with six pound side by sides loaded with an ounce and a quarter  :???:

 

[ChrisPackham]

As Martyn says i thinks its detrimental in respect of fibre wads, my game guns (18.4) and my clay gun (18.6) pattern very differently with the same degree of choke applied with the same fibre cartridges.  The patterns are much less consistent with my Beretta clay gun with many more 'fliers' (although that may suit some of the high bird guys).

I'm sure it wont be long before cartridges are all fibre wad, with this in mind i wouldn't be keen to buy an overboard gun.

 

[Hamster]

There is no question Perazzi make a quality product but to say the HiTec reduces recoil whilst giving higher velocity is simple nonsense. If they won hundreds of medals with 18.4mm barrels then there is clearly nowt wrong with their patterns either  :huh:  so how's 18.6mm going to help ?

I had the cones of my old spec 682 enlarged by hand reamers then polished while I watched  :lol:  at some British Open back in the very early 90's, it made zero difference to recoil or my scores. 

To ascertain whether overboring or enlarging the cones make a material difference to recoil or patterns you have to first conduct repeatable, exact tests then do so again after the work is done making sure the gun weights the same each time. 

If you remove metal from the cones by retro barrel work you are in fact reducing the weight of the gun so in actuality you will increase recoil, no other way round this or Newton wouldn't be so damn famous. 

Over in the states they have done before and after blind tests with recoil and found it all to be a load of old baloney, same with patterns which remained random as they should, the only things which affects patterns is shells and chokes and a dozen other variables such as air density/temperature. 

 

[MartynB]

I had the cones of my old spec 682 enlarged by hand reamers then polished while I watched  :lol:  at some British Open back in the very early 90's, it made zero difference to recoil or my scores. 

Probably around the same time,  Gunmark offered the cone service together with a spark erosion job to “ port “ the barrels. I sent a very nice 687 sporter and turned it into a noisy gun with long forcing cones. Thank goodness I stopped reading magazines and  “ expert “ reviews in particular .    But give a boy a toy and a credit card , that’s why they invented race exhausts for motorbikes , £800 fly rods ,  Chronograph watches that work 2 miles under water and all the rest .... 

 

[jwpzx9r]

Yeh but no but yeh but, in some sort of SW England accent :lol:  

Perazzi recognise this and added weight to the action before the ripped it out of the barrels !?!? So if Mauro says it works ... it does OK :lol:

" that’s why they invented race exhausts for motorbikes ," ... but they unquestionably work so why give them a mention?

 

[schmokinn]

Yeh but no but yeh but, in some sort of SW England accent :lol:  

Perazzi recognise this and added weight to the action before the ripped it out of the barrels !?!? So if Mauro says it works ... it does OK :lol:

" that’s why they invented race exhausts for motorbikes ," ... but they unquestionably work so why give them a mention?

" that’s why they invented race exhausts for motorbikes ," ... but they unquestionably work so why give them a mention?



In my experience not unquestionably,some have actually produced less power or completely ruined power delivery when used on their own,depends on state of tune of engine,jetting,timing etc
So a bit like forcing cones,back boring,porting,etc in some specific set of circumstances they may work....certainly not unquestionably!

 

[jwpzx9r]

" that’s why they invented race exhausts for motorbikes ," ... but they unquestionably work so why give them a mention?



In my experience not unquestionably,some have actually produced less power or completely ruined power delivery when used on their own,depends on state of tune of engine,jetting,timing etc
So a bit like forcing cones,back boring,porting,etc in some specific set of circumstances they may work....certainly not unquestionably!

Your experience means nothing actually. If they did not work Honda, Yamaha, Suzuke etal would not be spending collectively many hundreds of thousand of pounds annually on developing said items for their motor cycles. You can even go and ask Vale himself if exhaust tuning actually works... he can not only feel the difference he can make it work too :lol:

 

[MartynB]

" that’s why they invented race exhausts for motorbikes ," ... but they unquestionably work so why give them a mention?  

Because in real life they don’t all unquestionably work , and/or give a real world ben

Absolutely :  perhaps  for the pedantic   I should have said aftermarket “ race exhausts “ for street bikes . I have spent enough money on shiny  bike bits in my life to know that there are many “ race cans “ that do no more than make a noise, but us boys will be boys. 

 

[jwpzx9r]

Absolutely :  perhaps  for the pedantic   I should have said aftermarket “ race exhausts “ for street bikes . I have spent enough money on shiny  bike bits in my life to know that there are many “ race cans “ that do no more than make a noise, but us boys will be boys. 

Even after market exhausts work if you buy the correct type and manufacturer, what is more the modern motorcycle can actually better use the aftermarket exhaust system... just ask world superbike race teams who many of use the very same bolted on to their own race bikes. Yes in days gone by some systems were crap but I think to a great extent the better systems and the bikes they fit are much better today and can better use them.

 

[schmokinn]

Your experience means nothing actually. If they did not work Honda, Yamaha, Suzuke etal would not be spending collectively many hundreds of thousand of pounds annually on developing said items for their motor cycles. You can even go and ask Vale himself if exhaust tuning actually works... he can not only feel the difference he can make it work too :lol:

In that case yours opinion means F all too and as 4 Vale that is a specific set of circumstances...95% plus of "race" exhausts are sold to the general public for road use.

Some work some don't but most need some other fettling to get the best from them.

So i go several 350lc,s in various states of tune up to a totally loopy one with some massive lomas expansions that did nothing till about 6500 and then made things blur ,Rg500,Fzr600,750,1000 a couple of gixers and some other stuff...whats your motorcycle experience?

 

[westley]

Nigel T doctored an old 3800 Trap for me years ago. He opened the chokes (to 12 and 16) and lengthened the forcing cones.

After that it shot really well and the recoil was fine. Whether the longer cones had anything positive to do with that, I couldn't tell you.

But the cones did used to rust on the way home from shooting -  so I got into the good habit of spraying gun cleaner down the tubes as soon as I finished shooting and then rodding the barrels as soon as I got home. 

I think more modern Miroku guns have  less rust prone barrels !

THAT was simply the 3800 barrel rusting process, it was built into that model by Miroku  !!

 

[jwpzx9r]

Well

straight off

KH250, then KH650,KHZ1000J1,KHGPZ1100B2,KHGPZX1100, YamahaXT550,Kwasaki ZZR1100, KawasakiZX9R,Honda Fireblade 929RRY and now BMW1200 GS plus a lot of brit bitsas before all of them. But the point still stands I have never had an after market exhaust that did nothing when used properly yes some did need a bit of induction work but now most of they modern sports bikes can uses these things straight off the shelf and change things for a considerable better... the weight saving alone is worth something on its own. The thing about Vale is the most pertainant part of the equation... 99% of road going motorcycle riders do not have the ability to even sense what they are getting they rely on a computer print out telling them ! :lol:

 

[Wonko the Sane]

Not having had a motorcycle now for near 20yrs I can't comment on the current world of exhaust systems.  Fortunately for me I finally realized I was simply too stupid to have a motorcycle.  I was beginning to worry about you, John.  You bin missing.

As to the new Perazzi configurations I believe the situation is quite simple.  Mauro, no fool he, is tapping into the hype of several fads at once.  IMHO the MX8 based guns were in no need of anything.  But market forces being perceived as they are I'm guessing that Perazzi without the guiding hand of Daniele felt compelled to join in.  NBD to me, I got mine and feel no need to "move up".

BTW any of that barrel work, re-proofed or not, also removes entirely the warranty.  Besta luck