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55 gr. Lehigh Defense .311 Xtreme Defense Bullets — Extreme Velocities
4200 fps from a .308 Winchester
By Ron Colvin
Lehigh makes some interesting solid copper bullets. One of which is the 32 ACP 55gr./ .311 Diameter Xtreme Defense Bullet. Their web site is very well done and it describes this bullet which is also shown below. With a BC of .089, it is obviously not going to be good for long distances. Being intrigued by the velocity spec of 750-4000 FPS, we thought of how we might achieve 4000+ feet per second. We decided that we should try these in a .308. Exploring this in QuickLoad indicated that a good powder would be Accurate 2230. 54gr would fill the case to 101% with an overall length of 2.315” yielding a seating depth of .114”. Using the Quickload specified Solid Copper Shot Start Pressure of 4350 PSI, Quickload indicated a conservative/nominal 3620 fps at a pressure of 38900 psi. We felt this would be a good starting point and allow for any pressure anomalies that might result in a .311 bullet in a SAAMI spec. 308-.310 groove diameter barrel. We loaded up 12 cartridges in our trusty Dillon 550C press and headed to the range.
When testing loads we have found it beneficial to use more than one rifle due to variations in chamber/leade/barrels. In this case, we used a Savage Axis 22” Heavy Barrel .308, a Remington 600 with a 26” Shaw barrel and two AR10s with 20” chrome Bushmaster Hunter Barrels. We set up our CED Chronograph at ~8 feet from the muzzle. We did not adjust any of the scopes for point of impact. We fired off the first 3 shot group in the Axis and got an average speed of 4121 fps with an extreme spread of 18 fps; Backing the speed into Quickload indicated 59,640 psi and +10.6%–higher than the inital Quickload model. It is good that we started off low to allow for this higher pressure. We were pleased that the center of the group was within 2” of the bullseye and that the group size was ~2”. The Rem 600 gave a speed of 4244 fps with an extreme spread of 54fps. (The higher spread could be attributed to an”oily” barrel—the first shot was slower than the rest). Again backing this data into Quickload resulted in a pressure of 59,800 psi at +10% fast. The group size was ~2”. The 20” AR10 produced a speed of 3976 fps with a spread of 18 fps and groups size of <2”. Quickload indicated this to be 56,600psi at +9.5%. Only one shot recorded on the other AR10 at 3964 fps indicating a Quickload pressure of 56,100psi or 9% fast. The cartridges fed with no issues in the AR10s.
In summary, even if just for “giggles or bragging rights,” one can run the Lehigh 32 ACP in a .308 and make high speeds with reasonable accuracy without exceeding the pressure limits of the .308 cartridge.
From the Leigh Defense Web site:
The Xtreme Defense (XD) Technology is based on the popular Xtreme Penetrator product line. The design goal was to achieve the same barrier performance and massive permanent wound cavity and reduce the penetration depth to coincide with an individual’s personal comfort level. It was a goal we did not meet; it was a goal we blew out of the water!
- Progressive nose geometry 18″ penetration depth range
- A permanent wound cavity (PWC)that is 2 times greater than any expanding bullet
- A PWC near that of a 5.56 rifle.
- Reduced recoil.
- CNC machined from solid copper to overcome barriers to penetration
- Radial flutes that force the hydraulic energy inward to build pressure
- Minimal surface area to increase the force at the point of contact and sharp cutting edges that defeat barriers
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