Blowing Primers and other signs of high pressure in a mild load

[the long shot]

No die change. No shellholder change. The only thing that changed in the powder. The scale is reliable. I rezero the scale every three charges.

 

[the long shot]

BHEADBOY is on the right track I think. Is this a fresh can of 4350? If it is, you may have obtained a very fast lot. This happened to me at the Nationals but in the reverse. I ran out of 4831sc at a bad time and had been shooting the same lot # for 16 lbs. and had a real screamer of a load with low single digit ES/SD. I marked it in the tray so that I got to them, I was sure to use it as a sighter. Sure enough, 1.5 moa low. fired another to confirm before going for record. After the matches, I chronoed the "new" load and I was down 70-90 fps. If you can, try a different lot and see if you have any significant changes.
I hope this helps,
Lloyd

That may be the case. It is a fresh can of IMR4350, 8 lbs.

 

[the long shot]

Was it raining when you tested and had blown primers?

Much hotter than when you shot before?

I tested the load when it was 50 degrees. I shot it in competition at 75 degrees out.

 

[dkhunt14]

I see a lot of primer cratering and that wouldnt help with pierced primers. The primers still look rounded at the edges like it is not an excessive pressure load. Matt

 

[the long shot]

I see a lot of primer cratering and that wouldnt help with pierced primers. The primers still look rounded at the edges like it is not an excessive pressure load. Matt

But I have ejector marks on the case which would imply high pressure in some fashion.

 

[M-61]

No die change. No shellholder change. The only thing that changed in the powder. The scale is reliable. I rezero the scale every three charges.

Just a thought. "I rezero the scale every three charges"
Do you mean you throw 3 charges and rezero? Electronic or mechanical scale?

 

[the long shot]

No die change. No shellholder change. The only thing that changed in the powder. The scale is reliable. I rezero the scale every three charges.

Just a thought. "I rezero the scale every three charges"
Do you mean you throw 3 charges and rezero? Electronic or mechanical scale?

Electronic RCBS scale. There is a drift on the scale so I put the empty pan on the scale and rezero the pan and continue. Usually every three charges I rezero with empty pan.

 

[BenPerfected]

Have you double checked in the seating depth?

 

[the long shot]

Have you double checked in the seating depth?

I measured it last season to see if it changed. I did not check this year. I changed 3 thousandths in 8 years of shooting.

 

[M-61]

"There is a drift on the scale...."

There are plenty of good reasons posted here.

I think I would pull 3 bullets and if you have a mechanical scale see what it says. I have the same scale as you and I do trust it but then again I have NO drift. Also a 304 sitting above it as I occasionally dump a charge in there to see if everything is right. I do it more for peace of mind, and my age never lets me FULLY really accept it is always correct.

 

[bheadboy]

Long Shot,

I just went to the Hodgden page and looking at Varget load as you did for IMR4350 is see the range is 47.0-50.7gr --

thus your varget load was mid range, however I believe your 4350 load to be near the top, as it shows 58.0 compressed as max.

I would back off 2 gr and work up looking at the pressure, you may have a 4350 lot that is on the hot side where the varget may have been on the cool side of spec.

Bob

 

[bigedp51]

I have switched from my old standby load with Varget to IMR4350. The IMR4350 patterned well on the low end of the powder range and I went with that charge.

I went to a club match and I blew two primers. I did some practice the other day and I blew two primers and was getting ejector marks on the brass.

I clean my rifle regularly and double checked the charge on Hodgdon load data and the range for the load with a 168 grain bthp is 54 grains to 58 grains in a 30-06.

What could be the other cause of these high pressure signs? I don't want to, but may have to pull 100 rounds of preloaded ammo and lower the charge.

Savage 110, CCI LR primers, Black Hills Brass, IMR4350 powder. The previous load was 48.6 grains of Varget with all the same components.

What is the load where your getting brass flow into the ejector, 243winxb pointed out that 57 grains is max in the Nosler manual. And bheadboy has a great idea, reduce your load, your are exceeding the elastic limits of your brass and its flowing into the ejector.

Are all you Black Hills cases from the same lot? Black hills cases are rumored to be made by Winchester BUT they may have been made by other venders and differ in case capacity.

 

[the long shot]

I have switched from my old standby load with Varget to IMR4350. The IMR4350 patterned well on the low end of the powder range and I went with that charge.

