Misfires

[Oldbloke]

My first exp with it was back in about 1984. Dad had abought a 94 Winchester in 30/30 for me to use instead of the humble .22LR. But it would hangfire or misfire. Local gunshop said to use it for an anchor, as it had excessive headspace. Dad took it to the now defunct Kingstion Guns in Brisbane (a cafe now when Iast saw it), and the older fella disappeared into the back of his shop for a while. When he came back, he announced it was fixed.

Dad asked how much it was to fix, after the gunsmisth told us he had adjusted the hammer spring tension. It was $5. Never misfired again.

Knowledge is power.

[Oldbloke]

Feeling a tad better today.
Removed the stock.
Checking I found the font take down screw had potential to enter the locking lug area just behind the chamber. (Difficult to see)
No chance of rear screw touching anything it shouldn't.

The locking lugs are floating, so if interfered with could add resistance to fireing pin movement.
Upon close inspection I found,
1. The lugs were showing signs (minor patches of wear/polished) they were a very close fit.
2. The take down screw had tiny "burs" on the end made during manufacturing.

Although far from conclusive, and im not convinced, that the screw was causing the issue I decided to remove the burs with a very fine file.

Rifle now reassembled.

Next I found 3 of the cartridges that misfired.
1. Pulled the bullets
2. Dumped the powder.
3. Replaced the dented primer with a new one. (Retained the old ones)
4. Dug out 10 recently FLS'd cases and primed them. (abt .008" h space)

Perhaps tomorrow, I will fire the cases.
If all 13 fire I'll deem problem fixed.

If any misfire I will prime 10 fired (fire formed) cases but not sized, and see what happens. A misfire will of course indicate 0.008" is the issue.

Wish me luck.

[Oldbloke]

Meant to add this. The 3 misfires.

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[on_one_wheel]

They certainly look like shallow or light strikes.
Did the ones that fire look a little deeper?

[Oldbloke]

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3 mis fires again

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2 fired only with primer

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4 normal cases, primers

[Oldbloke]

I agree, the misfire primers look a tad more shallow than the others. And only about 1 in 7 misfires.

Really not much in it.

[GQshayne]

Are the primers fully seated in the case?

Are they all an even level with the case head, ie slightly below?

I am not sure the dents in the primer head are an accurate indication of anything, as the other fired primers change shape a bit when the round fires.

[Oldbloke]

Are the primers fully seated in the case?

Are they all an even level with the case head, ie slightly below?

I am not sure the dents in the primer head are an accurate indication of anything, as the other fired primers change shape a bit when the round fires.

Level

[Oldbloke]

Today I fired the following cases, primers only.

The 3 misfired cases s&b primers
10 FLS'd Hornady cases s&b primers
5 FLS'd ADI Cases. Unknown primers.

All fired fine. So, great news.
Fault was abt 1 of 6 were misfires.

Issue, not confirmed. But either take down screw or dirty firing pin.

However,

I disassembled the bolt out of my Marlin xl7 30.06. I've had no issues with this rifle. Fireing pin etc was clean. Washed and oiled bolt reassembled.

Removed front take down screw. No bur and no suggestion it has been touching the bolt lugs.

Conclusion: Well can't be certain but I'd guess it was the take down bolt interfering with the floating bolt head/lugs.

[bladeracer]

Are the primers fully seated in the case?

Are they all an even level with the case head, ie slightly below?

I am not sure the dents in the primer head are an accurate indication of anything, as the other fired primers change shape a bit when the round fires.

I saw the worst .38 Special handloads I've ever seen yesterday, in a 100rd box a good 30% of the primers were about 1mm proud of the case. You couldn't even stand them on end on a bench so how they weren't noticed is mindboggling. They would lock up the revolvers requiring pulling the cylinder to get them out. They ran okay in the rifle but needed to be hit once to seat the primer then again to fire it.

Cut the primer pockets so they are all the same depth and diameter with a nice sharp corner in the bottom, chamfer the top edge, and seat the primers below the case head.

[Oldbloke]

Well,,,definitely fixed. Put abt 70 rounds through today. No misfires.