Oversized bullets in a shot-out barrel?

wasa

wasa

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Looking for thoughts, ideas, and information....

I have a 1939 Turkish Mauser in 8mm Mauser. Although when you look down the barrel you see rifling, the bullets keyhole pretty much all of the time, even at 25 yards. I've tried 8mm milsurp, 180gr handloads, 125gr handloads, and even 180gr cast lead bullets (over Trailboss) and accuracy at 25 yards is horrible (can't make a visible group on an 8.5"x11" piece of paper). When you take a factory round and stick the bullet into the muzzle, the insertion is stopped by the case.

However, when I take one of the lead bullets and force it through the barrel (pound it through with a dowel and mallet) I do see rifling which tells me that the bullets should spin.

I talked to a gunsmith about rebarreling, but the cost of the work would be more than just buying another Turkish mauser.

So, here is my horrible idea. I also reload for my Steyr Mannlicher in 8x56R. Instead of 0.323" bullets for the 8mm Mauser, the 8x56R uses 0.329" bullets.

What if I take out my expander/decapper from my Lee 8x56R FL resizing die and put it in my 8mm Mauser FL resizing die. This should resize brass to accept the 0.329" bullets. Then reload "Reduced Load" with Trailboss (start at 70% case fill with projectile in place).

I guess the big question is will oversized bullets of 0.006" in a "shot out" bore result in excessive pressures? How many thousands of an inch oversize should I be targeting? Not sure if anyone makes 0.325" bullets for sale.

Thoughts? Ideas?

And yes, I understand I am responsible for my loads and if I blow up my gun it's on me.
 
I don't know if this helps at all but I knew a fellow, now deceased, that fed a chopped P17 Enfield a steady diet of 8x57 ammunition for years.

I know for sure that he shot at least 1500 rounds through, before I started hand loading proper 30-06 for him.

He didn't like the 30-06 ammunition I loaded because it "kicked" to much, so he went back to shooting 8x57 surplus ammo.

If you're loading to most reloading manual pressures, you will be fine as they are purposely loaded down for those trying to shoot .323 diameter bullets through .318 bores.

You are only swaging very ductile metals down by .006 in. That will cause an increase in pressure, but IMHO, not enough to worry about.

A little closer to your issue, I have a Model 1950 VZ24 Columbian Mauser made by FN and later converted to 30-06 in 1950 from its original 7x57.

This rifle was again converted in the early sixties to 7.62x51. There are all sorts of stories about where the barrels came from.

Some South American Mausers were converted using surplus US 1903 Springfield barrels, which were later set back and rechambered for the 7.62x51. One nation where this was done on a large scale was Brazil.

To the point, my rifle will not shoot regular .308 diameter bullets well, and some of them "keyhole" if they hit the target at all.

So, I load .312 bullets into the cases I load for this rifle and it will shoot better than my eyes can see.

Your worn barrel may or may not shoot the larger diameter bullets well, but I don't think you will have to worry much about over pressure. If you're worried, load to the mid range of what your reloading manuals tell you.

That wouldn't be my first choice as a hunting rifle, if you can't get it to shoot.
 
Not really too much to lose - I have a BSA sporterized M1917 rifle - there is a sneaking suspicion that the barrel was originally made for .276 Enfield cartridge - so it has .282" grooves, not .277" grooves that one would expect in a 270 Win barrel - bore hole (top of rifling) is 0.270". It will NOT chamber when I tried to put .284" (7 mm) bullets into a 270 Win case - the throat part of that chamber is proper sized, I think, for a 270 Win cartridge. A jacketed bullet that is 0.007" larger than spec, when installed, does not go in there.
 
It is ok so far as the barrel is concerned. Load and shoot like normal.

BUT, the chamber neck has to be big enough to allow the case neck to expand on firing, releasing the bullet. If the neck is too tight - you have a pipe bomb.

Take a fired case and see if the far bullet falls in.. If it is already tight, the chamber neck is too tight.
 
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Snider shooter said:
Make up a dummy round and see if it chambers easily. Neck mite be to fat. Worth a try. I use 0.325 cast in a 32 Winchester special as I don’t have a size die to reduce them. Chambers hard I wouldn’t use them.
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Made up two dummy rounds tonight. Both chambered so ended up reloading 10 rounds with Trailboss. Hopefully range trip this week.
 
