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 Post subject: Why do I hate the back bore
PostPosted: Thu Feb 13, 2020 1:04 pm 
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Joined: Sat Jun 01, 2019 3:38 pm
Posts: 69
Hello!

I could also title this my post like
why do you guys like the back bore?

I've had an SX3 and it was soft shooting. Some shells like Win SuperX were disaster for this shotgun while one of my buddies was shooting same shells out of his Baikal mp-153 just OK. His ducks were dropping, my ducks were just losing some feathers then giggling and flying away. I also tried to shoot some Brownings, to name it A5 and Maxxus -those were also kicking less.
SO, what's the matter?
Given same batch of shot shells, similar buttstocks and no shock absorbers, how come one gun can shoot softer than the other? The powder energy has to go somewhere to lesser the kick back, right? Here is my answer:
The standard bore diameter for 12ga is 18.5 mm, so the shell makers have to sticks with this numbers to make shells which would works equally good for all or most shotguns.
I.e. Beretta 390, Benelli and Baikal have 18.4 mm bore which makes even more sealing between barrel wall and wad. Just like in case of combustion engine, better sealing yelds better performance, the powder generates more pressure and burns cleaner as a result. Browning, Winchester are back bored 18.8 mm which is +0.3mm(!) over the standard. While it might help with shot patterning it can work not very well with some cheaper shots like Win SuperX and similar due to cheap wad with very minimalist or nearly non-existent skirt. In some cases this can even lead to gas leaks and pressure drops which can result in poor shot performance. This is one of reasons why I've been seeing unburnt powder particles inside the SX3's barrel more often than inside Baikal, Benelli or Beretta's. Especially for steel shot ammo which known to have slower burning powders. I've tried multiple shot brands. Some shot brands worked slightly better for that SX3 than the others. I was picking the spent wads, inspecting them then saw that those wads which were having slightly thinner and longer skirt which was helping to open wider enough to seal the 0.3mm excess of the back bore diameter were the ones delivering better results.
I realize that most of North American shotgun shooters hunt waterfowls over decoys which is usually 25..30yds max distance. I can also see that many people do not mind to spend extra on buying the expensive 3.5" 'candles' such as "Black Cloud" to ensure being properly gunned, shoot and stay happy. The short distance and super magnum shot shells cure the disadvantages of the back bored shot guns, so who cares...
BUT, look at this guy from Manitoba
https://youtu.be/_9OO7qoN52o
- he shoots Beretta A300:
"I am using a Trulock extended ported SKI hunting choke, which is 0.005" constriction. I find that the centre core of the pattern stays really uniform out to past 30-35 yds, so I am not afraid to take farther birds with it, but on anything less than 25 yds, the pattern is thin enough not to turn the birds into hamburger, and your percentage of kills goes way up."
So, do we really need back bore to improve our patterns?..
Do not be shy to check out some other videos on his YouTube channel. :)
I enjoy his channel. Warren Hicks is one of smartest among the gunned canadian rednecks.
Especially watch his earlier pre-2017 videos. It looks like some ammo businesses have finally engaged him for promotions. Warren used to shoot only the cheapest Canada made 2-3/4" ammo plus some his custom reloads. Now you can see him featuring bigger expensive brands in his videos.
Here he uses his favorite steel shot which is ... 7/8oz 1635fps in 2-3/4" shell - dig his comments under some of his early videos.
https://youtu.be/-zb_0-Zf58k
So, do I really need that back bore and 3.5" roman candles? Seriously?..

At the end let's sum it up and see why those back bore barrels are "soft shooting":
Let's take
18.8mm bore and 26" length yeld 203.342 cubic centimeters
and
18.4mm bore and 26" length yeld 175.603 cubic centimeters
-- the difference is nearly 28 cub.cm, which is frigging +16% volume increase against 18.4 bore! And bigger volume yelds lower pressure, which doesn't help powder to burn, especially the slow ones (steel shots).
And I've already mentioned the possibility of leaks, when gases blow around the wad which creates even more disaster.

