While coated pistol bullets are nothing new, coated rifle projectiles are an entirely new animal. Several manufacturers now offer .30 caliber rifle bullets designed for use in 300AAC or 300BLK, specifically for use in subsonic loads in suppresssed guns. 

Subsonic means the bullets travel slower than the speed of sound (roughly 1125 FPS), which is a velocity commonly achieved in just about any common pistol caliber. But what about high speed rifle applications? The AR-15 can easily fire 55gr bullets at over 3,200 FPS, almost 3x faster than subsonic loads are traveling. So is it even feasible to attempt loading coated bullets for the AR15?

There is an extra wrinkle when you consider that jacketed bullets should be sized differently than plated bullets, which can also be sized differently than cast lead or coated bullets. Why the difference? The primary reason is the hardness of the bullets. Jacketed bullets are the hardest, with cast lead and coated bullets being the softest, and plated bullets are somewhere in the middle depending on how thick the layer of plating is. When firing a cartridge, a cast lead or coated bullet can "squish" down substantially to fit into the bore, so you could run a bullet that's a good bit bigger than the bore! On the opposite side of the spectrum, you don't want to try forcing an oversized jacketed bullet down the barrel, the amount of back-pressure generated could result in a catastrophic failure (AKA a kaboom). Think of coated bullets as a marshmallow, and jacketed bullets as an overcooked piece of chicken breast. You don't want to try swallowing a tough chicken breast without chewing, a marshmallow would make it through just fine!

So with a polymer coated bullet, how do you decide what size bullet to use? A good rule of thumb with cast lead and coated bullets is to measure your groove diameter, and use a bullet that is 0.001" larger. So if your groove to groove diameter is 0.355", use a bullet that is 0.356". The question now is how do you measure your bore and groove diameters? This can be done using a process you can do at home called slugging. 

A slug is just a small piece of soft lead: It can be a cast lead or coated bullet, a lead fishing weight (not steel!), or just a round chunk of lead that's roughly the size of your bore (In any case, it needs to be a tiny bit bigger than your bore). Using a rod, push the slug through your bore from chamber to muzzle, you may need to use a mallet if it's a tight fit. Afterwards, you're left with a slug that has been swaged by the barrel, and should have rifling grooves cut into it. The measurement to take with your calipers is the larger overall diameter of the slug, not the smaller diameter from land to land. The overall diameter of the slug will be your actual groove diameter', the smaller diameter is your actual bore diameter.

What's another way to determine the ideal size for your firearm? An equally good method is to simply test various sizing diameters, we offer small sample packs for exactly this purpose. After loading, there are 2 aspects to look at during testing: How smoothly the ammo feeds and chambers, and the accuracy of the loads. In a 9mm, a .358" bullet may give you phenomenal accuracy, but if you have a tight chamber your ammo is having a tough time feeding and seating into the chamber, it's probably not worth the reliability trade off. Likewise, a .356" bullet might feed perfectly, but the groups it shoots may not be as tight. Find the right balance, and you'll find a load which matches your particular gun and gives you the best possible performance. 

Flaring, belling, expanding are all words which describe the process of opening the mouth of your brass case before attempting to seat a bullet. 

If there is one process that is crucial in the loading of our polycoated bullets, it's is the flaring of the case mouth!

Not properly expanding the case mouth can cause numerous issues such as:

• Shaving the coating during the seating process (exposing the lead can cause leading of your bore!)
• Damage to the base or shank of the bullet (possibly causing decreased accuracy)
• Crooked seating of the bullet
• Poor feeding or chambering of your completed cartridges

There are many different types of expanders, each die manufacturer is different, and there are even variations within each manufacturer. But, in any case, as long as you are able to expand the mouth enough to seat your bullet smoothly and straight, you are in good shape!

This test is basically just using your actual firearm's barrel as a cartridge gauge to determine whether your ammo will function well or not.

Step 1 - Disassemble firearm

Step 2 - Insert live or dummy cartridge into chamber to test for length

Step 3 - A good cartridge should 'plunk' right into the chamber and fully seat. A bad cartridge will not seat fully.

Step 4 - Remove cartridge, it should either fall out or take very little effort to pull out.

