Working up some new 300blk loads

Marauder · Aug 3, 2014

I have a new powder to try, Accurate 5744. I did some loading yesterday, 4 bullets to try. Can't wait to get to the range..

Minuteman · Aug 3, 2014

This should be interesting. I suspect the twist rate will be a significan factor as you take it over 100 yards. Did you resize the brass from 556, or start with 300Blk brass?

I hope you are able to do some impact testing too not just accuracy.

Marauder · Aug 3, 2014

Minuteman said:
This should be interesting. I suspect the twist rate will be a significan factor as you take it over 100 yards. Did you resize the brass from 556, or start with 300Blk brass?

I hope you are able to do some impact testing too not just accuracy.

My barrel twist rate is 1/7, I have mixture of reformed 5.56 brass along with factory 300BLK brass.
If I had my own private range I would do impact testing.

Minuteman · Aug 3, 2014

Marauder said:
My barrel twist rate is 1/7, I have mixture of reformed 5.56 brass along with factory 300BLK brass.
If I had my own private range I would do impact testing.

Cool. Barrel length and ranges?

If you are willing to drive I bet we could find some private property.

I'm discussing because I've been giving some serious consideration to a ~10" 300BLK pistol (see my thread on it). The round was designed around a barrel about half the length of the AR (20"). I'm most interested in velocity at various ranges. And terminal ballistics, especially out at range. The 5.56 really looses it at long range. So I'm thinking the 300 might be better at every range - from 0- it's max effective range.

Advantage for 5.56 is flatter trajectory, ammo price, options and availability. But if there are lots of other folks like you thinking about and working on the round, it's likely to get a lot better and more popular. Thx!

Marauder · Aug 3, 2014

Minuteman said:
Cool. Barrel length and ranges?

If you are willing to drive I bet we could find some private property.

I'm discussing because I've been giving some serious consideration to a ~10" 300BLK pistol (see my thread on it). The round was designed around a barrel about half the length of the AR (20"). I'm most interested in velocity at various ranges. And terminal ballistics, especially out at range. The 5.56 really looses it at long range. So I'm thinking the 300 might be better at every range - from 0- it's max effective range.

Advantage for 5.56 is flatter trajectory, ammo price, options and availability. But if there are lots of other folks like you thinking about and working on the round, it's likely to get a lot better and more popular. Thx!

The barrel is 16" all accuracy testing is at 100 yards supersonic loads. I have not worked up any subsonic loads as of yet.

My 110gr V-Max load@ 200 yards did not change much from 100 yard zero, it was still in a kill area for deer. So this load from 0to200 shoots flat from my gun.

Pinecone · Aug 3, 2014

Comparing 125 gr SMK in .300 BLK (2100 fps) to 77 gr SMK in 5.56 (2750 fps), you get the following.

Distance .330 BLK Vel Drop Energy 5.56 Vel Drop Energy

100 yards 1900 0 1083 2510 0 1080
200 yards 1700 7.2" 860 2280 3.0" 890
300 yards 1510 26.5" 684 2060 12.8" 725
400 yards 1330 61.2" 528 1854 30.7" 587
500 yards 1180 115.6" 417 1655 58.8" 468
600 yards 1075 195" 347 1472 99.7" 370

Working up some new 300blk loads

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