I recently bought a pretty nice borescope that allows me to see straight down the rifling and at 90 degrees to see the walls.  The resolution is pretty good as well.

So I have started pulling out my older C&R rifles just to experiment and take a look at the bores on them.  I've seen a very broad range of bore conditions - many are completely independent of the external condition of the firearm as well.  I know it was common to have older rifles use corrosive ammo and/or corrosive primers so that if they weren't cleaned properly to neutralize the chemicals, the bores would corrode, rust and otherwise deteriorate.

To my surprise, I found that my all-original 1905 Winchester Model 1894 SRC in 30 Winchester has a superb bore that's close to a mirror finish (very shiny) with no pitting and strong rifling.

On the other hand, to my dismay, an Arisaka Type 99 that I bought here a year or two ago that is in great condition externally with intact mum, AA wing sights, etc - has an abysmal-looking bore.  By far the worst of all my C&R's.  I've never shot it and simply took the seller's word on the bore condition.

I've also found that my previous method of checking bores is absolutely a POOR indicator of condition.  I had one of those bore lights that you can bend up into the chamber to look in from the muzzle and see the lit-up bore.  In almost every case, that resulted in a bore that looked acceptable and didn't ever really show any rust, pitting, frosting or imperfections.  At most, it would let you see how prevalent the rifling was and not much else.  After using a borescope, it really shows how poor of a job those lights do.  

Moving on, I tried to find a good online guide to describe bore conditions and terms that had associated pictures.  Alas, I am unable to find such a guide.  Perhaps my google-fu is weak, but there seems to be much disagreement in forums as to what the terms mean definitively...  things like "frosted", "rust", "pitting", "corrosion" etc.  I think, given my new borescope, I can easily determine what rust is.  Pitting seems obvious to me: the small depressions that form in the metal over time.  Corrosion seems to be a more generic term that can encompass all of it, or something else entirely.  "Frosting" is probably the one I am most confused on.  In some of my rifles, I can see that the bore is clean - no pitting, no rust...  but it's not shiny - it's more of a dull metal finish that doesn't reflect much light, albeit still "clean" with good rifling.  I assumed that was what "frosted" meant.  However, most forums seem to define it as a synonym for a pitted barrel.

Anyone know of a good, definitive source for barrel conditions that include pictures?

Also, for fun, here's the inside of my Type 99.  

Hmmmm I'm of no help. But I can definitely understand what you mean though. I also would have little hope deciding what is or is not a good bore.


Do you have any guns in various known  conditions and round counts you can use as examples? Say a rifle that has been kept clean and only has 500 rounds through it. That should look almost "perfect"
But if you have a rifle that's had oh say 2-3000?rounds through it. Maybe it hasn't been a safe queen it's whole life and has spent most of the time dirty. If that's still "perfect" or if it looks like rusty corroded poop there's a clue. Remember the arisaka is supposed to have a chrome lined bore, so whatever damage is done to it would have turned out way worse had it not had one. So if it's really in bad condition then it must have gone through something extra bad right?

This remind me of when I bought a 30 cal muzzle gauge. So I went around and measured every 30ish caliber gun I had. Some were so loose they swallowed the gauge, some wouldn't even fit the gauge, some gauged out to exactly what they were supposed to be. None of it had any correlation with accuracy or anything.

In the end I confused myself so much on bullet diameter, bore diameter, rifling depth, and everything else I didn't know what to think. Rifles with worn out bores but still shoot great, old guns with new bores, new guns with ugly bores.

Appreciate the reply.  

Yes, I have plenty of rifles with bores that are new (never fired), some that have had thousands of rounds through them and still look like new with the borescope, and  quite a new in-between.

This Arisaka - it looks like the stuff should scrub out, but I've tried everything and it still looks like that except a bit shinier in areas.  No idea how it shoots - never shot it and the ammo is not very easy to find for it.  From a collecting perspective, I've been told that the bore condition doesn't really matter - it's more about the external condition, completeness and originality.  Either way, I always want to have the OPTION to know that I can safely shoot the guns I collect without them patterning like a shotgun.  For all I know, this rifle could be accurate and just look like it has a horribly corroded barrel.  I guess I won't know until I pony up to find some 7.7mm Japanese ammo.

