[Anduril]

An exercise in futility? (Open to comments, suggestions, etc...)

I have a Mitutoyo 6" digital caliper and I'm not getting the "correct" numbers on some brand new Sellier & Bellot 6.5 Creedmoor ammo. (#SB65E, 142 gr HPBT).
I check the caliper calibration on our reference standard here at work and it is "dead on balls accurate".

So, maybe I'm just not measuring correctly (on a live round, so being careful, obviously).

I'm checking because this case of ammo (at least the few rounds I tried), do not chamber nicely.
It's a new rifle. (Ruger RPR in 6.5CM).
You don't have to SLAM the bolt home to get the breech closed, but you do need to be rather deliberate about it.
Otherwise, the bolt won't close.

The bolt itself looks fine, as does the chamber - but I don't have a way to measure that, and am not exactly sure what I'd be measuring anyway?
I only have this one case of ammo, so no other rounds or snap caps to compare to right now. I do have some snap caps on order.

I'm getting:
L6 = 68.97 mm
L3 = 48.62

G1 = 6.70
H3 = 7.43 (outside diameter)

I can probably measure the extractor end of things next week.
Right now, our warehouse work area is in disarray and the inspection microscopes are not yet set back up.
And I tried to measure it without a visual assist, but don't trust my technique.

Anything specific I should look for re: a bolt that's a little hard to close.
Or can this just be chalked up to a new (never-fired) rifle that just needs a little break-in?

 

[AFJuvat]

All of your measurements appear to be within tolerance.

My guess is that it needs a little break in and/or the chamber throat is a bit short.

After you close the bolt and then open it again, are there any marks/scratches on the bullet?

 

[gandrfab]

Could there be the slightest burr in the chamber?

 

[BeerHunter]

What does the projectile look like when you remove the round after chambering? You might need GO and NO-GO gages to measure your chamber to make sure it meets SAAMI specs (SAAMI Z299.4 – 2015 available here), but I'd be real surprised if your brand new rifle didn't.

 

[Anduril]

What does the projectile look like when you remove the round after chambering? You might need GO and NO-GO gages to measure your chamber to make sure it meets SAAMI specs (SAAMI Z299.4 – 2015 available here), but I'd be real surprised if your brand new rifle didn't.

I did not notice any scratches or gouging, but I will take an even better look tonight.

 

[Anduril]

No marks on the "bullet" of the snap caps.
However, there are marks (abrasion) on the rim of the cartridge where the extractor grabs the round for ejection.
The snap caps all eject OK.

When a live round does not chamber, I think the issue is the cartridge base is not seating under the ejector groove in the bolt. (?)
The spring-loaded part at the ejector moves freely with what I consider to be appropriate pressure.

Now, the way this LOOKS, is that the cartridge is loaded at an angle from the magazine so that the rim of the cartridge loads underneath a non-movable "ejector rim" that is part of the bolt assembly.
As you forward the side, the round engages with the chamber which straightens out the round and eventually pushes against the spring loaded button in the bolt (not sure what you call that).

So, I guess this could be a magazine issue (?) -- where the round is not approaching the bolt face at the correct angle?
Maybe I can verify that by playing with the inevitable "slop" in magazine attachment to the rifle?

Or, maybe there is a problem with the bolt face itself?
I think I'm going to try a little lubrication and see if that helps.
And if not, then off to a gunsmith and/or call to Ruger to find out WTF(?) on a brand new rifle.

 

[racer88]

I would try some different ammo. Maybe it's the ammo and not the gun at all.

I've got some Hornady we can try when we get together.

 

[Anduril]

Lubrication DID NOT help.
Factory (SB65E) rounds still will not chamber but snap caps will.

To the naked eye, there is nothing different between the two rounds.
If the SB ammo is the problem, what am I going to do with a case of 1,000 rounds?

How pervasive is the problem of a particular ammo not feeding into a given rifle, while other ammo works fine?

 

[BeerHunter]

I'm pretty sure it's not the ammo. Have you tried just opening the bolt, loading a single round in the breech, and slowly closing the bolt like a single-shot rifle? In other words, are you only trying to load from the magazine?

 

[Riverpigusmc]

Might try to mic a round before clambering then mic it again after clambering to see if OAL changes

 

[7.62Kolectr]

Few things you can try. Have you used a chamber brush to really scrub it? Might be some funk/gunk in there making it stick
Use a sharpie and color the bullet. Then chamber and eject it. See if you can then see visible marks on it
Pull a bullet from the case and try to load the empty shell. See if it works or you still have difficulty.
Also since Racer has the same gun you can swap bolts when you get together and see if his functions better/smoother?
I would also shoot a box thru it and see it things loosen up a bit. Might just be new and tight?

 

[Anduril]

I'm pretty sure it's not the ammo. Have you tried just opening the bolt, loading a single round in the breech, and slowly closing the bolt like a single-shot rifle? In other words, are you only trying to load from the magazine?

This morning, I tried just a single round (without the magazine).
The bolt still would not close on a live round, but would close on a snap cap.

 

[Anduril]

I may run up to Delray Shooting center and get a different brand of ammo.
If I do, updates to follow.

It definitely "feels" like its the extractor (retainer lip) part of the bolt head that is getting hung up on the rim of the cartridge.
Of course, by that time, the bolt is too far advanced to be able to see exactly what is not lining up.

 

[racer88]

Are you holding your mouth right? (a southern thing) 🤪

Ya gotta hold your mouth right!

 

[Anduril]

Tongue placement is also critically important !!

Heading up to get some different ammo now.
Going to drop by early voting on the way. Give me something to feel better.

 

[Anduril]

Just checked two more ammo types:

1) Hornady ELD Match 147gr
2) Nossler 120 gr. Ballistic Tip

Same problem.
This (brand new) rifle is going back to Ruger on Monday.

 

[7.62Kolectr]

Don’t wanna shoot it first and see if it loosens up a bit?

 

[Anduril]

Don’t wanna shoot it first and see if it loosens up a bit?

No.
On the Hornady ELD, it did chamber maybe 2 out of 10 tries, but on those two "successes", the round lodged in the barrel and did not eject when retracting the bolt.

Too much BS for me to put up with for a factory-new gun.

 

[racer88]

Yeah... Houston, we have a problem.

And, that suuuuuuuuucks.

Why send it back to Ruger? Send it back to the dealer, eh? Or can't do that?

Don’t wanna shoot it first and see if it loosens up a bit?

Can't shoot it if it won't chamber a round. And, I'd be reluctant to fire a round that was forcibly chambered.

 

[7.62Kolectr]

Yeah... Houston, we have a problem.

And, that suuuuuuuuucks.

Why send it back to Ruger? Send it back to the dealer, eh? Or can't do that?



Can't shoot it if it won't chamber a round. And, I'd be reluctant to fire a round that was forcibly chambered.

I don’t think it really matters where he bought it or how? Any gun that needs an issue to be addressed would need to go back to the manufacturer. No?
I thought he said it was sticky or difficult not that it won’t chamber a round. Just like the issue you had with your barrel and the one type of ammo. You ‘forcibly’ chambered rounds and they fired fine right? Fired it fine but was sticky when trying to hand eject a live round.
If they are sticky or a bit difficult to chamber yet still do and bolt closes I’d fire a box of two out of it to see if it loosened up. If it flat out won’t chamber or close on anything then yes that’s for sure an issue.