Velocity Node Help

[biednick]

I'm picking up what everyone is putting down. The method Scott Satterlee uses is not popular here

Lesson learned. Thanks for the input.

The big issue is trying to make a decision with a sample size of 1. Tests like this look good because our brains are really really good at picking out patterns, to the point we'll find patterns in noise. There's a lot of math and statistics behind why tests like this don't work, but the easiest way to understand the problem is to do a test more than once and see how inconsistent the results can be. You'd need so many rounds for a ladder test to give you good data you'd burn out a barrel just testing a few bullets.

Velocity nodes don't really exist with the exception of some powders that need a high case fill to give minimal velocity variation. You control SD by how consistent everything is from round to round. Ladders are handy for picking a charge that'll give you the velocity you want, but don't do much good beyond that.

 

[Koda_]

Thoughts on where I should focus my efforts?

IMO settling in the new barrel with some factory ammo, then starting over with your fireformed Peterson brass.

I thought the Staterlee method looked for POI elevation nodes on the target? You run your pressure ladder at longer range (eg 300yds) and track each charge weight POI. Look for 3 or more that are closest to the same elevation impact. Thats your charge node.

From what I see in your chart it might be a node at 66.2-67.1. I wouldn't count the last 3 as a node, Ive experienced similar velocity drop in pressure ladders and attributed them to virgin brass and new barrel (yes, been there too). Barrel temp can also play a role, when shooting to record velocities, let the barrel cool between each shot... its time consuming.
Hodgdon load data for H1000 with the 150TTSX shows a max load of 73.8gn @ 3083fps, since you didn't mention any pressure signs Id say you still have more to go on your pressure ladder. If your not comfortable exceeding the Barnes load data then redo your pressure ladder using your now fireformed brass and maybe the chart will smooth out and show a clear node. IMO I would go up to at least 1 shot at 68.3 (assuming no pressure signs).

It looks like the most likely velocity node is between 66.2 and 67.1, but 2800 fps seems super slow for a 150 grain bullet out of a 7RM.

150gn @2800fps is no slouch. "Listen" to your barrel harmonics above all other data, accuracy and velocity stability (ES) is better than more velocity. 2800fps is still above 2000fps at 800yds with that bullet (assuming a G7 BC).

 

[ShtrRdy]

I'm picking up what everyone is putting down. The method Scott Satterlee uses is not popular here

Lesson learned. Thanks for the input.

It's not popular with Scott Satterlee any longer either.

 

[victor3ranger]

I will let these gentleman advise you on what to do.
My belted magnum stuff I go a little bit different, letting my rifle tell me what to do, sometimes it' over anything any book tells you the max is

 

[Bob Wright]

So your variables of new barrel and new brass seem to show up on your chart. Measure headspace on a virgin brass and once fired. You will probably see .019- .020 difference. That energy is being consumed by that forming and if all your fired brass is measuring 0 to .003 variation, that's another problem. You can anneal all the fired brass at the shoulder to expedite the fire forming. The belted mags can be stubborn to fireform in one or 2 firings. Nothing on the chart makes me comfortable. It should be smoother and predictable on velocity increases at each charge. A 150 gr. should also be running north of 3000 fps. at a book max charge.
Reload the fireformed or annealed fire formed brass and start over looking for first signs of pressure. You can jump to the middle of your charge weight test and go up.
My 7RM never liked H1000 but for the 150 gr the Retumbo was really good.
Hoping your powder does what you need.

 

[nksmfamjp]

Any of those give you bolt lift?

 

[LALA]

That makes three of us. I load for accuracy, not speed. Find the load that shoots the best in your setup and go with it. If you just have to have more speed, then change up your powder or bullet to see if you can get the speed you want with the accuracy you are going for.

Just one more thing. A 3-shot group gives next to no meaningful information on how accurate a load is. I shoot 5-shot group ladders, and then shoot at least 30 more shots of a given load to make my determination on velocity and accuracy.

