Marlin 336 slugging .306"???

[nitrohuck]

I was under the impression that Marlin Microgroove 336's are supposed to slug on the larger side, often needing boolits as large as .311" to achieve peak accuracy...


Well after slugging my roommates 336, it came out at .306"... leaving me somewhat perplexed,

Is there something I am missing here?

[Lefty SRH]

That sounds tight, is the barrel thoroughly clean?

[tomme boy]

Where did you slug it? Did you use a dead soft slug? It might have a constriction on the muzzle end under the front sight.

[nitrohuck]

with wooden dowels and a rubber mallet I tapped it through from muzzle to breach,

Perhaps you are right about about a bore constriction being the culprit,

Is the best bet from here to try and get a bore slug started 5-6" from breach end and then reverse the dowels and tape it back out?

[youngda9]

Are you using calipers or a vernier micrometer ?

[nitrohuck]

calipers... that have thus far been accurate in slugging every other bore,

can't justify the expense of a micrometer :-/

[cwheel]

Might want to reconsider on the 1" micrometer. You can go to ebay and get a nice used one in the $20 range. After working as a machinist for more than 40 years, I have yet to find a caliper that comes closer than .001. Most often, the cheap ones sold to reloaders aren't nearly that good, some as much as .003 off. Calipers are great for lots of reloading stuff that have a wide tolerance, close measurement, not much. Save yourself some grief, get a nice used micrometer, Starrett, Brown and Sharpe, Lufkin, Sherr-Tomico that are all made in the good old USA, and your grandkids will still be using them long after you have gone. Might want to take that slug to a friend that has a micrometer, you will see the difference.
Chris

[MarkP]

2nd Getting a good quality 0-1" micrometer w/ venier scale in 0.0001"with a standard. I have ran several higher quality calipers over traceable standards; I would only trust them to about +/- 0.001"/inch measured. So +/- 0.006" on a 6" part.

[captaint]

Getting micrometers that aren't expensive is easy. I got a set at Harbor Freight - the Chinese variety, digital - that have never lied to me. I have 3 other American made mic's to check them against. Mike

[cwheel]

The cheap plastic calipers often sold to reloaders I've seen as far off as .005. Stay away from Harbor Freight on this one. Not saying they won't work, saying that they aren't made to go the distance. For almost the same money, you can get a nice made in USA version that will last the average person generations, money well spent. A 1" standard is nice to have as well, some used ones come with it. When looking at used ones on ebay, look for one in the case with the adjusting tool and a 1" standard. The common standard is a round steel disc that is exactly 1". The zero is set with the spindle against the anvil, and the used mic should come with the adjusting tool and case. If after setting the zero, measuring the 1" disc, and it's off, you know the threads are worn out. Worn out is something that should never happen to the average person. Still with all of this stuff, you are still in the $20-25 range if you shop. Sad that all of these expensive machinist tools on ebay going so cheap. But with most machinist jobs going offshore there is less demand today and machinist quality machinist tools are cheap used.
Chris

[MtGun44]

Get a micrometer, calipers are not accurate enough for the results to be meaningful for this
kind of work. You can get a new Fowler .0001" reading mic from Enco Tools online for well
under $35 most of the time. On eBay you can often find a good name brand (Brown & Sharp,
Starrett, Mitotoyo) for $20-25 in excellent shape.

I doubt your number is correct.

Bill

[Goatwhiskers]

On a separate note, NEVER use a wood dowel to drive the slug. They can split and wedge into the barrel with the slug, then you got real problems. I've seen 'em wedged so tight that I had to make a piloted drill to get it out. Use a brass rod, steel if you have to, with some tape wrapped around it every maybe 5 or 6" to keep it from contacting the rifling and bump-bump, don't beat the heck out of it to drive the slug. GW

[R.M.]

How big was your slug. Shoving a .307" slug down a .309" barrel won't tell you a thing.