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Double Rifles, Single Shots & Combinations >> Double Rifles
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doublegunfan
.275 member


Reged: 26/04/05
Posts: 60
Loc: Brazil
Re: Long shotgun actions [Re: banzaibird]
      #51578 - 06/03/06 01:37 AM

This thread could almost be renamed to "Best Practices for building a Double Rifle, or converting a shotgun frame to a Double Rifle".

So far we covered things like sleeving barrels, calibers, regulation, frame selection, wood work, and now safety precautions. I like that.

My own Beretta also has these vents on the face. Its strikers are not very thin, but I reworked them, because they were protuding too much from the face (almost 1,5mm). This way, I have had no problems with the strikers perforating the primers or jamming the gun shut.

One question for all: all accidents I have seen with primers were either caused by faulty firing pins (too long or too thin) or by very high pressures in hot handloads. If we consider that the modern Large Rifle primers are built to withstand pressures much higher than those of normal DR calibers, is it really a necessity to bush the strikers?


Fred

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tinker
.416 member


Reged: 12/03/05
Posts: 4835
Loc: Nevada
Striker bushings, questions of safety... [Re: doublegunfan]
      #51581 - 06/03/06 03:22 AM

I think we can look at vented and bushed strikers as a couple more examples of cheap insurance, kind of like quick detatch scope mounts and auto ejectors.
Essentially a bunch of stuff that comes along for the ride, but if the bullshit hits the fan they come to the rescue for whatever measure of buffer they offer.

I think it also stands to reason that anyone who's looking at an action with that long and willful *come hither you brass sucking tramp* leer of want for a conversion into double rifle service should make double damn sure to put the strikers and thier smooth little puckerholes on the checklist -- and like everything else, to check them twice.



--Tinker

--------------------
--Self-Appointed Colonel, DRSS--



"It IS a dangerous game, and so named for a reason, and you can't play from the keyboard. " --Some Old Texan...

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BlainSmipy
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Reged: 24/11/05
Posts: 558
Loc: Washington, USA
465NE [Re: doublegunfan]
      #51587 - 06/03/06 04:34 AM

Are there very many out there?

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Marrakai
.416 member


Reged: 09/01/03
Posts: 3482
Loc: Darwin, Top End of Australia
Re: Long shotgun actions [Re: banzaibird]
      #51636 - 06/03/06 07:32 PM

banzaibird:
In reply to:

Wow, look how thin the wall on the barrel is


You're kidding, right?

It doesn't matter how thin the ferrule is, so long as it has sufficient thickness at the front of the monobloc, and that is dictated by the taper on the original shotgun-barrels. Remember that the primary receptacle is a thin brass case, which is supported by the chamber wall. ("Wow, look how thin the wall on the case is..."). The Greener conversion has ended up with better than 1/4-inch chamber walls at the breech all-up. Personally I reckon that's plenty for the safe discharge of an 8-ton cartridge.

The finished weight of the gun is 10 1/2 lbs. Nothing else to reduce recoil except time-honoured British design (!) ...modified a bit! It's very comfortable to shoot.



--------------------
Marrakai
When the bull drops, the bullshit stops!
--------------------------------
www.marrakai-adventure.com.au

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banzaibird
.333 member


Reged: 18/09/05
Posts: 358
Loc: S.C. Pennsylvania, USA
Re: Long shotgun actions [Re: Marrakai]
      #51657 - 07/03/06 12:59 AM

I didn't mean anything by the thin comment other than I have a long way to go and a lot to learn before I'd attempt anything like that. I do understand exactly what you are saying about the ferrel thickness but there is still hoop stress to that area. Not nearly as much where the chamber ends but still some pressure. It was made because I was truly surprised at how thin they left it not in anyway meant to be a derogatory comment. I'm still trying to come to grips with the whole profile of the barrels. It differs so much from bolt actions. There is generally so much less barrel weight in the DR profiles.

Sorry if I offended you that wasn't my intention. I also didn't mean my comments as derogatory to the make of the firearm. To me that is amazingly thin. Still is, but as I said in my ealier post it is obviously safe.

BB

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doublegunfan
.275 member


Reged: 26/04/05
Posts: 60
Loc: Brazil
Re: Long shotgun actions [Re: BlainSmipy]
      #51659 - 07/03/06 01:23 AM

One thing that I considered regarding the bushed pins is that it seems, to me at least, to be something very complex and not very easy to change from an integral striker to a bushed pin. The geometry of the pins in relationship to the original strikers have to be considered. Any mistake and your action is gone.

