When shooting groups at long range on paper it can be difficult to distinguish which bullet holes belong to a particular sequence of shots. If, for example, you shot three 5-shot groups at 600+ yards on a paper target, you would have 15 bullet holes on the target (assuming no misses). But at that distance it would be difficult to see the holes on target (even with a spotting scope). Accordingly, when you inspected the target up close, it would be hard to tell which shots belonged to which group. You might have a vague idea, but couldn’t be sure, without a target camera recording the shot sequence.
Here is a method to separate multiple shots into specific groups so you can better evaluate your load and shooting skills. The trick is pretty simple — mark your bullets with a color from a Sharpie or other felt marking pen. If you are shooting three 5-shot groups, mark five with red, five with green, and five with blue (or purple). Then, when you inspect the target, you can identify the group placements by the colors that appear on the paper.
Round Robin: Using colors you can shoot “Round-Robin” to evaluate seating depths, neck tension, or other variables without having the shot order (and barrel heating) affect group sizes unequally. For example you might have three different neck tensions, each marked with a different color on the bullets. Then shoot Red, Blue, Green in that sequence for five total shots per color.
Smart Tip to Show Colors More Vividly
If the bullet inks are not showing up on your target paper clearly, here is a simple trick that can make the colors “bleed” to be more visible. In your range kit, bring some alcohol solution along with some Q-tips. Then dab the shots on the paper target lightly with wet Q-Tips. Here is the front of a target before and after application of alcohol:
Forum Member NewbieShooter explains: “Dabbing a bit of alcohol on the bullet holes with Q-Tips makes the color pop a bit… especially on the back side.” See below:
In short order you will see the colors spread into the paper, clearly marking the shot holes by distinguishing colors. If you were shooting a dark bullseye, view the the BACK side of the target to see the colors on a light background.
Credits: Bullet Tips photo by Forum Member Dave Way; Target photos by Forum Member NewbieShooter; Story tip from Boyd Allen.
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Probably the most popular centerfire rifle round in the Western Hemisphere is the .223 Remington and its metric match, the 5.56x45mm. Though many folks use “.223 Rem” and “5.56×45″ interchangeably, there are some meaningful differences in specifications for the original .223 Rem and the 5.56x45mm cartridge, as adopted by the U.S. military and NATO armies. The default chamber throats are slightly different and the .223 Rem is rated at 55,000 PSI vs. 62,366 PSI for the 5.56x45mm.*
.223 Rem vs 5.56x45mm — Key Differences
There is a truly outstanding, very thorough article on the subject, published by LuckyGunner.com.** This involved extensive testing, with pressure monitors, of 5.56x45mm ammo in .223 Rem chambers. Those tests revealed the peak pressures. Here is one of the ammo test charts:
NOTE: “The observed chamber pressure for Federal XM855 5.56mm ammunition in a .223 Rem chamber exceeded .223 maximum pressures, but not by a massive amount. The ninth shot (the red line) was an underpowered cartridge which exhibited significantly lower velocity and pressure than the other rounds, so it was excluded from the average velocity and pressure numbers for this chamber.”
And if you’re curious, LuckyGunner also fired .223 Rem ammo in a 5.56x45mm NATO-chambered AR15 rifle. As you would expect, the peak pressures were significantly lower, but the .223 Rem ammo still cycled the semi-auto AR-platform rifle perfectly well:
UltimateReloader.com Explains .223 Rem vs. 5.56x45mm
To explain the key differences between the .223 Rem and 5.56x45mm cartridges our friend Gavin Gear of UltimateReloader.com has created a very thorough 12-minute video. This covers the cartridge specifications and explains key considerations for hand-loaders. Gavin also addresses the oft-asked question “Can I shoot 5.56x45mm ammo in my .223 Rem chamber?” Gavin’s video is definitely worth watching. In fact, this is one of the most popular videos Gavin has ever created — it has been watched nearly 4.5 million times on YouTube.
What Exactly Is the 5.56x45mm NATO Cartridge?
The 5.56×45mm NATO is a rimless bottle-necked intermediate cartridge family standardized by NATO with development work by FN Herstal. It consists of the SS109, SS110, and SS111 cartridges. Under STANAG 4172, it is a standard cartridge for NATO forces as well as many non-NATO countries.
Bullet diameter: 5.70 mm (0.224 in)
Maximum pressure (EPVAT): 430.00 MPa (62,366 psi)
Maximum pressure (SCATP 5.56): 380.00 MPa (55,114 psi)
Case length: 44.70 mm (1.760 in)
Rifling twist: 178 mm or 229 mm (1 in 7 in)
Parent case: .223 Remington (M193)
Ammo-Maker Federal Premium Compares .223 Rem and 5.56x45mm
Here is a video from ammo-maker Federal Premium explaining the difference between .223 Remington and 5.56x45mm NATO. Federal states that you may experience excessive pressures when firing a 5.56x45mm in a standard .223 Remington chamber:
One leading gunwriter has addressed the question of shooting 5.56x45mm ammo in .223 Rem chambers. He advocates caution (for more info, SEE pressure tests by LuckyGunner.com):
“I have received a slew of questions — many from first time AR-type rifle buyers — about the .223 Rem and the 5.56×45 mm NATO cartridges. Can I shoot 5.56×45 mm NATO in my .223 and vice-versa? Are these the same cartridge?
Externally, the two cartridge cases are identical. The main differences are that 5.56×45 mm NATO operates at a higher chamber pressure (about 60,000 PSI versus 55,000 PSI on the .223 Rem.) and the 5.56’s chamber is slightly larger than that of the .223 Rem. Also, the throat or leade is longer in the 5.56×45 mm chamber. What does this mean? You should not shoot 5.56×45 mm NATO out of a rifle that is chambered in .223 Rem [with a standard short throat]. And be aware that some .223 Rem ammunition will not reliably cycle through some AR-style .223 Rem rifles, but it usually does. As a matter of fact, I have not encountered any difficulty with current .223 Rem. loads cycling through a 5.56 mm AR-style rifle.” — Mark Keefe, Editor, American Rifleman
* According to the official NATO proofing guidelines, the 5.56×45mm NATO case can handle up to 430.0 MPa (62,366 psi) piezo service pressure. The U.S. SAAMI lists Maximum Average Pressure (MAP) for the .223 Remington cartridge as 55,000 psi (379.2 MPa) piezo pressure with deviation of up to 58,000 psi (399.9 MPa). The chamber for military 5.56×45mm NATO has a longer throat prior to the bullet contacting the rifling which results in lower pressures when firing 5.56×45mm NATO ammunition. If 5.56×45mm NATO is used in rifles chambered for .223 Remington the bullet will be engraving the rifling when chambered. which can increase pressures past SAAMI Max levels. NOTE: The C.I.P. standards for the C.I.P. civilian .223 Remington chamber are much closer to the military 5.56×45mm NATO chamber.
** The full-length LuckyGunner article is well worth reading. It even provides specifications for a number of .223 Rem reamer types, and compares the original .223 Rem, the 5.56x45mm NATO, and the modern .223 Wylde chamberings.
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