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Magnus Vassbotn

Brush Gun Test 2


At last the stars aligned. Weather is getting better, days are getting longer and a couple of Saturdays had some blank space, so we got to do the second test. If you haven't read the first one, called “Brush Gun Test”, you should consider reading it first. This test is a continuation of the first one, and quite a few terms, theories, goals and conclusions from that test are more or less vital, in order to get the context of this second one right. If you find it too overwhelming and just want some useful info, you can skip to “Conclusions for now” at the bottom. But then you're probably gonna wanna go back and see how the conclusions were reached, so you might as well get on with it right away.



Test 2A


This time we primarily wanted to find out how stability factor (SF) and length to diameter ratio (LD) affects results, as tumbling appears to be the main problem with brush shooting. Not only does a tumbled bullet have poor penetration, but it usually also deflects more than a non-tumbled bullet, something that's become quite evident throughout all our testing. In order to study the effects of SF and LD properly, I made some loads with very high stability, by cutting and grinding down a 180 grain 30 cal RN to 170 grain FN, and the 285 grain 9,3 Mega to 232 grain FN. Both bullets were very cylindrical/ wadcutter-like, and wouldn't feed properly, so not practical for hunting unless one is using a single/ double rifle of some sort. These bullets were only intended as a way to test whether the positive effects of high stability would outweigh the negative effects of loss in sectional density/ weight/ momentum.


This time I considered ditching the term LD, as it seems redundant when one has SF. However, I believe the results of this test shows that the term is useful on it's own. Two bullets of very different SF and weight, but almost identical LD, performed in a similar fashion, with regards to tumbling. They also had a very similar meplat size/ weight distribution, which also seems to be part of the equation, later indicated by test 2B.


We also wanted to give the 6,5x55 another go, but this time with 160 grain RN bullets. These are 3 mm shorter than their PP counterparts, resulting in a 30% higher theoretical SF.


In the first test, the 30-06 and 9,3x62 performed almost identically, at least from a practical point of view. We now wanted to test more thoroughly if there actually is any meaningful difference, that will justify a 9,3 (or 358/ 375 for that matter) over a 30.


Also, we wanted to test the 45-70 further, to try to consolidate (or debunk) our impression from the previous test. Considering how well it performed during the first test, we used the same load this time.


Apart from the 45-70 load, I tried to get all loads more or less in the same velocity range, in order to eliminate velocity as a variable.


During the previous test, I believed the 9,3x62 to have a 1:14 twist. I measured it, and it turned out to be 1:12. Also, this time the 285 grain load was cranked up to full power, yielding about 350 fps more. These two factors combined, raised the SF of this bullet by 34%.


Bullets tested



Apart from the loads themselves, the most important difference this time, was the consistency of the shrubbery, and the number of shots fired. This time we made sure none of the branches were more than 4-5 mm thick at the core, and took great care to make things as equal as possible from shot to shot. Apart from two loads where we aborted after 5 terrible shots, we fired 10 shots from each load. Distance from brush to target was 23 meters/ 25 yards. The target was the same as the last time, with the 30 cm “vital zone” circle at the center.


Shrubbery front



Branch thickness






The loads tested


6,5x55 – 160 grain Woodleigh RN @ 2475 fps. SF: 2,51. LD 4,73.

30-06 – 170 grain modified S&B FN @ 2475 fps. SF 4,36. LD 3,24.

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

9,3x62 – 232 grain modified Lapua Mega FN @ 2350 fps. SF 7,53. LD 2,44.

9,3x62 – 285 grain Lapua Mega RN @ 2280 fps. SF 3,73. LD 3,36.

45-70 – 405 grain Woodleigh FN @ 1915 fps. SF 3,63. LD 2,24.


6,5x55/ 160 RN – Disappointingly, but not unexpectedly, the 6,5x55 did not make it this time either. We aborted after five shots, as it was clearly pointless to continue. 3 of the 5 shots showed full expansion and tumbling, and hit outside the 30 cm circle. At least 2 of the shots fully tumbled after only 2 inches of brush, creating a wide tunnel/ gap through the shrubbery. We could clearly see the trace of something cutting sideways through the brush. 2 shots did not tumble, and hit well inside the circle. Total group size was 54 cm. Maximum deflection from the center of the target was about 45 cm. This load is a clear failure. High risk of tumbling (poor penetration) after passing through only a couple of inches of brush.


