Back boring or long forcing cone barrels

[RobertBeard]

What is the difference or is it just a different name by a different manufacturer?

I have heard about the Beretta 692 and DT11 and their long forcing cones and a potential problem with fibre wads.

What about back boring which I believe is done to Brownings and to Miroku's? Does this affect their ability to shoot fibre?

I shoot at a club that is fibre only should this make me want to avoid long forcing cones or even back bored guns?

I'm no doubt nowhere near good enough to understand or tell myself through shooting so I'm trying to avoid buying something and then having to change it later.

Perhaps I need something to shoot fibre and something else to shoot plastic.

Any advice would be welcome.

 

[Jonny English]

My 525 is supposed to be back bored to 18.8mm but the barrels say 18.7mm and it shoots fibres just fine, like emmsy said you can sometimes need to go 1/4 of a choke tighter. I've had no problems with any fibres apart from a bit of lead fouling in the barrels.

 

[androu]

Long forcing cones first and secondly backbored barrels do help , especially in recoil reduction and patterns.

My experience says that after lengthening the forcing cones on a browning ultra xtr , the gun was definitely improved , especially in the recoil department.

John

 

[Iggy]

From a technical point of view I believe 'back boring' is done aftermarket on standard bores to lengthen the cones whereas 'over bored' or lengthened forcing cones etc are factory done.....although I could be wrong of course....

When I think about it, having only been shooting a few years I don't think I've ever had a 'standard gun that wasn't either over bored or had longer cones from the factory so I've nothing to compare it to from a performance point of view. I also never shoot fibres so can't comment there either.

What I can say is that moving to the 692 recently has allowed me to start using 28g shells for the first time since taking up shooting as from a recoil perspective it feels like shooting my previous gun with 24g shells. Wether this is attributable to the longer forcing cones or not I've no idea, but something's happening somewhere and my scores have increased.

 

[maddmatt]

Forcing cones and back boring are different things, back boring is the process of increasing the bore diameter greater then the 0.729 inches of a standard 12 bore. Forcing cones are designed to 'force' the wad and shot down to the bore diameter, this action also ensures the gas seals behind the wad and also builds breech pressure to push the wad/shot out through the barrels.

Lengthening the forcing cones will not have any effect on fibre cartridges, all it does is, give the wad/shot an easier journey through the forcing cone into the bore. If you have a gun with lengthened forcing cones AND back bored barrels (also known as over bored), the overal effect is less felt recoil, reduced muzzle flip* and generally more consistent patterns.

* if this is a problem you may to get your gun fit checked, could be a pitch, length of pull and comb drop issue, usually its a mix of all of those

 

[squimp]

It sounds like you have an analytical mind set like me !

I'm trying to stop worrying about this sort of thing and concentrate on where I point the gun.

FWIW I shoot a Perazzi with over bored 18.7 barrels and have NO problems with fibre wad cartridges (even 21g) - heavy game shells in mid Winter aren't an issue either.

Unless you are an 'AA' shot or better; point it in the right place and the target will break. regardless.

Hope this helps.

 

[Gene Holmes]

My 525 is supposed to be back bored to 18.8mm but the barrels say 18.7mm and it shoots fibres just fine, like emmsy said you can sometimes need to go 1/4 of a choke tighter. I've had no problems with any fibres apart from a bit of lead fouling in the barrels.

Shoot fibre most of the time with my 525 and never had a problem, but then again, I'm new to this so what do I know.

I do see the lead fouling in the chambers thou.

 

[Wonko the Sane]

Been there, done that, could tell no difference whatsoever.  There is no empirical evidence of any kind and never has been to support the contentions put forth by the barrel butchers.  The factory pandering to the fad is nothing more than that.  Porting, back boring, lengthening forcing cones cannot defy the laws of physics and in the real world only move money from one pocket to another.  Even in the ATA (Fad Inc.) the rep for the mods is down bigtime.

And, among the OT crowd it has become a mantra that the old 0.724" bores "hit harder".  Which is as well a case of Hogwarts physics, but go figure.

And the comment about nothing new is spot on - there were "long range chamberless" 0.800 bore fowling guns the turn of the 20th Century.  So if it was such a killer idea it had a 100 yrs to catch on and didn't really.  I wonder why.

