Maritime Environment project

[1168]

Update:
Those inconel springs have been sitting in saltwater for 11 days without a hint of corrosion that I can detect. Color me impressed. The other springs are more or less destroyed.

However, I’ve gotten a refresher lesson at keeping corrosion at bay on the rest of a rifle. I do most of my outdoor shooting in the rain (except for matches), to avoid Bubba and Cletus at my unsupervised public range. Its crowded with unsafe idiots in nice weather, but in an all-day downpour, I get it all to myself. And here in the Lowcountry, we’ve been having something resembling a monsoon for a week or two. So I’ve been shooting outdoors almost every day that I have off(24-48 on/24-48 off), and my rifle has been wet near continuously. Plus I cleaned it with a hose one day, and its been submerged a few times. Some thoughts:

All ferrous metal, regardless of treatment/coating needs either paint, or a light coat of oil.

Nickel Boron coated parts, such as in a trigger, are not impervious to rust with long term exposure to water, and oil wash-away.

Nitride, such as on a barrel and gas block, is also not invincible.

Stainless parts can get rust.

A Sprinco Blue will rust.

A gun full of sand and water (freshly submerged) is likely to experience stoppages unless horrendously overgassed.

Some parts that you may not have considered that will rust: roll/coil pins, ejection port cover detent, sling hardware, QD ball bearings, QD cups on URX4, MLOK fasteners, selector levers, crush washer (or maybe it was the barrel shoulder), front sight post and detent, mag catch.

Conclusion:
Even on a build where you choose parts for real or perceived corrosion resistance, you must stay on top of preventative maintenance when subjected to Neptunian abuse.

[1168]

I bought two sets of these Neverwear inconel spring kits. They were not expensive. I also bought an LPK from a vendor well respected on this site, we’ll call them Brand X. They claim the springs come from a source that also supplies USG. I chose them as a control, a known quantity, since I have assembled several guns with their LPKs. I set aside the trigger and detents. And I bought a set of PSA lower springs, the cheapest ones they have. They came from in-store assemble-your-own-cheapwad-gun unlabeled parts bins, and cost like $3.

I put one set of inconel springs in a rifle, and ~1,000 rounds in, it still works. No surprises there.

I prepped the remaining springs by degreasing them with 91% rubbing alcohol. I dipped them in seawater and placed them on top of seawater-soaked gauze in three identical individual tupperwares at 13:48 yesterday. One each for springs from PSA, Brand X, and Neverwear. By 15:11, the gauze in the PSA and Brand X was staining orange. At 0812 this morning, I added more seawater to each container until the springs were sitting in about 1mm of water. By 1700, the PSA and Brand X springs had enough rust to make the wire visibly thicker. Inconel springs were still bright and showed no signs of corrosion. I will update when they eventually corrode, or if the unmolested set wears out.

TL;DR: Neverwear inconel springs appear to be much more corrosion resistant than the other two brands in this very limited experiment.

About a week ago, I roughed up the inconel springs with a grinding stone, in case they have some magic coating. Added more salt and a few drops of vinegar. Put them back in the saltwater. Nothing. Nada. Not a speck of orange.

[Rogue556]

Thanks for the update on these 1168. That is certainly impressive as far as corrosion resistance is concerned. I am going to order one of these spring sets and test them in one of my builds.

I wonder if the difference in material affects spring rates, and if so, to what extent. (Perhaps someone with that knowledge can chime in).

For the price, the spring set sounds like a winner for anyone in humid areas or those building a rifle from stripped receivers, so long as they hold up over time.

Sent from my SM-N910P using Tapatalk

[Diamondback]

Too bad we can't get 'em to do a complete Inconel LPK...

[tehpwnag3]

Thanks for the info 1168. It's experimentation like this that makes this forum great.

[Diamondback]

Just to spitball another idea, anybody do a corrosion test on V Seven's titanium parts? I know Ti can be picky--the Skunk Works used to actually cut sheetmetal when they were building the Blackbirds by drawing lines with ballpoint pens and watching the ink eat through the metal, and they even had to install a distilled-water facility at the factory because city water supply was doing weird things to it.

[556BlackRifle]

Just to spitball another idea, anybody do a corrosion test on V Seven's titanium parts? I know Ti can be picky--the Skunk Works used to actually cut sheetmetal when they were building the Blackbirds by drawing lines with ballpoint pens and watching the ink eat through the metal, and they even had to install a distilled-water facility at the factory because city water supply was doing weird things to it.

