1928 Ishapore No1 MK3 headspace

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   I've got a "new to me" Ishapore No1 MK3 that shows signs of excessive headspace.  A test shot with new/modern ammo produced a distinct shiny ring just above the rim on the spent brass.  There's no bulge, but the ring is noticeable and the brass has clearly "fire formed" to the chamber.  :)  I've included a picture of the fired brass vs the unfired.  The bolt closes on a Forster SAAMI field gauge (which I know is less forgiving than an old school field gauge).  I measured the bolt head at 0.6355" with a micrometer.

I've looked all over for a replacement bolt head that's got more "meat on it" than this one and haven't had any luck yet.    I'm not overly concerned about head separation on new brass, but I was hoping to be able to reload the brass a couple of times. 

It's my father's rifle (and his fathers before that) and he was hoping to shoot it occasionally.  I just want to make sure it's safe to shoot.  Looking for some wisdom on how to proceed.  Perhaps I'm just being overly cautious....

Best,

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Sauron Members Profile Send Private Message Find Members Posts Add to Buddy List Groupie Joined: November 30 2025 Location: Virginia, USA Status: Offline Points: 90	Post Options Post Reply Quote Sauron Report Post Thanks(0) Quote Reply Topic: 1928 Ishapore No1 MK3 headspace Posted: November 30 2025 at 9:01am
	I've got a "new to me" Ishapore No1 MK3 that shows signs of excessive headspace. A test shot with new/modern ammo produced a distinct shiny ring just above the rim on the spent brass. There's no bulge, but the ring is noticeable and the brass has clearly "fire formed" to the chamber. :) I've included a picture of the fired brass vs the unfired. The bolt closes on a Forster SAAMI field gauge (which I know is less forgiving than an old school field gauge). I measured the bolt head at 0.6355" with a micrometer. I've looked all over for a replacement bolt head that's got more "meat on it" than this one and haven't had any luck yet. I'm not overly concerned about head separation on new brass, but I was hoping to be able to reload the brass a couple of times. It's my father's rifle (and his fathers before that) and he was hoping to shoot it occasionally. I just want to make sure it's safe to shoot. Looking for some wisdom on how to proceed. Perhaps I'm just being overly cautious.... Best,

Shamu Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Logo Designer / Donating Member Joined: April 25 2007 Location: MD, USA. Status: Offline Points: 20510	Post Options Post Reply Quote Shamu Report Post Thanks(0) Quote Reply Posted: November 30 2025 at 11:13am
	That's a fairly normal fired .303 case! The "ring" indicating excess headspace looks like this! & can be checked with a paperclip straitened out one end bent to a "L" shape & run up & down inside the case. If it "snags on something" about 1/2" up from the base it indicates a problem
	Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force)

Sauron Members Profile Send Private Message Find Members Posts Add to Buddy List Groupie Joined: November 30 2025 Location: Virginia, USA Status: Offline Points: 90	Post Options Post Reply Quote Sauron Report Post Thanks(0) Quote Reply Posted: November 30 2025 at 11:59am
	Ahhh! Well, OK then it just seems to be excessive caution on my part. :) In that case, I'll likely leave the bolt head as it is, clean everything up, replace the broken extractor spring, lubricate, and put it back in service. Thanks for the sanity check. Best,

DisasterDog Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: February 21 2025 Location: Brewery Status: Offline Points: 256	Post Options Post Reply Quote DisasterDog Report Post Thanks(0) Quote Reply Posted: November 30 2025 at 5:10pm
	Agree with Shamu, that case looks fairly normal for an Enfield. Max headspace is 0.074”, make sure that’s actually the gauge you are using as Forster does make other sizes that are all referred to as “field”. The other thing to keep in mind is that most commercial brass actually has undersized rims, with PPU being the closest to milspec.

Sauron Members Profile Send Private Message Find Members Posts Add to Buddy List Groupie Joined: November 30 2025 Location: Virginia, USA Status: Offline Points: 90	Post Options Post Reply Quote Sauron Report Post Thanks(0) Quote Reply Posted: November 30 2025 at 5:44pm
	This particular field gauge is marked as .070". Forster now makes one in the military field spec of .074 (just my luck....that only became available as of a few days ago. So I'm guessing I'm somewhere just outside of .070, but still within the original spec. https://www.forsterproducts.com/303-military-field-gage-available/ Perhaps the thing to do is for me to just start buying PPU ammo or pick up some of their unprimed brass. I only have a couple hundred rounds of the S&B 150gr ammo that I bought for testing. I'm sure I can find a home for it. Best,

Shamu Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Logo Designer / Donating Member Joined: April 25 2007 Location: MD, USA. Status: Offline Points: 20510	Post Options Post Reply Quote Shamu Report Post Thanks(0) Quote Reply Posted: November 30 2025 at 8:02pm
	Check your PMs.
	Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force)

britrifles Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: February 03 2018 Location: Georgia, USA Status: Online Points: 8404	Post Options Post Reply Quote britrifles Report Post Thanks(1) Quote Reply Posted: December 01 2025 at 3:47am
	The "shiny ring" you mentioned on your other post and shown in the photo you posted here is not an indication of case web thinning. Web thinning/cracking shows up as a very narrow lighter coloured "ring" that occurs prior to case head separation that Shamu showed in his photo, you can see that white ring on the case below the one with the head separated. The "shiny ring" as you described is actually the part of the case body that does not expand to contact the chamber walls. It is this area of the case that moves back under the 18.5 tsi chamber pressure and compresses the bolt body. This is normal. As long as the bolt does not lock on a 0.074 FIELD gage, your good to go.

Sauron Members Profile Send Private Message Find Members Posts Add to Buddy List Groupie Joined: November 30 2025 Location: Virginia, USA Status: Offline Points: 90	Post Options Post Reply Quote Sauron Report Post Thanks(0) Quote Reply Posted: December 01 2025 at 4:37am
	Appreciate the follow-up. Yep, it seems I was over-reacting a bit. Best,

Shamu Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Logo Designer / Donating Member Joined: April 25 2007 Location: MD, USA. Status: Offline Points: 20510	Post Options Post Reply Quote Shamu Report Post Thanks(0) Quote Reply Posted: December 01 2025 at 11:35am
	"As long as the bolt does not lock on a 0.074 FIELD gage, your good to go. " I'd just add "with MINIMAL trigger pressure, don't crank it. Just one finger lightly".
	Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force)

britrifles Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: February 03 2018 Location: Georgia, USA Status: Online Points: 8404	Post Options Post Reply Quote britrifles Report Post Thanks(0) Quote Reply Posted: December 01 2025 at 11:43am
	Yes, with VERY LIGHT pressure on the bolt handle, don't ever try to force the bolt to close on a steel headspace gage...