drilling rifle bullets to improve terminal ballistics

[Todd Morley]

I have previously posted elsewhere about drilling rifle-bullet tips to improve terminal ballistics, a practice that's been around since at least when Dr. Martin Fackler (https://en.wikipedia.org/wiki/Martin_Fackler), founder of the US Army's Wound Ballistics Laboratory, experimented with it and documented the results in a 1995 article in the Wound Ballistics Review. (Hollow-tipped bullets have been around for over a century. I don't know if manufacturers have ever drilled bullets to create a hollow tip.)

Some hunters continue to hunt with target bullets, and even some hunting bullets, that don't expand effectively. (The Berger 156-grain 6.5mm Extreme Outer Limits bullet is an example. Per a Barbour Creek video on YouTube, that bullet travels over a foot in ballistic gel before initiating expansion. Most Berger hunting bullets similarly tested in YouTube videos start expanding an inch or two into the gel.) Drilling such bullets properly can improve their terminal ballistics for hunting. Without intending to advocate for this practice in any particular case, I have prepared the attached document about the history of the practice, and about my own procedure and successes doing it.

 

[762plinker]

drilling does not rework the jacket to act like a hunting bullet...
me thinks better to buy a hunting bullet to begin with.
BUT
i am not a hunter

 

[Todd Morley]

I agree (and the document points out that target bullets generally have thicker jackets than hunting bullets, which is one reason they don't expand rapidly on impact). However, some hunting bullets (notably the Berger 156-grain EOL 6.5mm hunting bullet) also are known not to expand on impact as one would wish for hunting. (The document includes the URL of the YouTube video posted by Barbour Creek of a 20% gel-block test of the EOL. Even in the stiffer gel, that hunting bullet traversed 13" of gel before expanding--not at all what you'd want in a hunting bullet.) And some target bullets expand effectively, regardless of their thicker jackets, when properly drilled, at a cost of losing 1-4% of their G1 ballistic coefficients (but without loss of accuracy).

Whether we'd like it or not, some folks want to hunt with target bullets--especially the Sierra MatchKing (SMK)--because they like their high BC, accuracy, and/or availability. For example, you can read an American Rifleman 2017 article (https://www.americanrifleman.org/content/unsung-hero-the-mk-248-mod-1/) about the history of the SMK in military sniper rounds. The author concludes by reporting his experience handloading the 220-grain SMK for the .300 Winchester Magnum, citing the round's retained kinetic energy at 1,000 yards--a figure that's only meaningful to civilian shooters interested in shooting something other than paper.

The U.S. Army researcher cited in my document experimented with drilling the SMK because military and police snipers favored the bullet, but reported at his seminars that the SMK's terminal ballistics were not always satisfactory for their purposes. The Army researcher experimented with drilling the SMK, and found (and published in a scientific journal) that drilling produced the terminal ballistics of a hunting bullet. He tried to persuade Federal to drill SMKs and load them in a round specifically made for police snipers.

Years ago I had the same experience with the 220-grain 30-caliber SMK. I used it to hunt elk, persuaded by some posts in a long-range hunting forum that it was a good bullet for long-range elk hunting. Using that bullet I made a perfect broadside shot on a nice bull at 460 yards. The bull walked away, and kept walking over hill and dale through miles of snow, falling down every few hundred yards and leaving a dent in the surface of the snow with a pin prick of blood where the unexpanded bullet had evidently passed through the ribs on the far side of the lungs. I tracked that elk for nearly seven hours, into a blizzard, before I lost the trail.

That experience motivated me not to hunt with the SMK until (years later) I learned about drilling. (Meanwhile I discovered Berger hunting bullets, and have hunted with them ever since.) You can read about my very different experience hunting nilgai with a properly drilled SMK, in the document.

 

[big5ifty]

Open tipped lead core bullets have better terminal ballistics than closed tip. This is a known, well established, 120+ year old fact, recorded in the Anglo-Boer war, when Boer soldiers cut the tips off their Mauser cartridges. The British were sufficiently annoyed by this to execute any captured Boer soldier with "dum-dum" bullets on the spot.

