Blackhorn 209 Velocity drop with Powder Increase

[tjvance]

I recently purchased my first container of Blackhorn 209 after shooting Triple 7 for years. I also just got into reloading and measuring powder by weight about a year ago. I'm hoping some of you who know more than I do on this can help with some things.

According to the CVA manual, the max charge for my Accura is 110gr by volume or 77gr by weight. It's been my experience that BH209 (at least my jug) weighs more than I see published. 110gr by volume is roughly 87gr by weight. I didn't compact the powder at all. I used two different volumetric measures and two different powder scales just to make sure it wasn't something I was doing.

When trying to find a load for my gun I tried 63gr, 70gr, and 77gr by weight. Average velocity was 63gr/1763.5, 70gr/1852.2, and 77gr/1760.1. This was a 285gr Powerbelt ELR. I shot four rounds of each and swabbed the barrel between loads. What do you think would make a velocity drop like that with more powder? Insufficient powder burn maybe? I'm using standard Winchester 209 shotgun primers. CCI or Federal are recommended but I can't find any.

 

[SloppyJ]

Something's not right with that. Are you using the correct breech plug for the 209? My MRX came with a different plug for it. I'm also using 209 magnum CCIs and have had no issues.

 

[tjvance]

Something's not right with that. Are you using the correct breech plug for the 209? My MRX came with a different plug for it. I'm also using 209 magnum CCIs and have had no issues.

I do have the 209 breech plug that CVA makes for blackhorn 209. I know they have a couple different ones. My gun came with this one.

 

[ElDiablito]

The newer lots of Bh209 weigh more per unit of volume than the early lots. This has been well established scores of times on various forums.

As for why the velocity dropped on your 77 grW load, who knows. Velocity should go up fairly linearly. Never heard of anyone experiencing that. What were the velocities in that group that averaged 1760 fps? Was there one really low velocity that skewed the average? I wouldn’t worry about that too much - I’d shoot whatever charge gives you the smallest groups.

No need to swab (or clean) between shots with Bh209.

110 grV is max according to your manual? Interesting. I thought it was 120 grV in all current production rifles. Does your manual specifically mention Bh209? When I look up the digital version of the Accura manual it says 150 grV max for all subs.

 

[tjvance]

The newer lots of Bh209 weigh more per unit of volume than the early lots. This has been well established scores of times on various forums.

As for why the velocity dropped on your 77 grW load, who knows. Velocity should go up fairly linearly. Never heard of anyone experiencing that. What were the velocities in that group that averaged 1760 fps? Was there one really low velocity that skewed the average? I wouldn’t worry about that too much - I’d shoot whatever charge gives you the smallest groups.

No need to swab (or clean) between shots with Bh209.

110 grV is max according to your manual? Interesting. I thought it was 120 grV in all current production rifles. Does your manual specifically mention Bh209? When I look up the digital version of the Accura manual it says 150 grV max for all subs.

Good to know, I was wondering if something had changed with BH209.

I didn't have an outlier shot. The lowest was 1748.8, the highest was 1773.5.

I should have mentioned this before but I'm shooting a 45 caliber. The manual says 150gr of pelletized powder or 120gr vol of BH209 for 50 cal. 110gr vol or 77gr weight of BH209 for 45 cal.

It actually says BH209 is the only recommended propellant for 45 cal. I've been shooting Triple 7 for a long time and if I don't get this load figured out I will be again soon. I have a mule deer tag for the Pecos this year.

 

[tjvance]

I went to the range again this morning and it was consistent. I did change bullets to a Barnes Expander MZ 195gr.

1827.9fps avg at 77gr
1915.2fps avg at 70gr

At 70gr it was shooting a nice group so I guess that is going to be where I stay. I don't know much about these bullets. I've had good luck with Barnes in my rifle so I trust them.

 

[SloppyJ]

I went to the range again this morning and it was consistent. I did change bullets to a Barnes Expander MZ 195gr.

1827.9fps avg at 77gr
1915.2fps avg at 70gr

At 70gr it was shooting a nice group so I guess that is going to be where I stay. I don't know much about these bullets. I've had good luck with Barnes in my rifle so I trust them.

Those bullets are a great choice. One of my favorite. My gun loves the 290gr Bore drivers but I do not like their terminal performance. The worst I've experienced are the powerbelts. I've had good luck with the barnes bullets or the PT gold scorpions.

If you can find a good charge for the barnes expanders, shoot with confidence.