Reloading for the new .277 Fury from Sig

[Batsin]

The neck diameter of the 277 Fury chamber is 0.312", which might be different from your 270/308. Otherwise, the Fury case has less taper and the shoulder is farther forward than a 308, so the Fury reamer should work for you. The part in front of the case is likely different. The Fury has a very short freebore since the ogive of the bullet is very close to the case neck. In other words, it is designed to have most of the bullet stuffed into the case. The freebore ends at 2.075", only 0.060" from the case mouth.

 

[K.E.C.]

I'll let Mike speak for himself, but I'm not sure what you mean by 260 Fury. Do you mean a straight necked down version? Clearly the shoulder angle is different, but compare a 260 AI print to the Fury and it's quite close in brass OAL, shoulder diameter, and neck-shoulder junction height.

As far as a Fury reamer for your chamber, compare the SAAMI print to yours: https://saami.org/wp-content/uploads/2020/11/277-Sig-Public-Introduction-Orig-2020-11-11.pdf

Thank you for your help. Okay that makes sense. I'm learning in this wildcat/ Ai.
I have picked up some 277fury Hybrid and regular brass hoping to get a Fury reamer to bore out my 277/308 chamber. Or do I need another barrel.

 

[Mike D Texas]

Let me see if I got this right. Your necking down the 277fury, for a 260ai. Or are you making a 260fury. I have been looking at this since I made my 270/308. To me is a great cartridge. I'm really close to a 270win with performance.
EDIT: Can I take a 277 fury reamer to my 277 chamber 308. Or will I need a different barrel.

Simple neck down to 264 and fire form for me.

I will note that the neck is very thick, averaging .019" on the pieces I have measured so far. I'm necking straight down using my 260 AI bushing die and a .292 bushing and then setting final tension with a .263 mandrel.

 

[K.E.C.]

The neck diameter of the 277 Fury chamber is 0.312", which might be different from your 270/308. Otherwise, the Fury case has less taper and the shoulder is farther forward than a 308, so the Fury reamer should work for you. The part in front of the case is likely different. The Fury has a very short freebore since the ogive of the bullet is very close to the case neck. In other words, it is designed to have most of the bullet stuffed into the case. The freebore ends at 2.075", only 0.050" from the case mouth.

Okay then I should get a reamer with more freebore for a 277fury. Thanks

 

[Eric_F]

Simple neck down to 264 and fire form for me.

I will note that the neck is very thick, averaging .019" on the pieces I have measured so far. I'm necking straight down using my 260 AI bushing die and a .292 bushing and then setting final tension with a .263 mandrel.

Yeah the necks are super thick after necking down, neck turning is required for 6.5 CM unless you get a custom reamer.

 

[Eric_F]

Thank you for your help. Okay that makes sense. I'm learning in this wildcat/ Ai.
I have picked up some 277fury Hybrid and regular brass hoping to get a Fury reamer to bore out my 277/308 chamber. Or do I need another barrel.

Like I said, you need to compare to your current print. If your chamber is bigger in any area than the 277 Fury chamber print, then no, you'd need to either set back your barrel or get a new one.

 

[Batsin]

Okay then I should get a reamer with more freebore for a 277fury. Thanks

My point was that if you already have a 270/308, the freebore/throat is likely different from that of the 277 Fury. Probably with a longer distance to the lands. Since the 270/308 is not a SAAMI standardized cartridge, it might have one of several different freebore/throat designs.
Although the 277 Fury CAN use bullets designed for the 270 Win, the Fury was optimized for slightly longer ogives, yet still be basically the same overall length as a 308. This means that there won't be a lot of the bullet shank sticking out of the case and many 270 bullets will be loaded kinda short. The 135 Sierra Matchking and 140 Berger Classic Hunter are two bullets known to work well with the Fury, since they were specifically requested by the Army Marksmanship Unit for match ammo... and interestingly, loaded to under 60K psi.
If you are starting off with a new barrel, it depends mostly on whether you want to run factory ammo or load long to gain powder capacity. The length of your action and magazine might be the determining constraint.

Here is a pic of the lower-pressure, all-brass-case factory ammo to give you an idea of how it looks with a typical 270 hunting bullet. Below that is a photo of it loaded with a longer-ogived match bullet.

Here is one of the match bullets.

 

[akmtnhnt]

SAAMI free bore is largely irrelevant. No one is factory cambering this round. You're having a barrel made. Give them a dummy round and have it throated properly. You're 90% in wildcat territory, might as well not handicap yourself for no reason at all. I can't for the life of me think of why you'd spend custom barrel money and put up with SAAMI limitations.

 

[Batsin]

SAAMI free bore is largely irrelevant. No one is factory cambering this round. You're having a barrel made. Give them a dummy round and have it throated properly. You're 90% in wildcat territory, might as well not handicap yourself for no reason at all. I can't for the life of me think of why you'd spend custom barrel money and put up with SAAMI limitations.

He initially asked if he could rechamber his 270/308 rifle. That is a different proposition.
The chamber largely depends on the action and if he will be a dedicated reloader vs someone who often uses factory ammo. Some Remington actions can't get much past 2.85" and the SAAMI spec for the 277 Fury is already 2.825". You could be stuck single loading with a lot of bullets if you put a longer throat in that action and want to get relatively close to the lands. Either that, or you will just be shooting stubby, low-BC bullets a little faster.
On the other hand, if you do not want to use factory ammo, it makes sense to get a longer action and get the bullet out of the powder compartment. If you want to load high performance bullets like the Berger 170 EOL and want to keep the shank ahead of the donut, you need an action and mag over 3" long.

 

[Bravo 4]

Bolt thrust is related to the max chamber pressure pushing the "piston" of the interior diameter of the case. Running some rough numbers, the bolt thrust of the 277 Fury at 80Kpsi is about 13% LOWER than the fatter WSMs at 65Kpsi. It is also slightly less, about 4%, than a 6.5 PRC, so there are a lot of actions that should be able to handle it.

The action I seen lug setback is a Remington 700, after a couple hundred rounds.

 

[Mike D Texas]

The action I seen lug setback is a Remington 700, after a couple hundred rounds.

How is this measured?

 

[Bravo 4]

How is this measured?

My/our gunsmith measured it, he compared the galled area of the locking surface to a part unaffected. The locking surfaces had been lapped previously to ensure proper contact. Unless I imagined this, he said there was .007" worth of setback. When you pulled the barrel it was very easy to see naked eye.

 

[Eric_F]

How is this measured?

You could also use Go / No Go gauges and some tape shims, which is what I'm doing.

 

[Mike D Texas]

You could also use Go / No Go gauges and some tape shims, which is what I'm doing.

For lug setback?