1.125" Tenon Thread

[Edd]

Anyone ever increase the tenon thread size on a Defiance action?

 

[WSnyder]

Nope. Took a 700 to 1.125” though. It had some thread damage and it cleaned right up when taken to that diameter.

 

[hoz53]

Nope. Took a 700 to 1.125” though. It had some thread damage and it cleaned right up when taken to that diameter.

that would be 60+ over. i wonder what the safe upperlimit would be

 

[WSnyder]

that would be 60+ over. i wonder what the safe upperlimit would be

The threaded portion of the action doesn't do much but hold the barrel in place. The barrel tenon and its hoop strength is what contains most of the the pressure and with a larger diameter its hoop strength goes up. I'm not sure at what point the action wall would be thin enough to where the threaded portion might want to separate from in front of the lugs though. Good question

I'm certainly not the first one to take a Remington out that far.

 

[hoz53]

The threaded portion of the action doesn't do much but hold the barrel in place. The barrel tenon and its hoop strength is what contains most of the the pressure and with a larger diameter its hoop strength goes up. I'm not sure at what point the action wall would be thin enough to where the threaded portion might want to separate from in front of the lugs though. Good question

I'm certainly not the first one to take a Remington out that far.

i wasnt questioning if it was safe. just never thought of how much could be taken out before.. im no gunsmith so i dont know what hoop strength is? it seems to me if the bolt is held closed by the lugs in the action and the receiver lets go in front of the lugs (barrel side) the barrel and action would seperate? i amglad this came up and got me thinking about it. sorry OP didnt meen to hijack ur thread

 

[DaveTooley]

Anyone ever increase the tenon thread size on a Defiance action?

Why?

 

[Edd]

Why?

To make the chamber walls thicker for a large diameter cartridge.

 

[WSnyder]

To make the chamber walls thicker for a large diameter cartridge.

What cartridge? If you’re trying to put something like a big Lapua mag or something like that and want the added tenon strength the action may not have enough lug abutment to handle the pressure. That’s what the larger overall actions are designed for. Back when people were modifying Remingtons for Lapua mags that’s the part that wasn’t safe. You can increase the tenon diameter for safety but you can’t do anything to increase safety for the added bolt thrust of the big magnums.

 

[SKWERLZ]

What cartridge? If you’re trying to put something like a big Lapua mag or something like that and want the added tenon strength the action may not have enough lug abutment to handle the pressure. That’s what the larger overall actions are designed for. Back when people were modifying Remingtons for Lapua mags that’s the part that wasn’t safe. You can increase the tenon diameter for safety but you can’t do anything to increase safety for the added bolt thrust of the big magnums.

I concur
Lapua boltface cartridges on a standard diameter R700 or clone is always a compromise Regardless of tenon diameter.

Even the little 338 Norma msg hits pressure early in a 700

 

[Edd]

Even the little 338 Norma msg hits pressure early in a 700

Isn’t that because of the tenon diameter?

 

[Edd]

What cartridge? If you’re trying to put something like a big Lapua mag or something like that and want the added tenon strength the action may not have enough lug abutment to handle the pressure. That’s what the larger overall actions are designed for. Back when people were modifying Remingtons for Lapua mags that’s the part that wasn’t safe. You can increase the tenon diameter for safety but you can’t do anything to increase safety for the added bolt thrust of the big magnums.

Defiance sells actions for Lapua diameter cartridges but they have 1-1/16” tenons.

 

[WSnyder]

Defiance sells actions for Lapua diameter cartridges but they have 1-1/16” tenons.

Okay. That tells me they believe that the hoop strength at that diameter is safe but have chosen to go with larger lugs and lug abutments for bolt thrust.

 

[WSnyder]

i dont know what hoop strength is

A chamber/tenon is part of a pressure vessel. Hoop strength refers to how much outward circumferential pressure a pressure vessel can withstand.

 

[SKWERLZ]

Isn’t that because of the tenon diameter?

tenon+action diameter

A big tenon won’t do squat in a thin action.
That’s why most 1 1/8 tenons are on 1.4” or bigger actions.
The action I hope to get this winter for a .375 project is 1.6”

 

[SKWERLZ]

Defiance sells actions for Lapua diameter cartridges but they have 1-1/16” tenons.

So does ARC
Still a compromise in my opinion but if for hunters it’s an acceptable compromise.

 

[SKWERLZ]

A chamber/tenon is part of a pressure vessel. Hoop strength refers to how much outward circumferential pressure a pressure vessel can withstand.

Similar to rebar hoops in a concrete column.

 

[Edd]

tenon+action diameter

A big tenon won’t do squat in a thin action.
That’s why most 1 1/8 tenons are on 1.4” or bigger actions.
The action I hope to get this winter for a .375 project is 1.6”

BAT has a 1.350” action that they put 1.125” threads on for every cartridge. I have one.

 

[WSnyder]

tenon+action diameter

A big tenon won’t do squat in a thin action.
That’s why most 1 1/8 tenons are on 1.4” or bigger actions.
The action I hope to get this winter for a .375 project is 1.6”

Just for giggles and info: The action doesn't add much to the day to day useful strength but it does (or may) when it gets to catastrophic levels. This has been proven out when it comes to excessive case expansion in thinner wall, smaller diameter tenons. It's the tenon wall thickness that matters in day to day pressure, the action adds nothing there.

 

[WSnyder]

BAT has a 1.350” action that they put 1.125” threads on for every cartridge. I have one.

Again okay but you still haven't said why you want to open up a std Defiance????

The only reason I did the Rem 700 is the threads were damaged and that fixed it.

 

[Edd]

Again okay but you still haven't said why you want to open up a std Defiance????

I did and you quoted it.

BAT is who told me you get early pressure with a 1-1/16” tenon.