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November 9th, 2024

How Travel Humidity Changes Can Affect Ammo Performance

powder bullet velocity humidity test bryan litz applied ballistics

This article comes from the Bryan Litz Ballistics Facebook page. That page offers valuable tips on ballistics, marksmanship, and precision reloading, with updates nearly every day of the year. One recent post relates to velocity changes that can occur when traveling away from home.

Q: Is there a physical reason, other than temperature, why sometimes we see a difference in muzzle velocity when we travel to a different location?

Bryan Litz notes: “One reason we found for this is powder humidity. We put out a video on our YouTube channel called “Powder Humidity / Temperature and Storage”. Watch the video below to learn more specifics about the effects of humidity and temperature changes on your loaded ammunition.

Basically, if you develop a load at home, then travel to a dramatically different environment (drier or wetter), and your ammo isn’t hermetically sealed, it can affect the powder burn rate. This can cause muzzle velocity to change.

Humidity Field Tests with 6.5 Creedmoor and H4350

To learn more about the effects of humidity on velocity and ammo performance, we recommend another article found on the ChronoPlotter.com website. This article begins by reviewing research done by Applied Ballistics, Norma, and Vihtavuori.

Then author Michael Coppola covers his extensive experiments with Hodgdon H4350 powder stored with different relative humidity (RH) levels then loaded in 6.5 Creedmoor rounds. The results were quite dramatic: “At its lowest humidity (14.5% RH), our 41.50 gr H4350 charge clocked in at an average 2,879 fps, peaking at 2,901 fps. Its highest humidity (83.5% RH) saw an average of 2,650 fps with a lowest velocity of 2,635 fps. The entire experiment saw an Extreme Spread of 266 fps. Between the desiccated and 66.5% samples, a 10% change in RH resulted in a velocity change of about 25.6 fps. Above 66.5%, this effect nearly doubled and a 10% change in RH resulted in a change of about 57 fps.


ChronoPlotter: How Does Humidity Affect Powder »

powder bullet velocity humidity test 6.5 creedmoor h4350 chronoplotter coppola

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December 1st, 2015

TEN TIPS for Winter Firearms Storage

winter gun storage tips

It’s December already. That means winter has definitely arrived — no doubt about it. If you plan to put away all or some of your firearms for the winter, here are TEN Tips for winterizing your firearms.

Barrel Crown1. Bore Cleaning and Coating — Clean your barrels and neutralize any solvents you may have used. Then run a couple patches with a corrosion-fighter down the bore. We recommend Eezox or CorrosionX. Eezox leaves a glossy dry film shield with excellent rust resistance. CorrosionX is more like a conventional oil, but with special anti-rust additives. Other products may work well too. Just be wary of the “all in one” products that have a strong solvent, and don’t use any fluid that contains ammonia — this can actually promote corrosion. Here’s a test of various anti-corrosion products: Rust Block Comparison Test.

2. Crown Inspections — After cleaning the barrel, inspect the crown with a magnifying glass. If you see any unusual wear, abrasion, or “shark’s teeth” at the very outer edge of the rifling, make a note — it may be wise to recrown the barrel next spring. Before you place your rifle in the safe, we recommend putting a piece of electrical tape or blue masking tape loosely over the muzzle to protect the crown. This is just to protect the delicate crown during handling — you are NOT trying to seal off the bore.

Bore-Store Gun Sacks3. Optics Storage — If your gunsafe is crowded, you may wish to remove the optics and rings from your rifles before winter storage. You can use a white crayon to mark the ring position (on the rail) for next season. We recommend that you store your optics inside a warm part of your house, where temperatures and humidity are relatively stable.

4. Trigger Group — Inspect your trigger assembly. Trigger housings accumulate dirt, grit, and oily gunk over the course of a season. If you have some basic mechanical skills, you may wish to remove the trigger from the hanger and clean it per the manufacturer’s recommendations. Don’t flood it with any kind of thick oil.

5. Bolt and Action — Clean the gunk off your bolt and raceway in your receiver. Put a thin coat of anti-corrosion product on the bolt, and re-grease the lugs and camming surfaces as recommended by the manufacturer. Don’t forget the fasteners and pins on the action and scope rail — these may not be stainless even if you have a stainless steel receiver.

Bore-Store Gun Sacks6. Use Thin Gloves — When oiling firearms during the winterization process, we recommend you wear thin latex or nitrile gloves. This will prevent you from leaving skin oils and acids that can actually promote corrosion. This will also protect YOU from any chemicals in the corrosion-blockers you put on your guns.

7. Applying Surface Protectants — For blued firearms, put Eesox or other rust-fighter on a cloth and wipe the barrel and exposed metal. Eezox works best with a couple light coats. Don’t forget iron sights, bottom metal, trigger guards, bolt handles, and sling swivels — they can rust too if not protected. Use Q-Tips or small swabs to reach small, internal parts.

Bore-Store Gun Sacks8. Use Gun Sacks — We put rifles and pistols in Bore-Store Gun sleeves. These thick, synthetic-fleece sacks cushion your guns, preventing nicks and scratches. The breathable fabric wicks away moisture, and the fibers are coated with corrosion inhibitors to help fight rust. Bore-Stores are offered in a wide range of sizes, so you can find something to fit everything from a Snub-nosed revolver to a 32″-barrelled 50 BMG. Rifle-size Bore Stores can be purchased for $9.00 – $22.00 from Brownells.com or Amazon.com. While we prefer Bore-Stores for regularly-used guns, if you have heirloom firearms that will be kept in storage for very long periods without seeing any use, you may want to grease them up and place them in the thin, but rugged three-layer storage bags sold by Brownells. Here’s one VITAL bit of advice for using these bags. Be absolutely sure, before you seal up the bags, that your guns are DRY and that all metal surfaces have been coated with an effective rust-blocker, such as BoeShield T9 or Eezox.

Foam-lined hard case9. Take Your Guns OUT of Foam-lined Cases — These common foam-lined cases are Rust Magnets. This may be the most important Tip in this article. Just about the worst thing you can do in the winter (short of leaving your rifle outside in the rain) is to store firearms in tight, foam-padded cases. The foam in these cases actually collects and retains moisture from the air, acting as the perfect breeding ground for rust. Remember, those plastic-shelled cases with foam interiors are for transport, not for long-term storage.

10. Make Your Gun Safe Ready for Winter — If you don’t have a Goldenrod (or equivalent), buy one. Sold as a “dehumidifier”, the Goldenrod is a simple electrical element that can maintain temperature in your gun vault. This helps prevent moisture in the air from condensing on your guns. A small incandescent light-bulb can help as well (just make sure it cannot touch any flammable fabrics or objects). In addition, you may want to purchase Dessicant packs to put inside the safe to absorb moisture. If you have an electronic keypad for your safe, we recommend replacing the batteries at least once a year.

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