Factory barrel with tight freebore

[Phys86]

I just put on a new factory takeoff 6.5cm Tikka barrel.

I go to find the cartridge base to ogive length for shooting 140gr match burners and use my Hornady tool to do so. I sharpied up the bullet.

When I push the bullet with the rod up into the throat, it doesn't go very far. I pull it out and look and the bullet is abnormally deep in the case. I know the Tikka factory 6.5cm barrels have very long throats.

So I put it back in and push the rod a little harder and then it suddenly jumps further forward. I give it another firm push to make sure it's all the way in. I do that several times and each time it takes a firm push to get the bullet seated to the lands.

Looking inside with the scope, I see drag marks where the sharpie came off the bullet. All the way around the freebore.

Wtf.

Problem #1 I had with this barrel is that the headspace is short (that's ok I'll just handload for it) #2 is that it seems the freebore is tight.

Maybe this barrel was reamed with a worn out reamer? How did this pass the factory test shooting and inspection?

My question is ... Has anyone had a rifle with essentially zero freebore clearance and if you did, did you shoot it and did it shoot ok? Did it give excessive pressure signs with lower charges? Group horribly?

 

[dakor]

Tikka chambers have shorter throats because they use a SAAMI spec OAL. A short throat does not have any effect on accuracy and to avoid pressure just seat the bullet a little deeper in the case.

If you want a longer throat its an easy fix with a throating reamer. The best part about a Tikka is you can mill the current bolt stop or get the long action bolt stop and get a long action magazine for it.

Have someone throat it so you can seat the bullet out farther and it will feed like a dream. I am running this on one of my daughters rifles thats a 6.5 creedmoor and it works very well.

 

[Phys86]

This doesn't have a short throat. It has a very long throat. After pushing the Hornady tool rod a little harder and the bullet fully seated into the lands, there wasn't much bullet left in the case neck.

The issue is the freebore seems to be a smaller diameter than it should be.

6.5cm saami freebore diameter is .2645 with a tolerance of +0.002.

The bullet should not be contacting the freebore at all, but it does as evidenced by it hanging up before seating into the lands and it leaving sharpie marks on the sides of the freebore portion

 

[Dimner]

I just put on a new factory takeoff 6.5cm Tikka barrel.

I go to find the cartridge base to ogive length for shooting 140gr match burners and use my Hornady tool to do so. I sharpied up the bullet.

When I push the bullet with the rod up into the throat, it doesn't go very far. I pull it out and look and the bullet is abnormally deep in the case. I know the Tikka factory 6.5cm barrels have very long throats.

So I put it back in and push the rod a little harder and then it suddenly jumps further forward. I give it another firm push to make sure it's all the way in. I do that several times and each time it takes a firm push to get the bullet seated to the lands.

Looking inside with the scope, I see drag marks where the sharpie came off the bullet. All the way around the freebore.

Wtf.

Problem #1 I had with this barrel is that the headspace is short (that's ok I'll just handload for it) #2 is that it seems the freebore is tight.

Maybe this barrel was reamed with a worn out reamer? How did this pass the factory test shooting and inspection?

My question is ... Has anyone had a rifle with essentially zero freebore clearance and if you did, did you shoot it and did it shoot ok? Did it give excessive pressure signs with lower charges? Group horribly?

I commonly feel that 'jump' in my barrels when I use the Hornady tool too. In new factory barrels and prefit custom Tikka barrels.. Mostly the jump ends up adding like 0.010-0.015 or readings where you don't let's it jump

I don't really sweat it. Because I don't 'chase the lands' and not too worried about what the free bore is. That's because during load tuning I run an OAL test from that point where you can feel the jump and go backwards in increments of 0.003 or 0.004.

I have also noticed it's best to keep the modified case oiled when using the Hornady tool. I also keep forward pressure on the device (not the bullet pushing rod) so that the brass is firmly in place while in the chamber.

I usually take 5-8 readings of 3-5 bullets of the same make. It's a lot of readings but it allows me to see a pattern through the noise and figure out what the most common result is. I don't think of the result as touching the lands measurement, I just consider it a starting point

 

[ronemus]

It looks like the freebore is rough, perhaps do to machining issues - worn reamer, wrong speeds, poor chip clearance, etc. That roughness will probably disappear after a few rounds are fired. The bullet appears to be making contact with only the high points in the freebore.

 

[Phys86]

The several Tikka barrels I've looked at look pretty similar in the freebore. They generally seem kinda rough, but the bore and grooves are like mirrors.

Not sure if I want to shoot it and see if it's going to be problematic or not

 

[DaveTooley]

Have you measured the diameter of your bullets?

 

[Phys86]

Have you measured the diameter of your bullets?

0.264-

It is a roughly cut throat. Could it be they're just burrs and will go away with some shooting?