This is the first article in a short series about making the most reliable and accurate ammo possible in your specific handgun.

We'll start by talking about the plunk test. This is a test where you drop a loaded (or dummy) cartridge into your pistol's chamber as shown above. If the cartridge 'plunks' down into the chamber, and can be pulled out with no effort, you know that round will chamber and fire reliably. If it does not fully seat, then your ammo may be too long! Sometimes the cartridge will fully seat with a light push, but pulling the round back out of the chamber requires some effort, and this means your bullet is jamming into the forcing cone or touching the rifling in the barrel. It could also be that the case wasn't properly resized and is too big, or an extremely tight 'match grade' barrel may not like oversized bullets.

You'll find many of the top competitive shooters are using ammo which is not loaded to an exact recipe according to one of the many load manuals out there. This is possible because they have A LOT of experience trying out different loads until they find one that is both safe to shoot, and ideal for performance in that particular gun. The end result is a load which may be under or over the recommended powder charges, and with a Cartridge Overall Length (C.O.A.L) which does not match what's listed in the manuals. 

Just like precision rifle shooters will often try to load the longest possible cartridge to squeeze every bit of accuracy out of their shots, pistol shooters can use a similar technique to find the ideal C.O.A.L for their ammo.

So, to get back to the plunk test, if your ammo is not fully chambering in your barrel, shorten your round in your seating die little by little until it successfully passes the plunk test. I personally load my ammo too long when first developing a load for a new gun, and shorten it until I find this state of equilibrium. 

Also, when you do finally pass the plunk test, it's always a good idea to shorten the C.O.A.L just a tiny bit more. Most presses do not seat to the exact same seating depth every single time, so give yourself a little bit of margin for error. 

Designing a projectile which can be used successfully in a rifle has been a huge challenge, and the bullets have been in the works for some time now. 

We've tested projectiles for several popular firearms and cartridges, from the AR-15 in .223/5.56 to the gamut of .30 caliber and .308/7.62x51 NATO rifles available. 

Not only do we need to prevent leading of the bore and excessive smoking, but the projectiles need to be accurate at range. They also need to have all these characteristics, while operating at the high pressures needed to cycle a semi-automatic action. Shooting a bolt-action rifle simplifies things considerably, you can load them as slow or as fast as you'd like, and pick whichever load gives the best accuracy.

Several pieces of information became apparent during testing:

1. The range of powders and charge weights that can be used with success is narrower than what can be used with jacketed bullets.
   
2. The bullets can be fired at very high speeds (3,000+ fps) without leading, but the coating begins to smoke A LOT when they are pushed this fast.
   
3. The top speed at which these projectiles yield the best accuracy is between 2,000 and 2,300 fps. This seems to be the "sweet spot."
   

Because of #3, we began offering heavy .30 caliber bullets in the 200-220gr range. If the speed is capped at 2,300fps, the heavier bullets offer more momentum during flight, and easily generate enough pressure in the chamber and bore to cycle the action on a semi-automatic gun when using standard load data for a jacketed bullet. 

The powders I've had the best luck with in this testing have been Varget and H4895, using data from an equivalent weight jacketed bullet, but sticking to the low end of charge weights. This range of powders appears to be in the burn-rate sweet spot, but of course finding a variety of powders to test with has been an ordeal for the last couple of years!

I'm no expert rifle shooter, but the best load (so far!) with our polymer coated bullets groups well enough that I feel 100% confident using it for short-mid range targets in a 3-gun match. I'm sure that once more shooters begin adopting these bullets and fine-tuning their pet loads, we'll see some incredibly accurate shooting! 

The load that shoots best out of my PTR-91 (a .308 / 7.62x51 NATO cartridge) is as follows:
Unsorted, once-fired LC 7.62x51 brass.
Brass trimmed to minimum SAAMI spec
Neck expanded using Lyman Neck Expander (M-Die)
CCI Large Rifle Primers
Varget: 38.0 gr.
EM 200gr. Polycoated Bullet, sized to .311" (http://www.egglestonmunitions.com/rifle.html)
C.O.A.L of 2.775" 

The load has gentle recoil compared to factory NATO ammo, gives 100% reliable feeding and ejection, and groups well. 

This might be a good starting point for other folks looking to start developing their own loads!