When you take a target bullet, and remove the tip, you have a fragmenting target bullet, not an expanding hunting bullet.

You could use that to hunt, but it would have to be a much smaller animal than you would typically hunt using a hunting bullet of that weight for that caliber. It's useful to know what caliber, bullet weight, velocity, hunting distance and animal is being referred to in these types of discussions. Chopping the end of your Nosler Custom Comps to shoot squirrels, for example, means you can successfully and ethically hunt with the bullets.

A target bullet does not have a thicker jacket than a hunting bullet.

A hunting bullet is designed to hold together under impact, a target bullet is designed to fragment on impact.

Using target bullets for the higher BC to be able to make longer shots on game opens the ethics discussion. How far is unethical ?

You can decide what distance for yourself by honestly answering these questions :

1. can you reliably place a kill shot at that distance
2. will your bullet retain enough energy to make a quick kill if placed correctly
3, can you reliably find the animal for a follow-up shot if you wound it

Should you drill holes in your target bullets, you've destroyed the bullet concentricity, changed the bullet weight and distribution around the bullet axis, as well as diminished the BC. Not something you can expect long range accuracy from, so why hunt with it.

 

[Todd Morley]

Please read my document, and the authorities it cites. I think if you do, you'll reconsider some of your opinions. For example, the notion that target bullets have thicker jackets comes from Berger's web site (which explains this design decision). It's not (only) my opinion.

I encourage you also to watch Barbour Creek's series of YouTube videos testing the terminal ballistics of numerous types of hunting bullets. You can see that most of the tested hunting bullets (especially the Bergers and similarly constructed cup-and-core bullets) fragment about 1-2" into a gel block. More traditional bonded and H-cross-sectioned hunting bullets, such as the Sierra GameKing and the Nosler Partition, are designed for high "weight retention" rather than fragmentation. I do not mean to stir up the debate about whether fragmentation or weight retention is better for hunting. But the assertion that hunting bullets "hold together under impact" is only true of the more traditional hunting bullets such as the Partition. Even traditional cup-and-core designs such as the Nosler Ballistic Tip fragment violently inside quarry (or a gel block). I hunted the Ballistic Tip for years, and saw what it (quite consistently) did to big game.

The U.S. Army researcher my document cites reported in his publication that drilling the SMK did not affect point of impact (accuracy). I have had the same experience. My handloads with drilled bullets are accurate to 0.5 MOA at 200 yards, the same as my undrilled handloads with the same bullets. Point of aim and drop don't change perceptibly. There is no evidence of yaw or tumbling in the target paper, which there would be if drilling "destroyed the bullet concentricity." I have harvested elk at over 600 yards with the drilled 220-grain SMK, with one shot, DRT. Accuracy was not a problem.

I drilled some Berger 156-grain 6.5mm hunting EOL bullets tonight. Afterwards I collected the copper dust and weighed it. The results indicated that drilling removed an average of 0.12 grains of material, which is 0.08% of the bullet weight. Target shooters sometimes sort bullets into weight classes differing by 0.1 grains, and the extreme spread of bullet weight is usually a few tenths of grain. (See for example

.) So drilling might eliminate the heaviest class and create a new lightest class, but effectively would just shift the weight scale downwards 0.1 grains, with most of the bullets still very near the center of the undrilled bell curve. I have no evidence (in my own experience, or in published literature) that drilling adversely affects accuracy, except by decreasing BC by up to 4%, which adds about 3/8" drop to the 220-grain SMK's trajectory at 500 yards.

There is a real difference between science and engineering on the one hand, and poorly considered opinion on the other. Perhaps you're just trolling me. My post's intention is to help folks who choose to hunt with an open-tipped bullet having poor terminal ballistics improve the terminal ballistics, in the interest of humane harvests. Hopefully we can agree that's a worthy goal.