6,5x55/ 160 RN


6,5x55/ 160 RN Tumbled in brush entrance


6,5x55/ 160 RN Tumbled in brush



30-06/ 170 FN – This one was also aborted after 5 shots, being the worst performer of all. These 5 shots created a total of 8 holes in the target, plus a piece or two of shrapnel, spread all over the target. No shots hit the circle. A more stout, factory made FN bullet might have given better results, but I have enough doubts to not bother anymore with it. Total group size about 130 cm. Maximum deflection about 90 cm. This load is a clear failure. Very high risk of wounding or clean miss.


30-06/ 170 FN







30-06/ 220 RN – Another disappointment. During the previous test, this load seemed to handle light brush pretty well, landing all bullets well inside the circle, only one tumbled. This time however, 5 shots were good and well inside the circle, while 5 shots tumbled and landed outside. A couple of these shots also tumbled fully after only 2 inches of brush, creating a large gap through the shrubbery, just like the 6,5. Total group size about 55 cm. Maximum deflection about 45 cm. So identical to the 6,5x55, but with twice the amount of shots fired (possibly slightly better with the same amount of shots). This load is a clear failure. High risk of tumbling/ poor penetration after passing through only a couple of inches of brush.


30-06/ 220 RN



9,3x62/ 285 RN – Yet another disappointment. During our first test this load performed very similarly to the 30-06/ 220 (which was pretty good). This time they also performed in a very similar manner, but in a bad way. This load also had a few bullets tumbling after only a couple of inches of brush, nearly cutting the whole shrubbery in half. 7 bullets showed clear tumbling, while one bullet also shed a fragment. Still, 5 bullets hit inside the circle. Total group size about 60 cm. Maximum deflection about 40 cm. This load is a clear failure. High risk of tumbling/ poor penetration after passing through only a couple of inches of brush. Though, it is quite possible that the heavy 285 grain bullet might have enough momentum to penetrate sideways through the shoulder bone of smaller medium game and such. Still, nothing I would personally rely upon.


9,3x62/ 285 RN


9,3x62/ 285 RN tumbled in brush



9,3x62/ 232 FN – The first load of the day to show some promise. None of the bullets tumbled inside the brush. Only two bullets showed clear tumbling. Unfortunately, one of them deflected about 100 cm, dampening the joyous mood. Apart from that, the remaining 8 shots showed some degree of expansion or deformation, similar to the 45-70/ 405 through finger-thick sticks during the previous test. Interestingly, this bullet has a very similar meplat size to the 45-70, which could explain the expansion (a PP/ RN is slightly better this way, something discovered later on). LD is almost identical to the 45-70/ 405, while SF is much higher. Sectional density is slightly lower, and momentum/ mass is much lower. Total group size of the 9 shots near center was about 60 cm. Maximum deflection about 40 cm. 4 shots in the circle, 1 more touching the circle on the outside. So apart from that wild flyer, the load performed very similar to the others, with regards to group size/ deflection. However, the clear reduction in tumbling gave hope, and reason to investigate further. This load is not a clear failure, as it did not show a high degree of rapid tumbling. It would in most cases quite likely work well on an animal standing close behind the brush. I believe a bullet that has initiated expansion before impact is significantly less of a problem than a tumbled one. Just common sense. But considering that this was a home made, non-feeding crap bullet, it's not a real option in it self. Still, the results from this bullet were used to further home in on the best performing load for the cartridge (or any cartridge for that matter).


