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Sizing or crimping issue with 40 S&W


zzt

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I use a chamber checker for all the rounds i will be using in a match. With the unit I have using resized brass and 175 or 180gr bullets seated to 1.126", the "ggod" rounds drop in but the entire rim of the case is above the checker. They feed fine. They chrono fine and I get good SDs. I just assumed it was a defect in the checker.

The other day, on a lark, I dropped in some resized and primed cases and everyone of them was flush with the top of the checker. When those same cases are loaded, they do not drop flush. Any ideas as to what is the cause? It seems it has to have something to do with the crimp, too much or too little, or bullet diameter.

Sized cases drop in flush and drop out. Loaded cases drop in to the rim, but will not drop out. They have to be pulled out with a fingernail.

Edited by zzt
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Are you saying the rounds drop out freely of the case gauge, but not out of the barrel of the gun? If that is the case, you bullet is likely contacting/wedging in the lead or rifling of your barrel. You would either have to have the barrel throated a bit, or load a little shorter.

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I'm saying that sized and primed, but not loaded brass will drop into the chamber checker flush and drop out when inverted. Once that primed brass has been loaded to 1.126" it will drop into the chamber checker to the rim of the brass and will not drop free when inverted.

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Are your bullets lead, plated or jacketed? Sounds like either your crimp is excessive or the bullet is touching the gage. Most lead bullets have a larger diameter than jacketed so could be contacting the "throat" of your gage.

Color your loaded cartridge with a marker.and drop it into your gage and maybe even spin it a bit. Look for contact marks on the cartridge or transfer of ink to your gage.

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Interesting results kamikaze1a. I did use magic marker because I can't locate my can of Dykem Blue. At first I could see no rub marks on the "good" shells. The bad shells were easy. The "Glocked" brass showed rub marks on one side of the base wall and on the opposing rim wall. As expected. Other "bad" rounds had rub marks either at the base of the seated bullet, or one one side but only where the bullet was seated. Upon examination I discovered the brass had been drawn (either at the factory or in a pistol) so that one side was thinner than the other. There was literally a bulge on one side of the case where the bullet was seated, but none on the other. I have no clue what caused that.

Anyway, I decided to ink the brass and the bullet. When I did I discovered an annular ring on the truncated cone just above the full diameter junction and scuffing on the edge of the full diameter section with LSWCs.

This is all once fired police range, mixed headstamp brass used for the first time. The chamber checker is the 4-hole EGW unit. Neither a .400" brass plated nor a .401" lead bullet will pass through the reduced diameter section of the hole (equivalent to the "leade", I believe). So either 1.126" (what I was told to load for the CZ 75 TS) is too long for an "official" 40 S&W chamber, or the EGW unit is not manufactured correctly. BTW, the 45 ACP hole works perfectly.

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you need this case gauge. your bullet is hitting your case gauge. Take a unloaded bullet and drop it in your case gauge ? will it fall all the way though? If not that is your problem.

http://www.benstoegerproshop.com/100-Hole-40-S-W-Long-Case-Gauge-p/cg40-100-l.htm

Edited by CZ85Combat
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Thanks all. It is a problem with the case gauge. I pulled the barrel and dropped in sized, primed cases. They all seated with a thunk of the rim against the shoulder of the chamber. Loaded rounds with different profile bullets did the same and to the same depth. So the bullets are not hitting the rifling. They are hitting the EGW 4-caliber case gauge, so I'll get another. Thanks again to all.

Edited by zzt
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you need this case gauge. your bullet is hitting your case gauge. Take a unloaded bullet and drop it in your case gauge ? will it fall all the way though? If not that is your problem.

http://www.benstoegerproshop.com/100-Hole-40-S-W-Long-Case-Gauge-p/cg40-100-l.htm

I use that gauge. My 1.135" loads with 180 gr BBI bullets won't always go all the way in. I measured a couple of the bullets at .4015" diameter (the 4th digit on my calipers is a 5 or 0) and the gauge says bullets up to .401" diameter on their site. So that gauge isn't the perfect solution for all bullet types. The rounds drop in fine upside down though.

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I concur with Chandler. The lead bullets are about .001" bigger than the jacketed bullets for which the gauge is designed. I put a 3/8" aluminum rod in my drill press, wrapped it with tape to get a running fit in the gage, coated it with valve grinding compound, and opened the gauge up a bit.

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  • 2 weeks later...

I had the same issue with my EGW, I found that I could drop a sized case in and it would fit but loaded rounds did not. Then I tried dropping loaded rounds rim first and the brass would fit completly in the gauge. When I tried next time i pressed the rounds into and out of the gauge I noticed that the coating was shaved on the bullet. I started measuring some of my bullets and saw they measured 0.4025" and they are supposed to be 0.401". The bullet was the issue I tried some xtreme bullets with the same profile loaded to the same COAL and they dropped in freely. BTW I did have some feeding issues with the oversized bullets, and I know that anything that fits my EGW will fit easily in my guns chamber.

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