302 Whisper

[Rikky Lee]

Results with the faster pistol powder are showing promise. With no load data for H4227 I decided to load three loads; 13, 14, 15 grains to get a velocity trend pattern.

Starting with 13 grains produced an av velocity of 1145. 14 grains produced 87 fps more at 1232 fps. 15 grains was not tested.

The five shot group using 13 grains produced a 2 inch group which showed good promise.

Next loads will be 11.8, 12, and 12.2 grains I think.

Getting closer!

[HotGuns]

If you think that your powder is not burning at the same rate, try backing off the powder a bit and using a magnum primer.

I have done this over the years with various loads and it seems to work.

In your case, it may work or it may not. It certainley couldn't hurt to try it.

[Rikky Lee]

Latest test results:

11.8: 906 fps

12: 918 fps

12.2: 1024 fps

I'm thinking its time to try 10 of 12.5 grains and play from there.

It is also quite obvious from the group's shape that the smaller amounts of powder have the most vertical structure and there is a tipping point in the load where things start tightening up.

[Rikky Lee]

Failure, big and total and unmitigated failure at 12.5 grains. Worst results for while.

12.8? I have had about enough of this though - can see exactly why the 30Br hasn't been taken and run with at the subsonic level.

I will do a bit more experimenting and then rechamber to a 300 Whisper proper.

[HUNTER2]

You have probably thought of about everything, but- Have you tried crimping, and- Would the small amount of extra room be enough for trail boss? And - Who made your barrel?

[Rikky Lee]

Thought of Trail Boss but I do not want to buy a canister that size.

Done the crimping.

Barrel is a local one that shoots 1/4 MOA with 155s.

Feel the frustration?

[Hoser]

Have you tried 220s?

[Rikky Lee]

I have tried:

180s various.

200 Lapua.

220s various.

240s and 250s SMKs.

With the 30BR, supersonic loads for all these weights work very well. It is when you try to get to 1050fps that vertical groups emerge....

One more thing to try and that will be another, faster powder but it does show that the 30BR is not the ideal case for this type of subsonic activity. Part of me would like to try a 30 PPC but rhe reality probably is that a 300 Whisper style would work easily without this level of fuss and bother.

[Rikky Lee]

Success - a move to a faster powder - a straight pistol powder from my 9mm has resulted in a three shot group of just under an inch. Two shots through the same hole.

No velocity yet...

The bulk volume of the powder at 11 grains is significantly more than the bulk volume of 12 grains of the previous powder used.

[Rikky Lee]

OK then. After a break due to sickness and the birth of a child I did some more work to get this thing running properly.

11 grains - pistol powder:

a. 1180

b. 1228

c. 1187

d. 1218

Average: 1203 fps. SD: 23 fps.

Drop to 10.5 grains for velocity and group testing as the next step...