Boolit vs bore

[southernshooter40]

I've got a question for you folks. I'm casting a 175 grain TC for my Glock 22 with a KKM barrel that I slugged and bore measures at .400. My unsized boolits measure at .401-.402 which is ideal. After I made up some dummy rounds and pulled the bullets to check the measurements, I found that they were all measuring at .399-.3985. I've tried sizing my brass with rcbs dies and dillon dies and am crimping to .4205-.421 and have had the same result with both. Is this something that I should be concerned with? And if so, what should I do? On a side note, I have loaded and shot a few hundred of these bullets with great results. I had no leading and better accuracy than any jacketed or moly bullet that I have used.

[jarex]

My guess its probally you expanding die wich is not expanding the case deep enough and swaging you bullet when you seat it.

Probally what you need is a Lyman Neck Expander M Die

[runfiverun]

if they shoot fine you need
nothing.

[wallenba]

My money is on your taper crimp die being the culprit.

[Max Brand]

If you are using a Lee FC die for the crimp you are resizing the brass (and boolit) every time you run a round through it. Seat a boolit without the crimp and see what it measures when you pull it.

Max

[trk]

If the bullets are accurate and don't lead and don't work loose in the process - you don't have a problem.

you may well squeeze the lead bullet a bit. Not unexpected. You could increase the expander diameter and/or crimp differently - worth the experiment IF you are dissatified with your results.

Brass squeezes the lead bullet a little and it expands to fit the bore when fired.

[southernshooter40]

Yeah, I just bought a lee fcd to help with my abundance of glocked brass. I made up some dummies and crimped them with the fcd and I got the same result as crimping with the dillon and the rcbs crimp dies.

[MtGun44]

You don't slug the barrel to measure "the bore", you measure the groove diameter of the
barrel. The bore diameter is the dimension to the tops of the lands, and is not of much
interest in pistols.

These are all technical terms and must be used consistently and correctly or we cannot
effectively communicate about this technical topic.

Bill

[runfiverun]

These are all technical terms and must be used consistently and correctly or we cannot
effectively communicate about this technical topic.

Bill

you gotta learn the lingo or you and us both will be lost.

[southernshooter40]

Alright, yeah, the groove diameter is .400. And I pulled a bullet that was seated and not crimped and it measured .3985-.3995.

[thx997303]

My suggestion is to go with a boolit .001" - .002" in diameter LARGER than your groove diameter as a start.

In the 40 SW I would suggest going to the largest boolit diameter that will reliably chamber.

I'm willing to bet that .399" diameter boolits will lead your barrel quite severely.

.401" after seating is absolutely the smallest I would go.

[Harter66]

I'm w/the guys above if it isn't leading don't mess w/it.

Making an expander ball isn't a big thing and can be done pretty readily w/ a drill press and a file .I have several I use w/an RCBS universal decapping die or to fit your regular die set.

If you are using a lee deglocking die for sizing you might lap it out a 1000th or 2 .

[44man]

Why not make the boolit harder so it opens the brass when you seat?
Might shoot better from a .40 too.

[Lance Boyle]

if they shoot fine you need
nothing.

I would have to concur, no accuracy issue and no leading.

I too would suspect the taper crimp. In the Glock .40's a firm crimp to me is a good thing. The last thing I'd want is a boolit getting pushed back on chambering and running chamber pressure too high. At least your aftermarket barrel has a bit more support at the back of the case to prevent a blowout and glock smile.

frankly, I'd change nothing.

[southernshooter40]

I would have to concur, no accuracy issue and no leading.

I too would suspect the taper crimp. In the Glock .40's a firm crimp to me is a good thing. The last thing I'd want is a boolit getting pushed back on chambering and running chamber pressure too high. At least your aftermarket barrel has a bit more support at the back of the case to prevent a blowout and glock smile.

frankly, I'd change nothing.

Yeah, I feel like I may have answered my own question before I ever finished asking it. I have shot atleast 300 of these bullets that started out at .402 and they were loaded with the dies that squeezed them down to .399. I have seen no signs of leading and had great accuracy out of these.

[southernshooter40]

I will say that the ones that I have shot were sized to .401 and were atleast a month old and the ones that I did the dummy test rounds with were 1 to 2 days old. That may have been the difference. These newer, softer boolits may not have held up during seating and swaged down a few thou. Thanks for all the input. This is a learning process for me.

[Max Brand]

I will say that the ones that I have shot were sized to .401 and were atleast a month old and the ones that I did the dummy test rounds with were 1 to 2 days old. That may have been the difference. These newer, softer boolits may not have held up during seating and swaged down a few thou. Thanks for all the input. This is a learning process for me.

If you are losing that much boolit diameter during seating the alloy must be pretty soft. Try water dropping a few the next time you cast and see how well they hold up when you seat them.