The diameter of the vent in a double rifle with bushed pins are so small when compared to the diameter of vent holes in a 98 Mauser bolt, for example. Will those small channels be enough to divert hot gases?

Anyway, I have to aggree with Colorado. For me, it seems a better approach to keep your loads on a safe margin and avoid the overpressure by all means, than try to discover the limits of strength and safety of your gun action .

Fred

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BlainSmipy
.375 member


Reged: 24/11/05
Posts: 558
Loc: Washington, USA
Hollis 500/450 [Re: doublegunfan]
      #51673 - 07/03/06 05:12 AM

Jones underlevers, opinions?

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Judson
.300 member


Reged: 21/09/05
Posts: 192
Loc: St. Albans Maine U.S.A.
Re: Long shotgun actions [Re: BlainSmipy]
      #51692 - 07/03/06 09:22 AM

This thread really has taken on a life of it's own!!! I never thought it would create so much intrest when I started it. As for blown primers and such, for the most part it is a thing of the past with modern components and the pressures involved in double rifles. Modern large rifle and large rifle magnum primers are designed to take over well over 70,000 psi. This is far beyond any sane loading and the only cartridges loaded this hot are some of the Lazeroni stuff. The firing pin diameter should be around .074" plus or minus .004" and protrusion no more then.064" pluss or minus .002" for a modern high intensity cartridge. so with a double we have a little bit more leway as to diameter but not much. As important if not more so then diameter is how well the pin fits the hole in the face. Thi firing pins should be as close fitting as possably as this in it self limits the chances for flow back of the primer and blown primers.
By the way nice pictures guys and thanks for your input and the checkering on my .450 # 2 N.E. is about half done and I will have pictures soon.

--------------------
It is the small calibers that are the biggest bores.

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BlainSmipy
.375 member


Reged: 24/11/05
Posts: 558
Loc: Washington, USA
Re: Long shotgun actions [Re: Judson]
      #51698 - 07/03/06 11:25 AM

Wish I had one!

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Marrakai
.416 member


Reged: 09/01/03
Posts: 3482
Loc: Darwin, Top End of Australia
Re: Long shotgun actions [Re: BlainSmipy]
      #51724 - 07/03/06 10:06 PM

colorado:
I wasn't particularly offended by your post, didn't mean to give that impression, just a little perplexed by your surprise at the ferrule thickness, you having built one and all. When chambering for the straight-wall American .45s or .50s you can retain plenty of meat around the chamber, but the much larger .577 chamber must result in thinner ferrule walls. Simple geometry.

I'm slowly working my way 'round to building another one myself too, on one of my Greeners using the pair of Shaw rifled 12-bore barrels I've had sitting in the back of the cupboard for several years. Unfortunately I've convinced myself that I need to build a new monobloc from scratch, in order to get an extra couple of pounds weight 'between the hands' while keeping the muzzles shotgun-trim, so it will be no simple task.



Unfortunately I keep blowing my budget on vintage pommie doubles in the meantime!

--------------------
Marrakai
When the bull drops, the bullshit stops!
--------------------------------
www.marrakai-adventure.com.au

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BlainSmipy
.375 member


Reged: 24/11/05
Posts: 558
Loc: Washington, USA
Re: Long shotgun actions [Re: Marrakai]
      #51742 - 08/03/06 03:31 AM

Great gun I love it!

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banzaibird
.333 member


Reged: 18/09/05
Posts: 358
Loc: S.C. Pennsylvania, USA
Re: Long shotgun actions [Re: BlainSmipy]
      #51743 - 08/03/06 03:54 AM

Hey, I wasn't dissing anybody. I was however surprised at how thin it was.

It just seemed that you were offended by the way it read. That's the problem with this type of forum beause I didn't mean it that way at all.

As I said earlier the barrel profile is something indeed that is quite different than anything else. This is an area I'm still working hard on getting right. I only have had the oppurtunity to shoot 2 professionaly made DR's. One is an old BPE and isn't nearly as lively as the much later manufactured 303.

