Bolt jump

[SMOKEY]

I have not shot many bolt action rifles in my time but I notice that when the Enfield No.4 and 5 that I fired, the bolt moves slightly upward. I do not remember that with any other bolt gun I have shot, can someone tell me why? Or is it just my imagination. Thanks

[Parashooter]

It's a completely normal result of the mainspring delivering a bit of incidental torque as it decompresses, simultaneously releasing mainspring pressure on the locking lugs as the firing pin stops on the rear face of the bolt head and transfers its forward momentum to the bolt. It's common with many other turnbolt rifles as well - but it seems folks notice it only with those much-maligned British service rifles.

I suspect your observation is based on dry-firing with an empty chamber. Observe when firing a live cartridge (or even a good "snap cap") and the effect diminishes or disappears - largely because the firing pin is arrested on the primer instead of on the bolt head, maintaining some degree of mainspring pressure on the lugs. When this pressure is enough that friction between bolt and receiver is stronger than mainspring decompression torque, no "jump" occurs.

Furthermore, a thoughtful examination of the rear end of the bolt and the top surface of the cocking piece will reveal an arrangement whereby the bolt is prevented from rotating more than a few degrees before the cocking piece lug meets a cam surface on the bolt and stops rotation until torque is applied to the bolt sufficient to begin compressing the mainspring.

Another study aid is to watch the cocking piece while opening the bolt slowly. You should be able to observe that the bolt rotates easily for a few degrees but gets a bit stiffer at the same time the cocking piece starts to move away from the rear of the bolt. Further rotation demonstrates that a portion of the cocking effort is actually applied on opening even though the Lee is ordinarily described as a "cock-on-closing" action.

[Weasel]

Smokey I just check 3 03 A3's and they do the same thing only not as much. As I told you in the past it is normal and don't worry about it. Both No 5's and my No 4's do the same thing it is normal. That bolt isn't going to come back and smack you in the face as you should know by now as you have fired both your Enfields. I mean after all don't you think after all these years I would lead you down a dangerous path?