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Double Rifles, Single Shots & Combinations >> Building Double Rifles & Gunsmithing

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ducmarc
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Reged: 14/07/14
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Loc: fla
marlin ou 12ga
      #275617 - 25/12/15 03:20 PM

Picked up a prewar marlin 103-10 in 12ga. For a song. Nice heavy O/U for a donor.any thoughts on how big I can go? Would like a 500-450 or 470 or 500ne.has a malleable iron receiver
which files like steel.if not fall back to 405 Winchester

--------------------
'killed by death' Lemmy.. ' boil the dog ' Elvis Manywounds "my best friend is my magnum forty four" hank willams the third.


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DarylS
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Re: marlin ou 12ga [Re: ducmarc]
      #275623 - 25/12/15 04:40 PM

The .405 has a working maximum breech pressure (@ 90 degrees) of 46,000PSI according to the SAAMI chart.

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


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


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ducmarc
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Re: marlin ou 12ga [Re: DarylS]
      #275635 - 26/12/15 02:40 AM

First off merry Christmas to all. is there a run down on larger NE caliber pressures? Like 450 and up.

--------------------
'killed by death' Lemmy.. ' boil the dog ' Elvis Manywounds "my best friend is my magnum forty four" hank willams the third.


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DarylS
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Re: marlin ou 12ga [Re: ducmarc]
      #275640 - 26/12/15 04:33 AM

This is also a good read about pressures and how they are obtained.

http://kwk.us/pressures.html

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


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


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crshelton
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Re: marlin ou 12ga [Re: DarylS]
      #275685 - 27/12/15 02:21 AM

Daryl,
Thanks for the pressure info.
I had a copy save once, but misplaced it, so I save your link on Dropbox so I cannot lose it.

--------------------
CRS,NRA Benefactor Member, TSRA, DRSS, DWWC, Whittington Center
Android Ballistics App at http://www.xplat.net/


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DarylS
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Re: marlin ou 12ga [Re: crshelton]
      #275687 - 27/12/15 04:36 AM

That is what I did as well - saved in a long list of bookmarks.

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


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


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ducmarc
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Reged: 14/07/14
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Re: marlin ou 12ga [Re: DarylS]
      #275708 - 28/12/15 12:15 PM

Looks like roughly 40 to 46,000 lbs for most of the big bores wounded how much an overunder can take its heavily built and nice and tight.

--------------------
'killed by death' Lemmy.. ' boil the dog ' Elvis Manywounds "my best friend is my magnum forty four" hank willams the third.


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ducmarc
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Re: marlin ou 12ga [Re: ducmarc]
      #275709 - 28/12/15 12:16 PM

That's wonder

--------------------
'killed by death' Lemmy.. ' boil the dog ' Elvis Manywounds "my best friend is my magnum forty four" hank willams the third.


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Birdhunter50
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Re: marlin ou 12ga [Re: ducmarc]
      #275759 - 29/12/15 11:53 PM

ducmarc,
I had a friend who had one of these over and under shotguns that he wanted to sell me. I had considered buying it to convert to a rifle but rejected the idea because of the lockup on the gun. I honestly don't remember what it has for a lock up but I know at the time I didn't think it was fit to convert to a rifle. If your gun has a malleable iron frame on it, that to me would disqualify it for any kind of conversion, in my humble opinion.

I would suggest you enjoy it as a shotgun and find something different to convert to a rifle. Both calibers you mentioned are way too high in pressure to even think about putting into a conversion gun like yours. The .405 is about at the top of the pressure list as far as what can be done, and that needs to have a good tight donor gun with double under lugs and a third fastener on a hardened steel frame. Anything less and you may be wearing certain parts of your gun for life. Sorry to rain on your parade but I would rather disappoint you now than to have you get hurt or worse. Bob


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Birdhunter50
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Re: marlin ou 12ga [Re: ducmarc]
      #275760 - 30/12/15 12:23 AM

I did some additional checking on the Marlin Ranger 103 that you mentioned, and it only has one lockup bite at the lower rear of a large recoil lug. I still do not recommend using it as a donor gun for any kind of rifle cartridge. Sorry. If you want an over and under donor for conversion, look for an Ithaca 500 with rusted, bulged, or blown barrels. You should be able to find one cheap if you look long enough. That gun has the Kirsten double bolting system that is one of the strongest on the market. Bob

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ducmarc
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Reged: 14/07/14
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Re: marlin ou 12ga [Re: Birdhunter50]
      #275805 - 30/12/15 02:40 PM

It is a nice shotgun and have debated cutting it up plus I wanted some input on it .i ordered the Ellis book to try to gain more knowledge about it. I'll start a hunt for a Ithaca I found an aya matador receiver but was hoping for a complete gun.theres a jp Sauer at a local shop but its well used at 700$ ot does have auto ejectors though. I'll keep on the hunt.thanks

--------------------
'killed by death' Lemmy.. ' boil the dog ' Elvis Manywounds "my best friend is my magnum forty four" hank willams the third.


