Home Forums Hunting & Shooting Hunter's Campfire SAFETY WARNING - BUILDING DOUBLE RIFLES ON SHOTGUN ACTIONS

Anyone considering the shotgun action conversion TO RIFLE WITHOUT DECIDING TO BUSH THE STRIKER HOLES TO A SMALLER, MORE SUPPORTIVE DIAMETER let me point out 2 things.

A 45 COLT 280 gr SAA over 8.0 gr Unique will come out at 1,100 fps and cause wonderful damage to test media. Calculated pressure at 16K and life is good.

HOWEVER, FOR THE 30-30, 173gr cast FN using 10gr unique has a calculated velocity at 1470 and pressure at 30K.

The chrony read 1472, and the stock wrist splitting from the primer rupture says that 30K is too damn high for rifle primers over an unbushed firing pin hole.

The action is still OK, and the wrist split is minimal - but it could have been worse. Thank God for lead sleds, safety glasses and whatever else He gave me today.

Save any criticism, please. I just want folks to know before they jump.
If you want any other specifics, ask away....

And yes, Dave & Nate, the colt is working fine. I will fix the stock, complete the regulation and kill a deer with it before season's over.

Want pics of my shorts in addition to the stock and rupture?

Merkel's being doing it for years.

Thanks for the warning, I am very intrigued by the idea. Did you build the rifle yourself or have it done?

A good quality double trigger 20 SxS, Prince of Wales grip and semi beavertail forend with an extra set of 9.3x74 barrels has me most curious.

Pics of just the rifle and damage, please

?? never seen one of their double rifles without bushed pins? I owned two of them? 9.4x74 and a .470NE

IF you ever feel the need to trade off that 9.3x74, PM me.

rifle - your chrony is safe as well. I'm going to check my Weatherby 30-06, then ship it back. My 30-30 testing is done for a while.

Dsink did my 45 colt, and vapodog did my 30-30. Both are great craftsmen.

The 30-30 was a total monobloc build and I did all the final shaping, cutting of lumps, etc by hand - with files, dremel and lots of time.

The Colt barrels were threaded to a cutoff monoblock, and again, final fit all by hand.

The quarter ribs, front sights, and stock/forearm work are being done by hand as well.

I have an old Stevens 311 16 ga that my dad left me. I have heard they make reliable donor actions for double rifles.

My only concern with the stevens is there is only one fastener on the breech face.

The Zastava M75 has two lumps under neath and most have a third fastener on the breech face.

But given todays physics lesson, I may be the last "expert" you need to consult on that.

OK - primer ruptured is a CCI mil spec LR primer
Other's shown are Win LRP I used before on some lighter loads. I switched to the MilSpec in hopes that they were less resistant to rupture. (irony)


And the stock damage:

Wow, quite an explosion.

Glad you are still with us.

Something like handgun cartridges are much less of a worry, but when you get to the higher pressure centerfire rifle cartridges, there's a lot more than just bushing the firing pins that you need to be aware of. I'd recommend you buy the book on the subject and study up; had you done so, you could have avoided the issue you ran into. Making double rifles is FAR more than just putting a set of rifle barrels on a double action.

Yeah,..but how did the bullets group..?

You gonna need another round of pulls..?



So I'm still not sure what happened..?

Primer ruptured and then what..?

I bought the book. And this project has been going on a lot longer than just calling up a few guys to put rifle barrels on a double action.

Amongst spending time early on calculating hoop stress and deciding on cartridges to use, and consulting a few folks for suggestions, I decided in order to avoid the necessity of creating the enclosed striker bushing needed in a standard load, I should keep the pressures LOW.

I decided to go with cast which responds better terminally to the slower velocity and subsequent lower pressures, hoping in case of the 30-30 to achieve 1500 fps. I consulted some tables of calculated data since test data for pressure using cast in the 1,500 area is limited and assumed that I could reach my target without getting high enough to blow.

I was wrong, apparently. Plain and simple.

Of course, I'm not so sure there wasn't some other issue involved, because I had fired 150gr standard loads in this contraption before, numerous times, without a failure, and in those cases, the table values were indicating that I should have been in the 33K+ range. Who knows.

In this case, I started at 8 and went up in increments. Didn't get any primer cratering till I hit 9.0 - and should have stopped there, however it wasn't near as bad as it was in the standard loads, which cratered to the point of locking in - so I carried on. To go from mild crater to catastrophic failure certainly caught me off guard.

Did I double charge? I don't think so. Using a Lee Loader, but still weighing the charges, and doing one shell at a time, inverting before pouring powder.

Could it have been the relatively low powder to case capacity issue? Probably not. People have been using 10gr Unique and 170 cast and never reported an issue.

Freak primer?

bug in the barrel?

I can only relay what I know to be accurate, and that is 10 grains of unique - which calculates under quickload to be about 30K did this.

So, it wasn't necessarily as flippant as you make it sound re: just putting rifle barrels on a double action.

LATE ADD:

The "Book" by Brown indicates "If the cartridge I have selected is pushing 44,000 PSI or greater, then I should probably seriously consider bushing the strikers" (process described later).

The minute I realized he was optimistic, that's when I decided to try and stay lower.

Worked on the colt project.....

vented gas came back through the ruptured primer, around the firing pin and into the action and cracked the stock.