So, finally I've decided to dismiss the back bore for myself. The SX3 which has never pleased me has been sold. Now I'm happy owner of couple of Berettas, Baikal and Benelli.
Well, I own a Browning also, but it is a BPS in 10ga and no back bore :)

Now tell me, what do you think guys?




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 Post subject: Re: Why do I hate the back bore
PostPosted: Thu Feb 13, 2020 1:47 pm 
Crown Grade

Joined: Thu Dec 05, 2013 7:11 am
Posts: 4083
Location: Western Tampa, FL
IMO a larger ID bore can only cause lower pressures and lower velocity if all other factors such as the shells are the same. Yet I know that Stan Baker used to make a lot of Baker Big Bore barrels and there were various claims as to the velocity actually increasing due his over bore size barrels. Don't know how that was possible but then I am no expert. I remain unconvinced that it is possible.

Recoil lessens with the back bored or over bored barrels because velocity drops. Same as shooting slower shells. Not difficult to understand. I think back boring of barrels should be used to lighten the barrel weight for balance and handling purposes. As for patterns or any other reason, I am not convinced they are as effective as better quality ammo.


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 Post subject: Re: Why do I hate the back bore
PostPosted: Thu Feb 13, 2020 1:51 pm 
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Joined: Thu Jul 15, 2004 1:56 pm
Posts: 1119
I think Tom Roster made tests showing lower velocities as a result of backboring. The larger bore is going to increase volume of the combustion area which will reduce pressure, and that could account for the decreased velocity, I suppose. Also, some shooters have noted more problems will low pressure blooper loads in light shells with light charges of powder with backbored barrels. So there could be something to it, that there could be issues with the over sized barrels. All in all, I suspect that someone deciding to make the bore larger to fix some problem was actually working on a problem that did not have to be worked on at all.


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 Post subject: Re: Why do I hate the back bore
PostPosted: Thu Feb 13, 2020 1:59 pm 
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Joined: Sat Jun 01, 2019 3:38 pm
Posts: 69
oyeme
of course I meant having same shells for comparison.
Back boirng to lighten barrel weight doesn't sound like reasonable approach to me. Because you gonna have thinner barrel walls which is dangerous thing. If the wall thickness is to be same, then you end up having heavier barrel. The easier way to have fast swinging barrel is to simply shorten it.

The velocity increase inside bigger bore can be only for a bigger size shots. I.e. BBB, T etc. Because big diameter pellets create more friction inside smaller diameter barrel, so the back bore may be lowering those friction forces. There is too many variables here: shot size, wad, powder, choke tube and more.
So I wouldn't fully trust Stan Baker not knowing all the details for sure.


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 Post subject: Re: Why do I hate the back bore
PostPosted: Thu Feb 13, 2020 4:27 pm 
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The mythology of shotgunning is hard to unwind.

No reason to hate back-boring. No reason to attribute magical powers to it either.

_________________
Nsca # 540300. Been loving this game since 01.

Our prentice Tom may now refuse
To wipe his scoundrel master's shoes
For now he's free to sing and play
O'er the hills and far away.


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 Post subject: Re: Why do I hate the back bore
PostPosted: Thu Feb 13, 2020 4:48 pm 
Diamond Grade

Joined: Mon Mar 07, 2005 7:12 pm
Posts: 1294
Location: South east Michigan
I would think only .010 or .020 over bore would have very minimum affect on velocity.
Like 2 or 3%
Browning seems to use a lot of over bore . My new Beretta 694 has tapered forcing cones that go halfway down the barrel . I would think manufacturer’s would not handicap there
Products .

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 Post subject: Re: Why do I hate the back bore
PostPosted: Thu Feb 13, 2020 4:55 pm 
Tournament Grade

Joined: Thu Sep 29, 2011 8:27 pm
Posts: 292
Location: Kentucky
Interesting.


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 Post subject: Re: Why do I hate the back bore
PostPosted: Thu Feb 13, 2020 8:00 pm 
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Joined: Sat Jun 01, 2019 3:38 pm
Posts: 69
My a400 has 18.6mm bore and it works well.
+0.1mm over the 12ga 18.5mm standard seems to be acceptable and works good. . I've been even checking penetration using flat piece of wood at 40yds, 3" #2 steel shot. against my a390 using same shot and similar choke tube (both tubes are Trulock). The results were very similar.