Charlie

 

[Hamster]

There is no empirical evidence of any kind and never has been to support the contentions put forth by the barrel butchers.  The factory pandering to the fad is nothing more than that.  Porting, back boring, lengthening forcing cones cannot defy the laws of physics and in the real world only move money from one pocket to another.  Even in the ATA (Fad Inc.) the rep for the mods is down bigtime.

Charlie

:friends:  No quantifiable evidence ever. Newton's Law must be broken in order to reduce recoil by enlarging forcing cones. Removing metal from the cones will decrease the guns weight so if anything in a before and after test it WILL increase recoil. 

 

[RobertBeard]

Thank you all for the comments so far.  To take my aspirations further I suppose I hanker for a DT11 but think it might be a bit heavy and a 692 might be a very good alternative.

Then I hear about issues with fibre with these sort of guns so think I don't want to pay all that money and find that fibre won't go so well as I belong to a fibre club.  Then I gather that Browning and Miroku have back bored barrels as standard - is that true or false?  Will this also be a problem with fibre?

I just want, when I buy a dearer gun, to get it right first time provided that I get it right on fit and balance.  I don't want to then find that I should have bought something else if I shoot as much fibre as plastic.

Mind you the way that grounds seem to be likely to close in the South West I might be shooting even more fibre with fewer registered comp shooting grounds around in future.

I like to know the technicalities and understand them and buy accordingly but am happy to then forget about them and just shoot.  I am not anal or an anorak over these issues but just want an understanding so that I can then make an informed decision, purchase and then move on.

 

[ips]

Buy a dt10 or a perazzi job done.

Buy something else by all means but you know full well that you will eventually end up with one of the above so save yourself the unnecessary expense of trials.

692 looks very very nice but thus far un tested. Dt11 has not taken off anything like what beretta expected and that is a fact which i won't elaborate on because i can't be arsed with another round in the ring with you know who but its a fact end of.

Edited because of dodgy mobile predictive text. Bloody technology.

 

[Gene Holmes]

Thank you all for the comments so far. To take my aspirations further I suppose I hanker for a DT11 but think it might be a bit heavy and a 692 might be a very good alternative.

Then I hear about issues with fibre with these sort of guns so think I don't want to pay all that money and find that fibre won't go so well as I belong to a fibre club. Then I gather that Browning and Miroku have back bored barrels as standard - is that true or false? Will this also be a problem with fibre?

I just want, when I buy a dearer gun, to get it right first time provided that I get it right on fit and balance. I don't want to then find that I should have bought something else if I shoot as much fibre as plastic.

Mind you the way that grounds seem to be likely to close in the South West I might be shooting even more fibre with fewer registered comp shooting grounds around in future.

I like to know the technicalities and understand them and buy accordingly but am happy to then forget about them and just shoot. I am not anal or an anorak over these issues but just want an understanding so that I can then make an informed decision, purchase and then move on.

I have a 7 month old B525, back bored as standard. Also go regularly to a club which is fibre only. No problems at all

 

[Salopian]

Could one of the resident experts on ballistics please explain how the sub-gauge adaptors work !

 That will be really interesting listening to them explain about obturation and wad expansion of a .410 cartridge being fired in a 12 gauge barrel or even a 20 gauge.!

I look forward to the replies with wonder and excitement.

 

[Skeet UK]

Could one of the resident experts on ballistics please explain how the sub-gauge adaptors work !

 That will be really interesting listening to them explain about obturation and wad expansion of a .410 cartridge being fired in a 12 gauge barrel or even a 20 gauge.!

I look forward to the replies with wonder and excitement.

Any projectile / charge combo, will have an optimum barrel length that it requires to fully utilise the available gases and enable to to reach its maximum velocity. 

For example, in a .68 calibre paintball gun, a barrel length of 8 inches is required to allow the paintball to be accelerated to 300 fps.  Longer than that at true bore, will reduce the speed due to friction. Barrels of this type are usually longer than 8 inches, but the remaining portion is of a larger bore.

With a shotgun, the same rules will apply, but as to what that required length would be, one can only guess.  The adapters you mention are are usually very short, so one suspects that a certain loss of velocity will result.  As to premature opening of the wad, or expanding into the larger bore, again one can only guess, but I should think that a much smaller wad could not expand laterally to 12g size and I further suspect that the "free air" within the barrel section, is much kinder to the petals of the wad, than the air upon exit. 

