243 Fury and 243 Fury AI

[Chris in TN]

With sustained 80k psi you are not going to get a catastrophic failure, if anything youre going to get bolt set back.

I'm assuming this would show up as a growing headspace issue or be really obvious when you went to rebarrel. Correct?

 

[Tanner]

they never leave the chat, the case necks split.

That’s pretty cool. How many firings before you’re splitting necks?

 

[Waltersobchak]

That’s pretty cool. How many firings before you’re splitting necks?

with 16 inch 22 creed shooting 88tmk's at 3100 FPS, two firings. With 6 creed, 109 elm doing 3175 out of a 22 inch barrel, 4-5. With 308, 212 eld doing 2500 fps out of a 16 inch barrel, 10 firings. with 8.6 blackout, 10+

 

[z987k]

Honest question, and I'm not asking to be critical - the numbers you're posting here are fascinating.

I'm not afraid of 80kPSI. What I'm afraid of is 80kPSI in a rifle designed for 65k.

From a metallurgical standpoint - I am not an engineer but I kinda worked in that world for a while and there was a very common rule of thumb that a part or gadget that would fail catastrophically at, say, value X, would likely run forever at value 1/2X and the engineers I worked with would spec things to run at that 'forever' load point but in reality they often exceeded it and always got away with it, until they didn't, which usually occurred after the original engineer had retired and it was someone else's problem. If we apply that to rifle actions we would want to design a rifle action that would hold together up to perhaps 130kPSI in order for it to 'run forever' with 65kPSI ammo. Or, in terms I used to play with a lot, my old Ruger Blackhawk was, per John Linebaugh, good for about 65kPSI before the cylinder failed, so in theory we could run 32kPSI loads in it forever, and when I went through a phase of being enamored with big bore handguns that's what I did. And, yes, I exceeded that a few times, likely pushed it to nearly 40kPSI a very few times, but stopped that because there's nothing I could really do with a handgun at 40kPSI that I couldn't really also do just as well at 23kPSI. But I digress.

So, to apply the above to your project here: If it's true that the Tikka is a true 65kpsi action, then what you're doing is somewhere on a sliding scale between 'run forever' and 'suddenly gernade on you'. It's also possible that the Tikkas have been failure tested and are stronger than I assume. If they'd hold together up to 160kPSI then I'd be fine with the 80kPSI figure, assuming primers held and you don't get gas in your face.

So....either a) the rifle is rated to handle the pressures you're seeing, or b) you're at pressures that won't create instant failures but you're turning the receiver into a consumable with a finite life. My question is, do you know which it is, and if the latter, how many rounds before you cease to trust the receiver and retire it?

I'm not asking to be critical and I'm not asking from the standpoint of looking down my nose like I'm smarter than you. I think the project you're working on is incredibly neat. I'm simply wondering what the long-term implications are for the integrity of your rifle action.

You need to specify where you're actually concerned with the pressure. Do you think the bolt can't handle it? The action where the bolt lugs ride? Or do you think the chamber/barrel can't? Very very different things.

You can't just say X is an action that can handle Y. Actions have multiple parts that are all subject to different forces.

We can show through math how a 308 bolt face at 80kpsi has almost the same bolt thrust as a magnum bolt face at 65kpsi. It seems everyone that asks this question doesn't know that bolt thrust has the radius of inside diameter of the cartridge as a variable. And R is squared, because it's the area of a circle.

 

[Chris in TN]

You need to specify where you're actually concerned with the pressure. Do you think the bolt can't handle it? The action where the bolt lugs ride? Or do you think the chamber/barrel can't? Very very different things.

You can't just say X is an action that can handle Y. Actions have multiple parts that are all subject to different forces.

We can show through math how a 308 bolt face at 80kpsi has almost the same bolt thrust as a magnum bolt face at 65kpsi. It seems everyone that asks this question doesn't know that bolt thrust has the radius of inside diameter of the cartridge as a variable. And R is squared, because it's the area of a circle.

I’m familiar with the math. Don’t see much point in chasing it down with you.

 

[walk2112]

with 16 inch 22 creed shooting 88tmk's at 3100 FPS, two firings. With 6 creed, 109 elm doing 3175 out of a 22 inch barrel, 4-5. With 308, 212 eld doing 2500 fps out of a 16 inch barrel, 10 firings. with 8.6 blackout, 10+

Curious about this 308 shooting 212’s at 2500, are you running a 8 twist barrel or faster maybe? What barrel and action? Sounds like an awesome use of the hybrid case.
I’d build a fast twist 308 just to have the benefits of versatility with bulk ammo and these hybrid handloads as an option, but tbh the chamber etching thing has me nervous to drop $$ on a barrel just for it.
Never any chamber etching issues or anything weird reloading hybrid 308 10 times? Thanks

 

[Waltersobchak]

The issue with the brass from American reloading is that is literally rejects from sig. you have to be diligent about what brass you use. The first sig fury brass I got was from a demo at Garand Thumbs ranch. It was all marked 23 on the head stamp. I have not had any issue with that brass. The best luck I had shooting the 212 and 215s was with a 1/7 twist Noveske barreled 16 inch Q fix.

