Hornady - WTF does this mean?

[Toast]

I was shooting Hornady factory loads, 6.5 creedmoor 140 amax bullets. They were shot out of an AR-10 type gasser rifle with 22" Lilja heavy barrel. I didn't have a chronograph there and was just having a good time shooting. I didn't notice anything odd about the rounds. Figured the factory loads were fine.

However, when I collected up the brass, I realized that about 10% of the primers were blown out. Also, two of the primers were halfway out. (The two primers in the back row.) Every one of the primers that were still in were flattened. (See front row.) I wouldn't think the factory loads would be too hot. I was shooting outdoors in San Diego, so about 80 degrees, low humidity. About 500 feet elevation.

Can someone explain what is going on? Should I be concerned about shooting any more Hornady factory loads? Thanks for your advice.

 

[elfster1234]

Over gassed. Can happen with high performance ammo in a gasser

 

[moparguy]

I think it might be the brass. I have had problems with Hornaday 6.5 Creedmoore brass having loose primer pockets.

 

[CoryT]

Most probable cause, you are getting the bolt unlocked with too much pressure still in the chamber. This is a matter of the barrel length/gas tube length/gas port size/buffer weight/buffer spring combination. Who did the build and what load did they use to test it?

 

[Toast]

Accuracy Systems built it. Carl used 120 grain Hornady Amax bullets to test. It had an issue with the 140 grain amax bullets getting stuck in the chamber/barrel without the bolt closing. I pulled the charging handle back and it pulled the case out, but the bullet was wedged in the chamber/barrel. Turns out the 6.5 reamer he used was out of spec so he had to recall about 5 other builds. They shot 120 grain Amax's all day long, but the extra length on the 140 grain caused the bullet to stick. So I sent it back and he used the same batch of bullets I bought to test fire it.

When I sent it back, it went full auto on him. He decided to use an AR-10 bolt in the DPMS bolt carrier because the firing pin hole is smaller and the DPMS bolt allowed some of the primers to be pierced. The AR-10 firing pin was too long so it was causing it to go full auto on him. So he machined the firing pin down to ensure it wouldn't go full auto on me.

Guys, I'm a noob, so this is new to me. I don't want to get hurt and someday when my son is shooting it, I want him to be safe. I appreciate any advice. Thanks, Keith

 

[ChrisGarrett]

Did your smith actually ream out the throat to accommodate the longer bearing surface of the 140s, or did he just fiddle with the bolt?

You could be jamming those hands and spiking pressure.

Chris

 

[Toast]

No, he said he used the new reamer. He didn't want to just "ream the throat." He wanted to make sure the chamber was correct.

 

[hessian]

It's the ammo. Hornady's 6.5 in 140's powder charge is a relatively slow powder. The chamber pressure is too high when the bolt is unlocking. Note that the Hornady manual for this cartridge lists a custom Rem. 700 as test rifle.

 

[buffybuster]

Port pressure is too high = Premature movement of the bolt carrier.

 

[Aimsmall55]

Hell yes you should be concerned. Read this thread I started a while back.

http://www.snipershide.com/shooting.../236169-hornady-140-amax-ammo-old-vs-new.html

 

[richidaho]

If you don't want to mess with the gun just shoot 120's. If you want to shoot the 140's you could get a GP adjustable gas block. You would have to take off the hand guard but its not too hard. Lots of YouTube vids out there. I have a 300 black out I shoot subsonic cast bullets with and the adjustable gas block was the easiest way to insure non over-pressure. When I started working up a load for the 220g cast bullet. With the primers popping you can jam up your gun real bad. I went and look up the Hornady ammo its designed for a bolt gun; just a hessian said.

 

[Brux]

There is a Savage Model12 LRP on the forum having the same issues.I think it is the ammo.

 

[Sharpsman]

Most probable cause, you are getting the bolt unlocked with too much pressure still in the chamber. This is a matter of the barrel length/gas tube length/gas port size/buffer weight/buffer spring combination. Who did the build and what load did they use to test it?

+1

 

[Ring]

"It had an issue with the 140 grain amax bullets getting stuck in the chamber/barrel without the bolt closing"


errrr..... if its still doing that, the chamber is cut way to tight, and nowhere near enough lead on the throat... the 140 amax is not a VLD and the profile is dam near the same as the 123


"Every one of the primers that were still in were flattened"

that has nothing to do with over gassing.... thats pure over chamber PSI

if u want to test it quick, "shut off" the gas system... loosen the gas block, give it a 1/8th turn to the side so the gas port is covered and no gas will flow back, tighten the screws and shoot 2 or 3... look at the primers... if flat, ship that back to the GS to fix it...

 

[rg1911]

I had similar problems with my new AR-10 in .260 Remington. It definitely was over-gassed and starting the extraction long before the case had released from the chamber. This got much worse when I added the suppressor.

Two different solutions fixed the problem.

- A heavy buffer from Slash's Heavy Buffers | Home ($125 plus shipping)

- A Sentry adjustable gas block from SLR Rifleworks ($114 plus shipping)

I decided to go with the adjustable blocks on all my ARs so I would be able to tune the action for use with and without a suppressor.

Richard

 

[I Am Hero]

I had this issue with my M1A when I was shooting some handloads. I loaded them below factory Hornady specs (Hornady loads their 168 gr to 2700 (sometimes I have seen 2680) FPS and mine were shooting ~2650). What I noticed was that my load of 43.5 gr of Varget was giving me signs of overpressuring. These loads were originally loaded for my bolt gun but then I sold that. When reading on M1A handloads, they recommended loading to 2550 FPS and using a faster burning powder like 4895.

Bottom line is, in the Hornady manual they have a 308 service rifle section specifically dedicated to the M1A and the max loads for the M1A are lower than the max loads for the bolt loads. The max bolt load that they have listed there is barely on par with their factory loads. Therefore their factory loads are well over the max load listed for the 308 service rifle.

You problem definitely sounds like over-pressure and yes, as mentioned above the Hornady 6.5 CM brass has had issues with lose primer pockets as well. When reloading, some of mine would make it to 7 or 8 loads and others were done at 3.

 

[briang7511]

That is a nice lookin rifle.

 

[Killswitch Engage]

This still sounds like you have a tight freebore to me same as when you posted the problems with loading 140's in the gun smithing forum.

 

[USMC-FURY]

READ THIS: http://www.snipershide.com/shooting/snipers-hide-reloading/246570-blowing-primers-minimum-load.html