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 Post subject: Re: Why do I hate the back bore
PostPosted: Thu Feb 13, 2020 10:52 pm 
Limited Edition

Joined: Sun Oct 14, 2007 8:17 pm
Posts: 434
Location: South Alabama
I used backboring and longer forcing cones to get 3 ounces out of two barrels sets setting up a skeet set. 18.6 Perazzi to .745” which was biggest Briley option with thin-wall choke tubes. Fixed choke would have allowed larger overbore but not enough steel to thread barrels and fit choke tubes. 31.5” barrels. Gun handles great and crushes targets. I hated to spend the money to modify a new gun but, in this case, I’d do it again.


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 Post subject: Re: Why do I hate the back bore
PostPosted: Thu Feb 13, 2020 11:07 pm 
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Joined: Sat Jun 01, 2019 3:38 pm
Posts: 69
LG wrote:
I used backboring and longer forcing cones to get 3 ounces out of two barrels sets setting up a skeet set. 18.6 Perazzi to .745” which was biggest Briley option with thin-wall choke tubes. Fixed choke would have allowed larger overbore but not enough steel to thread barrels and fit choke tubes. 31.5” barrels. Gun handles great and crushes targets. I hated to spend the money to modify a new gun but, in this case, I’d do it again.

well, the clay target shotgun doesn't need to hit hard. The clays can break being hit even by #7 steel shot. In this topic I speak about hunting application including pass shooting which asks for maximum performance.

p.s. I probably wouldn't dare to overbore such an expensive shotgun.


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 Post subject: Re: Why do I hate the back bore
PostPosted: Thu Feb 13, 2020 11:23 pm 
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Joined: Fri Jan 16, 2004 4:07 pm
Posts: 1284
Location: Van Alstyne, Tx
I think that 18.5mm is 0.72834645669291338582677165354331"

give or take of course.


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 Post subject: Re: Why do I hate the back bore
PostPosted: Thu Feb 13, 2020 11:26 pm 
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Joined: Fri Jan 16, 2004 4:07 pm
Posts: 1284
Location: Van Alstyne, Tx
LG wrote:
Gun handles great and crushes targets.



Good lord! so does my mossberg 930


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 Post subject: Re: Why do I hate the back bore
PostPosted: Fri Feb 14, 2020 1:27 am 
Crown Grade
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Joined: Thu Nov 27, 2008 2:26 pm
Posts: 3404
i3rider wrote:
...Back borng to lighten barrel weight doesn't sound like reasonable approach to me. Because you gonna have thinner barrel walls which is dangerous thing. If the wall thickness is to be same, then you end up having heavier barrel. The easier way to have fast swinging barrel is to simply shorten it.


A barrel steel possessing a higher yield and tensile strength permits a thinner barrel wall which reduces barrel weight without a reduction in strength/safety. The solution therefore is to employ a higher strength steel. A number of European gunmakers have selected premium Boehler barrel steels for this purpose:

Boehler Blitz Steel: 45kg/mm2 yield strength - 70kg/mm2 tensile strength
Beohler Antinit NG: 70kg/mm2 yield strength - 85kg/mm2 tensile strength
Boehler Super Blitz: 100kg.mm2 yield strength - 110-125kg/mm2 tensile strength

Substituting Boehler Antinit NG barrel steel for Boehler Blitz will reduce the weight of 70cm long shotgun barrels by 0.10 kg. or approximately 1/4 LB. For many years, this option has been catalogued by the Ferlach gunmakers. A further reduction in weight can be achieved by employing Boehler Super Blitz steel.

DF

Montani Semper Liberi


Last edited by doppelflinten on Fri Feb 14, 2020 12:23 pm, edited 1 time in total.

