Originally Posted By METT-T:
Got an old 50's Marlin 336 .30-.30, probably less than 1k rounds thru it.
Got it how, when, where? Was it a family heirloom or ya bought at a gunshow a few years ago? How did you arrive at 1K rounds fired thru this rifle?
A couple of years ago it keyholed several rounds during pre-season sighting-in. Switched ammo and it went away, fired 3-4 more rounds with no problem. Didn't use it last year. This year, fired one shot that was at 10 o'clock, made the corrections, and then had half a dozen keyholes using three different types of ammo.
Please, describe what you call keyholing.... What brand, weight, and type of 30/30 rounds are we talking?
Gave it a good cleaning and it keyholed again.
A cleaning using what type of cleaner? Did you check the bore with a bore scope or just shine a light into it? What does the "throat" look like on this rifle?
The only thing I can think of is copper fouling.
If rifle was properly cleaned there should no longer be any copper fouling, see cleaning question above.....
I can't find anything on the net about copper fouling causing keyholes, but I'm thinking the Micro-Groove barreling might be especially prone to it. The only other thing I can think of is rifling wear near the barrel from cleaning rods (can't clean these guns from the breech). But the rifling looks sharp and I can't see any problems with the crown. Any ideas?
I've seen at least two old 336 Marlins with way more than 1K rounds thru them which is why I posted the questions above.... Neither of them keyholes rounds, perhaps additional back-ground information might clear this up.
Originally Posted By mr_wilson:
btt for the night crew, I'll check back tommorrow
Originally Posted By METT-T:
OK, lemme see...
It's a family rifle, probably bought new or near new in the '50s. My Dad and my Uncle both killed their first deer with it as did I. If it's been fired an average of ten times a year I'd be surprised.
The rounds went thru the paper clearly sideways at 25 yards. Except for the first one. Grouping was nil, altho they did stay on the paper. I don't remember exactly what weight of bullets I was firing this year. I know I shot Winchester, Federal and Remington Core-Lokts in at least two different weights. The first time it did it two years ago I believe I was shooting reloads which led me to blame them.
I cleaned it using BreakFree, my usual. I've got a seperate copper solvent that I'm bringing up (rifle's at my father's house) to try, hoping that would fix the issue. I just shined a light down, don't have access to a bore light or scope. I can find no obvious problems in the barrel with my level of expertise and available equipment, such as it is. What should I be looking for? How would throat erosion occur and how would it affect the flight of the bullet after it leaves the barrel?
IF rifle has a history of good shooting groups and no other problem in regards to accuracy, I'd assume your initial assessment is correct, rifle has a severely fouled bore and needs cleaning.
Get yourself some Sweets 7.62 bore cleaner, as mentioned in post above, the Break Free has been little help in the copper removal task, hence IF copper fouling IS the problem we need something abit more aggressive to tackle it with. Pelican makes a small 2-AAA battery, twist on twist off pocket flashlite (sometimes labeled by Browning) that comes with a rubber cupped, bent piece of glass looking (plastic) addition which fits over the end of the bulb (I sure you've seen them). They are relatively inexpensive and can be had usually from the same place ya get the Sweets. They will work for viewing the bore (if your present option is lacking) somewhat better than just shining the light. The area you’re focusing on should be the first 2 inches of the bore, forward of the end of the chamber.
Wish I could be more technical about "how" a cooked "throat" affects bullet flight, but I ain’t no rocket scientist, trust me once throat of the rifle has been shot out, the only repair is to have the barrel trimmed (not an option with type of rifle/barrel we're discussing, unless it's got a longer barrel than I'm picturing for the normal 30/30) and re-chambered in order to removed the shot-out portion of the barrel. (fwiw, the rest of the barrel, further away from the initial blast of hot gasses that eventually "cook" the throat, is rarely the problem and re-chambered "most" quality barrels will return to their previously exhibited accuracy).
Here's what I'd do. Shoot the rifle 3-4 rounds to heat up the barrel, with barrel warm (not hot!), using a new nylon bore brush of the correct diameter, place the bore brush into the muzzle end of the rifle a few inches, tip rifle up w/ action open and pour a liberal amount of Sweets into the chamber and allow gravity to pull the Sweets down to the brush (which should keep it from running out).
Using your finger or an empty 30/30 hull or a paper towel plug the chamber end, set rifle horizontal (bench-it) on the bench and slowly push the bore brush into the rifle. As brush reaches chamber end, slowly pull bore brush back to muzzle (stopping before the brush reaches the muzzle) and pump the brush inward slowly then back to muzzle again, (this is to make certain the Sweets coats not only the bore brush, but the complete interior of the bore). Marking the cleaning rod or simply holding your hand on the rod at the point where the inward stroke pushes the bore brush to the back-edge of the chamber, begin your back and forth, in & out strokes. (always careful to not to let the bore brush exit the muzzle) Put about 40-50 (w/ in and out being 1 stroke) strokes in & out on the bore. The Sweets (due to the heat) will begin to "froth", IF your correct about the copper, this froth will be a blueish-green, a sure sign of copper present in the bore. After your series of strokes, let the Sweets set for about ten minutes, then rinse it out. (from the chamber end), I use a non-methanol carb cleaner called SuperTech 2000 sold at Walmart and the little red tube taped to the side of it makes directing the rinse easily where ya need it. Rinse bore completely of the Sweets (careful w/ the rinse as it can stain the wood). Inserting the rod with the patch holder, place patch in the holder while in the action and ”pull” a patch or two, discarding them afterward from the chamber out the muzzle (or running a bore snake would work the same, just work from the chamber toward the muzzle) The patches should be quite blueish-green where land contact occurred, another sign your copper fouling is present…
Repeat the bore cleaning procedure, the setting of the Sweets for 10 minutes and the rinsing, following with dry patches or boresnakeing again. Was froth the second time still blueish-green, was patch still blueish-green, then there's still copper in the bore.
Repeat until, as your putting the strokes on the bore, the froth is very "white", almost like whipped cream and no it won't hurt (due to the "nylon" brush) to focus on the portion of the barrel close to the lands with additional strokes. Patches should also be free of the blueish-green, another indicator bore is copper free.
If shooting is to occur pronto, then no lubing w/ CLP necessary, but if it’ll be a day or two, run a patch of CLP thru the bore and few dry ones behind it.
Barrel can be considered clean of all copper fouling at this point. Using good factory shells take her to the range and put a few rounds downrange.
I’m surprised and bothered by the “went thru the paper clearly sideways at 25 yards” statement as this just don’t sound right, but accept your assertion that it does….. If rifle, with factory ammo, keyholes again your at the “find a gunsmith stage” one with a bore scope and the ability to mic the bore, again given the ”statement” this might be advisable to do now, without going thru the cleaning/scubbing , it’s up to you.
No need for thanks just yet, as sounds as if ya got a major problem with this rifle, or the wrong diameter bullets, something I assumed was NOT so, although 25 yard keyholing ain’t none to good. Cleaning may resolve it, but given the severity I wouldn’t be holding my breath. Don’t shoot any more reloads, just stick with factory fodder for now. Hope this helps and let us know how your problem turns out. It’s a puzzle.
Originally Posted By PONY_DRIVER:
Just an FYI
Sweets 7.62 copper fouling remover has a high concentration of ammonia that CAN screw up your barrel.
Originally Posted By ken_mays:
Not to insult your intelligence, but are you sure it's a .30-30? It may be a .35 caliber. Could it have been rebarreled at some point?