Titanium is tough. You might find the info in the below document interesting.

https://www.nrc.gov/docs/ML9932/ML993210187.pdf

[1168]

Thanks for the info 1168. It's experimentation like this that makes this forum great.

Y’all are welcome.

Thanks for the update on these 1168. That is certainly impressive as far as corrosion resistance is concerned. I am going to order one of these spring sets and test them in one of my builds.

I wonder if the difference in material affects spring rates, and if so, to what extent. (Perhaps someone with that knowledge can chime in).

For the price, the spring set sounds like a winner for anyone in humid areas or those building a rifle from stripped receivers, so long as they hold up over time.

Sent from my SM-N910P using Tapatalk

On spring rates and materials, what I was able to learn on the internet is that in initial strength there’s not as much difference in material choice as we’ve been led to believe. And a correctly designed spring can reduce that difference further by using different thickness and number of coils and such. Obviously, this might not work out in some applications due to coil bind or some other stuff I haven’t thought of. And of course, some materials can maintain their strength over more cycles. In any case, LPK springs don’t appear to have the same types of stresses as an action spring or extractor spring, to my eyes. It looks like a fairly low demand task, with fewer cycles over the life of the weapon. “Hold this thing here, and make it go click”.

I found a comparison of materials here:
https://www.engineersedge.com/spring_general.htm
Here:
http://www.tribology-abc.com/calcula..._materials.pdf
This one also discusses corrosion resistance with a little more depth, and mentions cadmium is better than zinc for saltwater resistant coatings:
https://www.theengineer.co.uk/spring...ial-selection/
And here’s this:
http://optimumspring.com/technical_r...materials.aspx
And this:
https://www.acxesspring.com/properti...ing-wires.html

I don’t know how to interpret all of the numbers in the links above, but by comparing them, and reading the commentary, it appears that Inconel 600 is a good material for small springs and combines good strength and lifespan with corrosion resistance. The lower I have these installed in has fired about 2,750 rounds so far, without issue. I’m starting to think that the main reason these are not used more frequently is the small difference in cost.

Edit for clarity: I am not using the trigger springs that came in the Inconel spring kit. I am using the springs that came with the trigger.

Too bad we can't get 'em to do a complete Inconel LPK...

There are LPKs that use stainless for detents, takedown pins, and other parts. As far as I can tell most of them use CS springs. Some of them come from brands that seem a little Chinesey, or don’t have a strong rep. I think BCM sells a stainless LPK, though. I just ordered a couple SOLGW LPKs, and the takedown pins are stainless.

[Sry0fcr]

Since you guys are actually taking this seriously, I'll try not to be a snarky dickhead. Based on my experience with manufacturing equipment for the subsea O&G industry a coating of some type and regular maintenance + freshwater rinsing is probably part of the solution. I chatted up one of my engineer pals and he recommended the same. Of course you can substitute more resistant materials but then you run into the problem of possibly having to re-engineer components where the material was chosen for specific mechanical properties (springs, extractors). At the end of the day, you're mostly just buying time, but the best we came up with for someone that doesn't have and R&D budget is to have nearly everything coated with a corrosion resistant finish prior to assembly and regular cleaning and lubrication. We used alot of Xylan in conjuction with cathodic protection for wellheads and such that were going subsea for 10-20 years.

[1168]

Since you guys are actually taking this seriously, I'll try not to be a snarky dickhead. Based on my experience with manufacturing equipment for the subsea O&G industry a coating of some type and regular maintenance + freshwater rinsing is probably part of the solution. I chatted up one of my engineer pals and he recommended the same. Of course you can substitute more resistant materials but then you run into the problem of possibly having to re-engineer components where the material was chosen for specific mechanical properties (springs, extractors). At the end of the day, you're mostly just buying time, but the best we came up with for someone that doesn't have and R&D budget is to have nearly everything coated with a corrosion resistant finish prior to assembly and regular cleaning and lubrication. We used alot of Xylan in conjuction with cathodic protection for wellheads and such that were going subsea for 10-20 years.

You’re not wrong.

However, even with freshwater rinsing, and choosing coated parts, I still run into some corrosion sometimes. Like you said, its about buying time. I’ve found that choosing parts with more resistant materials and coatings help. I Would not choose a part solely for corrosion resistance at the cost of second and third order effects, such as sharply reduced lifespan. But I am willing to pay extra for my “builds” to get stuff that is long lasting, reliable, AND corrosion resistant. Some parts are difficult to maintain, such as LPK springs.

I terminated the trying to get inconel springs to rust experiment. I was unable to make them corrode despite my best efforts, much to my surprise.

Corrosion prevention is one of my reasons for painting my rifles.