Advice needed ... bolt opens on firing!

[WarPig1976]

Umm,,yah forget the duct tape!! Even though I have no clue what's going on with this rifle,,, I just have to say Fatman is a animal.!!,,My man is fearless.

[spentprimer]

Very useful video! First, if the cases are coming apart with military or factory "new" ammo, then you likely have excessive headspace. Which is why it's less than desirable. Puts you out of the fight until the front portion is removed...One more thing to sort, but it's probably easier with the SMLE than the No.4!

The "auto bolt lift" seems on first viewing to occur more when the bolt is not fully bottomed out, but that could be an optical trick, so no conclusion there, except that's the opposite of what I would have thought.

But the massive rub marks between the butt socket and bolt handle shows that there's a lot of action going on that ought not. Suggesting that relieving the underside of the handle in that area might stop the reaction. (Recall my previous theory that vertical play of the rear of the bolt in the raceway is a prime culprit.)

One test: With either no round or a spent round in the chamber, close the action so that the striker is cocked. Push down on the top rear of the bolt, then release. Use a punch, pencil, screwdriver, etc. to ensure the force is straight down with little rotational constraint. Try this with the bolt handle touching the butt socket and then with the handle slightly raised so that no contact is made...

ETA: It could be that the case head separation is also due to the auto bolt lift! Due to the inclined plane nature of the locking lugs, a bolt that is opening during pressure would give the same results as a static "excessive headspace". But this seems fairly unlikely because if the bolt was lifting significantly under pressure, then it wouldn't stop when the rotation was complete...Hmmm. where's a high speed camera when you need it? Would have to be well over 4,000 frames per second because barrel time is only 0.002 second or less. (Did have a fellow do motion captures of modified M14 hammers at 10.000 frames per second, but it was in a lab. Not too useful for live firing exercises!)

There was one complete case head separation and two others that cracked through partially and did not separate ... these were reloads that I acquired last week from a commercial reloader here in Minnesota. Those three were the only reloads that were shot through the rifle today, and all of the cases were on their last legs. I think the separation is a bit of a distraction from the issue, although, I cannot say for certain.

On the test you suggest I can report the following:
1) With or without a loaded chamber the bolt handles moves upward when the bolt handle contacts the socket and when it doesn't.
2) The movement is less on a loaded chamber.
3) The movement is less when the bolt handle does not contact the socket.

Yes! A high speed camera would be very useful and would be very interesting to watch when this problem happens.

[303Guy]

That's very interesting. May I suggest you get that rifle to a Lee Enfield qualified gunsmith or armourer?

So there was mention of flattened primers. Flattened primers are normal for factory rounds, even crimped ones that cannot back out without a tell tale. Uncrimped boxer primers can back out then get reseated which flattens them so in reality it doesn't mean much. It does mean something if the primers remain rounded though.

Have you checked the bolthead to see how much it lifts the striker?

What I noticed was when your rifle half opened the bolt, there was camming of the striker on fully opening. It would have been interesting to see what would've happened if the bolt was pushed down instead of up. Would the striker have lowered into the bolt? Looking at the photo of the bolt is looks as though the camming lug only engages the cam face about halfway along. You can check that simply enough by lifting the bolt handle until the cam engages and see how far it has lifted.

That separated case head is a concern. Were those reloaded cases? I thought I heard something to the effect that that case was about to separate in the back ground. Many folks say cases only last 3 to 4 firings in the 303 but I get indefinite case life (apart from neck splits if I neglect to anneal the necks). I do not usually get case elongation other than first time firing of a full body sized case (even then I'm not sure). I have my case trimmer set to spec and it doesn't take anything off normally.

If your bolt is turning close to 30° then there could very well be enough angular momentum for it to cam the striker into the short slot.

My rifle (the one at hand) draws the striker back some 4mm before the bolt is fully unlocked. It it drops back about 1mm into the short slot. The overall striker travel is just over 7mm on unlocking the bolt (bolt cam plus striker cam). My rifle starts to draw the striker back at about a sixth turn of the bolt from fully locked and on dry firing it lifts half that.
I've just taken a photo of a bolt lying next to me and by zooming in on can see a little wear on the cam face at the start. The wear is so small that the bolt still needs about a sixth of a turn to engage it and zooming is needed to actually see it.

[303Guy]

So the Head separation question has been answered. Mmm ... there is a rule to never fire someone else's reloads. These were from a commercial source? Wow.

Could someone explain how to upload photo's from my PC please? I have a photo of my rifle bolt I'd like to show.

[spentprimer]

Could someone explain how to upload photo's from my PC please? I have a photo of my rifle bolt I'd like to show.

I uploaded pictures to photobucket and then utilized their link info to copy the url and pasted it to the post via the picture icon at the top of the reply page on the forum. I think. Did I confuse you yet?

[Ridolpho]

We all should have a friend like "fatman"! Super slo-mo would be good- there's a mind boggling super slo-mo of an SVT-40 on you-tube that kind of blew my mind. The magnitude of oscillation of pretty much everything is incredible. I think I'll be nervous next time I shoot one of mine. This Lee-Enfield makes me think of some historical efforts at semi-auto fire that relied on perfect angle of bolt lugs to lock at peak pressure but then allow the bolt to rotate and open with enough remaining pressure to blow it back and cycle the action. I believe even the great Ferdinand von Mannlicher experimented with such a design. Has someone screwed with the resistence shoulders on this rifle? Given Peter Laidler's comments about the collective Lee-Enfield "group mind" having never seen such a problem is enough for me to conclude this is a one-off problem. Let us know if you ever do resolve it!

Ridolpho

[Brian Dick]

Are those bullet holes in the overhead cover at the range in the video?

[spentprimer]

As far as the resistence shoulders go, this is my first Enfield Rifle and my knowledge on the rifle is very limited, so I have nothing to compare to, as a result, I have no basis for a yes or no answer.

---------- Post added at 07:20 PM ---------- Previous post was at 07:12 PM ----------

Are those bullet holes in the overhead cover at the range in the video?

The club I shoot at is rather small and is really more geared towards ATA trapshooting. The four shooting benches are very old, but, the concrete and overhead roof are a few years old. Those are indeed holes and they were there within weeks of the shelter being put up. That little sunroof is only about 80 feet from a gravel county road and the number of times things get shot from vandals passing by from the road are uncountable.

There are berms out to 500 yards though. We had a very lovely morning to shoot. Enough of a breeze to keep the mosquitoes off and cool enough to not sweat too much!

[Brian Dick]

Thanks. I sure thought they looked like bullet holes. Jeez!

[Maxwell Smart]

Interesting video; no wonder you have some concerns about it....

If you view the still photos in original size for a close up view ( left mouse click over photo, new window opens, left mouse click on magnifying glass bottom right, third window opens, left click on magnifying glass again to view full size) then images 3, 11,12 & 13 seem very interesting.

In my (enthusiastic amateur) view, there seems to be some wear marks which should not be there. Although the lug on the cocking piece is present, it seems deformed at the front. The small lug on the back of the bolt also seems to have a strange wear pattern on the rear edge.

Any chance of some more pictures of the cocking piece, showing the shape of the lug?

The wear mark on the side of the short cam groove might be from the cocking piece lug, or maybe even the safety might somehow be coming into play?

Perhaps try the dry firing exercise with the safety removed completely - see if it has any effect.