6.5 cm load too hot. what now?

[johnfkingmatrix]

hi.

i loaded what i thought was a ~min load for my 6.5 cm howa oryx. due to limited poweder options i was forced to.. research a bit to find a load that seemed to be correct for my powder.

upon shooting, it seems it was not correct. Although the bang was arguably louder than usual, notbing seemed out of the ordinary. the bullet impact on target was normal and as expected, however, the bolt was LOCKED shut. couldnt even budge it. after ram rodding the case/bolt back, heres what i discovered. (attaching pics)

not sure if deformation/primer being knocked out was from the shot or the ram rod. also primer was poked deep as a mfer. also not sure if its 100% a sign of being too hot, or something else all together??

looking forward to any idea as to what caused the problem.. naturally im just assuming it was too much powder.. ?

2nd question: where do i go from here as far as backing off the load?? do i take off 2gr? 4 gr? etc... back off COAL? not sure how much to tweak it.

also posting load data LMK if u see any glaring retardation. tyvm

6.5 creedmoor 140g btmatch hornady
40g imr 4451
cci 400 small rifle primers
coal 2.76"


OK last pic was a joke, thats ketchup XD

 

[Bill Norris]

WOW She was "hot" no doubt about that.

Hodgdon site list this IN HORNADY BRASS If your brass is alot thicker then that could be an issue.

U r seated alittle deeper as well.
MAX LOAD 41.1

IMR

IMR 4451

BUY NOW

0.264"

2.820"

37.0

2,414

47,700 PSI

41.1

2,670

60,700 PSI

 

[Ol Thumper]

DANG,,, you were way hot lol. Id be backing that way down, you were teetering on the edge with that load.

 

[hambone1971]

If you have some unfired rounds I'd pull a bullet and double check that powder charge.
My Hornady book says 36.6 min and 41.3 max for IMR4451 and a 140gr bullet. Any way you cut it your charge is way too much. Misread the analog scale , digital scale need calibrated? Probably have a few thou extra of headspace now. :-0 Good luck.
HB

 

[johnfkingmatrix]

thanks for answers, at least i was within the limits. Yeah ill pull them and re-weigh... i also loaded some other rounds that day for 300 blk with same scale setup and everything was A-ok.

I guess ill start them off at 36.6?
What would cause that giant primer dent ? i noticed when i was putting the primers in they were pretty hard to get in there...

its winchester brass.

Seems my COAL is the big issue, based upon previous post.

 

[Bill Norris]

NORMALLY, Win brass would be thinner but sometimes u never know without weighing and checking case volume.

Noticed u were using SRP. How cold was temp when u were shooting?

 

[prwhite]

thanks for answers, at least i was within the limits. Yeah ill pull them and re-weigh... i also loaded some other rounds that day for 300 blk with same scale setup and everything was A-ok.

I guess ill start them off at 36.6?
What would cause that giant primer dent ? i noticed when i was putting the primers in they were pretty hard to get in there...

its winchester brass.

Seems my COAL is the big issue, based upon previous post.

From the looks of the picture of the entire case it looks like an unsupported case head.

 

[Bill Norris]

From the looks of the picture of the entire case it looks like an unsupported case head.

Certainly appears to be a ridge swelled up just ahead of the 200 line.

 

[wagonman]

double check your scale make Shure it calibrated

 

[Rook 6]

Agree with all said. For sure, pull and re-weigh on a scale double checked for calibration. Glad it held and glad you were able to lift the bolt and extract ok! I may have missed, but was this the first shot of this reloading lot, or had you fired rounds from the same lot prior to this one?

 

[Kracken McGraw]

I load 39.9 imr 4451 all the time in hornady large primer brass in the 6.5 Creedmoor, it’s only 2615 MV. