Glasers and Other Pre-Fragmented Projectiles


There is a lot of talk out there about High Velocity Pre-Fragmented Projectiles such as Glaser Safety Slugs and Mag Safe ammunition.  Some tout them as ‘the ultimate self-defense round’ and others decry them as useless and a rip-off.  In fact they are neither- they are a special-purpose limited application round and within their limits they work quite well.

What is a Pre-Fragmented Projectile?

The most common form is a bullet-shaped copper shell filled with shot.  The size and quantity of shot varies with the design.  The end of a Glaser Safety Slug is capped with a polymer sphere.  Mag safe has no cap, but rather fills the space around the shot with an epoxy resin.  Since these bullets are lighter than conventional bullets they are fired at higher velocity than conventional bullets- usually 150-200+% of typical bullet velocities for a given caliber.  This gives them a proportionately higher kinetic energy load as well. Another advantage is that they tend to have relatively light recoil, allowing faster follow-up shots.


They are called Safety Slugs for several reasons;  first because they are designed so that if they hit a hard, angled surface instead of ricocheting they will break up into small pieces that are unlikely to have lethal effect at any significant distance from the impact.   They are also likely to break up in a standard interior wall, especially if they strike at an angle, emerging if at all as a diffuse spray of small projectiles at low velocity that are unlikely to inflict a lethal wound.  They will not over-penetrate a human body and possibly go on to strike an innocent bystander. Such rounds were originally designed for Air Marshals as it was felt that they would be less likely to over-penetrate the fuselage of an aircraft in flight and cause explosive decompression.

There have been a number of theoretical studies; many of these are well thought out and theoretically sound if you accept their basic assumptions. The primary assumption is that it is necessary to penetrate at least twelve inches to result in a ‘stop,’ as a cross-body shot might have to penetrate that far to disrupt vital organs and structures in the body. Unfortunately these studies don’t take into account documented cases of actual shootings in real life with high-velocity pre-fragmented projectiles. In these cases they have most often worked extremely well- overall at least as well as conventional hollow-point ammunition in their given caliber.

There are stories of these bullets failing to penetrate heavy clothing, leather jackets etc.  To the best of my knowledge not one of these stories has been documented by any reliable authority.

One problem is that an intervening limb might take the hit, causing the bullet to break up before hitting the torso and failing to result in a ‘stop.’ That an intervening limb might take the hit from the bullet is well-taken. On the other hand a hit in the hand or arm with a service caliber Glaser will virtually insure that that limb is out of action- and we shouldn’t ignore cases where an intervening limb has deflected a conventional bullet.

Marshall Evans study of actual coroner’s reports of real-life, documented shootings did include two examples of 9x19mm Glasers failing to stop a suspect with a single hit. One was a cross-body shot that struck the back by the shoulder blade at an acute angle and while it did massive surface damage did not stop the perp- though it is doubtful that a comparable hit with any conventional bullet would have done better under the circumstances. In the second case the Glaser round passed through the upper arm and started to break up before hitting the suspect’s chest. A conventional round under these circumstances would likely have been more effective.  In a few cases locally of use by police officers in the late 1980s and early 1990s they performed at least as well as conventional ammunition.

There have been a number of shootings with 9x19mm Glasers since that have been documented- on the average Glasers have performed about as well as a good conventional hollow-point. However that average doesn’t tell the entire tale. When broken down into full-frontal hits and oblique hits the statistics change noticeably. In cases of oblique hits effectiveness drops due to the low penetration of these rounds. In cases of full-frontal hits 9x19mm Glasers have been extremely effective at stopping with torso hits- but it should be noted that almost none of these were single-shot shootings. It is only on oblique (crossing the body) hits that effectiveness drops lower than good hollow-points-  Since most home defense shootings involve full-frontal shots this is less of an issue for home defense uses than it is for law enforcement.

Then there is the argument that HVPFPs have very poor penetration against car windows, doors etc.  This is hardly surprising- they are designed to not penetrate these types of obstacles. Many will argue that this makes these rounds unsuitable for general law-enforcement use.  I happen to agree with this however it has no bearing on most civilian in-home self-defense situations.

Some also argue that an overzealous prosecutor can claim that you were using ‘special killer bullets.’ If you get hung up on this one some one should shoot your lawyer; the ‘killer ammo’ charge in the case of Glasers and their ilk is laughably easy to shoot down in court. You weren’t carrying special ‘man-killer’ ammo. Far from it- you were carrying ‘Safety Slugs’ that wouldn’t over-penetrate or ricochet and hurt innocent bystanders; you were in fact concerned enough about this possibility that you were willing to spend as much as $3 a shot to insure against accidental injury of innocents. It helps of course if this is actually true and reflects your real reasons for using this ammo.

Which brings up another issue: these rounds are expensive, often costing $3 a round or even more. I lived in an apartment years back and at a gun show a fellow questioned spending $3 a shot for defensive ammo. I asked him if he didn’t think maybe my neighbor’s 3 year old daughter’s life wasn’t worth a bit more than $3 a shot? Currently I live in a house with a wife, six dogs and a cat. It would really suck if a round from my gun penetrated a wall and injured or killed one of them, which even very good hollow-points frequently can.

HVPFPs aren’t perfect, nor are they useless. They are special application ammo that I believe is not suited to use as a police duty round. They are suited to special circumstances and civilian use in densely populated areas, apartment buildings or for homes where other family members are usually present. In these cases it would be wise to balance the situational effectiveness of these rounds against the likelihood of causing unintended injury to bystanders.

One thing that I feel is important to note- shot placement is critical with any defensive ammunition. You can have the best defensive ammunition on the planet and it’s not good if it doesn’t hit something important. Practice is paramount, and with Glasers or Mag-Safe the cost of that is prohibitive. Your best bet is to find a less expensive ammunition that hits the same point of impact and practice with that.

Another thing to consider- these rounds work because of their velocity, and since the bullet is light weight they lose velocity relatively quickly; they are a fairly short-range proposition. Since most defensive shootings- especially in the home- take place at very short range this is unlikely to be an issue.

For home defense in almost any good quality service-caliber revolver I would not hesitate to recommend them- with the proviso that you fire a cylinder full to insure that there are no issues. In a semi-automatic pistol I wouldn’t unless you are completely satisfied that they will function correctly- how you establish that is your judgement. My wife’s Kahr E9 cycled a magazine of Magsafes flawlessly. Normally I would still be a bit dubious but since the gun has never experienced any feeding problems with any type or profile of 9mm bullet I’m not concerned.

For general law-enforcement and self-defense outside of the home HVPFPs are often not the best choice due to their lack of penetration of obstacles.  Law enforcement officers in particular may encounter situations where they need to fire on a vehicle or through obstacles and to a lesser degree legally-armed civilians may face these same situations.  In these cases modern, good-quality hollow-point ammunition remains the choice of professionals.


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