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 Post subject: Re: Why do I hate the back bore
PostPosted: Fri Feb 14, 2020 4:32 am 
Diamond Grade

Joined: Thu Jul 15, 2004 1:56 pm
Posts: 1119
Quote:
Boehler Blitz Steel: 45kg/mm2 yield strength - 70kg/mm2 tensile strength
Beohler Antinit NG: 70kg/mm2 yield strength - 85kg/mm2 tensile strength
Boehler Super Blitz: 100kg.mm2 yield strength - 110-125kg/mm2 tensile strength

It would be interesting to know how they obtain the extra strength.
The strongest steel I have heard of is called maraging steel.
Iraq used that steel when they developed the centrifuge that
was needed to enrich Uranium to get weapon's grade Uranium
for the development of nuclear weapons, back when Saddam's
nuclear scientists were working on uranium enrichment.
They got that steel from Germany, and the guy went to prison
that ran the company that sold it to Iraq. Anyway wiki says this
about maraging steel:
These steels are a special class of low-carbon ultra-high-strength steels that derive their strength not from carbon, but from precipitation of intermetallic compounds. The principal alloying element is 15 to 25 wt.% nickel. Secondary alloying elements, which include cobalt, molybdenum and titanium, are added to produce intermetallic precipitates. Original development (by Bieber of Inco in the late 1950s) w…


Wow, 15 to 25% nickel, that must be some really stainless stuff, cobalt and titanium thrown in for good measure.

Reminds me of reading about the steel in Fabbri shotguns:
Quote:
Fabbri: Italian gunmakers - The Field
https://www.thefield.co.uk/shooting/fab ... kers-26748

Jan 29, 2015 · Our barrels are made from aeronautical-grade stainless steel, which is 80% stronger than the carbon steel used in most guns. They are proofed to 1,370kg and the steel is so hard that you can fire Hevi-Shot or steel shot through them, full choke, with no damage whatsoever.

and another:

A Conversation With Tullio Fabbri - Shotgun Life
https://www.shotgunworld.com/shotguns/ar ... abbri.html

The sears in the locks are coated with a diamond dust finish for durability. Materials for making a Fabbri shotgun include titanium alloys and stainless steel for strength and agility. All 150 individual parts of a shotgun are manufactured in the Fabbri workshop -- an entire shotgun completing a rigorous 1,500 production steps.



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 Post subject: Re: Why do I hate the back bore
PostPosted: Fri Feb 14, 2020 11:19 am 
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Joined: Sat Jun 01, 2019 3:38 pm
Posts: 69
I will probably never understand all these efforts to shave a quarter pound off the gun barrel. Especially by overboring it. To me it is not about the total weight of the gun, but rather about its balance. So if you add 50...150g to the stock area then basically you have very similar effect without ruining the strength of the barrel wall. As a result:
- your shotgun will be swinging somewhat faster
- you will probably have less of felt recoil. Because the heavier your gun the less it kicks.

Also I remember myself at least couple of times whet it happens for the shotgun to fall and hit a hard body object i.e. a rock by its barrel. This usually gives that "oh sh.t!.." feeling, then your heart fading while you inspect your barrel to make sure you haven't dented it. It is pretty much possible scenario when you walk hills or mountains then it happens to stumble and fall or just seat down to have a rest and put your shotgun leaned against a tree, etc. So the custom over bored barrel gonna be even more fragile... For me any gun weighting around 8Lb is totally OK. If you like the active style of hunting, walk enough and making about 7mi/day or more having your shotgun in your hands, then 3rd or 4th weekend it becomes like integral part of your body and you stop feeling the weight. I look at it like best possible way of physical exercising. What else can be better: you walk, hunt and breath forest air. You get home tired then have excellent rest, sleeping like a baby. Does 1/4 or even 1/2 pound matter here? My answer is "NO".

Being back to the topic, it would be nice if someone could share some data in regard of penetration testing by shooting the back bored vs a regular barrel having same 12ga caliber and same shot shells at 35...40yds. I kinda regret not having done such a test before selling my SX3. I have no back bores anymore and not planing to have any in the foreseeable future.


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 Post subject: Re: Why do I hate the back bore
PostPosted: Fri Feb 14, 2020 12:24 pm 
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Others "might" have a different answer.

There's no requirement that we have to be ninjas to shoot shotguns. Even folks confined to a wheelchair can and do shoot.

_________________
Nsca # 540300. Been loving this game since 01.

Our prentice Tom may now refuse
To wipe his scoundrel master's shoes
For now he's free to sing and play
O'er the hills and far away.


