Max load-W760, 30-06 w/168g HPBT

[sawdustdad]

I just spent an evening loading 250 rounds for my Ruger M77 in 30-06. I have two reloading manuals from the late 1980's which list my load of 58g as under the max load for this bullet/powder combination. I developed this load as the most accurate in my rifle some 25 years ago, but have not done much shooting since then. Recently getting back into the hobby.

Looking on line now and in a couple new manuals, the max loads are listed at 56.5-57g.

Why would the max load change over time?

How can I tell if this load is too hot? What should I look for in a few fired rounds, or would you advise pulling the bullets and starting over? I have a collet set for my rock chucker press.

[jwrowland77]

Check and see what they have on www.imrpowder.com.

Powder manufacture shows 56.5 as max.

Is the powder from the same time period as your manual, or is it fairly recent powder?

Reason for change is the formulas could have changed over time.

I would definitely do a new complete workup just to check how the powder will do.

[Bart B.]

Depending on the barrel, powder lot and pressure measuring system used, a 2 to 3 grain spread in maximum charges listed across loading resources is normal.

[sawdustdad]

Thanks, Bart B. I'm concerned that my 58g load is 1 to 1.5g over the max listed in all the modern resources I can find. I'm loading with new powder.

I also have a vintage Springfield 03-A3 in very nice shape. I don't shoot it much, but now wondering if my max load would be too much for that rifle.

[Brian Pfleuger]

Even when changing lots of the same exact, modern powder it is always recommended to back off from max loads by 5-10% and work back up.

All that's needed to verify a safe load in your gun is to start at the listed starting loads and work up to the listed max.

I note that Hodgdon's data for this combination is listed in CUP (Copper Units Pressure), which indicates that it's data that they have not retested in some time. "Modern" data is always (should be) listed in PSI and is much more accurate in absolute terms.

Since you do not have their chamber, barrel, bullets or powder lot, your gun may well want a different (lower or higher) max load.

If you have a chrony, that would be the easiest way to compare your result to theirs if you otherwise match the components exactly.

[jmr40]

Over the last 30 years tolerences in production gun barrels has gotten better. This is part of the reason. The same powder charges will often produce more pressure and speed than years ago. Among other reasons already listed.

I'd chronograph a few loads. If bullet speed is pretty close to where it should be I'd use them.

[sawdustdad]

I think I'm going to pull the bullets on this lot and reload. I'd like to feel safe shooting them in my '03-A3. Since I'm just shooting for fun, reaching max velocity or max accuracy is not critical. Based on my skill level, I might never know the difference. I'll back it down to under 55g. I don't have a chronograph. (yet).

Thanks for the advice.

[sawdustdad]

Still mulling this over, of course. If I shoot a few rounds, don't see any flattened primers, and the bolt opens easily, can I reasonably assume the load is safe? What else would you look for? (short of a chronograph)?

[Brian Pfleuger]

What I would do is a load work up.

You've already got your max loads, back off Hodgdon's listed starting load and load one each at the first 3 increments, 3 at the remaining increments and shoot your max loads if you don't experience any problems with the lower loads.

Viola

Just be aware of using them at significantly higher temperatures that you test at. Otherwise, the only thing you might be doing is adding a little extra wear and tear to your gun. It's not going to blow up. As I recall, those rifles (03-A3s) were tested to an estimated 125,000psi. You'll need to test it with a work-up in both guns though.

[T. O'Heir]

"...Why would the max load change over time?..." Different powder lot used on the day of the tests. However, like Brian says, you need to work up the load, not just pick one and hope.

[sawdustdad]

Brian, taking your advice. I pulled the bullets on a dozen rounds, reloaded three each at powder weights of 55g, 56g, 57g, and 57.5g. I'll take these, with several of the 58g loads to the range tomorrow and report back on the results.

I have several hundred rounds of 30-06 loaded in the late 80s and early 90s from when I was developing the most accurate loads for the Ruger. With a 3x9 scope, from the bench, I was in MOA territory. (just under 1 inch groups of 5 shots at 100 yds.). All of these rounds were loaded with 58g of W760 (168g BTHP bullets). The Hornady manual I have lists 58.5g as the max load. I fired a few dozen of these older rounds last week at the range without issue. Based on those results, I loaded the extra 250 rounds to the same specs.

As I was reloading these "work up" load rounds, it really struck me how small 1 grain is, and as I'm sitting there, it put the 1 additional grain in perspective. Less than 2% of the total load, so I can see that it's not such a big deal after all.

Should get a chance to fire these loads at the range tomorrow.

[sawdustdad]

OK, back from the range. (nice to work 2 block from the range). Fired all the test loads. No problems with any of them. Even the 58g loads chambered, fired, and ejected without issue and no noticeable deformation of the primer cup. I think I'll just shoot this ammo as is.

Brian, and jwrowland77, thanks for the suggestion to run the test loads.