This right here is the way to go in my opinion

 

[Ronald W Schaefer]

My recommendation is to switch powder. H1000 might be a tad slow for the 150 gr bullet. The jury is out on the value of Satterlee node method, and you'll get 100 opinions from 50 guys on here, but I've had very good results using it and I usually include a few more measurements than 10. I finally found a lights out load for the wife's 7 RM after decades of settling for good-ish results. Try the RL 25 with a 160 gr Federal Trophy Bonded bullet or the TTSX. I have discovered I get a "free" ~ 70 fps bump using RL powders in the comparable burn rates of other brands and about the same using monolithic bullets with several friction bands on the bearing surface than bonded bullets. I settled on 68 grs of RL-25, Federal 215 primers and new Lapua brass with the Federal trophy bonded bullet. Yay--go me. That gives me about 2970 which is respectable, and about a .7 MOA. Now I can't find any more of those bullets...Boo. Luckily, I loaded a stash of 100 for her hunting.
FYI--I like the 160 gr bullets in the 7 RM because the ballistics are better numbers for long range use than 150. When the bigger bullets came out, I think manufactures should have jumped on slightly higher twist rates for factory 7RM and IMO breathed some new life in the venerable "seven mag", competing with the new barrel burner cartridges. High BC Rollin out a little slower will still gets you there long range with a bigger rock--a consideration for hunting bigger fellers. In summary of all this rambling--if you're dead set on the 150, change powders. If you're still flexible/fiddlin' and LR hunting is in your plan, maybe try the heavier bullets and Alliant products like RL-25/26/33 (33 might be a tad slow) or N575, Retumbo or Mag Pro.

 

[ewnanney]

I don't know half of what you guy's know, but blaming this on virgin brass and barrel doesn't sound like issue based on my experience. I think it just not the right powder for 7rm and 150's. I am working with 7prc with less than 150 rounds down barrel shooting virgin Peterson brass, getting single digit SD's, smooth velocity curve and sub-quarter MOA groups. Those velocity swings above 67gr looks real fishy

 

[MOA or bust]

Ewnanney,
What bullets and powder are you using in your 7 PRC? And what velocities are you getting?

 

[Laguna Freak]

Number one, never do ANY testing with powder on virgin brass, you're just wasting time and components because the case volume is gonna change drastically.
Reserve virgin brass for seating depth testing.


Cheers.

Back when my hunting bullets cost half what they do today, I did what you recommend. These days I buy cheap factory 2nds of the same weight for fire forming and don't conduct any tests until I have to bump shoulders.

 

[ewnanney]

MOA, I can't help you much. Figured I would use some discontinued Norma MRP that I had to do barrel break-in and chamber forming, top that off with some inexpensive 171gr Barnes Match Burners. Turned out to be great load. Too bad powder is not available anymore, RL22 is suppose to be same but load listings show some differences. I got them to run just a tad over 3k but settled on 2960 range, they just shot lights our there. Working with MagPro now, waiting to see some RL26 if that ever happens.

 

[matt_3479]

Seems everyone has already given great advice but I figured I might as well chime in too.

With new barrel and new brass first thing I do is load a light load to moderate load and shoot it. I'll play with seating a bit, tuner if that's your thing as well, and just learn the rifle. Get all brass once fired as well as barrel broken in and sped up/settled in. This gives you time to learn the new rifle.

After that I'll load a ladder to shoot at distances preferably exceeding 450 yards out too 700 (as far as I have locally) I tend to lean on that 550-650 yard range. I shoot 2-3 ladders of the same change and film it so I can plot shots in order. I will shot from low to high charge, let it cool, high to low, let it cool and shoot low to high again if I do 3. I like to run a chronograph to see if the velocity and impact nodes match up and most of the time they do or darn close.

I'll look for 2,3 or 4 shots in a row that show very little vertical and repeat on both or all 3 ladders. Sometimes you'll see 4 shots on 1 ladder, 3 on the other 2 ladders. So I'll load in between those 3 shots (example being 30gr, 30.2gr's and 30.4grs. I would load at 30.2)

Sometimes I'll verify a quick seating or tuner test again but normally that gets me there. Here's an example with the last barrel I did this with.

2 string ladder

4 shots that repeated at 550 yards gave me 3/4" vertical or less.

Did a quick tuner test for this one which didn't seem to be picky

 

[FireFlyFishing]

maybe try the heavier bullets and Alliant products like RL-25/26/33

Don't plan on finding these in a store near you anytime soon.