.300 Blackout load data

[PSLguy]

Looking for some references for load data for .300 subsonic loads.

Just picked up some Berry's 200 grain plated bullets and want to give it a try. In no rush as I still need to order dies. I have a Dillon 550B and Dillon dies are hard to find. May wind up going with Lee dies in my press.

In any event, powders I have available are 1680, H4198, H110 and Win296.

Brass I'll be using is commercially made stuff I bought that is cut and re-sized .223 brass.

Gun will be AR pistol (which I haven't built yet. LOL) with either 8-10 barrel.

[MongooseV8]

Id try the H4198 out of the listed powders. H110 is pretty dirty but works well. I didnt have any 1680 when I was dabbling in 300BO.

[brando]

Just remember that when working up a load for subsonics, you have to work backward: start high and work low. It's a little tricky because obviously you don't want to start too high to be problematic, but you also need to verify that the barrel will stabilze the bullets with these loads. So load a bit higher than expected, work your way down, and check for keyholes on paper. That last bit is CRUCIAL if you're running a suppressor.

According to Hodgdon, around 11gr of H4198 should be sufficient for 200gr subsonic loads. So start a bit higher and work down from there until you're in the 1050fps zone.

https://www.hodgdonreloading.com/data/rifle

[godofgamblers]

I don't have Berry's 200 grainers, but the most comparable that I have are some Palmetto Projectiles and Eggleston Munitions 200 grainers. Please note, while these work and cycle for me, they were highly inaccurate as well in my barrel. I did try some 220 gr plated subs from Everglades which actually worked much better. I assume the 200 gr Berrys would also work well in my setup (my barrel just isn't accurate for moly bullets). Barrel is 7.5" in length.

200 gr Eggleston Moly bullet, 10-10.4 gr H110, 2.06" OAL
203 gr Palmetto moly bullet, 10-10.5 gr H110, 1.96" OAL

I did not have a chrony to test for speed, so it could be possible that the high end of these were supersonic. If I went below 9.5 grains, I would have cycle problems. At maybe 9.8 grains the bolt would stop locking back . I should also note that my barrel has a rather enlarged gas port hole (0.125), which should aid in cycling subs without a suppresor.

[PSLguy]

I don't have Berry's 200 grainers, but the most comparable that I have are some Palmetto Projectiles and Eggleston Munitions 200 grainers. Please note, while these work and cycle for me, they were highly inaccurate as well in my barrel. I did try some 220 gr plated subs from Everglades which actually worked much better. I assume the 200 gr Berrys would also work well in my setup (my barrel just isn't accurate for moly bullets). Barrel is 7.5" in length.

200 gr Eggleston Moly bullet, 10-10.4 gr H110, 2.06" OAL
203 gr Palmetto moly bullet, 10-10.5 gr H110, 1.96" OAL

I did not have a chrony to test for speed, so it could be possible that the high end of these were supersonic. If I went below 9.5 grains, I would have cycle problems. At maybe 9.8 grains the bolt would stop locking back . I should also note that my barrel has a rather enlarged gas port hole (0.125), which should aid in cycling subs without a suppresor.

Thanks for the reply. I'm curious why I'm seeing such a difference in reloading COL. Lyman manual shows recommended 2.260 for 200+ grain projectiles. I've seen videos and posts where people use a 1.92 or similar length. I usually load to COL in my manual for each projectile, but of course can't find anything for this specific one.

Won't a lower COL raise pressures, or is that the point so that the action cycles reliably and you get bolt hold open? Or, is it so that the mag feeds off bullet and not the case rim to prevent jams? Just curious.

Also, I have plenty of SRP, but no magnum primers. Is this truly an issue?

[brando]

COAL can vary for a number of reasons. Yes, seating the bullet deeper will increase pressure, but also seating far out will cause the bullet to get jammed into the lands increasing pressure significantly.

Not all bullets use the same profile, so while the mass may be the same across 200gr bullets, the profile differences may allow for longer seating before touching the lands.

Also, magnum primers become handy with subsonic loads because they tend to more reliably ignite the powder when the case isn't filled near capacity. Most supersonic loads have a powder fill rate in the 90+% range, and it's generally dangerous to drop below 70% fill rate. That's why faster pistol powders that use bulky kernels (like Trailboss) are common for subsonic loads.

