Brass and headspace question

[Butcherbill]

Quick question on a no.4 Lee Enfield, I picked up a couple longer bolt heads to tighten up headspace. It’s current headspace is acceptable but can be improved, I’ve been keeping brass separate for this rifle and it’s all fire formed on the existing bolt head.

If it won’t chamber on the new tighter bolt head what is the best approach? My thought was a light shoulder bump till it chambers snug and re form it to the new headspace, I haven’t changed bolt heads yet or tested if brass will chamber, just thinking about it in case it is an issue. I have a longer #1 than it’s current bolt head as well as a #2 to play with.

 

[Hitzy]

Rimmed cartridges headspace off the rim...

 

[Butcherbill]

Rimmed cartridges headspace off the rim...

Fire formed .303 Brit essentially headspacees of the case neck as well, as it has filled the chamber after firing. I’m now creating less space by tightening up the headspace at the rim with a longer bolt head, if you get my drift.

All my once fired .303 brass is fire formed to the chamber with the shorter bolt head.

 

[Gatehouse]

First step is to replace the bolt head and see if the brass chambers. If not, just keep adjusting the die down until the brass does chamber.

 

[Butcherbill]

First step is to replace the bolt head and see if the brass chambers. If not, just keep adjusting the die down until the brass does chamber.

Thanks, that confirms my thoughts on how to deal with it if it’s a problem.

 

[Hitzy]

Just make sure it will chamber a piece of unfired or full length sized brass, if it won't close on that it's because of the rim thickness or headspace as it's otherwise called.

 

[Potashminer]

It might help you to understand that "headspace", as measured with common head space gauges, is like "end play" - CIP and SAAMI spec a minimum and maximum distance from the bolt face to a particular datum point. On a rimmed case (30-30 Win or 303 British), that datum point is on the front edge of the rim - so from the bolt face to the seat for the case rim. On a belted case (7mm Rem Mag or 300 Win Mag), that datum is on the front edge of the belt - so from the bolt face to the forward face of the cut-out in the chamber for the belt. On a rimless case (like 308 Win or 30-06), that is to a particular diameter on the chamber shoulder - so from the bolt face to a particular point on the case shoulder which is at a particular angle - I think a circle circa .400 is commonly used on many beltless cases as the reference point on the shoulder.

Normal headspace gauges simply "gauge" (measure) a length - none of them that I have will measure a case body diameter, although both CIP and SAAMI will spec those dimensions. Some head space gauges for 303 British look like a coin - smaller than a dime - all they have to measure is the distance that the case rim sits in - that is what you alter by swapping bolt heads - you do nothing at all regarding the case body diameter fit into that chamber, except how it might change with the taper and how far that case goes in there. You did not alter the seat when you swapped bolt heads, so the case will not be able to go any further forward, than it could before you swapped heads.

So, especially in the instance of various military 303 rifles, the body of the chamber was cut slightly over-size, and the space within the chamber to the shoulder was cut slightly longer - it "headspaced" on the case rim, so the specific body machining really made no difference - they did not reload - their only concerns were that the head did not come off the case body on the FIRST (and only firing), nor did that the case body "burst" - at least most of the time.

 

[Potashminer]

Many belted cases or rimmed cases can be altered to "headspace" on their shoulder, like a rimless case does. But not likely that you will find a commercial headspace gauge to measure that - is not a "SAAMI or CIP" spec to do so. There are at least a couple ways that you can fire-form your brass to snuggly fit to your chamber - but typically you do not use a "head space" gauge to do that. You are no longer in "standardized" headspace territory.

The whole notion to fire form, resize and re-load 303 British is NOT what it was designed for - back in the day. It is us, today, who insist to re-load those previously fired brass, from those chambers.

 

[Butcherbill]

Just make sure it will chamber a piece of unfired or full length sized brass, if it won't close on that it's because of the rim thickness or headspace as it's otherwise called.

I think you’re misunderstanding what the question is, it’s not about the headspace of the rifle as it is or as it will be after the new bolt head has been swapped. It’s about already fire formed brass shot in that rifle fitting the chamber once the longer bolt head is in place, gatehouse got it and confirmed what I figured to be the solution should it exist.

 

[Hitzy]

I think you’re misunderstanding what the question is, it’s not about the headspace of the rifle as it is or as it will be after the new bolt head has been swapped. It’s about already fire formed brass shot in that rifle fitting the chamber once the longer bolt head is in place, gatehouse got it and confirmed what I figured to be the solution should it exist.

I get it, 100%, I just don't think what you are trying to fix is an actual problem, or the way to fix it.
I load for lots of sloppy old milsurps, neck size, super easy.

 

[bearhunter]

I think you’re misunderstanding what the question is, it’s not about the headspace of the rifle as it is or as it will be after the new bolt head has been swapped. It’s about already fire formed brass shot in that rifle fitting the chamber once the longer bolt head is in place, gatehouse got it and confirmed what I figured to be the solution should it exist.

BB, once you change out that bolt head, like it or not your previously fireformed brass will very likely be "too long" to chamber or even allow the bolt to close.

If you already have fireformed brass, specifically for that rifle, and it works well, why fix it?

If you're looking to not having to keep your cases separated, they you will have to set your die for the rifle with the smallest chamber and tightest headspace.

Even then, you won't be able to just neck size your cases anymore, if you fire them in the other rifles with larger chambers, more headspace.

There isn't a glory fix for this issues when it comes to Lee Enfields.

 

[Butcherbill]

I get it, 100%, I just don't think what you are trying to fix is an actual problem, or the way to fix it.
I load for lots of sloppy old milsurps, neck size, super easy.

