I went to the range today to shoot some 7mm RM hand loads. I loaded them up using some Federal Premium brass from a box of 160g partitions and TBT’s I had shot about 2 weeks ago. That outing went fine with no issues.
I hooked up my chronograph and started by shooting what I had left of the factory loaded partitions. Right away I noticed readings of 3040fps. This is almost 100fps faster than what’s stated on the box. I fired 5 of my 7 rounds before checking the brass. Sure enough I found flattened primers and 1 ruptured case near the base. I opted not to shoot the remaining 2 rounds.
So I figured I’d move to more moderate loads by starting with my handloads. I started with my most mild load, 63g of RL22 pushing a 150g E-tip. Chrono read 2820. I checked the brass. The case showed a stress mark in the same shape and in the same location of the factory ruptured case. I stopped there.
Is this an issue with my rifle? A bad batch of brass?
What gives? Should I shoot the rest of the handloads I made from this same brass? I’ve shot about 200 rounds through this rifle. It is cleaned regularly, hunted with, and has never had any issues. My handloads were run through an FL die and not crimped. COAL= 3.294.
Included are pics of the factory ruptured case and the handload with the stress mark.
I went to the range today to shoot some 7mm RM hand loads. I loaded them up using some Federal Premium brass from a box of 160g partitions and TBT’s I had shot about 2 weeks ago. That outing went fine with no issues.
I hooked up my chronograph and started by shooting what I had left of the factory loaded partitions. Right away I noticed readings of 3040fps. This is almost 100fps faster than what’s stated on the box. I fired 5 of my 7 rounds before checking the brass. Sure enough I found flattened primers and 1 ruptured case near the base. I opted not to shoot the remaining 2 rounds.
So I figured I’d move to more moderate loads by starting with my handloads. I started with my most mild load, 63g of RL22 pushing a 150g E-tip. Chrono read 2820. I checked the brass. The case showed a stress mark in the same shape and in the same location of the factory ruptured case. I stopped there.
Is this an issue with my rifle? A bad batch of brass?
What gives? Should I shoot the rest of the handloads I made from this same brass? I’ve shot about 200 rounds through this rifle. It is cleaned regularly, hunted with, and has never had any issues. My handloads were run through an FL die and not crimped. COAL= 3.294.
Included are pics of the factory ruptured case and the handload with the stress mark.
Have you seen this mark on previously fired brass? Are they dents or cracks? Hard to see from the picture. No dark smudge of gas leakage is visible. They look a wee bit high on the case for a headspace induced separation. The curly nature & similar shape of the marks looks like possibly debris dents.
If dents, make sure your chamber is clear of all debris. I use a correctly sized bore mop damp with Brakleen to clean the chamber after cleaning the bore. Earlier this year I lost most of a box of 358 Norma Mag brass due to what I believe was a piece of a belt shaved off by a freshly cut chamber that got stuck in the chamber neck. A borescope showed the offending brass sliver floating around. Once it was removed, new marks stopped appearing. After 2 or 3 more firings the brass cracked where the marks were.
If it's cracks maybe your sizing die was set down too far, but that wouldn't explain the factory loads having the same mark or the possible pressure signs. Flat primers mean little by themselves. Is there an ejector mark? Was bolt lift hard? Was your ammo sitting in the sun at the range? A straightened paper clip with a point filed or ground on one end, then bent at a 90* angle about 1/8" up from the tip will make a feeler for down inside the case to feel if the case wall is thinning above the web. It's a simple tool every handloader should have.
If it's beyond your pay grade, maybe a trip to a local gunsmith is in order? Most of them are real nice folks & glad to help. Brass in hand is worth 2 pictures on the internet.
Sacred cows make good burgers when you know what temperature to cook them at.-Rev. Billy
I have not seen this on any other brass from this rifle. They are cracks, not dents. The factory load that cracked wasn’t run through a die. It went straight from the box into the rifle, so I don’t think it’s a die adjustment issue.
Get rid of the brass and start over, First, I'd look at the brass, then the chamber, Buy a box of factory and try that, if the mark are there, then its a chamber problem.
A few $$ in preventive is a lot cheaper than taking it to a 'smith to have the ruptured brass removed (speaking from experience).
And these zombies line up and eat from the media’s trough
Brass quality, usually a "given" has begun to show up as lower (if not bad.) Perhaps it is a volume or availability issue. Anyhow, hot-rodding loads and hot factory loads say 'caveat emptor.'
Die was adjusted Normally? I followed the directions on the box. I’m a new hand loader.
You could have created excessive headspace that way. My dies setup according to the instructions way oversized my brass. Ignore the belt and set your dies up to headspace off the shoulder not the belt.
Back your dies out so they just touch the shell holder, size a case and check the fit. If the bolt closes with resistance turn your die in an 1/8ish turn and resize then recheck. You’re looking for easy chambering just past the crush fit.
But remember, the ruptured case happened on a factory loaded ammo. It never passed through my FL die. It has to be something in the chamber or a bad batch of brass. Other factory loads have worked just fine. Which leads me to believe I randomly found some weak brass and some hot loads from the factory. Should I scrap all the rounds I made and start over with new brass?
What is puzzling to me it the close similarity to both cracks and in almost exactly the same place. Could the problem be in the chamber itself? I would think it it only occurred with the reload then that would be some kind of reloading error but the fact that a factory load also did this leads me to thing there is a problem with the chamber. Maybe a close examination with a borescope might provide the answer. Paul B.
Our forefathers did not politely protest the British.They did not vote them out of office, nor did they impeach the king,march on the capitol or ask permission for their rights. ----------------They just shot them. MOLON LABE
Die was adjusted Normally? I followed the directions on the box. I’m a new hand loader.
Not to be a smartass or anything but someone with experience to help you out shouldn't be that hard to find locally in AK. We've all been there. Luckily the old jarhead that got me started worked next to me for a decade. That was almost 40 years & a lot of miles ago. We still bounce ideas off each other. Loading manuals, magazines, well meaning folks on the internet, & Youtube videos just dont quite get it sometimes.
Sacred cows make good burgers when you know what temperature to cook them at.-Rev. Billy
My dad ran into a box of factory loaded 300 WBY Mag (Weatherby Brand) that locked up the bolt due to the extremely high pressure. I wouldn't totally discount that possibility.
IME, what you saw on the second case, was the imprint of carbon flouling left in your chamber from the failed round. You can clean the chamber to remove it, or you will see the impression on the next few cases. You can ask how I know. Should be nothing wrong with the remaining cases.
