H4895 and 150 SST's

[TackDriv3r]

A few weeks ago, I tested a few 3 round groups for hunting for the 308 using H4895 and 150 SST Interlocks. Worked up from 44 grains to 45.6 and did not use a chrono at that time, and checked for pressure signs and there was none. The best charge was 45.2 grains which shot a ragged hole @100 . The other day I made 15 rounds of 45.2 grains H4895 to test and sight in for deer season and took the chrono this time, and unfortunately it did not shoot like it used to, and it was very humid, some groups were .75- .9 MOA instead of the .2 MOA I done previously a few weeks ago. After firing several rounds thru the chrono, and ES spread was 6 and velocity average was a whopping 2980 fps out of the 26 inch barrel. That is close to 30-06 speeds. Hodgdon data shows 45.5 grains as max with a 150 Ballistic Tip @ 2800 ish. Before I have fired the rounds today, I have shot about 80 rounds of 155 Palmas with RL-15 ( 3 trips to the range ) and shoots an inch or less @ 300 yards and gave it a good cleaning before I used the SST's.

Would humidity have any effect on patterns compared to a sunny day?

I am working on another set of 3 round groups but with a CCI 200 primer ( saving the Fed210M ) this time. Hopefully I see some change from the last patterns.

 

[STOMP442]

What chrono are you using? If you are using a magneto, did you fire your groups with it attached? H4895 and 150 class bullets is a thing of beauty. I have a 26" heavy barrel savage that I am running 46.0gr of H4895 and 155 TMKs with small primer Peterson brass and I am getting 3081fps and ragged hole accuracy with no signs of pressure.

 

[TackDriv3r]

Using the P35 Oehler
Pic below was with the 150 SST's a few weeks ago.

 

[JFrank]

Sounds like you broke out.
I’m at 44.2 around 2850 ish
155 Scenars
H4895
Nosler brass
Tikka 308

 

[STOMP442]

Another thing to check since you are using the SST is weight. Sometimes I am surprised with how well they shoot when I put them on the scale sometimes. I have seen variances of over 2 grains in one box of bullets before. I have since lost it but I had one that weighed a 137 grains one time that came out of a 150gr box. Dimensionally it was identical to the rest of them but was way off on weight.

 

[lotech]

I'll not argue with anyone's load data, but I generally find 44 to 44.5 grains of H4895 to be a near max. load that provides best accuracy with 150 grain bullets. That roughly has a muzzle velocity of around 2825-2875, depending on barrel length. Hard to find a better .308 powder than H4895 with bullets in the 150-180- grain range.

 

[D-4297]

Apparently you haven't tried the VV N530 . When 4895 was , and still is being made with unobtanium , I checked the burn chart . Lo and behold . Right between the two 4895 powders was N530 . What the , I said . Tried it . Liked it , and bought a 8 lber. a couple days later . Only had to increase my load by .1gr and it matched out velocity . A little more expensive , but I'm not looking for powder . And it cleans up nicely , too . Ya gets what ya pays for .