Discussion Forums

1 2

Forum Index > Rifles general discussion > Brush Gun Test 1

Brush Gun Test 1

02 Jan 2020
@ 08:49 am (GMT)

Magnus Vassbotn

Hi!

For a while now, I've been intrigued by the concept of a brush gun. Partly for practical purposes, and partly just out of curiosity. I've been contemplating a 9,3x62 in between my 30-06 and 45-70, to serve as a brush gun, and at the same time have a bit more practical reach than the 45-70. So this test was partly about finding out whether there is any point in getting a 9,3x62 (other than for the sake of just having one, a totally valid reason). Also it's interesting to put the 45-70 through some sort of test, rather than just get going at it and commence wounding.

I also wanted to put our 6,5x55 “meat load” through the test, as a friend of mine recently had a couple of incidents with it. He hit light brush on two occasions this season, causing tumbling. Both were on 90-100 kg deer (live weight), which is a very typical size here. Between us and a few more guys, we have now shot well over fifty red deer with this load, and it has performed very reliably within the 100-150 meters it's normally being used. But in these two cases, things didn't work out the way they should. One bullet hit sideways behind the shoulder, penetrating through the ribs and lungs, and stopping sideways against the opposite shoulder bone, killing the deer quite cleanly, but a bit slowly (luck). The retrieved bullet was almost unexpanded, and bent like a banana. In the other case, the bullet hit square on the shoulder, a perfect hit with good initial bleeding, but the deer kept going (limping) for an hour before the hunter got in a second shot to the neck. Unfortunately he wasn't there for the full “autopsy” of the carcass, and did not retrieve the bullet or examine the wound channel, so there is a degree of speculation in this case. We do know with a high degree of certainty that he struck brush a few meters before the deer, so we've concluded that the bullet must have hit sideways and stopped in the shoulder bone, never reaching the vitals. These two incidents are one of the reasons I wish to study the whole brush gun concept further.

I've tried to find some solid info/ experiences, but have found little more than established “truths” and stories of an animal here and there being shot through a bush, mostly right in front of the animal (I've done so too a couple of times). I also read the thread “Brush-buster myth” by Scott Struif here on the forum. It was interesting, with a lot of people sharing their views and personal experiences. It got me even more keen on doing a proper test, as I have yet to find any real, systematic tests on the WWW (though one comprehensive test from the last century was mentioned in that thread by Paul Leverman. Great if you could dig it up). The closest thing I've found is the “What is a Brush Gun?” videos (1 and 2) by Iraqveteran8888 at youtube (also mentioned in the thread). These test videos are very interesting and well made. The guy is entertaining, and clearly has good knowledge of guns and ammo. But the test is not going in depth, and is a bit lacking here and there. Specifically: No consistent point of aim, same brush being shot again and again (disadvantage to the first guns), random brush density from shot to shot, offhand shooting, not enough shots fired. Generally a lack of consistency or uniformity. Still, the test is interesting, and shows a pretty clear tendency towards heavy (and slow?) being better.

So, in this test, a friend and I put up a target (approx 1,5x1,5 m) with a large taped cross for aiming “around” the brush, and a 30 cm circle in the middle, resembling the vitals of an animal. We then set up a good, dense shrubbery of spruce branches, which pretty well resembles most our brush here in Norway. Juniper, birch and pine brush is much the same with regards to branch thickness and foliage/ needle coverage. The branches in our test were from 3-20 mm thick. The shrubbery was renewed/ re-aligned between every shot. We shot through the shrubbery from about 6 meters, and from there on, it was 20 meters to the target. This was meant to simulate a hunting scenario where an animal is standing at 70-80 meters, partly covered by brush. In such an instance, it's not always easy to tell whether the brush is 2 or 20 meters from the animal, unless you're able to range things up (which is rarely an option in the woods). Also, with a bit of distance between shrubbery and target, differences in dispersion becomes more clear. For other distances, one can probably just assume half the group size for half the distance and so on. The wild card is of course when the bullet passes through more than one bush on its way to the animal, but that's a project of its own.

Ammunition variables that I believe could have a profound influence on results are: Bullet weight, velocity, stability factor (SF), and bullet length to diameter ratio (perhaps LD? Length divided by diameter=LD), which of course is directly linked to terminal SF (low LD=high terminal SF). Regarding terminal stability versus external stability, I suppose there is a whole science and lots of established terms involved, but I haven't looked into it, and rely mostly on common sense, assumptions and the home made term LD. In this type of test, I guess external and terminal stability comes together in a way that is very hard to relate to in a proper theoretical fashion, as the bullet goes from external to quasi-terminal, back to external, and finally into true terminal ballistics.

Variables that I also believe could have an influence of their own are: Diameter, construction/ technology, material, nose/ ogive shape, sectional density (SD). When it comes to SD, I believe a high SD in itself is a good thing for brush busting, but not if it means a very high LD, compromising stability (small caliber cartridges). According to this theory, a 2-bore with short for caliber, yet very heavy bullets would probably rule the woods. But neither SD vs SF or any other variables were properly isolated and tested, so it's still just speculation. These things could be interesting to look at in a second, in depth test, with different bullet styles and weights etc. This test should be considered more of a preliminary test, just to see if the concept has merit, and also to take it one step further than the test by Iraqveteran8888.

The loads that were used follows under. They are all slow and heavy for cartridge-loads, intended for short ranges and minimum meat damage. Theoretical (external) stability factor is generated by the Strelok app.

6,5x55 – 160 grain Woodleigh PP @ 2475 fps. SF 1,88. LD 5,17.

30-06 – 220 grain Hornady Interlock RN @ 2450 fps. SF 2,62. LD 4,1.

