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Thank you Yerman for the 250 ATips info...well documented and always love the 3 guys graphic. Couple of questions:Wasn't going to post this...but since you asked...
This is my 8 twist 28" 300NM shooting 250gr A-Tips with R33. I am steering clear but you might have better luck.
View attachment 7147620
My update:
DT SRS with Proof carbon 28" 1-8T barrel.
Custom freebore to fit standard 338LM Magazine
250 A-tip
Lapua case
215M
VV N570
Jumped 0.025 from JAM
COAL 3.7095"
CBTO 2.8455"
Powder charge test #1
Soon will do more detailed powder charge weight test in 84-85 area (MV and POI based) also here it was very cold, so would like to get same winter/summer load if possible.
Shots #9-10 already were showing quite visible ejector marks, but no swings still. Primers were OK.
Sent bullet, case and mag to a smith and he adjusted freebore as per my requirements. I know its silly but right now I dont have measurement. it supposed to be 0.020" jump when bullet is seated @ case neck - shoulder junction, but not longer than MAG lenght.I saw in an earlier post, you were asking about freebore length. I am curious what freebore you went with? Did you have a custom reamer made? Or did you move it back with a uni throater?
84gr looks to be a bit on the hot side for a starting load. You might want to start closer to 77gr.
NOTE: if you read further up you'll see a discussion about how VV's load data for .300NM seems to be off.
I just shot a 15 round ladder of 250gr Atip / H1000 out of my 300 Norma. This was with once fired Lapua brass and federal 215M primers.
26" Bartlein 1:9" with chamber set to jump factory Berger 230 ammo (COAL 3.557", Ogive 2.655") .020" to the rifling.
At 125 rounds I measured .041" jump (.021" erosion?) and loaded the 250s at COAL 3.700". This OAL put the ogive at 2.690" from the case head and resulted in .005"-.006" jump to the rifling.
1/2 grain increments, 1 shot each, 62F, DA 5800, Alt 4400, Humidity 28%, tested with magnetospeed.
77.5 - 2732
78.0 - 2751
78.5 - 2750
79.0 - 2798
79.5 - 2812
80.0 - 2841
80.5 - 2860
81.0 - 2869
81.5 - 2893
82.0 - 2897 probably will test more here
82.5 - 2901
83.0 - 2923
83.5 - 2938 slightly heavier bolt lift?
84.0 - 2959 stiffness on bolt lift, slight ejector mark.
84.5 - 2986 noticeable stiff bolt and ejector mark. Stopped.
Sure would be nice if Hornady would put some Norma data up for their cool new bullets. I had to crunch numbers between 300 prc, 300 rum and other calibers to get a starting point. Hopefully this is useful for someone as there's not much out there.
N570 has been a bit of a pain in the Autotrickler v3. It doesn't have a problem every throw, but quite a bit more than similar powders like RL33. There's not a whole lot you can do about that either, so when it gets to the point where I get a bit frustrated, I use Lee scoops to throw instead.
What decapping die do guys use for .300 NM? My cheap Lee is too small for the case.
Interesting. Most guys I've talked to said things stabilized more around the 75-100 round mark. Most of my short action calibers stabilize around 150 or so.My barrel didn't get consistent until about 240 rounds.
Interesting. Most guys I've talked to said things stabilized more around the 75-100 round mark. Most of my short action calibers stabilize around 150 or so.
My barrel didn't get consistent until about 240 rounds.
ReddingYeah, I think I'll dig up some Lee scoops, will save me time and headache. I can't really be bothered to buy a charge master just to throw N570, haha. What decapping die do guys use for .300 NM? My cheap Lee is too small for the case.
Hi, would you guys be willing to share your bullet jump & bullet combination you use ? I'm struggling with my group size even with very low SD.