It is all about how it shoots. Bore scope is a waste of effort on mil surplus. Some rough looking guns shoot great other not so much

I have had good bores shoot bad and bad bores shoot good.

I have a bore of the same vintage in very similar condition. Never managed to clean it up any with conventional methods.

The most aggressive product I tried was JB bore paste on VFG felts with imbedded copper wire.

Some people go as far as lapping really rough bores with a lead lap and valve grinding compound.

I’ve had several bores in a similar condition to this and none of mine shot worth a damn, although some people get lucky.

Just picked up a box of RNSPFB bullets - old fashioned ‘torpedo bullets’ with a view to testing them in a bore like this. The large bearing surface of bullets like this is purportedly helpful in getting accuracy out of rough bores.

You can always get the barrel lined if you're determined to shoot it.

My late war Series 33 Type 99 does not have chrome bore. My Type 38: no chrome bore. So not all Arisaka have chrome bores.

When talking about Swedish Mausers I generally divide a barrel into two sections of 10" with the muzzle end being 9". The breech end will show the most wear, with "wear" being defined as the edges of the rifling being rounded, or worn off due to frictional wear. And the diameter of the "bore", measured from the top of the rifling to the top of the opposing rifling.... in the breech end of the barrel. But Swedish military also gauges the wear at the muzzle using pin gauges, same as the breech end. When a certain breech measurement is reached the rifle is sent for re-barreling. Garand collectors are fixated on the throat and muzzle gauges readings.

I have one m/1896 Swede that is completely washed out, no rifling left. It was literally shot to death. It came from a shooting club and not military stores so that explains why it escaped military maintenance protocol. This is where erosion gauges are used, to gauge the amount of wear to the rifling. The disc on the Swedes represents that breech-end erosion reading.

Dutch

OP:
There is no set criteria of different words mean or define.  

If you see something in your borescope that you don't understand, maybe send the picture to the borescope company they might know what it is?????

I'll be honest though, I don't see the point to borescopes.
Cool pictures and all but how does the gun shoot?  
I shoot my guns alot and I know as a consequence the bore wears, when it stops shooting accurately, I replace the barrel.

That bore could use something to remove the copper fouling and then some JB bore paste but the pitting is there for good. You can smooth out the pitting but not remove it.

However, if the rifle shoots well then that's really not a problem at all.

The borescope manufacturer is not a gun company.  They make cameras and borescopes, one of which is used for rifles whereas the vast majority are used for medical, maintenance, etc...  To email them asking about what I see would be like emailing Dell computer support about help with a certain web site you're having trouble understanding simply because you're using a Dell computer.

So why not shoot the Arisaka and see how it works?  First off, ever try finding 7.7mm JAP ammo?  It's hen's teeth.

Second; replacing a barrel on a collectible rifle would destroy the value completely.  Rifles like these are worth more in original condition, even if the barrel isn't great.

Is the 'pitting', the stuff that looks black in my pics?  I thought 'pitting' was holes or depressions in the bore - that black stuff looks like it's actually raised...

7.7 Japanese?

IIRC the practical way to shoot them is to reload.

Buy 7.7 Japanese dies, Lee is likely to actually make them.   Even PRVI ammo has about doubled in price locally and I don’t think even they make 7.7 Japanese all that often.

Use .30-06 brass, trim as required.  I cannot recall if you may need to trim some before sizing.

Load with .311-.312 bullets.   Cast bullets are also a nice option for old milsurps. With that bore condition it may fill up the pitting then stabilize.  I never got to load for it as the only Arisaka in the family was stolen during a burglary.   My step father got his while occupying Japan post WW2.  Every man on the ship got one from a pile if they wanted one.


Try finding ammo and components in 6.5 or 7.35mm Carcano.   Old milsurps can be a nuisance in some ways.  At least your bullet size is equivalent to com bloc .30 calls and .303 Brit for bullets.

That looks like black in the pitting to me.  Try a picking at it with a cheap Harbor freight dental pick set.  Not hard force of course, just poke and prospect the bore to feel how deep it is.  

If it is just carbon scaling off try cleaning the bore with Mercury Power Tune/ GM Engine Top Cleaner.  Same product, different label on the can.   Not much can clean carbon better.   Use personal protection like gloves and use it out doors.  

It is kind of a restricted product to buy now.