9,3x62 – 285 grain Lapua Mega RN @ 1935 fps. SF 2,78. LD 3,36. This was an undeveloped safe-load, thrown together for the occasion. From the 20” barrel this bullet would normally most likely be loaded to about 2300 or so.

45-70 – 405 grain Woodleigh FP @ 1915 fps. SF 3,64. LD 2,24.

The first part of the test consisted of shooting 5 shots from each rifle through stacked up spruce branches with a good amount of needles and various sized sticks. There was a bit of randomness, with regards to sticks being hit or not, but we checked and renewed the shrubbery after each shot, so we got a good idea of what caused what.

As expected, the long for caliber (but still relatively light) 6,5x55 bullets performed poorly. None of them hit anything thicker than 3-4 mm on their way through the shrubbery, but they all tumbled and hit more or less sideways in the target. Group size about 50 cm. Considering this was mostly from going through needles, we saw no reason to test this load/ cartridge any further. All 5 shots were failures.

The 30-06 performed much better than the 6,5x55. 3 shots hit only needles, and landed in a 3 cm group at the center of the target. The remaining 2 bullets hit some pencil thick branches and tumbled fully and slightly, both still well inside the 30 cm circle. Total group size about 14 cm.

The 9,3x62 performed very similar to the 30-06, all things considered. 4 shots hit only needles, and sat in a 5 cm group at the center, one bullet keyholed slightly. The 5th bullet hit a finger thick branch, and landed 10 cm outside the circle, fully tumbled. Total group size about 27 cm.

The 45-70 performed very well. 2 bullets only hit needles, and sat 5 cm apart at the center. The remaining 3 bullets hit several pencil and finger thick branches with good resistance, but still landed within the circle. One bullet barely keyholing, another one slightly expanded. Total group size about 17 cm.

The second part of the test consisted of shooting directly through a finger thick stick, this time placed 23 meters from the target. For the most part, we had good, solid hits, but some were off to the side, usually causing more dispersion then direct, central hits. 5 shots from each rifle, except for the 6,5x55, which we ditched for this part of the test.

The 30-06 failed miserably. 1 shot only just inside the circle. 4 shots outside the circle, spread all over. 3 bullets tumbled. Total group size about 60 cm, and way off. Would have been lots of gut shots in a hunting situation.

The 9,3x62 performed just as poorly as the 30-06. All shots outside the circle, 3 of them tumbled. Total group size about 50 cm, and even more off than the 30-06. If it was a dear, one would have been lucky to hit a kidney, or unlucky and shoot off the front hoof.

The 45-70 performed pretty well. 4 shots inside the circle, and one shot 7 cm outside. Total group size about 34 cm. No bullets tumbled, but most showed some degree of expansion (larger holes). At least 4 shots would have been clean kills on a deer, the 5th one perhaps a marginal kill.

This is all the testing we could squeeze in that day, but it showed some clear tendencies. Some definite and unsurprising conclusions that can be drawn are:

1 – The 6,5x55 with this load is a poor brush gun. Tumbles easily, causing poor accuracy and penetration.

2 – The 30-06 and 9,3x62 with these loads will be thrown far off by finger thick branches. Tumbles and spreads.

3 – There is something to the concept of a brush gun. As logic dictates, the bigger the better. Every cartridge/ load has it's limit with regards to branch size, which in turn means that one could establish a more or less precise science or “recipe” around which cartridge/ load works for which brush density/ branch size.

Some less than definite, but quite likely conclusions to be drawn are:

1 – The 6,5x55 with this load will need a clear path, but like most cartridges, it will probably work through light brush if the animal is standing “in” the actual brush, giving the bullet almost no distance to tumble or veer off.

2 – The 30-06 and 9,3x62 with these loads can handle light brush, provided the animal is not very far from the brush. Little practical difference between the two cartridges.

3 – The 45-70 can handle light brush and small sticks/ branches, provided the animal is not very far from the brush.

4 – A combination of heavy weight, high SF and low LD is good.

5 – Brush busting will probably not justify the purchase of a 9,3x62 when one already has a 30-06. Damn...

One day we will delve deeper and get more data, shooting at least 10 shots with each gun through a more uniform shrubbery. Only needles/ leaves and 3-4 mm branches max. Than we will probably do at least 10 more shots with the 45-70 through finger thick sticks. Further finger thick stick testing is clearly pointless with the 30-06 and the 9,3x62, as 9 out of 10 shots were failures, and one just barely passed.

After this it would be natural to experiment with the different cartridges with different stick thicknesses and wood types, in order to establish where it all clearly goes south with all cartridge/ stick combinations. And then to see if there is any practical difference between the 30-06 and the 9,3x62, how big that difference might be, and how it will translate to real hunting situations. Then the next step would be to do the same with just one cartridge at a time, but with different bullets, and at different velocities. A hell of a lot of shots... I can't guaranty it will ever happen, but I will do one more test with the uniform shrubbery and more shots fired.

Even though there are a lot of variables and coincidences when it comes to shooting through brush and into a target, the same can be said about long range shooting with all it's predictable and unpredictable variables. And kinda like the reading, guessing, and estimation of wind speeds and wind patterns, perhaps one could get very good at reading and understanding brush variables and use science based on good statistics to take shots within the limitations of a particular cartridge/ load? For example, based on the very limited amount of shots fired in this test, one could feel confident about shooting a deer standing 10 meters behind a light bush, using a 30-06 heavy load, or an animal standing 10 meters behind a moderately dense bush, using a 45-70. Just a theoretical exercise for now, but at least it would be an interesting subject to play with, in lack of anything better to do out of season. If not for hunting purposes, then at least the knowledge could be used for target shooting through brush, which would most certainly make for a fine gentleman’s sport.

Some pics from the test:

Target with guiding tape