Website Updates 8-17-2020

Good Monday Evening,

We are busy settling into the new home, with that comes quite a bit of unpacking and set up. This does not mean that I’ve been completely lax in keeping up on the website. I am working on some updates for the Powder Burn Rate Chart. This is in the response to a two different emails I received in regards to Midwest Powders. We want to maintain a complete listing of powders, so when gaps appear, I appreciate the help in pointing them out.

We are also working on putting together a new set of drawings for a single shot rifle. These will be free for download, along next to the AR-15 lower receiver prints. I have something of a hobby of taking hand drawn or published prints, modeling them in CAD checking for completeness, and then generating prints. I have been disappointed to find many of the prints published in books to be lacking in details, however so far this print has been quite good. Here’s the rendering of the receiver.

When I hit a roadblock sometimes I try and work through the design, but often times the prints are so vague or incomplete I feel uncomfortable continuing with the project. A notable example of this is The .50‑Caliber Rifle Construction Manual written by Bill Holmes. The trigger and bolt assembly is quite lacking in detail, and if someone has an example and would be willing to share some dimensions I’d be interested in getting more info. I think the design would be well adapted to utilize an AR lower style fire control group, as has been done more recently.

As always, credit goes to the original designer. My goal is not to take credit or diminish their work in any way, rather to make their work more accessible. Because of this I do not feel comfortable charging for the work I do, and I actively encourage others to used the published plans in companionship with the authored work.

Thanks again to everyone who sent me an email this week, I appreciate the feedback. For those who are interested in the MP 350, the website lists is as having a very similar burn rate to Accurate 1680, which is a St. Marks ball powder in common use and is pretty much the go to powder for 300 Blackout Subsonic loads. This powder would likely be a good choice for 300 Blackout if the burn rate is similar to A1680.

While they list the OEM equivalent as WC 842, there is some mixed information out there on what WC 842 is, some sources are claiming it is similar in burn rate to CFE 223 or H335. I do not have it listed on my burn rate chart as it was not a powder listed by St Marks when I assembled the chart. This means it was likely unavailable for purchase by an OEM manufacturer of ammunition, the likely reasoning is that it is out of production. I deem obsolesce likely as there are references to this powder being sold as a surplus powder 10+ years ago.

Based on the Information that Midwest Powders is presenting, DO NOT USE CFE 223 OR H335 LOAD DATA FOR WC 842!!!

There is quite a bit of difference in burn rates between A1680 (WC 680) and CFE 223(SMP 746) and H335 (WC 844). Just because the numbers are so close (WC 844 vs WC 842), doesn’t mean the burn rate is. Personally I think if a powder distributor is going to sell powder they should give a few example loads….the fact they are saying to use 10% below the MINIMUM load for WC 842 makes me wonder….then there’s the fact load data for WC 842 is not readily accessible…the more I dig into this the less comfortable I feel about it based on the information that’s being presented.

Accurate 1680 is an excellent powder in 300 Blackout as it produces a lot of gas for cycling a rifle. It also does it at a fairly low pressure, at around half of SAAMI MAP for 300 Blackout. The powder is slow enough, and a 220gr OTM bullet takes up so much case capacity, that you are very unlikely to blow up a gun using A1680 in 300 Blackout. If you try MP 350 in 300 Blackout subsonic load, and the gun cycles and the bullet velocity is roughly 1100fps, then you know A1680 is likely a correct approximation of burn speed. I can count on one hand the number of powders that does this and they all fall within a very narrow burn rate window. (By the way, H322 falls outside the window)

And if it doesn’t…then it’ll make fine but expensive fertilizer. With that said, A1680 is a fine powder used in a lot of magnum loads, and light rifle loads that are loaded to SAAMI MAP, and while my “smell test” might verify it’s suitability for use in 300 Blackout subsonic loads, it still might be different enough that you’ll want to take reasonable precautions when working with it in loads that develop pressures closer to the SAAMI MAP of a cartridge.

I really cannot say more on this except how this powder is being sold, without example load data, really bothers me. I get it, not everyone has a ballistics lab at their disposal, but at least give us what the pull down roads were. I.E. Cartridge, bullet weight, and mean powder recovery weight. 300 Blackout supersonic and subsonic loads are in military circulation, it’s not a lot when compared to 5.56x45mm but they are out there. I am working on trying to get a bit more information on both MP 350 and WC 842, so there may be some updates to the story, but for now that’s what I’ve got.

I think I’ve beaten the dead horse on this. To the guys who asked me about it a few days ago, I’ve had a few more days to think on it. It’s one of those things that gnawed at me. I’ve done some more research, and this is what I have so far. I’ll continue to work on this.

Thanks again to everyone who has subscribe. If you have comments, complaints or suggestions email them to jayandrew338@gmail.com. You can also check us out on Facebook or drop us a like over at Instagram.

Stay Safe Out There!

The Ballistic Assistant