My bolt is getting tighter, or?

[Redonthehead]

Increasingly more often, I can't close my bolt on factory ammo. Vanguard/Howa 7mm Rem Mag never used to have this problem with Federal but two of my last 20 refused. I bought a box of Winchester and can only close the bolt on two of them. Bolt head and extractor had brass crud build-up, which was easy to clean. Casings that don't fit are not marked at the belt but have slight scuffing at the shoulder.

So I suspect I have crud in the shoulder. What is the best way to remove (carbon or brass?) build-up at the shoulder?

TIA,
Red

 

[spife7980]

Soak it in chemicals and scrub it with patches and brushes.

Next.

 

[6brshooter]

Ejector push down flush or lower than bolt face?

 

[Redonthehead]

Ejector push down flush or lower than bolt face?

The plunger goes all the way in freely. I made sure there was no gunk in there, and was not leaving marks on the brass. The ejector claw had brass in it, which I cleaned out but no difference. Maybe the claw is not getting over the rim all the way and getting jammed?

 

[BurnOut]

Carbon ring in the throat? Take a Sharpie and run a couple of longitudinal stripes from the tip of the projectile down past the shoulder (of a round that won't chamber), and try to chamber it. Like, *really* try. No need to break out a hammer or a cheater bar, but give it some elbow grease.

Then pull the cartridge, and see where the Sharpie marks have been worn.

 

[Redonthehead]

I got 3 marks: on the bullet in front of the crimp; on the neck at the crimp; and on the shoulder. All marks at 3 o-clock. Solvent and brush cleaned before doing this.

 

[spife7980]

I got 3 marks: on the bullet in front of the crimp; on the neck at the crimp; and on the shoulder. All marks at 3 o-clock. Solvent and brush cleaned before doing this.
View attachment 7275102

Was that directly opposite of the ejector? AKA, was the ejector forcing the left side of the case forward causing it to drag on the right side on its way out?

 

[SonicBurlap]

Was that directly opposite of the ejector? AKA, was the ejector forcing the left side of the case forward causing it to drag on the right side on its way out?

Sure sounds like it if it was in the 3 o'clock position as he says.

 

[Redonthehead]

Yep, 3 o-clock made me wonder that too. I'll remove the ejector spring and try again... If it's a carbon ring, it's damn stubborn. I ordered a bore scope, arriving Friday.

 

[Redonthehead]

Good call gents. The marked ink was due to ejector dragging against the right side. So I'm back to square one.

New box of Winchester: 1 of 20 went into battery no problem. 19 not even close.
New box of Federal: 14 of 20 no problem. 6 tight or no go.
Is factory ammo really that inconsistent?

 

[6brshooter]

Factory ammo is usually at minimum size, with some under min and some just over min. Sounds like the undersized ones chamber easy.

 

[6brshooter]

Not familiar with belted cases, but is there a chance it's got something to do with the belt?

 

[Redonthehead]

Some say headspace for belted magnums is limited at the belt, not the shoulder. Measuring belt to face is pretty damn close.

 

[spife7980]

Belt only controls it on the first firing by limiting how deep it can fall into the chamber, once its fired and formed to your chamber the shoulder should have moved up to fill the chamber so you can now function as if it were rimless.

 

[Ledzep]

Do you shoot with a suppressor? Sometimes little pieces of carbon fall back down the bore and get wedged/plated to the shoulder in the chamber and causes tight feeling HS.

 

[Redonthehead]

No suppressor. This rifle has no more than 100 rounds through it.

 

[Redonthehead]

OK, I got my new caliper and bore-scope yesterday. Here are my findings:

• There appears to be no carbon ring.
• There is a bit of brass color on the lip of the chamber that mates to the cartridge belt, but very thin.
• Belt to face: (12) casings fit nicely with min 0.2170", max 0.2220" headroom.
• Belt to face: (26) casings don't fit with min 0.2225", max 0.2305" headroom.
• Case diagrams from the internet have the headroom spec at 0.2200".

Therefore, it appears my chamber allows only 0.002 over spec for headroom. I have no idea if that is reasonable "slop" for factory ammo. At least most of the Federal is in spec versus only one of the Winchester cases.

What do you guys recommend I do? Return the "bad" ammo and exchange for (insert your favorite ammo here)?

I appreciate the advice!

 

[mick243]

a quick check - if you can find someone who has an appropriate set is to check the action with go/no-go gauges - or even better yet a set of headspace gauges to determine if the chamber has been made the right size and the headspace set correctly - it's starting to sound to me that only slightly undersized cartridges chamber properly for you - suggesting slightly under dimension somewhere in the chamber/headspace - not a common problem in a new rifle, but certainly not unheard of either

 

[Redonthehead]

This rifle is around 25 yrs old and I haven't had this issue until recently. Logically, the only possibilities are: carbon fouling at neck or shoulder; brass fouling at head; brass fouling on bolt face or lugs; ejector malfunction; ammo out of spec.

So far, I have ruled out: bolt and ejector; carbon ring. There is the color of brass on the lip of the head so I need to get the right tool to clean that. However, even if there is a couple thousandths worth of brass on the rim, my chamber headspace is currently 0.2220" which is .002" larger than spec. I have almost a full box of Winchester ammo that needs between 0.2240" and 0.2305" or greater to fit (Gander Outdoor will take it back for full credit).

So I am left with this question: What is the reasonable, or allowed, deviation from spec for factory ammo?

 

[Redonthehead]

Spoke with a tech guy at Hornady. He assured me Hornady 7RM belt to face will be 0.216" + tolerance of 0.003" for a max of 0.219".
We'll see...

 

[clcustom1911]

A couple years back, I had a buddy with a brand new Remington 700 in 7mm RemMag that only 20% of winchester 150gr white box ammo would chamber.

Federal, Barnes, Remington, Hornady would be just fine.

 

[Redonthehead]

Gander Outdoor gave me full refund for the silver box Winchester. 25% of my Federals won't fit so I'll pull the bullets, modify the cases and reload. Hornady for me now.

 

[Vodak]

If you have not done so already brush out your locking lug recesses. I had a similar issue recently caused by a kernel of powder getting wedged and smeared into the corner of the lower lug recess.

 

[Redonthehead]

Worth checking again. Since we're talking thousandths, a little crud can be a big fail. Thanks for the reminder.

 

[AKMarty]

Is the extractor hitting the bottoms of the non chambering rounds?

 

[AKMarty]

Is the extractor hitting the bottoms of the non chambering rounds?

The claw

 

[Redonthehead]

I removed the extractor and claw, no difference...

 

[SnowMan]

Try a variety of ammo. I had a box of Winchester brand 300wm. It was for shit. Could not even come close to closing the bolt on some.