9,3x62/ 232 FN





45-70/ 405 – Once again, this cartridge/ load proved far superior to the others. No bullets showed clear tumbling, but the one that deflected the most, also showed clear expansion. 3 more holes showed what may have been slight deformation or slight tumbling, 2 of them being inside the circle. A total of 7 shots inside the circle. Total group size about 45 cm. Maximum deflection about 30 cm. So far, I will still give this load a passing grade, even though a couple of bullets may have tumbled. I would be very surprised if this bullet is unable to penetrate the shoulder bone of a 200 pound deer, going sideways. It is a very massive lump of metal. Considering this, along with a group size of 45 cm at 23 meters, including the 10 shots from the previous test (total of 16 shots inside the circle), I would almost feel comfortable with a shot through light/ moderate brush, with the animal standing 8-10 meters behind. Keep in mind that 5 of the shots were fired through finger-thick sticks during the first test. All this being said, even the 45-70/ 405 have had a couple of shots pretty far outside the circle, so it does have it's limitations. But these limitations seem to be somewhat predictable/ moderate, compared to the other cartridges/ loads tested up to that point.


45-70/ 405 FN



After seeing the general results, we did not bother shooting through finger-thick sticks this time. At this stage it's not very useful, considering all but the 45-70 showed plenty of deflection and tumbling from 5 mm thick branches and down. Here I find myself agreeing more or less with C. Rodney James (whose test from 1987 was posted in the comment field under our first test by Paul Leverman), when he concluded that stick size isn't a very big factor. Sure, during the first test, finger-sticks threw the 30-06/ 9,3x62 off quite a bit more than the lighter brush, but at the end of the day this is all about finding out what cartridge/ loads can work for hunting, and they both eventually failed through light brush, so there is little point in testing further stick sizes with the small/ medium bores. When/ if we find the most ideal load for the 9,3x62 it might be natural to test it through sticks, and compare it to the 45-70.


Another thing that was consistent with C. Rodney James' test, was that long for caliber bullets has a clear tendency to tumble more than short for caliber bullets. This was most evident with his 45-70, loaded with 500 vs 200 grain bullets.


The results with 9,3/ 285 and the 30-06/ 220 shows the importance of firing many shots during such an unpredictable test. The random differences between a 5 shot group and a 10 shot group, gave a completely different impression, both loads going from “pretty good” to “clear failure”.



Test 2B


During this test, my partner in crime (Rune) was out pulling fishing nets, prepping for the end of days, so he missed out on all the fun. However, he kindly let me borrow his 9,3x62, so life does go on, despite what one might think these days.


After test 2A it was becoming clear that I needed to find short for caliber bullets, that are as stable as possible. For the 9,3 I got hold of some 250 grain Woodleigh RN and 232 grain Norma Vulkan (PP-design). For the 45-70 I got some 300 grain Woodleigh FN bullets. I also loaded up some 300 grain Barnes Socom with the tips pulled, just to see if the benefits of the stout copper (less deformation) could outweigh the drawback of less stability caused by the lighter material and large hollow point. As a side note, I should mention that I first used this bullet in the Marlin 1895 when I couldn't get hold of normal TSX a few years ago, and have been using them since. With the tips removed, they work very well in both gun and flesh.


When it comes to tip shape, I believe there is merit to the traditional view, that RN/ FN bullets are better at brush busting than spitzers. Not because of the meplat that meets the obstacle, but simply because these bullets are more stable (less rear heavy) than spitzers. I therefore sat down and drew a couple of ideas for the hypothetical optimum brush bullet, and realized one of them was a spitzer boat tail backwards. Naturally, I just had to test this. I wasn't actually gonna bother more with the 30-06, but for this purpose it was the obvious choice, as I have plenty of suitable bullets laying around. Not exactly an abundance for the 9,3 and 45. I decided on a 175 grain Nosler RDF that has a full metal jacket boat tail, and is therefore very resistant to deformation and fragmentation. I also loaded up a 180 grain Sellier & Bellot FMJ, that has the same shape, but an open boat tail, and could therefore hopefully serve as a hunting bullet. In the past, a backwards FMJ was supposedly not entirely unheard of as a poor mans alternative to expanding hunting ammo. So in other words, careful loading procedures would be fine.


Bullets used


175 RDF vs 180 FMJ


Barnes 300 vs Woodleigh 300


RDF Backwards



The loads tested


30-06 – 175 grain Nosler RDF backwards @ 2460 fps. SF 1,99. LD 4,32.

30-06 – 180 grain S&B backwards @ 2460 fps. SF 2,2. LD 4,22.

9,3x62 – 232 grain Norma Vulkan PP @ 2330 fps. SF 4,94. LD 2,85.

