Question on barrel slug size

I am new to this forum but have been lurking in the shadows for a few weeks and learning from the experts. I have been casting for several calibers of handgun for a year or so now. Have had a few problems but the lead still comes out of the end of the barrel and makes holes in paper at 25 yards center mass. Maybe not real proud of the results but can live with them easily.

Due to the shortage of affordable ammo now I am looking at casting for some of my rifles. The one I want to start with is a Chinese SKS in 7.62X39. This rifle is very accurate shooting Wolf 122 gr HP. Since I have, and like Lee products, I am looking at the C312-155-2R mold. This mold should cast a 155 gr bullet(heavier than I want) at .312 dia. and will be used with a gas check. All is well and good.

Finally, my question. I have read that I should slug my barrel prior to casting and sizing so that I can size the bullet .001 or .002 larger to prevent leading. The problem is that my barrel slugged at .315. What do I do now?

get a 316 mold.
http://www.accuratemolds.com/catalog.php?page=1
look here,you can specify diameter to your alloy.

Yep, Accurate can make a mold that fits and the weight you want but first please describe the method you used to slug your barrel and just as important, what did you use to measure that slug?

Rick

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Originally Posted by cbrick

Yep, Accurate can make a mold that fits and the weight you want but first please describe the method you used to slug your barrel and just as important, what did you use to measure that slug?

Rick

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Slugged the barrel using a soft lead sinker driven through the barrel with a 1/4" steel rod with electrical tape every 3" as described in another thread. Measured with a dial caliper (brand unknown). Lands measured .304-.306, groves measured .315 consistently. Measured several times because my book said it should be .311. Guess my Chinese SKS can't read English.

The calipers is what I was getting at. They aren't accurate enough for measuring bores, this really needs to be done with a micrometer. Could well give you a different reading by .001"- .002".

Rick

Thanks. Didn't realize that but it makes sense. I will try to find someone with a mic and re-measure.

+1 on calipers not quite cutting it for accuracy at the better than .001" requirement needed.

Look at Enco Tools online, Fowler brand mics reading to 0.0001" are typically $35-40, it is a
good brand and they seem to be about the cheapest I have seen on them.

Bill

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Originally Posted by MtGun44

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Look at Enco Tools online, Fowler brand mics reading to 0.0001" are typically $35-40, it is a
good brand and they seem to be about the cheapest I have seen on them.

Bill

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Thanks. I have a friend who owns an automotive machine shop. Might get him to mic it. Cheaper than $35-40 for one or two time use.