Ganderite said:
It is ok so far as the barrel is concerned. Load and shoot like normal.

BUT, the chamber neck has to be gig enough to allow the case neck to expand on firing, releasing the bullet. If the neck is too tight - you have a pipe bomb.

Take a fired case and see if the far bullet falls in.. If it is already tight, the chamber neck is too tight.
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Thank you. Since i have multiple 8mm bolt rifles my brass is all segregated. The 0.329 bullets fall into the fired cases so i think i am good to try my new reloads at the range this week.
 
wasa said:
Thank you. Since i have multiple 8mm bolt rifles my brass is all segregated. The 0.329 bullets fall into the fired cases so i think i am good to try my new reloads at the range this week.
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Good for Ganderite for pointing this out and good for you for taking his advice.
 
Took my Mauser to my 25 yard indoor range last night and was pleasantly surprised. Still have all fingers (and toes!).

As per the picture, none of the rounds keyholed, and I was able to get a "group" (stop laughing) that is acceptable to me at this time. No issues with chambering or shooting these Trailboss loads.

Aim point was the orange blob, with what I believe are the original 1939 sights. Need to adjust my front sight for sure


3Z0OuFkb.jpg
 
wasa said:
Took my Mauser to my 25 yard indoor range last night and was pleasantly surprised. Still have all fingers (and toes!).

As per the picture, none of the rounds keyholed, and I was able to get a "group" (stop laughing) that is acceptable to me at this time. No issues with chambering or shooting these Trailboss loads.

Aim point was the orange blob, with what I believe are the original 1939 sights. Need to adjust my front sight for sure


3Z0OuFkb.jpg
Click to expand...

That is a respectable group at 25m, for an old gun unsupported with irons. Nothing wrong with that at all. Little sight adjustment, and you're good to go.
 
Wasa, your rifle may have had a bore at maximum spec, but still acceptable to the procurers, fresh out of the factory. Add a bit of wear and everything goes to hFll in a hurry.

I used to have an Indian FN/FAL (SIR $119) that would only shoot .310-.312 bullets well. The bore didn't look worn at all. I've always wondered if this was the "norm" for those rifles.

One other issue that you have likely addressed by going to a larger diameter bullet is decreasing neck tolerances to a better place.

I tried some .329 bullets in an 8x57 case, from one of my surplus sporters, which shoots select handloads into sub moa, if I do my part on the bench.

I did the same test Ganderite suggested to you.

The bullet, flat base, wouldn't even begin to enter the case mouth.

Tight necks are a must for the best accuracy, but it's an effort in futility to make necks thinner if the chamber has neck dimensions that are on the large side of mean spec.
 
Best bet would be slug the bore both at the throat and a couple inches from the muzzle. Take this measurement and take a lee mold or something similar and use valve lapping compound on a pre cast slug to Polish it out and make it bigger. Repeat till it casts .001-.002 over sized.

If it were me I’d just rebarrel it make it a .308 even.

A lot of the issues could stem from wear at the muzzle as well if you have wear at the throat and wear at the muzzle with good rifling in between it’s not going to give you the best results.
 
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antiqueguy said:
Best bet would be slug the bore both at the throat and a couple inches from the muzzle. Take this measurement and take a lee mold or something similar and use valve lapping compound on a pre cast slug to Polish it out and make it bigger. Repeat till it casts .001-.002 over sized.

If it were me I’d just rebarrel it make it a .308 even.

A lot of the issues could stem from wear at the muzzle as well if you have wear at the throat and wear at the muzzle with good rifling in between it’s not going to give you the best results.
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That's what I was thinking. Slug the barrel, see what the tension feels like as you get to the end of the bor.
 
MRP said:
That's what I was thinking. Slug the barrel, see what the tension feels like as you get to the end of the bor.
Click to expand...

I would take 2 slugs one from the throat and one from the muzzle end. Use something like a muzzle loading round ball or even buckshot that will be bigger then the bore.
 
wasa said:
Took my Mauser to my 25 yard indoor range last night and was pleasantly surprised. Still have all fingers (and toes!).

As per the picture, none of the rounds keyholed, and I was able to get a "group" (stop laughing) that is acceptable to me at this time. No issues with chambering or shooting these Trailboss loads.

Aim point was the orange blob, with what I believe are the original 1939 sights. Need to adjust my front sight for sure


3Z0OuFkb.jpg
Click to expand...

Very nice!!
 
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