Before we get too many posts off track here. This is not a 303 brit.

Hi all, I adjusted a chamber in a SMLE in 7.62 NATO a few weeks ago and I just got it back. The chamber was too fat and too long, I set it back a thread and used a reamer and gauges from reamerrentals.com. I turned the reamer by hand and went until it would just close on a factory round. When it closed on the go gauge, it would not close on a factory round. I thought it turned out pretty good and the test fired cases looked good.
But I didn't notice a light line near the shoulder. That's why it's back.
I hope these pics are clear enough.




The ring is only on one side and is smaller than the rest of the case.
If I measure the ringed side, it's .455" and 90 deg from that it is almost to .456" on my dial caliper.

I haven't pulled the barrel yet to get a closer look, but I think it's on the bottom of the chamber.

I'm guessing that the rechamber didn't clean up all of the old chamber, so the smaller step near the shoulder is what the reamer cut and the fatter part just behind it is what's left from the oversized factory chamber.

So what do I do to fix it? Any suggestions?
I already sent the reamer back, but I guess I could set the barrel back another thread and recut it again? Or would 2 threads be too much and cause an unsightly gap between the barrel and stock?

I'm thinking about turning a brass rod to fit the chamber and put lapping compound on one side to try and polish out the step. Maybe cut a case in half to insert and protect the good side, then just try to hone out the step?

I'm open to suggestions.
TIA.

I think that you will have to cut quite a bit more and it needs to be cut in a lathe.
Butch

I agree. Determine the distance from the "mark" to a point on the shoulder which is just under the diameter where the mark is, set the barrel back and let the shoulder eat the mark. And use a lathe. The case mouth looks weird as well.

I get stretch marks that look just like that behind the shoulder, if I try to fire form a 257RAI in one shot. That chamber is .004" too long.

I have lots of cases that have separated right there.

The Brit action is so stretchy, that you could be getting the same thing.

Just a thought.

If you could poke an nit ize light in there, you could see if there really is a ring in the chamber.





Or, you could shoot some real wimpy loads and see if the case forms but does not stretch.

Lar

If it was mine, I'd try to polish out the step as much as I could and let it go. After all, it is an SMLE. If you keep setting the barrel back you're just getting into a smaller and smaller diameter barrel thickness over the chamber.

I'd be more concerned with the neck. What caused that??

I won't be as nice as the other guys and you probably won't like hearing any of this, but . . .

What the hell were you thinking in spending any money on converting an SMLE?? Especially to 308W. That action is designed for operating pressures of 45,000 psi, a lot less than the 308W cartridge. I know that SMLEs have been converted to 308 in the past and I suppose that most of them have held together but what is the logic behind doing it??

But, it's your money so I'll butt out from now on.

JMHO

Ray

Reload and fire the same case several times and see if it goes away. Orient the case the same for each shot. Reload a different case and fire several times with the case orientation changed between shots. If the step remains make a chamber cast and measure it with a micrometer. If the step is only .001 you might be able to remove most of it by just polishing the chamber. Polishing may not completely remove it but it may blend it well enough that you may not be able to see it easily and you then you may not care.

quote:

Originally posted by Cheechako:
Lar

I'd be more concerned with the neck. What caused that??

I won't be as nice as the other guys and you probably won't like hearing any of this, but . . .

What the hell were you thinking in spending any money on converting an SMLE??

But, it's your money so I'll butt out from now on.
JMHO
Ray

Honesty and constructive criticism are always appreciated.

The rifle is one of the Ishapore(sp) rifles that India made in 7.62 NATO. I've heard that they used better steel to give it the required strength.

It's not mine, I do some work on the side for a shop here in town. Mostly it's build replacement parts for things you can't buy anymore.
This rifle came in and was splitting cases. The chamber was too long and too big around. The bolt would close on a no-go gauge with room to spare and that was after the longest replacement bolt head was put on.
So with nobody else to tackle the job, I volunteered.
I took a chamber cast, pulled the barrel, set it back one thread, cut the new extractor slot and ran the reamer in slowly until it just closed on the go gauge.


I thought that I would get a tighter chamber by turning it by hand a couple turns at a time until it closed.
One puzzleing thing happened, when the bolt would close on the go-gauge, it would not close on a dummy or factory round. Why???
So I gave the reamer a few more turns until it just closed on a Win and Rem factory round.

I sent a note back with the reamer and gauges to reamerrentals.com but did not get a reply on it.

The neck: It does look odd. My dial caliper measures .309", so there should be enough room for it to let go of the bullet.
Maybe the neck from the shoulder almost to the mouth is left from the oversize factory chamber and the smaller portion at the mouth is what was cut with the reamer??

I think I'll take a chamber cast and if that is true, then maybe run a neck reamer in to make it all the same size??

The customer obviously wanted the chamber problem fixed and was willing to pay for the job. If at all possible, I would set the barrel back a few more turns to reduce the diameter, pick up and extend the threads and then rechamber the barrel using the precision of a lathe. The quality of the gun shouldn't dictate the quality of the job. If the job is safe, then it should be approached with the same attention to detail as if it were being done to a high dollar gun.

