***This thread will have reloading nerd talk***

What is Puff-Lon

It's a case filler that helps eliminate powder shift and other problems in reduced loads. This comes in especially handy for subsonic loadings for 300 Blackout.

I would venture to say the use of Puff-Lon is safe but for it to be most effective it's a medium to advanced reloading technique that can have really good benefits.


My Tests

I have been experimenting a bit with some cast bullets that have Hi Tek coating on them. My bullets are 217 grain non jacketed bullets. That said cast bullets or jacketed bullets Puff-Lon could provide a lot of benefits.

Cast bullets when put up against similar grain jacketed bullets will give you quite a bit more velocity with everything else remaining constant. 100 to 200 fps increase in velocity is to be expected, and quite possibly much more than that. In one test I reduced a published load data by one full grain (using cast bullets) and STILL got 200fps over the published data of it's jacketed counterpart.

For my test I chose to use Hogdon H110, precisely because it's a much more difficult powder to work with for subsonic use. I wanted to prove that it's either going to work or it will fail miserably. It's the go to supersonic powder, but I chose that one for my tests because it's hard, not easy to work with for my purpose.

My preliminary testing showed 7.9 to 8.2 grains of H110 with my bullet should produce 'about' what I was looking for. Starting at that baseline I noticed serious powder shift issues. My velocity spreads were wildly off by hundreds of fps.

Conversions

I figured out (using Lee's published powder volume tables) about how much case fill I would have. After the bullet was seated my rough estimations were that I had about one cubic cm of space to play with inside the case. With a 7.9 grain charge of H110 I have about 50% or 51% case fill. Such a low percentage allows the powder to shift all over and hence the wildly different velocities shot to shot.

So yes you will need to measure by weight (grains) but you also need to know the volume in cubic centimeters as well.

I tried just putting 'a little' puff-lon into the cases (no measurement). I also tried putting as much as reasonably possible in the case. The best results though came from calculating out my volumes and using a measured amount of puff lon. Using a .3cc Lee scoop and a .5cc Lee scoop I did some testing. The .3cc would leave me slightly under full, and the .5cc would leave me slightly over full based on my 1cc net case volume estimation.

The Standard

All of my bullets were seated exactly to the same length.
The same exact crimp was applied
All of my charges were EXACTLY 7.9grains.
Brass was mixed, once fired.

With the .3cc of Puff Lon my velocity was still way high for my target. The highest velocity was 1141 fps and the lowest was 1087. There were clear signs of powder shift and maybe pressure spikes although nothing dangerous at all. The gun functioned well but there was no bolt hold open. So far in all my tests I have not touched my gas block adjustments at all, but it's another option here.

With the .5cc addition of Puff Lon my average velocity was 1074fps with about a 30fps deviation. That 30fps could be from my not having a perfect chrono setup or the differences in brass. I had full function and bolt hold open on the last round all with my gas settings unchanged.

Other Benefits

Puff Lon seems to open the door to a much wider array of powders that can be used.

It also opens the door wide open for using a much wider array of bullets (hence a lot cheaper round). At this point I would be comfortable stating that I could make very light subsonic loads that will also fully run and cycle an AR platform. For plinking this is a big deal when it comes to cost. This alone could allow subsonic shooting for 1/3 the cost (or less) and it would still run the gun just fine.

Suppression Levels

I have long held that ammo can make or break the 'sound suppression levels'. I've shot some Remington 220 grain and that stuff is subsonic but it's BARELY tolerable. On the flip side I've shot some Hornady 208 grain factory ammo and that was substantially quieter out of the same gun and suppressor on the same day with everything else being equal.

In that vein, my loads easily challenged the quiet level of the Hornady ammo and I am not even close to done testing powders. There are several powders out there that are 'quiet' one of which I have, and the other I haven't gotten any yet. By the use of certain pistol powders you can achieve all the right velocities, have very good consistency, and your sound reduction will definitely be noticeable.

Once I get all worked up and ready I would be interested in sending some ammo off to someone with a meter so that I can prove the concept. I would say using that Remington 220 ammo (super loud) but still subsonic as a baseline, that you could easily shave 4 to 6 DB (and possibly more) off of the sound signature both at the ear and muzzle.

As a note, H110 is not on the quiet list of powders (that I know of) but my combination easily was quieter than at least 3 or 4 commercially available subsonic loads. I don't know exactly how many DB or whatever, but I could easily tell a difference.

Some Accurate Powder and some Vihtavuori powders are supposedly really quiet with reduced loads so I will test soon. I have some of the Accurate powder but not the other. Supposedly the VV powder is the quietest and cleanest. I will report back later and let you know if you're interested.

As far as I am concerned the concept is proven. Using slower burning pistol powders in reduced load(s) and adding Puff Lon for consistency in velocity and pressure should provide interesting results. That's not a bad deal at all, especially since we are not talking about some single shot bolt action but a fully functioning semi auto AR platform.

Maybe I am just a nerd but this is pretty exciting stuff.

On another note, the manufacturer claims that Puff Lon can help reduce FRP in many suppressors. I definitely think this is possible. Very much so.

Conclusion

The odds of me buying more Puff Lon at this point is right about the 99.8%. I am going to test other powders and put together other loads of varying grain weight bullets and see what happens. At this point I will probably try 180 grain and 190 grain jacketed bullets and see what happens. After that I might try some more stuff just for kicks. In the end though, if you are calculating enough and patient enough to try it, Puff Lon could be a pretty good ticket for certain applications.