9,3x62 – 250 grain Woodleigh RN @ 2330 fps. SF 4,65. LD 2,99.

45-70 – 300 grain Woodleigh FN @ 2230 fps. SF 6,93. LD 1,72.

45-70 – 300 grain Barnes Socom HP @ 2230 fps. SF 3,52. LD 2,24.


30-06/ 175 RDF backwards – On a rare occasion a hypothesis turns out to be just right. This was such an occasion (almost). 9 of the bullets landed I an 8 cm cluster, almost in the center of the circle. One bullet tumbled and deflected 28 cm from the center. Total group size about 30 cm. Needless to say, the satisfaction was beyond that which can be conveyed in mere words. Right on par with the finest of dumps. If this was an expanding bullet, it would have been a very good choice for hunting. It could turn any 30-06, 308 and similar rifles into top notch brush guns. Unfortunately, 30 cal is apparently just not large enough for expanding bullets (see 180 FMJ). Also, feeding from the mag was a bit crappy. Still, this load was a really good indicator of the properties we need to strive for: Front heavy and stout. The relatively poor SF of 1,9 and high LD of 4,32 also shows that these factors on their own are not to be looked upon blindly. Judging by these numbers alone, the load should perform about the same as the 6,5/ 160 and 30/ 220, but the difference in weight distribution totally changed the outcome. A very useful result.


30-06/ 175 RDF backwards



30-06/ 180 FMJ backwards – After the success with the 175 RDF, the disappointment with this load was immense. 4 bullets landed perfectly in the middle, while 5 deformed, tumbled and deflected wildly. One shot jammed during feeding, and got the bullet rammed in, so I ditched it. Total group size 60 cm. Maximum deflection from center 43 cm. The load is a clear failure, but when compared to the RDF, it shows that stoutness or structural integrity appears to be just as important as weight distribution. The only apparent difference between these loads was the fully jacketed vs open front (tail). In other words, integrity vs deformation. Both bullets made clear paths through the shrubbery, but the FMJ on average did greater damage, one shot almost blowing the shrubbery to pieces. So it was not a case of uneven resistance between the two loads, but the way the bullets handled the resistance.


30-06/ 180 FMJ backwards



9,3x62/ 232 Vulkan – This one performed pretty well, supporting theories further. It is a short bullet, but at the same time it's a semi-spitzer/ PP, which is slightly lighter in the front than an RN/ FN. Two opposing factors. 8 bullets landed in the circle. 3 bullets tumbled. Total group size 35 cm. Maximum deflection from center 23 cm. This load is not a complete failure, but I would rather try to find something better.


9,3x62/ 232 Vulkan



9,3x62/ 250 Woodleigh – This bullet performed very similarly to the Vulkan, but slightly better all in all. It had two less tumbled bullets than the Vulkan, despite being slightly longer. This may of course be pure coincidence, but I for now I take it as an indication that the benefits of the more front heavy RN design cancels out or outweighs the drawback of the added length. But while showing less tumbling, this bullet also showed more expansion, due to a larger exposed lead core. Still, it's apparently stout enough that detrimental deformation/ fragmentation does not occur. Total group size 30 cm. Maximum deflection from center 25 cm. 1 tumbled bullet. 2 clearly expanded bullets. This load is not a complete failure, and I would choose it over the Vulkan, simply due to the lower degree of tumbling – our main enemy.


9,3x62/ 250 Woodleigh



45-70/ 300 Barnes – This one was a disappointment. 2 bullets tumbled, one of them deflecting 37 cm from center, being the worst shot from the 45-70 so far. Only 5 bullets landed in the circle, 4 of them in a very tight cluster at the center. Total group size 42 cm. Maximum deflection from center 37 cm. Even though total group size is similar to the previously tested 405 Woodleigh, maximum deflection is worse, and the general impression is that of a more erratic, inconsistent nature. The load is therefore a failure, most likely due to the large hollow point, causing the bullet to become front light, and therefore unstable. Now, had that cavity been filled with tungsten, or perhaps gold...