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dudleybm
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Re: marlin ou 12ga [Re: ducmarc]
      #277518 - 04/02/16 09:10 AM

I am starting a build in 45-70 on one of these Marlin model 90 actions. I had the gun (in 20g.) hanging around and I wasn't attached to it at all, so I figured why not.

The best thing about the barrels on them is that they are already soldered mono-block construction, so taking them apart and giving yourself a usable mono-block to start with is a breeze.


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Birdhunter50
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Re: marlin ou 12ga [Re: dudleybm]
      #277556 - 05/02/16 01:16 AM

Brian,
Do you feel this donor gun is strong enough in it's lockup system to be building a rifle on it? I have looked them over before and didn't really care for them as donor guns. I guess if you were going to do a conversion on one, a low pressured 45-70 load would come as close as any to being a good choice. I recommended to him that he think about doing a 12 ga. rifled slug gun on his Marlin.
Another gun I hear about all the time as a possible donor gun is the L.C. Smith shotgun. The later ones would have better steel in them than the early ones but they still only have the one bolt in the barrel extension. I do not consider them a good choice either. That being said, I have seen a couple of 45-70 conversions done on L.C. Smiths that have held up so far. But I have to wonder if they are not over stressing that one bolt. A couple of other American gun makers also stole this idea from L.C.and used it on some of their guns, but I do not consider them as a good candidates either.
One of these conversions was done to help out a friend of the "gunsmith" who did the work. He made full length barrel liners that were somewhat loose at the muzzles and made threaded collars that were made eccentric to the outer threaded surface. By twisting and tweaking those threaded collars, they did manage to get it roughly regulated but I do not remember what the load was for it.
I also remember that he had to weld "ears" on the barrel liners back at the breech and machine out slots for those ears to fit into the 12 gauge rim areas because the barrels kept unscrewing themselves during the initial attempts at getting it regulated. I have not heard of this gun blowing up yet, and I think I would have if it had blown. Then again, I don't know the load nor how often they have fired it.
The gunsmith in question is an excellent machinist and he had matched the outside profile of the liner barrels to the 12 gauge chamber areas and some way down the inside of the 12 gauge barrels. It is possible that some strength was gained by this method but I can't believe it would be much. Also it did nothing to strengthen the lockup on the gun itself.
Lots of people out there would love to find a proper donor gun "Made in America". I have looked a bunch myself, and the only ones to surface so far have been the Winchester 21 and the Browning BSS, which I think was actually made overseas. There may be a couple more but all of them are marginal except these two and they are both expensive guns to be using for conversions. I think it is best, especially for beginners, to start with a good European made double with some kind of third fastener.
They can be bought reasonably cheaply and if you wreck it trying to do a conversion on it, you have not lost a couple of grand on a donor gun. Bob


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dudleybm
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Re: marlin ou 12ga [Re: Birdhunter50]
      #277580 - 05/02/16 09:53 AM

I am going to do the gun for myself. Not for a customer or anything. I know there are much better actions out there, I just had this thing laying around and that is why I doing it in 45-70 and not something hotter. I am doing it more just for the exercise of sleeving a set of barrels.

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DarylS
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Re: marlin ou 12ga [Re: dudleybm]
      #277584 - 05/02/16 12:17 PM

I was able to get 405gr. RP's running 1,850fps at a mere 22,000CUP - approx - not higher than 23,000CUP. I suspect a 26" set of tubes might get them up to about 1,750fps - excellent for most game up to moose, bears, elk, even big bears with the proper bullet construction.

