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Old April 24, 2011, 09:20 AM   #10
Unclenick
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Join Date: March 4, 2005
Location: Ohio
Posts: 10,346
At normal .45 Colt pressure with that bullet QL says you can get about 17% ballistic efficiency and throw not quite half the powder out unburned. If you double normal .45 Colt pressure you can nudge the ballistic efficiency up to about 22% BE and only throw a third of the powder out unburned. The extra powder mass expelled buys you extra recoil with no benefit.

The above assumes you can seat the bullet out beyond normal .45 Colt COL in a long cylinder. If your gun won't allow long seating, the situation gets worse because the distance the bullet has to travel to double the volume behind it is shorter (bigger expansion ratio), so the powder has a hard time making gas fast enough to keep up with the volume multiplication. At those pressures, top strap erosion from all the unburned powder being expelled from the barrel/cylinder gap will be increased over normal. So will throat erosion. The chance of the load squibbing out and leaving a bullet stuck in the bore when the barrel/cylinder gap vents pressure will be significant. It's the same problem you see with low loads of 296/H110. The squib event itself isn't dangerous, but the next round fired into the blocked barrel is.

Even in the handgun cartridges Accurate gave loads for, ballistic efficiency is poor and muzzle velocity not near the maximum achievable with other powders. It really is a small rifle powder, and not well suited to straight wall cases because of the expansion ratio. Plinking loads in the AR are still your best bet with it. At least then, you can get up to enough pressure to burn it more completely.
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