June 19th, 2021

Accuracy, Velocity, and Temp Stability — Can You Optimize ALL?

USAMU Reloading tips Handloading Hump Day

This USAMU article explores three different “Philosophies” of precision reloading. Some handloaders seek to produce ammo that yields the very tightest groups (without factoring in the wind). Other shooters load their ammo to deliver the highest safe velocity. That’s because a projectile launched at higher velocity will drift less in the wind. The theory is that even if fast ammo doesn’t produce the tightest groups in zero wind conditions, it will yield higher scores in a the real world (where the wind blows). Lastly, some handloaders favor ammo that is ultra-consistent across a wide temperature range. This last philosophy dictates selection of a powder that is temp-insensitive, even if it may not produce the very best raw accuracy (or speed).

USAMU Reloading tips Handloading Hump Day

What’s Your Handloading Philosophy?

Objectives of Reloading — Accuracy, Velocity, Temp Stability
What do you, the reader, primarily value in your handloads?

Viewpoint ONE: Accuracy Trumps Everything
Some shooters prize consistent, excellent medium/long range accuracy enough that they’re willing to give up some extra velocity (and reduced wind deflection) to obtain that. Their underlying philosophy could be stated: “Superior accuracy is present for every shot, but the wind isn’t”. One’s ability to hold well, aim well and read the wind are all factors in making this type decision. The photo below shows stellar raw accuracy. This is an 0.67″, 10-shot group at 300-yards fired from a text fixture. The group measures just 0.67″. (This shows the USAMU’s 600-yard load with 75gr bullets).

Viewpoint TWO: Load to Highest Safe Velocity for Less Wind Drift
Some shooters value obtaining the highest safe velocity, even if one’s pure, consistent mechanical accuracy at medium/long range isn’t quite as brilliant. The theory here seems to be that a really good hold extracts as much mechanical accuracy from the rifle/ammo as possible, and faster bullets equal occasional “bonus” points snatched from the jaws of wind.

[For example] one of the USAMU’s many Service Rifle National Champions revealed his philosophy. It can be stated thus: a super-accurate, but [relatively] “slow” load “required him to have a Ph.D. in wind reading for every shot, while a faster, but less accurate load netted him more points.”

Note — this was not mere speculation; his score book data backed up his claims, due to less wind effects. Remember, however, this fellow has a consistent, National Championship-level hold, and other Champions on the same team would have opted differently.

USAMU velocity chronograph testing

Viewpoint THREE: Temperature Stability Is Key
Still another approach is to place heavy emphasis on fine accuracy with absolute stability in changing temperatures. When this writer was actively earning his Distinguished Rifleman badge, that was his goal. The reason? Sighting shots are not allowed in EIC (“Leg”) matches. The first shot out of the barrel was for score. It had to be 100% consistent, with very reliable, predictable elevation and wind deflection regardless of the ambient temperature — even if it wasn’t the lowest wind deflection possible.

Naturally, selecting a powder that is insensitive to temperature changes is a key element here. Elevation zeros and wind effects HAD to be consistent every time. Hunters and military snipers might be among those who fall into this camp, as well as those in pursuit of their Distinguished Rifleman badges.

Contrast that with a traditional High Power shooter who gets two sighter shots before each event (offhand, sitting rapid, prone rapid, prone slow fire.) If there is a zero change on any given day, he/she can correct during sighters. This writer well remembers talking with another very high-level Service Rifle competitor who was happy to have high temperatures boost the velocities of his ammunition above their usual level… As far as this SR competitor was concerned, 60-80 fps more velocity -– even if only due to high ambient temperatures -– meant less wind deflection, and he was mighty happy to have it.

summer temperature chart USAMU loading tips

Particularly in the summer, with hot daily conditions, you need to be concerned about temperature stability. Loads worked up in winter may not work in the summer time.

This article has been confined to NRA High Power Rifle competition, which has relatively generous 10-ring dimensions in relation to the accuracy of well-built competition rifles. Hopefully, it will provide food for thought. For some, this might be an opportunity to ensure that one’s load development approach helps them attain their desired results.

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