I went to the range today to start my work up of Missouri Bullet 9mm 125 gr SWC bullet (I will post another thread after the work up) and noticed something interesting.
With my usual lead loads and W231/HP-38, I get light lube smoke while shooting at an indoor range. My initial 125 gr SWC loads were loaded with 3.9 and 4.2 gr of W231. Because the material was removed from the nose of the bullet to the bullet base, SWC bullet has longer bearing surface and gets seated deeper in the case. OAL I used with Lone Wolf barrel was 1.040"-1.050".
When I shot them out of factory Glock and LW barrels, they produced almost no smoke!
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October 22, 2011, 11:54 AM
It is highly possible that you are driving them with a higher pressure so they seal the barrel better and allow the wax to lube and not be melted and burned by the gas cutting that usually happens often with light loads. Most smoke is due to gas cutting and allowing the wax to burn as the bullet is pushed down the barrel as I understand it. So the better the seal the less smoke produced. Someone else may have a better take on the reason and they will offer up their answer soon.
October 22, 2011, 12:03 PM
Was there any lube on the bullet?
Also, some lube formulas tend to smoke less.
October 22, 2011, 01:48 PM
Was there any lube on the bullet? Also, some lube formulas tend to smoke less.
Yes. I believe Brad used the same blue lube he normally uses on his other bullets.
It is highly possible that you are driving them with a higher pressure so they seal the barrel better and allow the wax to lube and not be melted and burned by the gas cutting that usually happens often with light loads.
I am thinking the same. If you see lube smoke, you are getting liquefied lube blown out the barrel along with high pressure powder ignition gas (gas cutting). The SWC bullet has much longer bearing surface compared to RN/Cone bullet - BTW, MBC RN has even more bearing surface than older generation LRN mold designs due to shorter/rounded nose profile so SWC bearing surface is really substantial.
Because of the longer bullet base, the SWC bullet is seated deeper in the case and probably generating more chamber pressures. For this reason, I initially tested the 3.9 and 4.2 gr of W231/HP-38 loaded at 1.040"-1.050" OAL (Hodgdon load data listed 3.9 - 4.4 gr at longer 1.125" OAL for LCN).
I think the deeper seating of the bullet base in the case (getting around 90% case fill) with 3.9-4.2 gr of W231/HP-38 is producing high enough chamber pressures and obturation of the bullet base to seal with the barrel. The SWC loads were shot both in factory Glock and Lone Wolf barrels which are .355" in groove diameter.