I went to a club match and I blew two primers. I did some practice the other day and I blew two primers and was getting ejector marks on the brass.

I clean my rifle regularly and double checked the charge on Hodgdon load data and the range for the load with a 168 grain bthp is 54 grains to 58 grains in a 30-06.

What could be the other cause of these high pressure signs? I don't want to, but may have to pull 100 rounds of preloaded ammo and lower the charge.

Savage 110, CCI LR primers, Black Hills Brass, IMR4350 powder. The previous load was 48.6 grains of Varget with all the same components.

What is the load where your getting brass flow into the ejector, 243winxb pointed out that 57 grains is max in the Nosler manual. And bheadboy has a great idea, reduce your load, your are exceeding the elastic limits of your brass and its flowing into the ejector.

Are all you Black Hills cases from the same lot? Black hills cases are rumored to be made by Winchester BUT they may have been made by other venders and differ in case capacity.

I don't know if they are from the same lot. I did weigh and sort my brass and this sorted lot is a grain or two heavier than the first lot. I shot the last lot until I had to anneal them and use them for M1 fodder.

 

[the long shot]

Knowing the relative velocities between the two loads would be extremely useful in diagnosing problems just such as this. It seems likely your lot of H4350 is on the high end (burn rate) and the problem may have been exacerbated with the increased temperature and/or something else. Blown primers are almost always the result of excessive pressure. Cratered primers and ejector marks may be a sign of excessive pressure, but are not always. Given that you have experienced all the above, it's pretty likely your load is too hot. However, having solid velocity data would be an additional piece of information to confirm that suspicion. Recording velocity data during the reloading process is almost never a wasted effort.

I will have to unbox the Chrony and do some testing.

 

[bheadboy]

long shot

while you have a moment, pull 2-3 of the loads and check the powder weight just to make sure.

Bob

 

[the long shot]

long shot

while you have a moment, pull 2-3 of the loads and check the powder weight just to make sure.

Bob

Planning on pulling a few. Went out and bought a collet puller so I didn't have to hammer them all out.

 

[CaptainMal]

When you figure it out, add the explanation.

 

[the long shot]

long shot

while you have a moment, pull 2-3 of the loads and check the powder weight just to make sure.

Bob

Planning on pulling a few. Went out and bought a collet puller so I didn't have to hammer them all out.

pulled a few and the charge is within .1 grains of 54.3 consistently. brass is a few thou long on several samples.

 

[kmon]

long shot

while you have a moment, pull 2-3 of the loads and check the powder weight just to make sure.

Bob

Planning on pulling a few. Went out and bought a collet puller so I didn't have to hammer them all out.

pulled a few and the charge is within .1 grains of 54.3 consistently. brass is a few thou long on several samples.

I think in the first post and this one the problem could well be identified. Long brass can increase pressure. Trim those cases and I bet the issue will go away. Worst case I have seen of this was at the range one day, guy next to me was blowing primers and the case mouths had a bright area on them where they were hitting the end of the chamber. Cases that are long might not have enough room to release the bullet until pressures spike beyond where they should be. Not that it could not be any or several of the other suggestions.

 

[the long shot]

I think the mystery has been solved.

Pulled out the Chrony and loaded up some control rounds and changed variables to see what the problem was.

Long and short of it I believe it was the brass had stretched too far in certain rounds.

I shot my "hot" mild rounds that was blowing primers and it was pulling very good readings. Of the 5 shots, four were 2677 fps. The bolt felt stiff on the lift.
Black hills was pulling 2760, 2737, 2754, and 2765. Respectable.
My pet load of varget was pulling 2656, 2661, 2704, and 2688. (note..I was in a hurry with the scale so...)
I loaded up a full grain lower than my hot load and it pulled 2661, 2656, 2704, and 2645. (53.3 grains of IMR4350)
I FLed and trimmed the brass with my hot load and it was pulling 2721, 2783, 2770, 2763 and 2760. No stiff bolt lift with these.

Notes... The "hot" load shot brass that I was blowing primers had more loose pockets than I had originally thought so they were pitched.
The brass did not originally measure too far over max length when I pulled the bullets and put the micrometer to them. about 6 thou over. But when I FLed the brass then the overages were 13 thou over max length.

So speed wasn't the problem, likely the brass since I accounted for that variable in the Chrony test. I even chose a hot day to shoot on as the original testing was done at 50 degrees, and it was 90 the day I did the chrony test. Took forever to let the barrel cool.