7.62x54r .311 cast boolits detailing

[Sliver Shooter]

I loaded some 13gr red dot for my Mosin with .311 185gr cast with ww. I shot 5 @ 20yards and they keyholed. Would that be a clue that they are to small diameter? I haven't slugged the gun yet which maybe is putting the cart before the horse by loading before slugging.

[Mk42gunner]

I would think so.

Did they lead the barrel?

Robert

[Sliver Shooter]

It doesn't appear there is leading. Of 5 shots 2 were sideways key holes. The other 3 showed just a bit of off center entry.

[Jack Stanley]

Is the crown in good shape or has the rifling been worn away by cleaning with a steel cleaning rod ?

Jack

[GhostHawk]

In my experience, yes, keyholing = cast boolit is too small.

Beagle or leement that mold to 2 thou over groove. Or find a SMLE mold that casts at .314 to .316.

[pacomdiver]

my lee 312 185 drops at .3125, and i shoot them unsized after powder coat.

[RU shooter]

Yep too small IMO don't worry about slugging the bore just do a pound cast of the throat and that will tell you what you need to know

[dale2242]

My MN slugged at .314.
.314-.315 diameter bullets shot better than Russian light ball.
16 gr. 2400 = 1 gr dacron...dale

[Adam Helmer]

Sliver,

A Quick check on cast boolit suitability is to merely try to insert the boolit nose-first into the muzzle. IF it goes over half way, get a larger diameter boolit.

Key hole boolits usually indicates you have a too slow, or too fast boolit for the rifling twist. Experiment with various charges.

Adam

[Argentino]

IMHO, at 0.311" your boolits might be at least 3 to 4 thou smaller than they should. Of course the best thing to do is to slug the bore, but Mosins tend to be in that ballpark (around .314" or so).

Argie.

[GooseGestapo]

My Mosin has a very tight, clean bore. In fact, it needed 2-300rds to break in.
It MUCH prefers .314” cast bullets, though it shoots ‘ok’ with .311” gaschecked boolits with 20.0gr of #2400 under a tuft of Dacron.

My .312” 185gr Lee is a mismarked 180gr .309” as that is exactly what it originally cast at. I beagled it...

[Ray1946]

I have 3 Mosins and they all have generous leads. I have gotten my best accuracy with the Lee 185 as it came from the mold; as they came from mine were .3145. I used 24. grs. of RL7 and got under half inch groups at 50 yds with irons. I refuse to butcher up these old rifles with some kind of "rigged" optical sight.

[303Guy]

Nothing wrong with original iron sights. I'm leaning back toward irons. I've achieved MOA at 110 yds with old style Martini Henry sights - equivalent to the half inch at 50 yds.