NEA15-22 part III -tale of a crappy bolt

The plot thickens..

I had cleaned the rifle, done a little polishing and then of to range for test firing.

First 50 rnds (2 mags) seemed to be discharged without any problems, but then the problems started. Around 20% of the rounds failed to ignite on first try, but most ignited on second try, after being put back to magazine and re-cycled into the gun.

I collected some examples of fired casings and also some non-ignited rounds to check the firing pin markings. Then I also noticed that the first 50 rounds were not so successful and had included some bulged and deformed casings.

Some fired and deformed casings mixed with some failure to ignite rounds
Some fired and deformed casings mixed with some failure to ignite rounds

I then started investigating what could be the issue this time and it seems to be the bolt to blame.

1) The machined recess for the round to seat has very uneven edges:

Bad edges on the machining of round seating on bolt face
Bad edges on the machining of round seating on bolt face

2) The recessed part of the bolt face is not parallel to external bolt face and this equals that the round might not be properly seated while chambered

Round seating is not in line with external bolt face
Round seating is not in line with external bolt face

I chambered one round and the took the lower receiver of for further investigation. There seems to be pretty significant gapĀ on the left, between the bolt face and the chambered round. At first, this seemed a little inconsistent with the previous picture about the misalignment between seating and the bolt face, but further analyzing suggests that the round is even more out of place and appears to be resting on the little notch seen on right in the above picture.

Chambered round without proper seating of the round on bolt face
Chambered round without proper seating of the round on bolt face

The importer suggested that the deformation of the casings could happen if the chamber had too large bevels on barrel face, but I don’t think that is the case:

Dirty and cleaned barrel face
Dirty and cleaned barrel face

Continued in NEA15-22 part IV, previously: part I and part II

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