45-70/ 300 Barnes



45-70/ 300 Woodleigh – This load performed very well, even significantly better than the 405 Woodleigh. One bullet showed slight tumbling, landing 5 cm outside the circle. The remaining 9 shots hit front first, forming a nice 19 cm group in the circle. Total group size 32 cm. Maximum deflection from center 20 cm. This difference compared to the 405 can of course be coincidence, considering that 2 shots this or that way from either load would have flipped things around, so another 10-shot group from each would be necessary in order to conclude which one is truly best (this also goes for the 232 and 250 in 9,3). Still, the generally consistent performance of the 45-70 with these two Woodleigh bullets is becoming more and more obvious.


45-70/ 300 Woodleigh



As a whole, performance was noticeably better with the loads used in test 2B, compared to test 2A. Apart from the explosive tendencies of the 180 MFJ, not one shot showed clear tendencies of rapid tumbling within the brush. This shows that we are moving forwards, though ever so slowly. It is not in vain.


It must be pointed out that our artificial shrubbery was quite a bit more dense than most brush one would ever consider shooting through while hunting, but it was necessary for the sake of consistency. Also, it was a key factor in discovering that bullets can fully tumble after only a couple of inches. At the same time, a bullet shot through a natural, lighter bush may very well strike 2-3 pencil sized branches, causing similar resistance to our shrubbery. Therefore, we considered it a reasonable way to do the test, and will continue to use this method in future tests.



Conclusions for now


1 – Poor penetration and wild deflection caused by tumbling is one of the main concerns in brush busting, usually related to bullets that are too long for caliber (high LD) in this context, or too front light. Tumbling can also happen to short for caliber bullets, mostly with spitzer/ semi-spitzer bullets. Blunt, short for caliber bullets of a certain mass generally does not tumble. Deflection is the main limiting factor of such bullets.


2 – Weight distribution is an important factor with regards to tumbling. The further forwards the balance point of the bullet, the more stable it is.


3 – Wild deflection caused by deformation/ fragmentation is another main concern. This appears to be most profound with small caliber/ light bullets of a frangible nature (30/ 170 FN, 30 180 FMJ backwards).


4 – A heavy (long) for caliber bullet is not a positive trait, and will not make a small/ medium bore perform well through brush.


5 – With long for caliber bullets in 6,5/ 30/ 9,3 it is not humane to shoot animals even at a very short distance behind brush. Bullets might tumble fully in 20-40% of cases, before they are through the brush. High risk of poor penetration. Unacceptably high risk of wounding.


6 – 30 caliber and down (loaded with commercially available hunting bullets the right way) does not seem to have any real potential for brush busting, even though a lucky 5 shot group or hearsay might give the opposite impression. Bullets are either too long, too light or too weak. If a cartridge is too light to perform with short for caliber expanding bullets, it will most likely not perform well with any other bullet weight/ length. Still, it is theoretically possible to develop dedicated brush bullets that can make small bores perform well (175 RDF).


7 – There is such a thing as a brush gun. This is made evident by the 45-70, showing a good level of consistency all the way, relative to the other cartridges. No extreme fliers out of 30 shots (not counting the Barnes bullets). The 175 RDF also shows that there is such a thing as a brush load, in a cartridge otherwise generally not suitable for the purpose.



Thoughts and theories for further study


1 – A stout bullet is less prone to deformation and fragmentation than a softer bullet, resulting in less deflection. More mass to begin with is also good (45-70).


2 – With normal, commercially available hunting bullets loaded the right way, low length to diameter ratio is more important than a high stability factor on it's own. One can simply not just crank up the barrel twist and achieve stability through brush. An LD of less than 3 seems to be desirable. At the same time, an SF of more than 3,5 seems to be desirable.


3 – A balance point in front of the middle of the bullet is a very effective way to stabilize a bullet through brush. The further forwards the balance point is, the less likely the bullet is to tumble. This factor is much more important than LD and SF. Especially since weight distribution is not taken into account by ballistic calculators (as far is I know), SF is only useful to some degree. A term such as “55% BP” or something could be useful. Meaning that the balance point is 55% behind the tip of the bullet. The ideal would then be less than 50%. I will measure this during the next test.


4 – Considering how close the 9,3 seems to be to the limit of too light, it is unlikely that a 338 will show any noticeable improvement over a 30 cal hunting bullet (shot the right way). Somewhere around 9 mm might be the practical lower limit for brush busting. I am not sure I will bother with further investigation.


