Adding diameter to 45-70 bullets (to .4595)?

Les in Wyoming

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Glenrock, Wyoming
It turns out my two 45-70's like bullets a little bigger. I have different kinds and weights of .458 and .4585 bullets. I have a box of polymer coated bullets in .458. Can I put a powder coating over polymer coating? What can I do to add a thousands to make these bullets more accurate? Thanks for any help or suggestions.
 
If you are casting and sizing them yourself, here's a thought! I've never done it myself, but if you do a search on the CastBoolit forum.....there have been discussions on how to "open-up" your sizing dies. If you only need around 0.0005", it's supposed be be fairly easily done using "Jeweler's Rouge" or similar!

With the polymer coated bullets, put a couple into your powder coating oven, and hold at your desired powder coating temperature for a while....then determine "if" the polymer was affected! If the polymer is not affected....try powder coating a couple. I think, but may be incorrect, the powder coating should adhere! memtb
 
If your casting these your self , you can " beagle " the mould. Basically you add some small strips of aluminum tape to one side of the mold block.
Don't worry about them being out of round. I cast for a 35 marlin with the mico-groove barrel. I beagled a rcbs mold so I could size them to .360. 1.5" - 2" groups at 100 yards, no leading. The bullet will squeeze " round " when sizing or in your barrel.

Powder coat is soft, if the bullet doesn't fit the bore , I don't believe PC will help. If buying your cast bullets, I then suggest just ordering the proper size. If its a micro groove barrel, go .002 over slugged bore Dia. Don't go by what it " should " be, slug it yourself- easy., you would be surprised by the difference. ( Google slugging your barrel, beageling ) if your unsure
 
Les, to answer both of your questions!

Slugging a barrel: my method, is.....get a pure lead fishing sinker, tapered in shape, larger than the maximum expected bore diameter. I just pushed a sinker of about 0.325" into the bore of a .270 Win. Liberally coat the bore and the lead sinker with a lightweight oil, insert the tapered end of sinker into the bore, drive it (very carefully) into the bore. I use a small ball peen hammer, being careful "not" to contact the barrel crown. If you are uncomfortable with this.....a small "dead-blow" hammer will also work nicely. The excess soft lead will be shaved off by the barrel. I then use a brass rod smaller in OD than the barrel ID, and drive the lead through the bore, allowing it to fall into the breech area.I just used a 1/4" brass rod on three rifles from, .270 Win, through my wife's .338 WM, I used a 5/16" rod on my .375 AI. Though, I'm sure the 1/4" rod would have done the job! Then you simply "mic" the bore groove (high points) 180 degrees apart.

Not all firearms have the grooves directly opposite each other, which pretty much screws up the measurement. I just had that happen on my S&W 629! 🤬

Powder Coating: It does add to bullet diameter, approx 0.002". Different coatings add different thicknesses. If one coating still leaves you lacking.....do another powder coat. You will gain a bit more!


Good Luck! memtb
 
Wouldn't that add too much? Paper is usually.004. In circumference it would add .012 overall. If there is a way to do it, I would much appreciate knowing how.
I was just throwing it out there. I have not done it myself but did fire 3 rounds from my sharps given to me buy a trusted friend. He gave me the following website in case I was interested. The rounds were accurate. Personally I just buy .459 bullets and cast them at that size also. Here is the link.
 
Les, no experience here, but, dang near every metal has been powder coated for various reasons....copper should be no different. Just make certain they are very clean.....totally free of all oils, including oils from you4 hands. The powder should adhere! That's just my opinion! memtb
 
Well, it doesn't work. I cleaned some copper jacketed bullets and then pre-heated them to give an extra help in adhesion. Then I tumbled them for a half hour with air soft bb's. The powder did not stick. I have not had any luck trying to powder coat bullets. Anyway, I loaded these copper jacketed bullets as they are and they seemed to shoot ok.

Non-copper jacketed bullets do not fly as accurately unless they are .4595. I have some polymer coated bullets that do not shoot consistently in this bun (marlin 1895 CB). But they do in my other gun (regular Marlin 1895). I am guessing that my CB needs bigger diameter bullets. But I don't know how to add another .001 to these bullets. Nor do I know where to find bullets.
 
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