205 gr WFNGC LBT bullet loads

[doverpack12]

Had a chance to slug the barrel.  Grooves 0.402 Lands 0.399 Going Ballistic Bullet 0.4025

[sqlbullet]

.402" is about what I would expect.  And glock barrels tend to be very uniform.  Hopefully with the gas check this will work out well.

I don't think I would try .4025" plain based with any hope of good results though.

[doverpack12]

Should it be larger or smaller. I really don't know much about lead bullets or hardcast

[sqlbullet]

For a plain base bullet you want the bullet to be at least .001" larger than measured groove diameter.  This is especially important with modern "hardcast" alloy bullets, as the pressure may not enter the elastic deformation range of the alloy, meaning the bullet base won't be forced to confirm to the barrels size (obturate). 

I say "modern" because in Elmer Keith's day, 16:1 lead:tin was a hardcat, even though it is only 11-12 BHN.  Today, that is just considered a "standard" alloy hardness, with hardcast being 20+ according to marketing info.

If the bullet doesn't fit the bore, then pressurized gas can escape around the bullet, creating super-heated jets of gas plasma.  These will melt the surface of the lead and give leading.  Ironically, the harder alloys, such as linotype, have significantly lower melting points than pure lead, making this phenomenon worse in hard cast bullets, since they often don't compress and fill the bore, yet melt even more readily when exposed to gas blow-by.

The gas check effectively jackets the base of the bullet, helping to minimize these effect and allowing some additional margin of error.

[doverpack12]

My measurement was in between the lube grooves on the bullet so it may be 0.001 as you said the minimum should be with the gas check.  I will load one bullet with a starting load and check for leading after each successive shot then as I work up a load.  Thanks for your help and information.  If the bullet turns out to be too small I will talk with the owner and see if I can have him size some slightly larger for me to try.

[doverpack12]

Loaded a few of the 205 WFNGC tonight.  No leading in the barrel worked up to 12.3 grains and was at 1160 fps plan on going a little farther pressure looks good so far.  Primers seem to be inconsistent.  Sometimes one or two will flatten and the rest will still be nice and rounded.  Not much expansion so far. 

[doverpack12]

Powder was AA #9 and OAL 1.25" about one turn of crimp past just touching the brass.

[doverpack12]

Worked up loads with 12.6, 12.8 and 13.0 grains #9 seated to 1.25".  In my G20 these chronographed at 1170, for the 12.6.  12.8 was at 1185 and 13.0 grains produced right about 1200 fps.  Now I plan on testing these last three loads for accuracy all three of them give me velocity within the range I wanted to get to.  No problems feeding or anything like that.  15 fit in the magazine just fine.  No additional pressure signs.  Primers look about the same as Winchester silvertips when I shoot them.  Expansion is 0.4330 for the 13.0 grain load and goes down about 0.005 each powder increment as it decreases.  For Underwood/Buffalo Bore/Double Tap I usually get 0.434 expansion and sometimes with Underwood I am even up to 0.4345

[The_Shadow]

Expansion is 0.4330 for the 13.0 grain load and goes down about 0.005 each powder increment as it decreases.

I would think you meant to write -0.0005" each powder increment as it decreases.

It is very easy to get caught up in the typing a post...

[doverpack12]

Expansion is 0.4330 for the 13.0 grain load and goes down about 0.005 each powder increment as it decreases.

I would think you meant to write -0.0005" each powder increment as it decreases.

It is very easy to get caught up in the typing a post...

You are correct.  0.0005 increment of expansion for each powder step of 0.2 grains either up or down expansion follows with new starline brass.

[Caneman]

dont over crimp as this will reduce the OD of the boolit