Thus my expeirence is very limited other than the ones that myself and a couple other of guy's have built. About 15 in all currently. However some of them are pretty crude. I haven't refined things far enough that I'd feel comfortable doing the 577 currently. Though I deffinately want to in the future. I've been playing with an action design now for a few months. It is working but not quite the way I want to yet. However when i get everything working the way I want I'll be able to get it programed into the CNC mill then I can build DR's in calibers for myself as quickly as I can afford barrels and raw 4140 CM.

Anyway thanks again and as I said I wasn't trying to offend anyone.

Bill

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BlainSmipy
.375 member


Reged: 24/11/05
Posts: 558
Loc: Washington, USA
475NE [Re: banzaibird]
      #51752 - 08/03/06 05:24 AM

Searcy make these?

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DarylS
.700 member


Reged: 10/08/05
Posts: 26489
Loc: Beautiful British Columbia, Ca...
Re: Long shotgun actions [Re: BlainSmipy]
      #51757 - 08/03/06 05:54 AM

.155" is .030" over 1/8"(.125") and - .095" less than 1/4" or am I missing something here. .032" difference is closer to 1/32", not 1/8", which is actually 0.125". Quarter inch is .250".
: Even at these measurements, I am sure they are plenty strong enough for moderate loads.
: The muzzles, of course, can be very thin as the pressure at that point is very low with normal loads. I've seen in print that even the quite slow burning IMR 4831 developes it's gross(max) pressure at 13" from the breech in rifle barrels. Faster powders develope their max pressurs much closer to the breech, hense normal contours are safe.

--------------------
Daryl


"a gun without hammers is like a Spaniel without ears" King George V

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bonanza
.400 member


Reged: 17/05/04
Posts: 2335
Loc: South Carolina
Re: Long shotgun actions [Re: DarylS]
      #51759 - 08/03/06 06:07 AM

Check out this baby!

http://www.cabelas.com/cabelas/en/content/community/gun_inventory/inventory/kansas_city/english_sg/419519_greener_kc.jsp

--------------------


"Speak Precisely" G. Gordon Liddy.

"Life is absurd, chaotic and we must define its purpose with our actions" Abert Camus

"I''m the dude playing a dude disguised as another dude."

"Yo! Mr. White"

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BlainSmipy
.375 member


Reged: 24/11/05
Posts: 558
Loc: Washington, USA
Merkel 470 [Re: BlainSmipy]
      #51779 - 08/03/06 10:24 AM

Any good?

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Grizzly
.333 member


Reged: 05/12/05
Posts: 359
Loc: Dallas, Texas, USA
Re: Long shotgun actions [Re: BlainSmipy]
      #51780 - 08/03/06 10:39 AM

This thread has been a real education. It gives some unique perspective on the kind of work that goes into a quality double, and why they cost so much.

As for myself, my mechanical skills would have me going out and buying two singe shots, lining them up side by side and moving one slightly back, trimming the barrel on the forward trigger rifle, and using copius amounts of duct tape.



--------------------
SCI Life Member
DSC Life Member
DRSS Member

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Marrakai
.416 member


Reged: 09/01/03
Posts: 3482
Loc: Darwin, Top End of Australia
Re: Long shotgun actions [Re: BlainSmipy]
      #51800 - 08/03/06 02:59 PM

colorado & BB:
Apologies for the confusion, guys. ...actually I blame the grog!

I didn't follow the maths in detail on your previous posts, but it seems you may have overlooked or forgotten about boring or reaming out the monobloc prior to fitting the new barrels. Only the barest minimum existing wall-thickness is retained at the front of the monobloc, although a little more meat is needed if they are to be threaded-in of course. At the very least, the rim-recess of the existing 12-bore chamber has to be removed. If you factor this in, you should get a little better than 3/64-inch!

Holy Cow! Can't believe the asking price of 'ordinary' Greener shotties over there! That's $3,800 in our money, and a scruffy example to boot! ...and what are those brass hardware-store screws doing through both sides of the stock head? Sheesh!

At that rate, I could turn a profit of AU$6,750 on the last two I acquired!!

--------------------
Marrakai
When the bull drops, the bullshit stops!
--------------------------------
www.marrakai-adventure.com.au

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tinker
.416 member


Reged: 12/03/05
Posts: 4835
Loc: Nevada
Re: Long shotgun actions [Re: Marrakai]
      #51804 - 08/03/06 03:55 PM

Marrakai-

First up for discussion is the grog.
Share.
We'll all email you our shipping addresses so we can join you on the mead.
I'll take a flat of quart jars to start.


