Blown primers on factory Hornady ammo UPDATE

guntech59

UPDATE: I got an email from Hornady today. They are sending me a return shipment voucher. They (of course) want all the brass, primers and unfired shells. Nothing about replacement rounds. I suspect they want to do some checking first. I sent them an email back asking about it. Playing the waiting game again.

I was not satisfied with the accuracy I was getting with my Rem 742 so I bought a box of Hornady Custom (6mm). This is NOT the Light Magnum stuff! Took four shots at the range and this is what the brass looked like when it came out.










I have not had this problem with the Remington factory stuff. What do you guys think?

perry shooter

You will not want to hear my opinion but I bet the bolt lock up is worn and headspace is the problem.

bpost

The second case shows the extractor mark that Indicates a pressure problem.

The strange thing is you have expanded primer pockets, lose primers and primers falling out.

Then we look at the flatness of the primer. It seems to show normal pressures.

If I had to take a W.A.G. I would say that the brass used in the case is too soft, over anneald or a bad batch of raw material used to make them.. I might buy into high pressure if the primers indicated some nature of excessive pressure. They do not.

I would cease firing the load and ask for Hornaday to look at the remaining rounds. I would ask for a report on the brass from them.

guntech59

I am hoping it is NOT a headspace problem. If it is, why didn't the factory Remington stuff do the same? I just looked at the brass from that and the primers are not backed out at all. They are all flush.

My first thought was HOT LOAD, I know I bought the right stuff. They have a specific warning about using the light magnim stuff in semi autos.

Anyway, pics have been sent to Hornady, I'm sure they will want the brass and the unfired rounds back for testing.

Thank you for your help!

edited for spelling.

sandwarrior

Dumb question but does it say on your light magnum not to use it in a pump or semi-auto action? I know it says that on my Hornady .257 and 7x57 light magnum boxes.

guntech59

These weren't light magnums. I believe they have green trim on the boxes. These are just the "custom" loads with the yellow trimmed box.

I'm not sure if it says that on the boxes but it does say it on their website.

JustC

I have seen the exact same thing in a remmy semi-auto. I beleive they are too short for the chamber which is why some primers partially push out during ignition as the case is driven fwd by the firing pin, then as it slams back against the boltface, they are pertially re-seated. I say too much headspace.

sandwarrior

guntech59,

My bad. Sorry about that. I should have read your post a little closer. You did say they were not Light Mags.

Their website is not a valid warning. If they intend for you not to shoot the 'Custom' brand in a semi-auto they should say that on the box. All things considered though I wouldn't think the way a 742 operates would cause headspace problems. It's a gas system like the Garand and AR in that the Gas has to come back from the end of the barrel before it cycles the action. Unlike a direct-blowback or delayed rollerblock type action. the best thing I could say to do is check the headspace with the cases you have and the shells remaining. First see if the fired cases will go back into the chamber. Then take a sharpie, and see if the shoulder of the chamber marks a new case anywhere.* If it doesn't you may have a headspace problem. If it does mark the shoulder then you may have a hot ammo problem. It wouldn't be the first time that has happened.

* If you're not comfortable chambering a live round for fit, then pull the bullet and just use a new case. Or as noted, have a gunsmith take a look at the whole thing.

MIKE WISKEY

"a gas system like the Garand and AR in that the Gas has to come back from the end of the barrel before it cycles the action. "... not exatly true, the 742 uses a gas system similar the the m-14 (it bleeds gas off at mid-barrel) and acts on a piston. this may be the wrong propelant (pressure curve) for this type of rifle. an inquery to hornady is in order.

guntech59

quote:Originally posted by MIKE WISKEY
"a gas system like the Garand and AR in that the Gas has to come back from the end of the barrel before it cycles the action. "... not exatly true, the 742 uses a gas system similar the the m-14 (it bleeds gas off at mid-barrel) and acts on a piston. this may be the wrong propelant (pressure curve) for this type of rifle. an inquery to hornady is in order.

Good point Mike, and one that I certainly would not have thought of. I just took a look at ALL the other brass that has been shot out of this rifle. No protruding primers at all.

Again, thanks for help guys. I will discuss all this with Hornady when I talk to them again.

sandwarrior

quote:Originally posted by guntech59
quote:Originally posted by MIKE WISKEY
"a gas system like the Garand and AR in that the Gas has to come back from the end of the barrel before it cycles the action. "... not exatly true, the 742 uses a gas system similar the the m-14 (it bleeds gas off at mid-barrel) and acts on a piston. this may be the wrong propelant (pressure curve) for this type of rifle. an inquery to hornady is in order.

Good point Mike, and one that I certainly would not have thought of. I just took a look at ALL the other brass that has been shot out of this rifle. No protruding primers at all.


Again, thanks for help guys. I will discuss all this with Hornady when I talk to them again.


Mike and Guntech,

I agree, the gas port is mid-barrel not the end of the barrel, as I stated earlier. That, in my mind, would still do more damage to the rifle not the case, if the pressure curve was too high at the port. I'm thinking the loads are too hot to have primers popping out like that. Possibly the extra room they give a semi for feeding maybe?? Anyhow I think you're on the right track calling Hornady and seeing what they know.