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Discussion Starter #1
I've got a bunch of 170 grain round nose bullets to use in my 336w, 30-30. I think they are winchesters but they may be remingtons. They are the jacketed ones with the big lead round nose. Not the ones with the little flat spot on the nose.

I mic'd them and they were around .306 in diameter. Maybe a little bigger, but not 307.

So I then mic'd some 180s I use in my 30-06 and they were .308,. give or take.

Is and 3030 supposed to use a bullet that is smaller in diamter? Or did I get a bad batch of bullets????

With commercial jacketed bullets, I've never mic'd them in the past because I've always just went by the label. But for some reason, while I was organizing yesterday I grabbed a few and mic'd them, they were very consistent, but a different diameter than I expected.

Any ideas???
 

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Don't think I ever miked jacketed bullets either. But I will now. I would think that much undersize would make a difference in your groups. I know it can with cast bullets, especially with Microgroove rifling. All you can do is try them.
 

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If in doubt, slug the bore of your .30-30 and measure both the roots of the grooves and the ID on your lands. You should see 0.300" on your lands, and 0.308" on your grooves.

Not sure what to make of your 0.306" +/- jacketed bullets though. I am curious to see what others have to say about this as well... ???
 

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Believe it or not, diameters of jacketed bullets often vary by .001 or so between manufacuturers, just as land and groove diameters may vary among rifles of the same chambering, and it rarely makes much, if any, difference in accuracy. Of course, each rifle is a law unto itself, so Brand X may shoot better in yours that Brand Y. If it does, a different diameter may be one, but not the only, reason.
 

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Discussion Starter #5
As far as making a difference in my groups. You make the mistake of thinking i can shoot straight.
I am in my 50s and going on 100, and my eyes are going on 200.
Even on a bench rest I cannot hold it (scoped) on the bullseye at 100 yards..It just sit's and wavers.

So if I keep anything in under 4 or 5", I'm surprised. In my case, the shooter is becoming less accurate each year.. The good thing about age,...the older you get, the more you don't give a ">$"....you just want to know everything else is working properly...even though you yourself are not.

My twelve year old will take a can 500 yards out the back field...and I need a scope just to see what he's shooting at...And he's not even using a scope to do the shooting. What I wouldn't give to have my twelve year old eyes and stability again.

OK,
Beautiful day in the neighborhood.
 

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.3065" will be fine for your needs unless you have an overly large bore diameter. I am willing to bet your bore slugs at less than .309" and if so, these will not be highly accurate, but very likely will be in your 5-6 inch group pattern. If they were around here they would be shot up one way or the other.
http://shootersforum.com/showthread.htm?p=573332#post573332
 

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.30-30 bullets from Sierra and some of the other companies used to be .307 diameter (per markings on the box) but now the boxes are marked .308 diameter. Don't know how much difference it makes in .30-30 rifles, but I use .30-30 bullets in .308 rifles @ about 2400 fps for my woods load and their accuracy is fine. ;)

Cedar Creek
 

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Very interesting. I just grabbed a Rem 170, Sierra 170, Hornady 170 and Hornady 140 Monoflex. The Rem and Sierra are both .308 at the base but taper down to .307 or .3075 about midway on the shank. The Hornady 170 and monoflex are both .308 the full length of the shank (except for the boat tail on the monoflex)

Bob A
 

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Back in the dark ages the original spec for 30 WCF was a .307 diameter bullet.This was changed to .308 some time after WWII.This is why Sierra used to make .307 and .308 bullets for 30/30's.I used to have a 1949 336 that liked .307 bullets over .308 diameter.For the most part either size will shoot well.
 
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