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


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


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Birdhunter50
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Re: marlin ou 12ga [Re: DarylS]
      #277637 - 07/02/16 01:03 AM

Daryl,
Can you share the loading data with us and please tell us what kind of gun you shot these in?
Thanks, Bob


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DarylS
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Re: marlin ou 12ga [Re: Birdhunter50]
      #277641 - 07/02/16 04:43 AM



Ctg. - .45/60 or .45 1.9"
35" bl.GM 18" twist
Large diameter black-powder firing pin
405gr. Remington FN
48.0gr. Hodgdon's Benchmark
Federal 210 primer
Overall Ctg. Length: 2.580" - I use a modified Lee Factory Crimp Die
Velocity Av. at 15feet, 1,850fps.
Low pressure indicated.

11 shots off the bench 100 Meters .875" for 10 of those in the group. I pulled one - flinched for some reason and threw that one 1" from the group - the 9th shot. I then fired 2 more to make a 10 shot group, with the last 2 gong back onto the hole, which was quite round. The sights were a Soule Tang sight and Sharps Globe aperture front sight.

Data came from Hodgdon's Annual Manual in the .45/70 data. I suggest you check your copy of this Manual and follow along as I explain myself.

Note: We can assume similar pressures with similar overall ctg. lengths and loads due to Hodgdon using a standard 24" bl. for all their testing, and lot listing OAL. It appears the same weapon or test barrel was used. We also know for the Lever action data to be valid, they must have loaded to a maximum loaded length of 2.55", 2.60" at the longest as that length is needed for feeding in a lever gun. Also, crimp grooves are necessarily used in lever guns to prevent tube spring pressure and recoil from seating bullets deeper into the case, tying up the action, or worse.

In the Trapdoor section they list pressures up to 28,00CUP. Hodgdon shows, for instance, a weak co-relationship between a couple loads listed as max. for the Trapdoor and being starting loads in the Lever Action section.

Trapdoor max of 50.0gr. of Varget with 405gr. Cast bullet = 1,718fps @ 20,900CUP, which the same 50.0gr. Varget load in a Lever action being a starting load with a 400gr. jacketed bullet as producing only 1,655fps, but slightly lower pressure of 18,600CUP. This shows to me, the jacketed bullets seemingly was producing less pressure per grain of powder than the cast bullet, which was strange, but worth pursuing through testing, if careful loading practices were followed.

Thus, I started development at 45.0gr. Benchmark, the primer flow and slide lockup being my main concern/pressure indicator in this action. Due to the angle and size of the pin, this action shows pressures long before any other indicator arises or shows.

With Benchmark, the Trapdoor data shows 47.0gr. with 405gr. Cast bullet at 1,564fps @ 17,100CUP and 50.0gr. Benchmark at 1,695fps @ 22,600CUP.

I worked from there up to 48.0gr. Benchmark with the 405gr. Remington bullet, which produced 1,850fps in my rifle and the excellent accuracy shown. I have read other work on this bullet and it was suggested that 1,850fps was about the maximum speed one should load this bullet to, as it has a pure lead core and thin jacket. Also noted it is a wonderful bullet for moose and elk and bear. The article also noted it will make a huge hole in a whitetail, yet the bullet expands like bubble-gum, and does not break up at this muzzle velocity.

In this rifle, I also worked up to 50.0gr. Varget, which was close to a case full at an OAL of 2.580". The accuracy was not as good as with Benchmark, opening up to 2", however pressure indicated for that load in the Lever action data shows 18,600CUP at 1,655fps. I did not chronograph these, may some day as I still have some loaded, but they were totally safe in my BP firing pin 1868 Repro: Sharps action.

I expect they may produce approx. 1,900fps in my 35" barrel, thus they slightly exceed the suggested allowable speed for THIS bullet.

Thus, due to the comparisons between known data and the differences of Jacketed and cast using Varget, along with my extrapolations that the Benchmark load may produce 22,000 though not over 23,000CUP - a very soft load for most rifles, yet producing excellent ballistics- especially in the longer barrels. I firmly believe Benchmark to be a MOST excellent powder for the .45/70, with either case or jacketed bullets. It certainly is a very accuracy powder - in my rifle.

Hodgdon's data also shows that at 55.0gr. Benchmark, the 24" bl. will push a 400gr. Jacketed bullet at 1,856fps @ 29,600CUP, but Varget gets almost that speed using 55.0gr. @ only 24,000CUP - also within the realm of the double rifles by Baikal, having ceilings of 31,000CUP or PSI, as noted.

We have been told, that through pressure testing at the lower pressures, below 35,000CUP, that CUP and PSI numbers appear to be the same in the .45/70 ctg. I can tell from my own testing, the above information on this ctg. (and my own .45 1.9") is safe for lower pressure guns.


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