Berger 308 175 match OTM Tactical

[Buffalobob]

PART ONE

Berger has designed and tested a new 308 bullet that they claim will pass through the transonic zone without being upset. It is shown on their website under "tactical bullets" as a 175 grain match OTM tactical.. Bryan Litz, the ballistician for Berger has loaded ammo listed for sale on his website. The bullet may have some interesting applications for the military in terms of extending the range of the 308 sniper rifles and was tested by the Special Forces but not adopted. For the hunter or recreational shooter it extends the range of the 30 caliber cartridges beyond transonic distances.
Many manufacturers have made claims about their products and claimed to have tested them, but as many of us have found, not all claims turn out to be true. So, I ordered a box of the bullets for my 308. Here are a couple of pictures of the box and then there is a picture of two Sierra 175 MK on the left and two Berger 175OTMs on the right. It was misting rain at the time of the picture.

Deer season started Saturday after Thanksgiving so I needed to go to the rifle range to check some zeros and took along some loads for the OTMs to test for accuracy. I sometimes shoot 43.4 grains of Varget in RWS cases for competition with the Sierra 175 MK and on calm days that will group about 0.3-0.4 for three shots. (I more often shoot the Berger 155,5 Fullbore bullets for competition.) For this test I used Winchester cases that have about 1 grain more volume than RWS but are less consistent in quality. It was gusting wind up to 5mph so groups were a little more open.

First picture is of the standard 175MK loads where I am adjusting the zero between the top 3 shot group and the bottom 3 shot group. Aim point is the upper right corner of the small squares of tape.

Second picture is the Berger 175 OTMs with three different charges of Varget and 5 shot groups instead of 3 shot groups. All three groups go just under 0.5 for five shots. This is acceptable accuracy for me and this particular rifle.

 

[Buffalobob]

PART TWO
The performance of the RVN M21 308 sniper round with the 173 grain FMJ BT on humans beyond the transonic zone is known and documented and in my case it was even witnessed. I never personally examined the wound channels as I had no interest in cutting open NVA soldiers and the whole question was of no concern to me being as the end result was satisfactory to me. The question of the performance of the new Berger 175 grain HPBT OTM"tactical" bullet which supposedly survives the transition from super-sonic to subsonic with acceptable accuracy has become interesting to me just as a matter of nostalgia and personal intellectual curiosity.

After testing the bullets for accuracy at 100 yds and finding it to be acceptable (see Part One), I loaded up 25 rounds and waited for deer season to begin in Maryland. On Monday, a large bodied buck appeared on the hill side at 275 yards. The rifle used was a Remington 40X with an 11.25 twist 28 inch barrel, a 5.5X22X-56mm Night Force scope and a tall Harris bipod ¾ extended and dial ups were made using Exbal and a 20 degree cosine angle. A single round was fired at the deer while it was stopped in a small opening between two trees. Impact velocity is calculated to be in excess of 2100 fps. Weight of the deer is unknown but is one of the largest I have killed in the area in the last 15 years and the bone structure was fully developed.

The bullet struck the right side shoulder at the ball joint between the upper leg bone and shoulder blade bone. The bullet shattered that bone and continued its upward angle (firing angle was at least 20 degrees up) striking the front of the sternum at the last rib connection. It then hit the bottom side of a neck vertebrae and bone fragments were found another two or three inches through the neck muscles. A sizeable mass remained of the bullet and it punched an irregular shaped hole through the thick neck hide and exited. Having a degree in physics and another in engineering, I have often made calculations of momentum and impulse for bullets and elk and it is clear that in order for a bullet to exit a thick hide there must be a significant mass left of the bullet and a significant velocity or else the hide will stretch and catch the bullet.

While I am not an expert on the specifics of "tactical" bullets (whatever they are), a combat sniper bullet must be capable of penetration through some amount of hard surface such as a pack or web gear before encountering soft tissue. Berger bullets are believed by most people including the company, to be thin jacketed and to disintegrate quickly; however, this has not been my experience when engaging targets with high sectional density bullets at long range. As I have described, this 175 OTM hit three bones with soft tissue in between them and still retained enough weight and velocity to exit through three inches of neck muscle and neck skin.

Pictures are as follows:
1. The rifle and the deer with the entrance wound showing.
2. The skinned shoulder at the entrance wound
3. The rib cage with the shoulder removed and the damage to the bones of the sternum visible
4. The wound channel showing the impact on the bottom of the neck vertebrae
5. The exit wound in the neck muscle and skin.

 

[Buffalobob]

PART THREE
I needed to try to test the transonic stability of the bullet as this was the part of the Berger/Litz claim that interested me.. This has finally happened and as luck would have it the test weather conditions were pretty raggedy but I shot anyway.

Because I do not have access to a 1500 yard range I decided to develop a reduced velocity load that would go subsonic at about 700-750 yards. One of my loading manuals had a starting load for 175 grain bullets and Varget so I put together a load with a muzzle velocity of 2250 fps. This load was tested for accuracy at 100 yards by firing two groups from the bench. Groups size CTC was less than 0.4 MOA.

Ttransonic stability was tested during a F-class match at R4 Quantico USMC. There was the worst headwind I have experienced in the last six or seven years. It was about 20 mph and varying from 10:00 to 2:00. During the unlimited sighter stage at 800 yards the rifle was zeroed for the 155.5 Berger (MV= 2800fps) that I normally compete with and also the 175 OTM (MV-2250fps). The 800 yard stage was fired with the 155.5 Berger and produced an average per shot score of 9.3 which was a great score under those conditions and my score was being kept by a member of this forum. The "open" rifles were averaging about 9.0. But what I got was a period of wind that stayed at 11:00 so I didn't have the direction switches that are so damaging to the score. So the test was off to a bad start being as I had shot about 5 points better than normal under some of the worst conditions.

At 900 yards I used the 175 OTMs and got a per shot average of 7.3 being as the wind was back to switching direction. At 1000 yards I went back to the Berger 155.5 and got a per shot average of 6.75. Those of us shooting "FTR" (308) were recording misses off of both sides of the target because the wind was so unpredictable. The interesting thing is that the subsonic, slow moving 175 OTM produced a higher per shot score than the faster supersonic 155.5 Berger at the 100 yards difference --- 7.3 vs 6.75. This is about a half MOA difference.

So I conclude that the 175 Berger even when it is well below the transonic zone still retains very good accuracy.