Explain the Original SMLE 303 Headspace Situaiton?

[Peter Laidler]

Thread 6, Rifle bodies don't stretch.

[pocketshaver]

its a rather "known fact" on certain gunboards such as cast bullets and thefiring line that the enfield receiver stretch over time as its used, claimed to be the reason it could do the mad minute so well, that the receiver stretchs out and over time causes the head space to go bad.

SO that version of rifle was created with replaceable bolt heads so that as the rifle was used and stretched, an armory tech could put a longer one in and get it going again.

[Brian Dick]

Please don't take offense but "known fact"? No offense to gunboards either but I try to look at it from time to time and the crap on there is so overwhelming that i finally gave up.

[Bruce_in_Oz]

The bodies don't "stretch", unless subjected to something WAY nastier than tens of thousands of quality ball rounds, but they do WEAR.

If you look at a No1 or No4 body, there is very little bolt support in the vertical. What support there is, comes from heavily cut-away radiused surfaces in the bolt raceway, supporting a mostly round bolt body. It worked for millions of action cycles on millions of rifles. Some wear is inevitable.

Mauser bolts can be a "racing fit" and still manage to pick up a round and chamber it. The design of the SMLE is different, obviously. I am seeing more and more No1 rifles where the bolt-head disengages from the body, about halfway forward. Worn bolt-head, worn guide rail, worn raceway. Sometimes, a NEW bolt body and bolt-head will solve the problem. If not, it is getting to the time to consider permanent retirement of that action.

Those with "well loved" No4 Mk1* actions may encounter chipping of the corners of the bolt-head removal cutout. As this chipping extends, in company with bolt and body wear, the rate of bolt-head "escape" rapidly rises. It appears that at the time of manufacture, it was not deemed necessary to chamfer the ends of the tiny rib of the bolt-head to help the bolt-head through the gap. Maybe some Canadians can chime in here. In a huge Ordnance system, during rebuilds / "heavy" maintenance, one simply wrote off the worn / damaged body and other components and got fresh(er) ones from the parts bins.

I have seen a couple of chipped 1* bodies repaired with the aid of a TIG welder and a tiny grinder like a Dremel or Foredom, but that simply ignores the wear of other surfaces and components that caused the situation in the first place.

[Steve H. in N.Y.]

I have to think that if action bodies actually stretched over time we'd see a lot of cracked ones. And we don't.

[Alan de Enfield]

Please don't take offense but "known fact"? No offense to gunboards either but I try to look at it from time to time and the crap on there is so overwhelming that i finally gave up.

I think Pocketshaver was referring to 'various gunboards' (various forums) rather than THE Gunboards forum.

[Roger Payne]

......pocketshaver also put 'known fact' in inverted commas, suggesting he didn't necessarily believe it himself........at least to me that seemed implicit.

[Ridolpho]

With the rear-locking SVT 40 the Soviets determined that action stretch upon firing is measurable and contributed significantly to headspace issues- but if the elastic limit isn't exceeded it simply returns to original dimensions after each shot. The extensional stress is distributed through a lot of metal in both sides of the body and is, obviously, designed not to fail. The stress at the locking lug shoulders in the body is focussed on a rather small area which, I gather, lead to permanent deformation in that area and the ultimate demise of the body. "Stretch" is not what is happening.

Ridolpho (amateur engineer/ professional geologist)

[Parashooter]

Well put, Ridolpho. There seems to be much confusion between "stretch" and "deformation" (or perhaps between "elastic" and "plastic").

[RC20]

Thank you all, lots of interesting info and history all in one. Glad I asked.

I had one guy claimed the bolts compressed! Wow, really?

"Yes, you can compress steel, just hammer on it and see".

Uh sorry bud, that is called displacement, whole different thing.