5 – Velocity does not seem to be a significant factor, at least in this spectrum. Looking at the 405 and 300 grain Woodleighs that are basically the same bullet, but fired at 1915 and 2230 fps respectively, there is no indication that higher velocity has a negative effect. Quite the opposite (caused by lower SF due to lower velocity?). It is of course fully possible that there are certain velocity thresholds relative to bullet mass/ construction, where results are effected, but that's a chapter of its own.


The 358 bore might be interesting to try out. Specifically the 200 grain RN and FN bullets available. These will have about the same LD as a 220-225 grain 9,3 of the same shape, and also be quite front heavy. If these are not too light/ fragile, they might work well enough ta get a passing grade. Another interesting candidate is some sort of 375 caliber cartridge with the 200 grain Sierra RN or some 235 grain bullet. But I do not currently have access to either a 358 or a 375, so if someone else would like to test these bores in the same way we did here, that would be absolutely fantastic. The 358/ 9,3/ 375 might turn out to be a good middle ground between brush busting and reach, with ideal dual loads for both purposes. But in order to find ideal loads for brush busting in the medium bores, large amounts of testing is required to identify tipping points where all factors add up favorably. If we for example look at the 285 Mega vs the 250 Woodleigh, the difference in length is only 3,4 mm, but results are vastly different. But at the same time, the Mega is not quite a “true” round nose, like the Woodleigh, and therefore more front light. When little factors like these are combined, it seems to tip the scale.


Anyway, I have now found an interesting bullet for the 9,3 that I will test. It is a 232 grain Rhino Solid Shank RN. The only 232 grain RN I have found, and also I believe it has a solid copper base, and stout/ bonded lead front core. This should make it more front heavy than any of the other 9,3 bullets tested, and could make for a winner. So either this one or the 250 Woodleigh will probably be the winner load in 9,3x62 (I am not too concerned with wounding abilities from either of these stout bullets, as they will be cranked up a bit for hunting, and used at short range). Together with the 300 grain Woodleigh, this load will be used for a final “realistic” test, where we will set up an animal target at perhaps 10 meters behind a bush. Then shoot 10 shots from slightly different angles, in order not to plow one huge hole through the bush. Then we will move the same target to another bush and shoot 10 more shots, and repeat the process until we feel we have enough of a group to pass our final verdict. Perhaps a 30 shot group from each cartridge will do. Perhaps 50.


Of the two ideas for a brush bullet design that I drew, the second one was very similar to a bucket style air gun pellet, which is also very similar to the 300 Barnes backwards. Now, the light material gives a lower theoretical SF than if it was a cup and core of same dimensions, but considering that the bullet wants to tip around when it's shot the right way, it's not entirely impossible that it wants to not tip around when shot backwards. Also, the solid copper meplat (base) will be impervious to deformation, which I believe to be a good trait in this setting. I will test this one during the next test, just to find the ultimate brush buster. If it doesn't work, I have some 500 grain Hornady DG that I can modify into 300-350 grain “buckets”, to see if cup and core fares better. Whether I shoot it backwards or forwards, time will tell. Here in Norway it is not legal to hunt with non expanding bullets, so forwards would be best, even though there will be no solid base. Still a lot of mass and mess. The Barnes will for our own part mostly be of intellectual value. Still, others may enjoy the fruits of our labor. With that wide meplat and relatively sharp edges it's very likely to be quite effective. Check out Nathans wound testing of 45-70 backwards. Note that he also got good accuracy backwards, which does make sense when considering the stability of such a load.


Ideas for brush bullets



So far we have shot a total of 144 shots through brush during all tests combined, and still we can't say we have anything truly conclusive to show for. However, we are definitely getting a clearer and clearer impression of things, so this whole project just might turn out to be very fruitful. Hopefully we will eventually have a short set of simple guidelines for choosing a brush gun/ load. Some specific load recommendations or a short list of good and bad traits, which was pretty much the whole goal to begin with. That, and to justify the purchase of a 9,3x62, of course...


That's it for now. Next time I shall try to keep it shorter and more compact. Stay tuned!


Cheers

Magnus