Erratic Velocity

Aloysius · Posted: Fri Mar 23, 2018 1:39 am Post subject: Re: Erratic Velocity

When I was reloading for the .22 Hornet I noticed with rounds that had everything the same exept the primer, on 100 m the rounds with a magnum primer hit the target 1 to 1,5" (3-4 cm) LOWER than with normal primers. I have to admit that I don't own a Lee FCD for the .22 Hornet. And maybe because it's such a small case, the influence of the primer (and the difference in case volume due to bullet-travel before powder ignition) is more visible that with larger cases. But that early bulletstart due to the magnum primer was the only fair explanation I could find and sure: a firm crimp might have prevent it.

Pumpkinslinger · Posted: Fri Mar 23, 2018 2:47 am Post subject: Re: Erratic Velocity

From Hodgdon's web site:

"Because this propellant is tailored for specific applications, the number of cartridges and bullets is limited, but where it works, it really works!"

The .270 Win isn't on the list. The .280 Rem is and the heaviest bullet listed is 140 grains.

slimjim · Posted: Fri Mar 23, 2018 6:08 am Post subject: Re: Erratic Velocity

Pkslinger, you are correct. Its not listed for the .270 on Hodgdon's website but it is on Barnes. Other reloaders have reported success with up to 150gr bullets in the .270. I'm just cautiously giving it a try after being disappointed with Hodgdon's 7977 which is on Hodgdon's list.

slimjim · Posted: Fri Mar 30, 2018 5:46 pm Post subject: Re: Erratic Velocity

Pumpkinslinger wrote:

From Hodgdon's web site:

"Because this propellant is tailored for specific applications, the number of cartridges and bullets is limited, but where it works, it really works!"

The above has applied for my experience.

Got to shoot the 56.5 grains of Superformance with standard and magnum primers, 3 shots each. Velocity variation was greater with the standard primer which had the min and max velocities on the chart.

slimjim · Posted: Fri Mar 30, 2018 5:53 pm Post subject: Re: Erratic Velocity

Even though the velocity variation was not bad with the magnum primers (black lower triangle), the group size was not better than the standard primers (blue triangle above it). This target was at 200 yards. POA is the small orange dot 2" to the lower left of the center bull. This rifle has never shot a group this large before. Not sure any more precious metal will be sent down range with this powder.

The 1/2 moa group near the center was from my 6.8mm with 105gr MKZs which had the same muzzle velocity as the 145 ELD-X from the .270. Not bad for an AR-15 platform.

The extra hole next to the left side of the black triangle is a single shot from my .270 129 LRX load. I always shoot one or two at a range session to track this load's performance over time. The rifle is zero'd for 100 yards then I use a mil-dot reticle out to 600 yards. The impact was exactly where I expected it.

Elvis · Posted: Mon Apr 02, 2018 1:04 am Post subject: Re: Erratic Velocity

bugga...guess thats a non starter then Mate...worth a go .give remainder to someone with a dirty 06 they tell me its good with heavy projectiles...who knows.....

slimjim · Posted: Mon Apr 23, 2018 7:37 pm Post subject: Re: Erratic Velocity

Elvis, maybe I was premature. I got thinking that, with the magnum primers (black), that group wasn't too bad, at least it was a basic triangle. I had 6 new cases left in the batch of brass so why not try a COAL adjustment. Adjusting COAL (distance from the lands) can be a powerful lever for fine tuning a load. Since I was already at mag length with 3.370", I tried 3.345" and 3.320" just to see if there was any improvement. Attached is the resulting target showing the group size for the 3.345" compared to the prior groups. The 3.320" was larger like the blue (non-magnum primers) so I didn't include it.

The 3.345" COAL may have promise yet. I shot the 3 shots in 20 second interval and my barrel will heat-up and start to wonder after the 2nd round if I don't let it cool down. Velocities for the 3 shot were 2968 for a low and 3002 for the high. I'll work with it some more.

Elvis · Posted: Tue Apr 24, 2018 12:39 am Post subject: Re: Erratic Velocity

good stuff,find the sweet spot and throw away that chrony....lol.

slimjim · Posted: Tue Apr 24, 2018 7:33 pm Post subject: Re: Erratic Velocity

more to follow.

slimjim · Posted: Tue Jun 19, 2018 8:31 am Post subject: Re: Erratic Velocity

The next range session was was warmer, 88F. The grouping was not consistent with the prior session (back to 3 moa) so I'm done with this powder and bullet combination.