I have a new Winchester in 38-55 and tried a new gas checked bullet last weekend that has me a little baffled. The new Winchesters have a .377 groove diameter and I'm trying .378 diameter bullets. Most were in the black at 100 yards but a few were high and right by 10". Do I need a fatter bullet of should I try .377 diameter bullets? The far off flyers have me baffled. Not really a cast bullet guy.

The only cast bullets I have tried so far in my .38-55 were sized .375 and they go all over the place. I have some sized .380 I believe but have not tried them.

I am using Barnes Originals for my hunting with my rifle, 255 grain .377 diameter and they work really well.

Sample your bullets; i.e., weigh a sample of about 20. I am suspecting that you, like a lot of others, got a box of bullets that is all over the chart in weight. This happens most likely because the cast bullet suppliers use conveyor-style casters that eight, ten, or even 12 different two cavity moulds to cast the bullets. With that many different moulds, there is bound to be some weight variation, and sometimes that distribution is extreme. Rifles don't like bullets that don't weigh the same...

Try segregating your bullets by weight and work up a few loads that way.

And as for sizing, the only way to know for certain what your rifle likes is to try several different diameters; from .378" to maybe all the way to .380", and you may have to go to a custom caster to get that variation (a lot of moulds won't cast .380". You can always size down, but bumping up is extremely difficult).

Your rifle will tell you what it prefers...

I'm not clear whether the bullets you were shooting were made by you, or someone else.
Like Doubless said...the FIRST thing that should be done after making a run of cast bullets is to weight-grade them.
Your description of your first results "most in the black but a few high and to the right 10"
SOUNDS like a few bad bullets rather than a situation where ALL were undersized.
You say you're trying .378 dia. bullets...did YOU mic. them...?? Getting that third digit consistently correct without introducing measuring error takes a little skill with the instrument.
Just some quick random thoughts for you...worth what you paid for them..!!
Good Luck.

First things first.......

quote:

a few were high and right by 10"

Check the backstop; are the gas checks staying on the bullet?

Some good advise here. I have a Buffalo Classic in 38-55, very accurate with .380"s

Ken Water's take on the 38-55 from Pet Loads:

http://www.riflemagazine.com/m.../PDF/hl61partial.pdf

craigster- Great article. Thanks!

Pegleg
Have you tried jacketed bullets in your rifle?
Did they shoot consistently?

If your shooting technique varies or your rifle is sensitive to hold it might spray bullets around.

I can offer two things.
1. Shoot enough to know the bore is smooth.
2. Make sure the bullets are consistent as mentioned above. If you are buying bullets you may never find any that are 100% good.

If you are careful you can cast your own bullets. Then sort them by weight. If you still do not get good results a custom mold can help for the nose of the bullet to you land diameter.

Finally check castboolits.com forum