I'm new to reloading been at it for a year. I've been on a quest to build a 7prc that can produce 2950-3000fps velocity launching a 180g + bullet.
I think I'm there with my build but wanted some advice/guidance on over pressure.
My current load is as follows
once fired Weatherby 7prc brass
69.2 g Ramshot grand
COL 3.3735
180g ELDM
No sticky bolt lift, no flat primers, slight ring on base of brass. I've developed this load in the summer so its been tested in 80+ degree heat.
this group seems to fall apart .1 grain less powder and doesn't come together until about 68.8g.


Cases in load order 69.1 - 69.2 - 69.3

Congratulations!

I would ditch the weatherby brass and get ADG, n570 was the trick for me with a 26" barrel. Shooting 180 Berger hybrid at 3050

Well it's one of two things either the tune or node is really small and not what you want or you don't have enough data points and that is just the statistical variation. .1 grain spread is pretty tight on a large case. Also depending on what scale you are using your powder could actually be off .1 either direction. I usually test magnum rounds in .5 grains intervals to start. My thinking if the node is that small I dont want it.

Dmagna said:

I would ditch the weatherby brass and get ADG, n570 was the trick for me with a 26" barrel. Shooting 180 Berger hybrid at 3050

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I've heard great things about ADG brass and n570 for 6.5 prc loads perhaps I'll switch to ADG after this season.

cajun said:

Well it's one of two things either the tune or node is really small and not what you want or you don't have enough data points and that is just the statistical variation. .1 grain spread is pretty tight on a large case. Also depending on what scale you are using your powder could actually be off .1 either direction. I usually test magnum rounds in .5 grains intervals to start. My thinking if the node is that small I dont want it.

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Yes, all great points! so I'm using a charge master lite calibrating each loading session. I'm thinking along the same lines. My first test was to find pressure, loaded 67.5, 68, 68.5, 68.8 rem9 1/2m primers COAL 3.2915. At 68.8 grains I shot 10 shots group as it seemed to be the best 3 shot group (all holes in the black diamond), turned out 10 shots (all outside the diamond) was 2.5moa (no pressure signs).
At this point I decided to move my bullet to 3.370 as I was seeing 2946 at coal 2.215 w/ 68.8g, I figured I could get to 3000fps at 3.370.
Loaded 68.8g ,69g, and 69.2 best group was at 69.2.I cleaned the gun, went to the bench and loaded 1/10 charge both sides of 69.2. Shot 3 fowlers and 69.1, 69.2, 69.3.

69.1 and 69.2 looked very close; 69.2 seemed tighter.
I switched primers to fed 215M in my next test.
ran the test again, 68.8, 69, 69.2 best group was 68.8 but more vertical than 69.2.

picked 69.2 and loaded 1/10 to both sides.
69.1 was huge, 69.2 was .4moa, and 69.3 was .7moa

I figured there was a node at 69.2 being that it grouped well with either primer. The pattern i see is that the fed 215M node seems to be higher 69.2, 69.3 than the rem 9 1/2 primer node 69.1, 69.2.
I'm lost on where to go from here if anywhere, I feel like my engineering mind has taken hold and I'm going down the rabbit hole of perfection. I appreciate all of this groups knowledge!
@cajun what are the pros/cons of a small node?

Depending on your powder and how stable it is it can be easy to fall out if the velocity drops. Also if your scale is good to a tenth. Then 69 might be 68.9 or 69.1 now thats .2. I have found that if the rifle likes the load it can be very forgiving. With my 6.5 creed and H4350 8 shots over 2.4 grains of powder grouped inside 1".

Three shot groups don't tell you anything. Ten three shot groups and maybe you can tell a difference. But I'd look at loads that vary by half a grain not a tenth.

Rifle Nodes: How You've Been Wasting Your Time and Money on Load Development

fruitnut said:

Three shot groups don't tell you anything. Ten three shot groups and maybe you can tell a difference. But I'd look at loads that vary by half a grain not a tenth.

Rifle Nodes: How You've Been Wasting Your Time and Money on Load Development

MSN

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I was informed that once I found a good group doing my half grain charges; to fine tune the charge moving down .1 g and up .1 g. I just read the article you linked and feel somewhat free now. Thank You!

I'm impressed.
I think three shot groups CAN tell you something; they are just not dispositive.
I've shot three shot ladders before, thought I found the perfect load, just to come back next week to have a 20 shot group open up. But sometimes it is a perfect load.
I'd say see if a 10 shot group stays sub .5 in. If so, you have found your load!
Congrats.
T

ps: definitely agree on ADG or Lapua brass. Much better chance of consistency over the next 10 loadings.

fruitnut said:

Three shot groups don't tell you anything. Ten three shot groups and maybe you can tell a difference. But I'd look at loads that vary by half a grain not a tenth.

Rifle Nodes: How You've Been Wasting Your Time and Money on Load Development

MSN

Click to expand...

Three shot groups tell me everything I've ever needed to know and that's all I ever do
300 prc 1480 yards.two 3 shot groups. One on the first outing during load development second to confirm and called it good 270 wby 825 yards one 3 shot Group on the first outing during load development second to confirm and called it done 7 prc 1035 yards one three shot group on first outing during load development second to confirm and called it done 7 saum 825 yards one three shot group during load development second three shot group to confirm and called it done


So in my opinion 3 shoot groups tell me everything I need to know anything more like ladders is a waste of components for me.
Non magnum I develop in half grain increments and magnum I go full grain increments and will fine tune in smaller increments if something is showing promise.

With three shot groups like that at those distances I'd stop also. That's great shooting. Maybe you should take up competitive shooting if you aren't already.

How much development went into those loads?

And do you trust one three shot group to tell you one load is better than another?

What the article I linked to says is pick a powder and bullet combo for your gun, and it will either shoot well or it won't. If it doesn't, change powder or bullet and try again. The new combo will shoot well or it won't. To really tell how well a load shoots requires 20 shots. Lower charge weights usually shoot slightly tighter groups. Seating depth makes little difference.

Next load development session, I'll chose a powder and bullet. Load 20+ rounds at the starting charge weight. Shoot at least 20 shots to see how it shoots. If it doesn't shoot well, I'll change powders or bullets. If it does shoot well, I'll move up in charge weight to get where I want on velocity and pressure. Then see how that shoots. Can't be worse than what I've done before. But doubt I'll be shooting 3 inch groups at 1,000 yards.

fruitnut said:

How much development went into those loads?

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Very little with those loads
Those guns that shot those groups were amazing. I picked a starting charge and a max charge and I had loads first trip.
2 nd trip out confirmed load and went to shooting.
This does not happen every time but I've used my same system for over 20 years and it just works for me.

fruitnut said:

And do you trust one three shot group to tell you one load is better than another?

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I do but that's just the Way that I do it and it works for me.

Thank you for your response. I believe every word.

You've got guns and loads that shoot. Which isn't at all at odds with the article. If a bullet/powder combo shoots, there's no need for load development. Just choose the right powder charge that gives the velocity you want at a safe pressure. If that shoots, you're good to go.

My take is if a powder/bullet combo won't shoot, don't beat your head against a wall searching for the magical node, powder charge, or seating depth. Instead change powder or bullet. Sometimes it only takes three shots to know that a load isn't going to work.