 

[boltfluter]

The several Tikka barrels I've looked at look pretty similar in the freebore. They generally seem kinda rough, but the bore and grooves are like mirrors.

Not sure if I want to shoot it and see if it's going to be problematic or not

What have you got to loose? Just shoot it. Like most Tikka's it will probably be a tac driver. A tight freebore is most likely why they all seem to shoot amazing well for factory barrels.
Paul

 

[dakor]

This doesn't have a short throat. It has a very long throat. After pushing the Hornady tool rod a little harder and the bullet fully seated into the lands, there wasn't much bullet left in the case neck.

The issue is the freebore seems to be a smaller diameter than it should be.

6.5cm saami freebore diameter is .2645 with a tolerance of +0.002.

The bullet should not be contacting the freebore at all, but it does as evidenced by it hanging up pleasebefore seating into the lands and it leaving sharpie marks on the sides of the freebore portion

I would measure your bullet diameter like mentioned first. A throating reamer would clean up that area if you are that concerned about it. You can rent them but you could just shoot it and see how it goes.

 

[joshb]

I would polish that throat, if it bothered me. It looks a little rough. It will be hell to clean, once the carbon starts to build up.

 

[Phys86]

I would measure your bullet diameter like mentioned first. A throating reamer would clean up that area if you are that concerned about it. You can rent them but you could just shoot it and see how it goes.

I mentioned that in a post just above. They're 0.264-

Even if they were dead nuts 0.264, I wouldn't expect them to touch at all in an in spec factory barrel unless they're really nasty burrs sticking up

 

[Eagle Six]

I had a similar issue with a barrel replacement (not a Tikka). A light touch with a throating reamer and some polishing and it was good to go. Although it appears rough and has some left over machining from the reamer it probably isn't as bad as the sharpie marks look. As we push the bullet with black in to find the lands the bullet will shift around a bit and hit the walls of the throat dragging off some of the black. If it were me and I didn't have access to a throating reamer, I would wrap some fine steel wool around a brush with some JB and polish the throat a bit. But, I'm a backyard Redneck gunsmith!!!

 

[Phys86]

I had a similar issue with a barrel replacement (not a Tikka). A light touch with a throating reamer and some polishing and it was good to go. Although it appears rough and has some left over machining from the reamer it probably isn't as bad as the sharpie marks look. As we push the bullet with black in to find the lands the bullet will shift around a bit and hit the walls of the throat dragging off some of the black. If it were me and I didn't have access to a throating reamer, I would wrap some fine steel wool around a brush with some JB and polish the throat a bit. But, I'm a backyard Redneck gunsmith!!!

Ha I've done that with factory barrels before. A maroon 3m pad around an undersized nylon brush, some strokes til the pad is worn, add some JBs and oil and go at it again. It works pretty well and if it does change any dimensions I couldn't tell in my shooting.

I'd considered doing that with this one.

 

[Eagle Six]

I'd considered doing that with this one.

From what I have read many barrel manufacturers are concerned about throat break-in as the primary reason for barrel break-in. So if polishing a bit get's it to the point you feel safe to shoot it, that will also smooth the throat out some. I'm excited to hear how you overcome this and how the barrel groups!

 

[Jonnyofalltrades]

If it were me and I didn't have access to a throating reamer, I would wrap some fine steel wool around a brush with some JB and polish the throat a bit. But, I'm a backyard Redneck gunsmith!!!

Apparently Mickey Coleman would recommend that approach for a rough throat. Maybe you're not as redneck as you think!

 

[Phys86]

It's funny how high power CF is so different from the best of the best muzzleloader/blackpowder comp. Lee shaver is well known for "breaking in" his comp barrels by wrapping steel wool around a jag and running it back and forth through the barrel with a fit so tight it's hard to move the rod. And it works wonders! I did that in my flintlock and it made so much difference for loading and preserving patch integrity

 

[Phys86]

Well, maybe it'll shoot, tight freebore or not.

Ran a couple patches through the bore before leaving.

Started with the cheapest ammo on the shelf to smooth that throat. Winchester power points. Not good :/ 100yds.




Then went to my 140gr match burners loads. Starline SRP virgin brass, cci450, and 40.0gr h4350. Jumping around 0.110.

Keep in mind the wind was gusting, whipping left and right. I just held center.

25 shots. It will do I think the mantra "let the target decide" is right

Avg 2530
Sd 10.6
Es 37

 

[Eagle Six]

As you work on that load I'll bet you find at least two more powder charges that will tighten things up a bit. With that much jump you should have room for a bunch more h4350.

 

[Phys86]

As you work on that load I'll bet you find at least two more powder charges that will tighten things up a bit. With that much jump you should have room for a bunch more h4350.

Yep, this charge is just for practice and precious powder preservation