Thread: 284 win slow speeds

Hi team, I have read a few previous articles on this page about this topic but through I may as well get a few more ideas. I have recently had a remington 700 LA re-barreled and reamed into 284 win, along with an extended throat to fit bigger projectiles seated out. The barrel has been cut to 19 inches.

Anyway I had 3 powders on hand so I loaded up a 3 shots of each with 1 grain increments started at the lowest book recommendation to get a idea of the speeds each powder will give. The results are as follows:

H4350
50gr - 2554
51gr - 2609 - pressure signs
52gr - 2661 - high pressure signs

RL 23
53gr - 2583 - low pressure signs
54gr - 2619 - mid pressure signs
55gr - 2677 - high pressure signs

2213sc
55gr
56gr
57gr - 2607 - no pressure signs
58gr - 2544 - no pressure signs

I am using new norma brass, fed 210 match primers, norma bond-strike 165gr

The results seem slower than what is illustrated and what I have read from similar builds and online data. Does anyone have some ideas of where to go from here to get better speeds and lower pressures? I have done a bit of reading of similar issues where neck turning the brass has solved the issue but I suspect it is more of an issue with necked up 6.5-284 brass.

Brass neck dimension with seated bullet - 0.314
Brass neck dimension after firing - 0-317

Also to note on the fired brass the carbon/black that covers the neck after a firing does not come all the way down the neck as per photo. At this stage my thoughts are that above the neck shoulder junction on the brass the diameter is getting wider which is back up with a set of calipers although the measurements are not 100% accurate.

Any suggestions or ideas would be much appreciated. Cheers