That 'front portion of the bolt' is a separate piece called the Bolt Head'.
It screws into the face of the bolt body.
On the right side of the Bolt Head where it extends outward, there is a cut or slot in it that rides in a corresponding channel in the recv'r.
The slot-to-channal engagement keeps the Bolt Head from rotating out of place as the bolt is manipulated back and forth and as the bolt is opened and closed.
If there is something jammed in the channel in the frame that the BoltHead rides in, the bolt will be stopped from moving rearward (in this case.
Since that channel in the frame in a #4 is a 'blind' cut, you really can't get at it too well or see it very well just looking at the rifle, especially with the bolt body stuck in place in the frame.
Aside from something in place jamming the channel (I can't imagine what would be behind the bolt head),,another thought is a bent bolt body, or bent bolt head.
This would be very unusual to say the least.
This would only have occured with the firing of overloaded round(s) which stressed the bolt and/or bolt head to the point to ever so slightly bend them out of position.
With the locking lugs at the rear of the bolt, the entire length of the bolt is unsupported and can move side to side/up and down depending on the fit of bolt body to frame cut. Some are very sloppy but work well just the same with spec ammo.
Were the 3 rounds originally fired in the rifle Factory ammo? or were they handloads?
Was anything different noticed as far a recoil when they were fired? Was extraction normal on the first 2 rds..
That 3rd round being stuck in the chamber and the extractor pulling off the rim suggests something amiss about at least that round.
Were the rounds surely 303British ammo ?
**I notice the bolt head is a #0.
That is the smallest/shortest of the Bolt Heads for a #4 rifle.
They run #0 thru #5 IIRC. Shortest to Longest
A #0 would be used on a rifle with perfect chamber cut for headspace. No extra Bolt Head length needed for correction.
That is extremely rare to see.
Most any of these rifles needs a #2, 3 or 4 size head to give it correct HS.
Not saying the HS is absolutely out of spec..but I would suspect it so with a #0 Bolt Head in place.
I'd suggest it being HS checked once this issue is resolved.
A bent bolt body from an over load usually kinks the bolt body out to the right side. Same with the bolt head,,the joint where the bolt head and bolt body thread together pushes outward a tiny amt. Almost un-noticable.
A poor fitting bolt head, one that 'Over Threads' into place can compress due to fireing. More excess HeadSpace.
The bent/kinked bolt will usually lift and open, sometimes with some resistance.
But the bolt may stall coming back as the bent bolt body jams in the raceway of the recv'r.
Sometimes you can see the opened bolt hitting the underside of the charger bridge and jamming against it.
All this 'bent bolt' business is extreme. But at this point it's easy to check for and with everything else out of the recv'r it's time to start checking for the not so likely stuff and other things that are very hard to view.
Just some more thoughts....
