Adjustments after changing primers

[Jody Simcox]

I've shot some pretty good groups in my son's factory 270 Win-- H4831SC 56.9 gr, 130 gr accubond at COAL 3.32" and 3.36", but I believe there is room for improvement- gonna move from a WLR to a WLRM-- where should I start charge weights on these new rounds and what increments would you say I should move up in? And how high should I load above 56.9 gr?

 

[bloc]

1) I once compared mag vs standard primers in parallel, using all the same components and increasing propellant charge in 0.5 grain steps. I believe I used IMR4320 powder, 130 bullets and CCI primers, but I did this many years ago and I have an imperfect memory. (My go-to load with 4320 is 49.5 grains with any 130 grain bullet.)

I could find no difference whatsoever between primers in terms of velocity or accuracy. There were no signs of excessive pressure. The SDs were a little better with the mag primers.

2) When I use H4831SC or standard, I routinely use 59 grains. In my younger, wilder days, I've gone well above 60 grains and had no warning signs . . . just to see . . .. When I use either SC or standard H4831, with 59 grains I've got cases that have been fired 10 times or more.

I do NOT recommend you assume what works safely for me is safe for you.

 

[Prose]

WLR is one of the most powerful primers IMO. There may be some evidence to back that. If the WLR was a 9/10, the WLRM is a 10/10.

What I would personally do, if I were already at max load, is go down maybe .4 grains and work back up.

On the other hand, if you believe their is room for improvement, shooting a magnum primer probably isn't going to fix your perceived shortfall. If you aren't having problems with ignition than look elsewhere.

 

[HTSmith]

The Nosler manual shows 59.0 Gr H4831 as max with 130 Gr bullet--but they are using a Fed 210 Primer. I think the magnum primer would be worth trying. I've had good luck with the CCI 250 and the Fed 215M, but never tried the Winchester.

 

[dsculley]

I had been using magnum primers in my 6.5x47. I switched to non-magnum based on the results a friend was getting. I was not satisfied with the results in my rifle. Was testing today. Loaded 4 loads in 0.1 gr increments to explore a node. Each load had 3 rounds with non-magnum primer and 2 rounds with magnum primers. Shot all across a chronograph. The rounds with magnum primers grouped with the non-magnum rounds. I was really surprised at the chronograph results. I was using IMR4350. At 39.4, 39.5 and 39.6 four out of six rounds with magnum primers had the same MV. One varied by 6 fps, the sixth was an outlier with a 27 fps difference. I intend to load rounds to try at distance and see how they shoot. All three of these charges shot in the same group.

For me, it seems that the magnum primers provide a more consistent powder burn than non-magnum primers, therefore a more consistent MV.
You will have to test for yourself. I knew the powder charges I was using were safe as I had worked up with magnum primers before. If you are near max, you may want to load several rounds at lower charges and work up with the magnum primers.

FWIW,

 

[ssv1761982]

You should always back down the powder charge when changing components and start testing. I tried magnum primers in a 22-250 and it made for a mighty sticky bolt. This was years ago and I was new to reloading. Apparently I was closer to the max load for my 788 than I realized.

 

[BoydAllen]

A friend of mine who is no longer with us had a couple of AI varmint rifles. One was a .22-250 AI and the other a .220 Swift AI. Both were on custom actions, one a Panda and the other a Hall. He was one of those fellows that probably should have probably not been permitted to have a chronograph because if he read a velocity in a magazine article, his attitude was,"If he can do it, so can I." There was also the issue of AIs not showing pressure on primers like their parent cases. As a result of both his loads were hotter, much closer to the edge than he realized. When he ran out of Federal primers he saw that he had a case of Winchesters and without doing any testing loaded the identical load, with the exception of the primer substitution. The increase in pressure blew the primers clear out of the cases, and the firing pin clear back into spring coil bind, so that the triggers had to be worked on to get them to work. Fortunately he was not hurt. I told him that he should have reworked the load, to which he replied that he did not have time. and promptly went out and did the same thing again. That is when I thought of the term chronograph idiot. He is not alone.

 

[kvd]

I've shot some pretty good groups in my son's factory 270 Win-- H4831SC 56.9 gr, 130 gr accubond at COAL 3.32" and 3.36", but I believe there is room for improvement- gonna move from a WLR to a WLRM-- where should I start charge weights on these new rounds and what increments would you say I should move up in? And how high should I load above 56.9 gr?

Having used several different brands of LRM primers I found the best accuracy in my 7mm Remington Short Action Ultra Mag came from CCI LR (BR-2) primers. Many magnum caliber shooters use LR primers instead of LRM primers in their loads.

Ken

 

[711rollerdog]

You might want to make sure your firing pin will set a magnum primer off reliably. I would look at different manuals to see if any are using magnum primers . As far as load goes, get an up to date Nosler loading manual and go from there. ...

 

[A_Gamehog]

Nosler lists your Powder as the most accurate, their findings were the 55-Grain load was the most accurate. Back down to the 55 lower node and the same primer. Accuracy before speed. Then change things if not satisfied.

 

[Jody Simcox]

Nosler lists your Powder as the most accurate, their findings were the 55-Grain load was the most accurate. Back down to the 55 lower node and the same primer. Accuracy before speed. Then change things if not satisfied.

I shot from 55-59 gr moving in half-grain increments, then loaded around the tightest group in 0.2 gr increments, then 0.1... 56.9 gr by far the tightest group...accuracy is ALL I'm concerned with

 

[Brians356]

I told him that he should have reworked the load, to which he replied that he did not have time. and promptly went out and did the same thing again. That is when I thought of the term chronograph idiot.

The term that comes to my mind is "Darwinism".
-

 

[Zero333]

If you want to see improvements with a primer change, I suggest you try a NON-magnum primer.
Specifically BR-2 & 210m is worth trying.

 

[Shane Roya]

I have been using CCI BR2s in my 6.5 Creed with RL26 powder and decided to test with Federal GM215M to see if I could get better SD. It increased velocity with equal grains of powder the same as an extra 1/2 gr of powder. My SDs were better with BR2s. As was suggested drop down and work up, always works better that way.

 

[ranger3]

I believe Chuck O connor had a load of 61 gr. H4831 w 9 1/2M Primers. I still have some of these and they did not show pressure in two of my rifles and they shot extremely well. Bugholes in one of my rifles.