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 Post subject: Re: Why do I hate the back bore
PostPosted: Fri Feb 14, 2020 12:52 pm 
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Joined: Sat Jun 01, 2019 3:38 pm
Posts: 69
sera wrote:
Others "might" have a different answer.

There's no requirement that we have to be ninjas to shoot shotguns. Even folks confined to a wheelchair can and do shoot.


I don't mind. Absolutely. It was just my opinion. One can share it or not. Forums are just for this, right?
What you mention - is a special case. There are 20ga and even smaller shotguns - very lightweight, i.e. 20ga Benelli Montefeltro which under $1000 new
or one with more cash can think of i.e.
Benelli U828 12ga which is only 6.6LB .
Shoot whatever you like and stay happy.


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 Post subject: Re: Why do I hate the back bore
PostPosted: Fri Feb 14, 2020 1:54 pm 
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Joined: Thu Nov 27, 2008 2:26 pm
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[quote="i3rider"]I will probably never understand all these efforts to shave a quarter pound off the gun barrel. Especially by overboring it. To me it is not about the total weight of the gun, but rather about its balance. So if you add 50...150g to the stock area then basically you have very similar effect without ruining the strength of the barrel wall. As a result:
- your shotgun will be swinging somewhat faster
- you will probably have less of felt recoil. Because the heavier your gun the less it kicks... quote]

I agree that overboring is not a desirable way to reduce barrel weight. I also agree that it is not about the total weight of the gun but, rather about its balance. However, I would take it a step further, its not just about the gun's balance, its about attaining the least moment of inertia. Adding weight to a buttstock will probably reduce the felt recoil but, it can adversely affect handling.

Shaving a quarter pound off the gun barrel(s) should not be an aftermarket job, rather it is done by the gunmaker when building a gun to a specific weight for a specific use wherein barrels, frame and stock weight are all considered to achieve a dynamic handling gun. With regard to balance, two guns of equal weight can have the same balance point but, have different handling characteristics. The gun which has its weight more concentrated between the hands and having its balance point midway between the hands will be better balanced and have a lower moment of inertia resulting in a more responsive, faster handling gun.

Yes, the heavier your gun the less it kicks but, proper gun fit may do more to mitigate objectionable felt recoil than adding weight to the buttstock. JMO.

DF

Montani Semper Liberi


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 Post subject: Re: Why do I hate the back bore
PostPosted: Fri Feb 14, 2020 2:17 pm 
Limited Edition

Joined: Sun Oct 14, 2007 8:17 pm
Posts: 434
Location: South Alabama
A shotgun is a shotgun. You take the gun and select loads and chokes to make it work best for your range and targets. I prefer 1340 FPS but shoot 1200 without noting any real difference. I shoot 7/8 oz when available (usually loaded 3/4 oz when I actively reloaded) while knowing more shot in the air has to mean more hits in the long run. However, the Slow, light shells still do what they’re supposed to do—break targets in my case.

With all the heavy/fast loads I doubt you have to give up much when you backbore a shotgun whether you reload or not.

I’ve found it fairly easy to add weight to guns over the years to improve their balance—never needed to lighten one before this. The last time I restocked a gun the wood was selected based on light weight, not color, cut, or grade. We all do what we can to enjoy the guns we shoot and hopefully improve how well we handle them.

I agree about gun dynamics and I’ve set up target guns with the same dynamics with a difference in weight of over a pound.


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 Post subject: Re: Why do I hate the back bore
PostPosted: Fri Feb 14, 2020 2:30 pm 
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Joined: Sat Jun 01, 2019 3:38 pm
Posts: 69
doppelflinten wrote:
The gun which has its weight more concentrated between the hands and having its balance point midway between the hands will be better balanced and have a lower moment of inertia resulting in a more responsive, faster handling gun.

I agree.
Quote:
Yes, the heavier your gun the less it kicks but, proper gun fit may do more to mitigate objectionable felt recoil than adding weight to the buttstock. JMO.

Agree too.
To "add weight" - is just an example. The main point of that my message is that there are less expensive and less risky ways to improve gun handling.




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