 

[Todd Morley]

A Minnesota Dept. of Natural Resources study of hunting-bullet fragmentation (https://www.dnr.state.mn.us/hunting/ammo/lead-short-summary.html) concluded the following:

Copper and non-exposed lead core: These bullets averaged nine copper fragments in the animal with an average maximum distance from the wound channel of seven inches. By design, copper bullets leave no lead and the few fragments that were seen on x-ray were less than an inch from the exit wound. Overall, both of these bullet designs fragmented very little and left no lead.

Ballistic tip (rapid expansion): These bullets had the highest fragmentation rate, with an average of 141 fragments per carcass and an average maximum distance of 11 inches from the wound channel. In one carcass, a fragment was found 14 inches from the exit wound.

Soft point (rapid expansion): These bullets left an average of 86 fragments at an average maximum distance of 11 inches from the wound channel. In this research, bonded lead-core bullets (controlled expansion, exposed lead core) performed almost identically to the soft-core bullets and left an average of 82 fragments with an average maximum distance of nine inches from the wound.

Clearly whether a bullet is "designed to fragment on impact" is about the bullet design more than its intended use.

Here's some relevant language from the Corbin (maker of jackets for custom competition bullets, among other things) web site: "Corbin's VB (Versatile Benchrest) jackets are made for world-class competition, but we saw no reason why the world's finest target jacket could not also be designed to offer superior game hunting and varmint shooting performance. We started with a non-fouling, smoothly expanding copper alloy material drawn precisely over mandrels to exacting wall thickness. But we added features for custom bullet makers: thin nose-section walls that would accept the same seating punch diameter over a wide range of weights, and provide excellent expansion even at lowest velocities, with a gentle taper back to a heavier base to allow controlled expansion at higher velocities, especially when used with Corbin Core Bond to make bonded core bullets." (http://www.corbins.com/jackets.htm#general)

Bullet jackets (target and hunting) are nowadays generally made from 95% copper and 5% zinc gilding alloy. See for example https://www.sierrabullets.com/products/bullets/bullet-jackets/. The differences between target and hunting jackets (where they exist) are usually about thickness and taper rate. Sometimes hunting jackets are scored near the tip to encourage expansion. Drilling is another way to do the same thing. . . .

 

[big5ifty]

The amount of effort put into the theoretical analysis and the science is commendable.

If drilling holes in target bullets works for you, there is no reason not to do it.

 

[Homerange]

Tricks like these are as old as the hills but nothing has changed if you want/need good terminal performance on game of whatever size at whatever range.
With a dedicated hunting bullet specified for the game class, lets say our NZ red deer the rule of thumb for reliable kills for well placed shots is 2000fps and 1000ftlbs energy at impact regardless of distance.
If we are to properly respect our game and we should in order to dispatch them humanely so not to discredit our sport we should be very focussed on the terminal performance one can only achieve with a dedicated hunting bullet and not some conjured up attempt at one.

Here below is one of the world best terminal performance sites focussed on that and not ballistic performance, the subject of this thread:

Extensive Field-Tested Rifle & Cartridge Research - BallisticStudies.com

Expert rifle & cartridge research, carefully compiled through extensive field-testing & freely offered to the firearms community.

www.ballisticstudies.com

Here, in the Knowledgebase section much guidance is offered for all popular calibers which projectiles will reliably perform which if we are to properly respect our game it would be wise to study.

 

[Intheshop]

Couldn't read the file(me being computer challenged)..... so if this was discussed or explained,excuse/ignore this response.

Would be curious about the accuracy of the drilling? To the point(ha) of,not so much any fixturing but spin testing that "should" follow. So are you testing for any balance issues after drilling?

Just saying that bullet making is a swaging process.... to introduce ANYTHING that disrupts this makes me nervous(from a bughole standpoint,not personal safety in the shop environment).

 

[Homerange]

Couldn't read the file(me being computer challenged)..... so if this was discussed or explained,excuse/ignore this response.

Thanks.
Try this:

Knowledgebase

 

[coldboreshot]

Oh boy! Here we go...

 

[perazziguy]

Looooooong winter...

 

[jelenko]

Why? Why not just buy a bullet for the application?