 

[Liberty Risk]

The issue with the brass from American reloading is that is literally rejects from sig. you have to be diligent about what brass you use. The first sig fury brass I got was from a demo at Garand Thumbs ranch. It was all marked 23 on the head stamp. I have not had any issue with that brass. The best luck I had shooting the 212 and 215s was with a 1/7 twist Noveske barreled 16 inch Q fix.

Love to hear your thoughts on NAS3 and your load velocities ext..

 

[Liberty Risk]

Are my dreams of having a 77TMK leave an 18in ar15 @ 3,500fps unrealistic and unsafe or is it the future?

 

[Waltersobchak]

Love to hear your thoughts on NAS3 and your load velocities ext..

NAS3 is pretty amazing stuff, the easiest way to get more velocity out of it is because of the 8-9% more case capacity. The sig brass on the other hand has reduced case capacity compared to standard brass. Due to the metallurgy, the nas3 stuff has more bolt thrust than sig brass and can not be reloaded. Ive shot it in 300 blackout a lot and have a few hundred rounds of 308 down the tube. I imagine where this still will land, is in shorter, stubbier cases designed from the ground up to handle pistol powders, or at least faster powders than traditional 556, 6.5 and 308 powders. like a short stubby 22 cal running 90k psi shooting 88s at 2800-2900 out of short barrels, say 14.5

 

[Liberty Risk]

That's what I'm really looking forward to is the release of 6 arc nas3 and hopefully 22 arc. 6mm creed velocities in a 16in Ar platform.

 

[Waltersobchak]

That's what I'm really looking forward to is the release of 6 arc nas3 and hopefully 22 arc. 6mm creed velocities in a 16in Ar platform.

that is doable and is coming, the issue will be 750-900k barrel life.

 

[Liberty Risk]

How fun and ridiculous would it be if they released the wssm line in nas3...I would buy one.

 

[Waltersobchak]

How fun and ridiculous would it be if they released the wssm line in nas3...I would buy one.

they just came post 338 on their website today.

 

[surfr716]

with 16 inch 22 creed shooting 88tmk's at 3100 FPS, two firings. With 6 creed, 109 elm doing 3175 out of a 22 inch barrel, 4-5. With 308, 212 eld doing 2500 fps out of a 16 inch barrel, 10 firings. with 8.6 blackout, 10+

would you get better case neck life with annealing between firings, or is the juice not worth the squeeze? intrigued on the hybrid case design.

 

[Waltersobchak]

would you get better case neck life with annealing between firings, or is the juice not worth the squeeze? intrigued on the hybrid case design.

always anneal between each firing. it extends the life a lot.

 

[Sundodger]

Well done sir.

This is exactly what I have been dreaming since the Fury was announced; 243AI throated long for 6mm CM heavies, in a Tikka with a LA bolt stop and mag.

Any other insights as to how to select cases that seal so they don't act like a cutting touch? Is there external visual cues? Buy loaded ammo from SIG?

 

[Waltersobchak]

Well done sir.

This is exactly what I have been dreaming since the Fury was announced; 243AI throated long for 6mm CM heavies, in a Tikka with a LA bolt stop and mag.

Any other insights as to how to select cases that seal so they don't act like a cutting touch? Is there external visual cues? Buy loaded ammo from SIG?

the best way to insure youre getting good ammo is to buy factory sig ammo and pull it. its expensive. but realistically all you need is a 100 or 200 rounds to burn out a 243 ai barrel. you can buy the American reloading stuff, youre just going to have to roll the dice on the box you get. ive had some that have 26% differences in case weights. id focus on stuff head stamped with 23 or 24. I did a test yesterday after blasting a few hundred rounds of 25 fury and there wasn't any etching in the chamber.

if youre really concerned and not to worried about saving money, buy the sig ammo factory and then use a bullet puller.

 

[Waltersobchak]

Did some more testing yesterday with stabal 6.5 and the 109 ELDM. surprisingly the stabal grouped better than h4350. Im still getting used to the rokstok and find myself shooting a lot of horizontal spreads, but for my money, this 10 shot group will do hunting wise. at this velocity, the 109 eldm stays above 1800 FPS past 1k Yards and my dojo.

 

[Treelineasassin]

I may have to try some my hybrid brass in the 20in 6mm saw!