Next for comment is the retailer linked to that Empire Grade.
They're somewhat notorious for more-than-occasional *very high* prices on less than stellar pieces.
Sometimes they have a great deal on something to be had too, but more than not it's the former.


About that pair of twelve bore tubes, what would those cost today in USD?



--Tinker

--------------------
--Self-Appointed Colonel, DRSS--



"It IS a dangerous game, and so named for a reason, and you can't play from the keyboard. " --Some Old Texan...

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BlainSmipy
.375 member


Reged: 24/11/05
Posts: 558
Loc: Washington, USA
500NE [Re: Marrakai]
      #51811 - 08/03/06 07:19 PM

Loads?

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Marrakai
.416 member


Reged: 09/01/03
Posts: 3482
Loc: Darwin, Top End of Australia
Re: Long shotgun actions [Re: tinker]
      #51817 - 08/03/06 09:56 PM

tinker:
In reply to:

what would those ..twelve bore tubes.. cost today in USD?


According to the E.R.Shaw webpage, they currently retail at US$105 ea. I paid about $95 at the time. Not everybody likes Shaw barrels BTW, however these look fine to me. I haven't put a tool on them yet, so can't really comment. Hope they're OK! I'm sure there would be other manufacturers pricing competitively on your side of the pond.

Also the twist-rate is a little slick for 12-bore slugs, around 1:28 IIR, so probably designed for sabots. I'll be shooting 750gr Fosbery-style slugs for starters, if I ever work my way clear to getting this project underway!

--------------------
Marrakai
When the bull drops, the bullshit stops!
--------------------------------
www.marrakai-adventure.com.au

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DarylS
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Reged: 10/08/05
Posts: 26489
Loc: Beautiful British Columbia, Ca...
Re: Long shotgun actions [Re: Marrakai]
      #51829 - 09/03/06 07:24 AM

I would think 1 in 60" would be a better bet for full sized slugs in a 12 bore, and maybe .006" deep.

--------------------
Daryl


"a gun without hammers is like a Spaniel without ears" King George V

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Judson
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Reged: 21/09/05
Posts: 192
Loc: St. Albans Maine U.S.A.
Re: Long shotgun actions [Re: doublegunfan]
      #51859 - 09/03/06 12:12 PM



For those of you who have not seen it this is the .450 # 2 Nitro Express that I built on a French 16 gauge action. It was a lot of fun to regulate even though lots of people told me it would drive me crazy. At present the rifle is shooting about 1.25" at 50 yards for a composit group which should put it about right on at 100 yards but I have not shot 100 yards due to the winter very much. I am now checkering the stock which is of South African Black Thorn which I picked up on my wifes and my first trip. The stock blank was given to me by a South African custom rifle builder I spent some time with.

--------------------
It is the small calibers that are the biggest bores.

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BlainSmipy
.375 member


Reged: 24/11/05
Posts: 558
Loc: Washington, USA
Re: Long shotgun actions [Re: Judson]
      #51886 - 09/03/06 06:06 PM

What have you proofed the gun to? Do you run full nitro loads through it? Does it have a Greener crossbolt? What is the frame measurements...as in across the water tables, standing breech, length from breech to pin etc..

Are you doing any kind of wear or stress analysis on the frame?

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Judson
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Reged: 21/09/05
Posts: 192
Loc: St. Albans Maine U.S.A.
Re: Long shotgun actions [Re: BlainSmipy]
      #52406 - 14/03/06 01:28 PM

On my present rifle, the one pictured I fired several proof loads and checked the tolerances after every shot. Now I am checking measurements after every shooting session, nothing has changed so far, I will keep you informed.
The new french action I am giong to use is large and the barrels are of the chopper lump design. It has four bites, three on the under lugs and a fourth as a hidden third fastner. The firing pins are rather small in diameter though I think I may want to cut them back a bit. I will post pictures as soon as I can and give the dementions of the new action in the next few days. As for my .450 you will have to waite a bit for those dementions as it is in the checkering cradle at this time and I can only work on it in my free time so it will be a while befor I cane post the measurements you guys asked for.

--------------------
It is the small calibers that are the biggest bores.

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