The 303 uses a .313 bullet, .005 larger than a 308. I suspect that the goofy looking case neck is because of the 308 case neck expending into the old 303 neck that wasn't removed. The same thing with the step behind the shoulder. The old chamber did not clean up.

I'm afraid that this is going to turn into one of those jobs you'll wish you'd never laid eyes on.

quote:

Originally posted by Lar45:

The rifle is one of the Ishapore(sp) rifles that India made in 308 win. ??

Has it occured to you that the rifle was actually chambered for the 7.62 NATO and not .308 Win?

quote:

Originally posted by M Pursell:
The 303 uses a .313 bullet, .005 larger than a 308. I suspect that the goofy looking case neck is because of the 308 case neck expending into the old 303 neck that wasn't removed. The same thing with the step behind the shoulder. The old chamber did not clean up.

I'm afraid that this is going to turn into one of those jobs you'll wish you'd never laid eyes on.

Yeah, if that's an original 303 barrel and not a re-barrel in 308 then that is exactly the problem. This is one of those jobs that builds character.

quote:

Originally posted by Lar45:The rifle is one of the Ishapore(sp) rifles that India made in 308 win. I've heard that they used better steel to give it the required strength.

Lar

The Ishapore rifles were made with a slightly stronger steel but they were not intended to be used with commercial 308W ammo even though many have been, apparantly with safety.

But that brings up another question. How did the rifle get to be chambered for the 303 British cartridge? The Ishapore rifles were manufactured as 7.62x51 NATO with specially made bolt faces and extractors and with .308 barrels.

Did someone convert the rifle to 303?

I'd say a chamber cast is definitely in order. It's important to see what the front of the chamber looks like and what is causing the case mouth to be crimped like it is. Also, a chamber cast will tell you what the bore diameter is.

Good Luck. I apologize if I came on a little strong.

Ray

quote:

The Ishapore rifles were made with a slightly stronger steel

Stonger steel will not make a lot of difference with the SMLE design. The Young's modulus is the same for all steels. This is a ratio of stress to strain or how elastic the material is.
The long small cross section of the right receiver rail will still yield a springy action.

quote:

Originally posted by ireload2:

quote:

The Ishapore rifles were made with a slightly stronger steel

Stonger steel will not make a lot of difference with the SMLE design. The Young's modulus is the same for all steels. This is a ratio of stress to strain or how elastic the material is.
The long small cross section of the right receiver rail will still yield a springy action.

Bingo, saved me a post again.

Yes 7.62x51 Nato, not 308 win. Aren't the dimensions the same?

I didn't say 303 brit rechambered to 308.

I did take a chamber cast before I started it.
After the .375" of throat, the rifleings are at .300x.308"

The neck has a similar line in it, but is much smaller. That is the only case with the neck like that, so I don't know if the guy did something with the case after shooting? The other 2 look normal, mostly.

quote:

Originally posted by Lar45:
Yes 7.62x51 Nato, not 308 win. Aren't the dimensions the same?

No, simply put, the 7.62 chamber is more generous. Specifically in length but I find in practice they are usually larger in diameter too. Here is a comparison of headspace gauges for the two.

308 Winchester Gauges 7.62x51 Gauges
GO - 1.6300" GO - 1.6350"
NOGO - 1.6340" NOGO - 1.6405"
IELD - 1.6380" FIELD - 1.6455"

Okay,
the reamer prints I looked at had only minor variations in the base of the neck and the 7.62 has a longer throat.
Plus the 7.62's chamber pressure is around 50k and the .308 is 62ksi.

You can obsess over the differences between 308 and 7.62 nato if you like but it won't answer the problem. The problem arose because the original chamber was a bit off center. Your rented reamer pilot fit the bore better and resulted in a chamber, or a portion of a chamber, somewhat more in line with the bore. In addition, the reamer was likely a bit smaller in diameter at the shoulder than the original chamber. There are a number of ways to address the problem, some well known and accepted, others not. The first way and most accepted way, is to set back and rechamber. The slight body taper on the 308 case (and on the 7.62 as well!) means you would have to set back too far for this to be a viable method.
Another method is to make the reamer cut bigger at the front. to do this you have to first install a slightly smaller pilot. Then put a layer of hard paper (glossy magazine paper) on two of the cutting edges on the reamer. Let the paper come back to just back of where the step is. Ream. This will force the reamer to cut a little bigger (likely about two thousandths). The neck will end up a little larger as well but a couple thou on an Ishapore Lee Enfield isn't a big deal. This may not be a classic technique but it works.
Another technique is to bore the chamber out to the shoulder and shrink fit a bushing into the barrel then chamber the bushing. I call this an advanced corrective technique.
As to why the go gauge would go and the factory cartridge would not, I can see only two possibilities. The gauge was short or the throat on the reamer was short and the bullet was hitting the lands. Given the camming power of the Lee Enfield and the "springiness" of same, I don't think the short throat scenario is very likely. Regards, Bill.