A shotgun cartridge has an advantage over a conventional centrefire round, as the crimp on the shotgun cartridge is designed to retain the pressure much longer than with the centrefire round.

I should think that velocity overall would be reduced,  but that patterns are not greatly affected.

Full length tube sets, should offer no reduction in velocity.

The comparison between back bored barrels, or extended forcing cones and gauge adapters, is probably not a fair example as we are talking about much larger areas of bypass around the shot charge, with gauge adapters.

 

[jwpzx9r]

Buy a dt10 or a perazzi job done.

Buy something else by all means but you know full well that you will eventually end up with one of the above so save yourself the unnecessary expense of trials.

692 looks very very nice but thus far un tested. Dt11 has not taken off anything like what beretta expected and that is a fact which i won't elaborate on because i can't be arsed with another round in the ring with you know who but its a fact end of.

Edited because of dodgy mobile predictive text. Bloody technology.

Interesting ips. I was shooting at the weekend and a Perazzi shooter asked about my gun as he was looking to buy one. I let him shoot it for a round of UT and I used his. He shot well 23 for a first time use of an unaltered gun. We spoke afterwards and I will say that my French is not great but the jist of his observation of the Browning was it recoiled less than the Perazzi and handled great he is impressed and is definitely buying one! I thought the Perazzi was just that bit lighter than the Browning which I did not like as it did recoil more and I don't think it swung as well? I did like the way the Perazzi opened it was not lose by any means but it just fell open! I would not be rushing out to spend a lot of money on a Perazzi I just did not think it was that good but I am new to the game so who knows On the Beretta front may be that at the moment there is less money around to spend on £7k + guns go back to 2002-7 and there was loads of it about!

 

[Les53]

Interesting ips. I was shooting at the weekend and a Perazzi shooter asked about my gun as he was looking to buy one. I let him shoot it for a round of UT and I used his. He shot well 23 for a first time use of an unaltered gun. We spoke afterwards and I will say that my French is not great but the jist of his observation of the Browning was it recoiled less than the Perazzi and handled great he is impressed and is definitely buying one! I thought the Perazzi was just that bit lighter than the Browning which I did not like as it did recoil more and I don't think it swung as well? I did like the way the Perazzi opened it was not lose by any means but it just fell open! I would not be rushing out to spend a lot of money on a Perazzi I just did not think it was that good but I am new to the game so who knows On the Beretta front may be that at the moment there is less money around to spend on £7k + guns go back to 2002-7 and there was loads of it about!

Perazzi's tend to losen up pretty fast in comparison to Browning/Mirook, well all mine did anyway. As for the weight, well in most makes of gun you could pick up two more or less identical guns from a rack and find that one feels heavier than the other. This can be due to balance, or they may actually weigh different amounts. As for recoil, well weight and stock dimemsions both play a big part in things as you know. My 3800 weighs exactly the same as my last Perazzi did, but the MX8 felt much heavier, it must have been down to balance I guess. As for all this back boring stuff, well my old 3800 has old fashioned tubes and the MK38 has the back bored things and is heavier, but to be honest they both recoil the same as far as I'm concerned. :yes:

 

[Jason Mclean]

Just thought I would add to this.

I have a DT11 32 barrels only had it a short time but very pleased with its performance! Not tried fibre yet but don't normally shoot anywhere that require them.

It was doing a fine job today at Ian Coley's SG smashing them into tiny bits!

 

[PhilS]

Both my 525  and MK38 have back bored barrels and both cope with fibre wad perfectly well. 

It is the numpty behind the gun that can't seem to hit 'em all!

 

[PhilS]

Buy a dt10 or a perazzi job done.

Buy something else by all means but you know full well that you will eventually end up with one of the above so save yourself the unnecessary expense of trials.

692 looks very very nice but thus far un tested. Dt11 has not taken off anything like what beretta expected and that is a fact which i won't elaborate on because i can't be arsed with another round in the ring with you know who but its a fact end of.

Edited because of dodgy mobile predictive text. Bloody technology.

Ha!

you know Browning/Mirook is the way to go..................admit it..........