So how would you get already fire formed brass to fit after a new longer bolt head was swapped in? Neck sizing won’t change case length, which is exactly why you neck size in the first place.

 

[Butcherbill]

BB, once you change out that bolt head, like it or not your previously fireformed brass will very likely be "too long" to chamber or even allow the bolt to close.

If you already have fireformed brass, specifically for that rifle, and it works well, why fix it?

If you're looking to not having to keep your cases separated, they you will have to set your die for the rifle with the smallest chamber and tightest headspace.

Even then, you won't be able to just neck size your cases anymore, if you fire them in the other rifles with larger chambers, more headspace.

There isn't a glory fix for this issues when it comes to Lee Enfields.

Correct me if I’m wrong but a shoulder bump and not a full length resize will give me the clearance if I can’t close the bolt?

It’s not going to be much of a shoulder bump, I’ll be able to measure the difference between bolt head lengths and compare with a comparator gauge on my brass while bumping. Then cases will reform to the chamber and I’ll just neck size till I have to bump shoulders again, there should be no real wear and tear on brass.

 

[Hitzy]

So how would you get already fire formed brass to fit after a new longer bolt head was swapped in? Neck sizing won’t change case length, which is exactly why you neck size in the first place.

I would not change the bolt head in the first place... what's the point/benefit over neck sizing with the original bolt head?
What was the headspace (actual headspace for rimmed 303) before changing bolt heads?
I guess I just don't understand the reason or logic here, I wouldn't even consider partial FL sizing for sloppy milsurp chambers, as Potash mentioned above the brass is stretching alot already due to oversized chambers, not just to the shoulder but in diameter as well. 303 is not a real high pressure cartridge, in the sense you will run into chambering issues after 2 or 3 neck sizes, I don't even keep track of how many neck sizes I've got on 303 brass anymore, I just load them until the necks crack or they won't hold primers anymore...

 

[Butcherbill]

If you already have fireformed brass, specifically for that rifle, and it works well, why fix it?

I would not change the bolt head in the first place... what's the point/benefit over neck sizing with the original bolt head?.

Because I can tighten it up further now that I have the longer boltheads, I’m thinking of future once fired brass. If I can get headspace tight enough I won’t need to use elastics to keep the rim against the bolt face, potentially increase brass life at the web as just the shoulder and diameter ahead of the case head will change.

I’m just speculating at the moment as I haven’t had time to swap bolt heads and see if the once fired brass still chambers fine, I know no.4’s with tight headspace don’t need to use orings. I think less case head stretching is a good thing if possible, then it’s just neck size and shoulder bump when brass needs it. Should last awhile from the way I see it.

 

[woodchopper]

swapping the No1 with a No2 you will decrease the headspace, as long as the No2 will close on the rim of an unfired case you should be good to go

I have bought enfields that have had their bolt heads swapped with longer ones that were tighter then the Go gauge and would not close on a standard case.

now your fireformed brass will need to be resized with the full length die until they fit with the longer bolt head.

 

[dan belisle]

I would not change the bolt head in the first place... what's the point/benefit over neck sizing with the original bolt head?
What was the headspace (actual headspace for rimmed 303) before changing bolt heads?
I guess I just don't understand the reason or logic here, I wouldn't even consider partial FL sizing for sloppy milsurp chambers, as Potash mentioned above the brass is stretching alot already due to oversized chambers, not just to the shoulder but in diameter as well. 303 is not a real high pressure cartridge, in the sense you will run into chambering issues after 2 or 3 neck sizes, I don't even keep track of how many neck sizes I've got on 303 brass anymore, I just load them until the necks crack or they won't hold primers anymore...

The point is to correct the headspace, which in this case is measured on the rim. Once that is correct, you can then adjust your dies to bump the shoulder on your brass until it chambers properly in that rifle. Neck sizing is a useful technique, one I use a lot. But once you have modified the chamber (and in the OP's case, he may have, or not) you then need to make sure your brass fits that chamber. - dan

 

[bearhunter]

BB wrote "Correct me if I’m wrong but a shoulder bump and not a full length resize will give me the clearance if I can’t close the bolt?"

If you're sizing die is set low enough to bump the shoulder .010 or more, you're very close to full-length resizing the case body.

Less will partially resize the body dimensions as well.

As far as your case head expanding, IMHO, not enough to make any noticeable difference. If it did, it would be measurable. I've tried that and it isn't.

 

[Butcherbill]

Existing headspace was acceptable but not great iirc, I’ll have to recheck it tonight. My current #1 bolt head measures 0.629”, the other #1 is 0.631” and the #2 measures 0.635”. I’ll check if brass still chambers with the longer #1, it also clocks the best on the bolt body. Have a second spare bolt body to play with as well.

 

[Butcherbill]

So I rechecked this particular rifle, it has a #1 bolt head which basically closes on a no-go but won’t close on a field gauge. With the new longer #1 bolt head it won’t close on the no-go without force or close on the field at all. My fire formed brass chambers with the longer #1 bolt head with a bit of resistance as the bolt closes, the longer bolt head indexes perfect.

With the #2 head on the original bolt body it won’t index or clock enough to instal, with my spare bolt body the #2 head will clock nicely and not close on either the no-go or field gauges. Brass will chamber tightly but I can close the bolt, out of the 4 different brands of once fired brass I have the PPU is the hardest to close the bolt, it does close though. With unfired factory PPU and Federal the bolt closes nicely with the #2.

So it should all work well, I will have another bolt body to play with if I end up doing the .45 acp conversion with my new to me no.4. If that’s the case I’ll use the shortest bolt body/bolt head combo I have and headspace it tight with the barrel/barrel nut.