There's always discussion about coachwood foreends, recoil plates and the causes of cracking going on here and other forums as well. I've put together a few pics of examples and likely explanations for all to see and add comment to.

In the first pic, all four are '42 or '43 dated. The two on the left were sporterised, off restored or scrapped rifles. Both were most likely original and would have been assembled into rifles during the period between Dec '42 and May '43 when the recoil plates were discontinued as a wartime economy. Note the indentations from recoil impact at the points of contact with the sear lugs. The third foreend has the recoil plates but has cracked beyond serviceability anyway. (more on this one later). The fourth is "new" unfitted. Note it doesn't have the recoil plates. (I have information about why so many raw '43 foreends were about a few years ago, but am seeking more confirmation before I go into it.)

The second pic (apology for quality) shows the two sides coming away behind the recoil plates...(3rd foreend in first pic)

The third pic ...and the view from behind you can see the wood sheared off above the tie plate inletted into the rear. The butt screw has a square on the end which has to be positioned to allow the corresponding square in the tie plate to locate on it. This was to prevent the butt screw from coming loose in service. The fact that the butt screw had been removed with the foreend still on the rifle at some stage, has caused the tie plate to spread and break the wood.

The fourth pic ...Here you can see the broken bits out. It is not unusual to see cracks alongside the small piece in the centre on any No1 MkIII. Undoing the butt screw broke this one out and also stripped the grip the threaded brass rod through the back of the foreend had allowing the foreend to spread under load. This spreading possibly transferred the pressure further toward the inside edges of the recoil plates, and in conjunction with being a loose fit between the butt socket and the sear lugs on the receiver, the wood shattered. Having been soaked with mineral oil for many years would have contributed to weakening the wood as well.

The first foreend in the first pic has a bloody great bolt through it foreward of the kingscrew. I had eventually found out this was one mod done to some rifles for grenade firing.

Back in the first pic, on both of the first two foreends, you can see the indentations almost a quarter of an inch deep where recoil at the sear lugs has damaged the unprotected wood, leaving the foreend with forward backward movement. No matter how tight you do up the kingscrew, it only has so much grip onto the foreend due to being stopped by the spacer bush. There can only be one result, as the last pic shows. Despite a tight kingscrew and a "bloody great bolt thru the foreend", it has cracked forward of the kingscrew. The back end isn't damaged beyond the indentations at the sear lugs.

What to look for on your rifles....mainly for shooters only, I wouldn't muck around with rifles that are not going to be used often or collector rifles. Firstly, loosen the kingscrew and see if you can move the foreend forwards/backwards along the rifle. If it does move, or even if it doesn't and you want to be sure, use a fine feeler gauge behind the foreend at the buttsocket to see if it has contact (range rifle bedding instructions recommend at least %80 surface contact). Measure any gap you have with the feeler gauges and possibly fit shims this size under the recoil plates to firm up the fit. To ensure even tension on both sides, fit shims to each side individually with the other side plate off and make sure that it takes the same force to push foreend into place for each side. If fitting the recoil plates for the first time, make sure the angle of the inletting for the plates is correct. If the sear lug hasn't got even tension down the plate it could crack the wood. Fit the plates one at a time as for shimming. Don't be too concerned if the little section of wood at the back that joins the sides of the foreend has a crack down one side, but if the tie plate in the back has any signs of movement or damage from the butt screw, then check to see the brass threaded wire isn't loose. You may need to take the tie plate out to do this. Try to replace any damaged tie plates, as they have spread and would be putting outward pressure on the wood and brass threaded wire.Things to avoid....Do not leave mineral oils on the woodwork anywhere, it will eventually deteriorate the wood. When removing a foreend, never pull it away from the muzzle. You should have to tap it down from the back end to get it off. Twisting it from side to side to remove it can also cause damage as it should be a tight fit all around on the inside. Never undo a butt screw without removing the foreend first.There may be more to add here, just working off the top of my head at the moment. Please comment, correct or add to any of this. We should be able to end up with a good learning tool to refer others to.
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