October 11th, 2011

New Berger 105gr 6mm Hybrid Bullets Perform Well

105gr Hybrid Tests Demonstrate Excellent Accuracy and Consistency
By Robert Whitley
After the initial Daily Bulletin Report on the new Berger 6mm 105gr Hybrids, I did some accuracy and consistency field testing with these new bullets. They shot so well, I thought an update was in order. My 100-yard testing has revealed much about these new bullets — all of it good so far. The test rifle was a MAK Tube Gun with a trued Rem 700 action (glued in), with a 6mm Brux 30″, 1:8″-twist barrel chambered with a no-neck-turn 6mm BRX chamber (1.563″ max case and .120″ free bore). The 6mm 105gr Hybrids fit and work well in this 6 BRX chamber configuration. (CLICK HERE to view a print of the reamer I used for the 6 BRX chamber.)

Berger 6mm 105 grain Hybrid bullet

Hybrids Show Excellent Accuracy in Prone Tests (with Sling)
As some may know, I am predominantly a prone shooter and do most of my load testing prone with a sling. I chose to do the same with these Hybrids, to see how they would perform when fired as they would be in a prone match. In this case, shooting prone with sling, I shot four 10-shot groups (two 10-shot groups in each of two range session). All four groups were right around .5 MOA (i.e. each group about .750″ edge-to-edge, minus a bullet diameter of .243″ = .507″). The new Berger 6mm 105gr Hybrid bullets had no problems doing this. The groups shot were also consistent with the best groups I have been able to shoot in the past with the Berger 108gr BT bullets and the Berger 105gr VLD bullets, and I consider both of those bullets to be excellent and accurate. There is no question in my mind that these new Hybrid bullets are accurate, and the consistency is there! Check out my test targets below.

The two 10-shot targets above were shot at 100 yards on September 30th, prone with sling. The 6 BRX load was: Berger 6mm 105gr Hybrids, Lapua brass, 32.0 grains N140, Federal 205M-AR primers, .020″ jump. Note: If you put the targets over each other the groups line up perfectly.

These two 10-shot targets (above) were shot at 100 yards on September 23, prone with sling. The 6 BRX load was: Berger 6mm 105gr Hybrids, Lapua brass, 31.0 grains H4895, Federal 205M-AR primers, .020″ jump. When I can shoot 20 Xs in a row (as I did with these two targets) the rifle is really shooting well.

Accuracy needs to be coupled with consistency, especially when running longer strings of fire or in matches demanding a larger number of hits on the target. I am pleased to report that I have found the Berger 105gr Hybrid bullets to be consistently accurate bullets (i.e. there were no anomalies or fliers, they just keep going where you pointed the rifle). At each of the last two range sessions I shot back to back 10-shot groups with no break between the two (i.e. 20 shots in a row and only switching to the next target after 10 shots). Not only did the individual 10-shot groups stay tight, but if you hold each first target over the second target, the groups are right on top of one another. This is what I look for in terms of consistency — that I can keep shooting, and the bullets keep going right into the group, with no odd fliers.

105gr Hybrid Bearing Surface and Optimum Free Bore
Shooters may wonder how the new 6mm 105gr Hybrids function with the existing freebores on chambers set up for current Berger 105gr VLDs and Berger 108gr BT bullets. Based on the investigation and measuring of various chambers, here are some general guidelines:

1. For a chamber with a 1.5° throat angle, and the bullets touching the lands, the Berger 105gr Hybrid bullets sit up in the neck a little further than both the current production Berger 105 VLD Target bullets and the Berger 108gr BT bullets.

2. Based on basic measuring and testing, for the junction of the boat tail and bearing surface of a 6mm 105gr Hybrid bullet to be in the same spot as other bullets, the 105 Hybrid (Lot #3079) would need about .020″ – .025″ less freebore than recent production Berger 105gr Target VLD bullets (Lot #3220) and about .030″ – .035″ less freebore than recent Berger 108gr Target BT bullets (lot #2791).

3. Since the Hybrids are designed to work both in the lands and jumped away from the lands, some extra freebore may not be a bad thing. In truth, the 105 Hybrid bullets should work well and fit well in various 6mm chamberings (such as 6 BRX, 6 Dasher, 6mmAR etc.) which have been optimized for the previous generation, non-Hybrid 6mm Berger 105s and 108s.

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