[godofgamblers]

Thanks for the reply. I'm curious why I'm seeing such a difference in reloading COL. Lyman manual shows recommended 2.260 for 200+ grain projectiles. I've seen videos and posts where people use a 1.92 or similar length. I usually load to COL in my manual for each projectile, but of course can't find anything for this specific one.

Won't a lower COL raise pressures, or is that the point so that the action cycles reliably and you get bolt hold open? Or, is it so that the mag feeds off bullet and not the case rim to prevent jams? Just curious.

Also, I have plenty of SRP, but no magnum primers. Is this truly an issue?

You know, it's been so long I'm not quite sure why I used those lengths. I believe the Palmetto ones I probably used that COL from the manufacturer recommendations. However, I can't seem to find Palmetto Projectiles anymore on the internet; perhaps they went out of business (go figure, I could never get their projectiles to be accurate). The Eggleston ones are a bit longer, I'm guessing I probably started off with something that would cycle manually and just stuck with that length to find the right amount of powder from there on. The Eggleston projectiles are not quite spitzer shaped so I was worried about cycling if at the wrong length.

[McGuiver]

.300 Blackout load data

I like CFE BLK which is really close to 1680 . It does heavy sub sonics nicely. I usually use 200 to 230 grain subs with CFE BLK. 1680 has been hard to find but it is on my list to try.


I have a family member who uses only H110 or W296 in his sub sonics for 300 AAC.

Sent from my iPhone using Tapatalk Pro

[sigstroker]

I don't have Berry's 200 grainers, but the most comparable that I have are some Palmetto Projectiles and Eggleston Munitions 200 grainers. Please note, while these work and cycle for me, they were highly inaccurate as well in my barrel. I did try some 220 gr plated subs from Everglades which actually worked much better. I assume the 200 gr Berrys would also work well in my setup (my barrel just isn't accurate for moly bullets). Barrel is 7.5" in length.

200 gr Eggleston Moly bullet, 10-10.4 gr H110, 2.06" OAL
203 gr Palmetto moly bullet, 10-10.5 gr H110, 1.96" OAL

I did not have a chrony to test for speed, so it could be possible that the high end of these were supersonic. If I went below 9.5 grains, I would have cycle problems. At maybe 9.8 grains the bolt would stop locking back . I should also note that my barrel has a rather enlarged gas port hole (0.125), which should aid in cycling subs without a suppresor.

Thanks for the reply. I'm curious why I'm seeing such a difference in reloading COL. Lyman manual shows recommended 2.260 for 200+ grain projectiles. I've seen videos and posts where people use a 1.92 or similar length. I usually load to COL in my manual for each projectile, but of course can't find anything for this specific one.

Won't a lower COL raise pressures, or is that the point so that the action cycles reliably and you get bolt hold open? Or, is it so that the mag feeds off bullet and not the case rim to prevent jams? Just curious.

Also, I have plenty of SRP, but no magnum primers. Is this truly an issue?

Gavintoobe on youtube has a video on the Berry's 220's with H110. He got more consistent results seating the bullets deep.

I also have a primer question. I have no small rifle magnums, but I have small pistol magnums for my .357 loads. Can I use those instead?

[ar15barrels]

Looking for some references for load data for .300 subsonic loads.

Just picked up some Berry's 200 grain plated bullets and want to give it a try. In no rush as I still need to order dies. I have a Dillon 550B and Dillon dies are hard to find. May wind up going with Lee dies in my press.

In any event, powders I have available are 1680, H4198, H110 and Win296.

Brass I'll be using is commercially made stuff I bought that is cut and re-sized .223 brass.

Gun will be AR pistol (which I haven't built yet. LOL) with either 8-10 barrel.

Get a 10" barrel to make it easier to keep the gun functioning.
After that, load around 12.5gr AA1680 or 11gr of H110 and you will be in the zone.
In your 10" barrel, I would look seriously at 8gr of blue dot or 6.3gr of Power Pistol or 7gr of Winchester 540 as well as those are going to get a complete burn.