What's up with this throat?

[Ffjmoore]

I built 2 rifle in the last month with barrels from 2 companies. The carbon 6 barrel had some problems I posted in another thread. The second barrel is from proof. Now it's on the very edge of sammi spec for 7 mag. Max is .227, using my .223 nogo gauge and a few pieces of scotch tape I found my head space to be about .226. I'm still waiting on a field gauge to confirm but the minimum is .220 and they are not even close to that. Now look at this throat, my guess is the remer was not the tightest fit and favored one side over the other. What do you think? Should I bring it to their attention or is this just what I should expect from companies turning out barrels.

 

[PinesAndProjectiles]

How does it shoot?

 

[Ffjmoore]

It shoot a .7" 3 shot group using 160gr barnes and a 1.16" group of 145gr

 

[spife7980]

Now it's on the very edge of sammi spec for 7 mag. Max is .227, using my .223 nogo gauge and a few pieces of scotch tape I found my head space to be about .226. I'm still waiting on a field gauge to confirm but the minimum is .220 and they are not even close to that.

What the hell does this mean?

 

[Ffjmoore]

What the hell does this mean?

See headspace

 

[spife7980]

See headspace
View attachment 7716616

Yeah that doesnt explain why/how youre using a 223 nogo in a 7 mag or what your numbers mean.

 

[Steel head]

Head space is measured to the Datum line at 2.12” with a .420 datum gauge on normal cases but in reality it’s from base to front of belt on a belted magnum and .220-227.
So .226 would be in range.

If reamer cuts more to one side that’s a set up/dial in issue

 

[Steel head]

Yeah that doesnt explain why/how youre using a 223 nogo in a 7 mag or what your numbers mean.

I think he’s looking at the belt dimensions

 

[Ffjmoore]

.220 inches is the head space on the go gauge. .223 inches is the length of the no go gauge.
I added tape to the back of the no go, bringing the length to .226 inches which is .001 under the max of .227 inches.

 

[Ffjmoore]

I think he’s looking at the belt dimensions

Correct, the headspace gauges measure from the belt on the belted magnum.

 

[spife7980]

I think he’s looking at the belt dimensions

 

[Steel head]

Measure the belts on your brass
If its only growing 6 thou I wouldn’t worry about it.
If your measuring all this with calipers your numbers could easily be suspect.

 

[PinesAndProjectiles]

Measure the belts on your brass
If its only growing 6 thou I wouldn’t worry about it.
If your measuring all this with calipers your numbers could easily be suspect.

I’ve never reloaded for a belted cartridge, so I may be out of line, but do the belts actually grow during firing?

 

[Steel head]

I’ve never reloaded for a belted cartridge, so I may be out of line, but do the belts actually grow during firing?

Maybe at popular SH pressure levels!

 

[nn8734]

I’ve owned a bore scope for years however one thing I have never done nor will I ever do is use it on a rifle barrel.

If it shoots to your expectations (accounting for shooter and ammo) and functions normally that’s all you need to know.

 

[FisherT&C]

@Ffjmoore
What are you torquing your action to? (ft.lbs.)
What action is this barrel for?
As for the throat, it looks like one of the lands is still partially there. I've seen worse to the point that it effected seating depth and the barrel shot like shit.

 

[Ffjmoore]

@Ffjmoore
What are you torquing your action to? (ft.lbs.)
What action is this barrel for?
As for the throat, it looks like one of the lands is still partially there. I've seen worse to the point that it effected seating depth and the barrel shot like shit.

It's torqued to 80.
It's a tikka t3

Yes the throat looks to have a lands still there. It's shooting "ok" so far. I just expected better from proof.

As for worse, I have a carbon 6 barrel that the rounds get jammed in the throat and are super hard to extract unfired.

 

[1moaoff]

Remind me to never have you look at my barrels.

Anyway... I think we are still looking far a d explanation on your numbers that make 100% sense

 

[spife7980]

Remind me to never have you look at my barrels.

Anyway... I think we are still looking far a d explanation on your numbers that make 100% sense

Its a belted mag so it only measures this part instead of the useful part to the chamber shoulder

 

[FisherT&C]

It's torqued to 80.
It's a tikka t3

Yes the throat looks to have a lands still there. It's shooting "ok" so far. I just expected better from proof.

As for worse, I have a carbon 6 barrel that the rounds get jammed in the throat and are super hard to extract unfired.

The Tikkas can vary a little with head space but I've never found more than a .002 variation myself. I don't know where proof sets their dimensions on a Tikka prefit. As for loading a belted magnum, I would use a bump gauge and set your die for a .002 bump max on the shoulder. That way the cartridge is head spacing like a non-belted cartridge. As you can see on the SAAMI chamber drawing there is a +.010 allowance at the datum line so belted cartridges tend to fire fire form significantly so if you size it back too much you can over work the brass. I don't think your head space dimensions are dangerous but if your over resizing the brass you could get case head separation. I'm just trying to help, not attempting to insult your intelligence.

 

[Ffjmoore]

The Tikkas can vary a little with head space but I've never found more than a .002 variation myself. I don't know where proof sets their dimensions on a Tikka prefit. As for loading a belted magnum, I would use a bump gauge and set your die for a .002 bump max on the shoulder. That way the cartridge is head spacing like a non-belted cartridge. As you can see on the SAAMI chamber drawing there is a +.010 allowance at the datum line so belted cartridges tend to fire fire form significantly so if you size it back too much you can over work the brass. I don't think your head space dimensions are dangerous but if your over resizing the brass you could get case head separation. I'm just trying to help, not attempting to insult your intelligence.

Not insulted at all. Here to learn. Good info. So to confirm, your saying to use my full length die, but set it up to only bump the shoulder .002 back.

 

[DIBBS]

It's torqued to 80.
It's a tikka t3

Yes the throat looks to have a lands still there. It's shooting "ok" so far. I just expected better from proof.

As for worse, I have a carbon 6 barrel that the rounds get jammed in the throat and are super hard to extract unfired.

On the Carbon 6 have you tried shortening your COL? Sounds like a HARD jam into the lands or a burr in the chamber or oversized cases.

On the 7mag, whats the rifle weigh and how much have you shot heavy /heavier recoiling rifles?

It takes a fair amount of practice.

For the chamber... as another poster suggested...if it meets your accuracy requirements bump the shoulders -.002 and shoot the sumbitch. Life's too short .

 

[Ffjmoore]

On the Carbon 6 have you tried shortening your COL? Sounds like a HARD jam into the lands or a burr in the chamber or oversized cases.

On the 7mag, whats the rifle weigh and how much have you shot heavy /heavier recoiling rifles?

It takes a fair amount of practice.

For the chamber... as another poster suggested...if it meets your accuracy requirements bump the shoulders -.002 and shoot the sumbitch. Life's too short .

8lbs 1.6oz with the scope

The carbon 6 is most definitely to narrow. You can see where it grabs the bullet.

Carbon six barrel review and issues.

Got a new barrel. Shot fine, until I tried to extract an unfired round. It was jammed! It took me a bit to figure it out. But the bullet is getting jammed and sticking the round. As you can see the round is rubbing pretty bad. These are factory rounds in a barrel with 2 trips to the range to...

www.snipershide.com

 

[FisherT&C]

Not insulted at all. Here to learn. Good info. So to confirm, your saying to use my full length die, but set it up to only bump the shoulder .002 back.

Yes, that way you'll get a better fit in the chamber and won't be over working your brass. Yes, on FL die.