 

[David Milisock]

I'm just some old fart but after many decades of shooting I believe I'll stick with the advice from companies like Nosler, Hornady and the like.

Today it's easy to see the expansion velocities of modern projectiles, however it's nearly impossible to find out how tough the aft section of the projectile is.

An example is the 250 grain Hornady Spire Point in 358 diameter. In my 358 Norma it expanded at 400 yards but still exited an Elk with a traditional broadside shot, some would say good result. The animal trotted off for a half dozen steps and dropped. I know it expanded due to the size of the exit hole.

At 600 yards on another animal it hit the front shoulder and traversed back and across existing in the front of the hind quarter. The animal dropped where it stood, another good result. The exit wound was larger than the 400 yard hit.

Now my question has always been at my rifles velocity at what range should I avoid heavy bone hits? My judgment has been anything inside 400 yards stay off the shoulder.

Expansion is not always your friend just as much as non-expanding complete penetration is not always your friend. I do my best to avoid blowing up a projectile and place my shot as if I'll get litte to no expansion.

As far as me drilling my projectiles, hell no! However when I get my prostate checked I don't put my own finger up my ass either, maybe I'm the odd bird.

 

[TTE]

Years ago I had the same experience with the 220-grain 30-caliber SMK. I used it to hunt elk, persuaded by some posts in a long-range hunting forum that it was a good bullet for long-range elk hunting. Using that bullet I made a perfect broadside shot on a nice bull at 460 yards. The bull walked away, and kept walking over hill and dale through miles of snow, falling down every few hundred yards and leaving a dent in the surface of the snow with a pin prick of blood where the unexpanded bullet had evidently passed through the ribs on the far side of the lungs. I tracked that elk for nearly seven hours, into a blizzard, before I lost the trail

Without finding the Elk, there is no way to verify shot placement nor terminal performance of the bullet. Elk don't go far on 1 lung

 

[Pawnee Bill]

With proper shot placement and proper calibre, the target would be dead and I seriously doubt what ever you shot would know the difference in the bullet.

 

[K22]

Drilling rifle bullets? Are you kidding or is this real? I thought I've seen and heard everything but this one wins the prize. With all the high-performance bullets on the market today why would anyone even consider doing something like this?

Sorry, but I can't help commenting on this because some poor new shooter is going to try this, I'm afraid.

 

[big5ifty]

With proper shot placement and proper calibre, the target would be dead and I seriously doubt what ever you shot would know the difference in the bullet.

That's what the science and the math says.

Out there, Murphy rules. Bullets do not behave as they should if they can avoid it.

 

[Homerange]

I'm just some old fart but after many decades of shooting I believe I'll stick with the advice from companies like Nosler, Hornady and the like.

Not just your decades of hunting but their decades of making proper game projectiles in many calibers and for many types of game in each caliber.
There's no way the average hunter can even begin to accumulate that level of knowledge to then impart into projectile design.

Now my question has always been at my rifles velocity at what range should I avoid heavy bone hits?

Well this is a double edged sword as any animal well hit with an appropriate sized caliber won't go far on 3 legs yet an arguably too small caliber will effectively and humanely take down game with a carefully placed shot in the crease right behind the shoulder.

Trouble is we don't always get a nice broadside shot and to compensate for when field shots might be hurried or offhand we need to have enough gun with a projectile offering adequate terminal performance at the ranges likely to be encountered.
Simple solutions are short to medium range loads and long range loads each with projectiles that perform adequately as a high BC streamlined boat tail heavyweight designed for some magnum is very likely to keyhole at short range when under driven so projectile selection best suited for your quarry and your rifle performance is of utmost importance.

Yet the projectile manufacturers err on the side of caution and so they should with projectile design to provide some comfort in projectile terminal performance under tough conditions however that is not always optimal in every situation.
Thankfully we can easily reload and tailor solutions to each of our needs.

 

[wkdickinson]

When I first read the title of this thread I laughed. But I came back to it twice. Honestly I can't believe people have written well thought out responses.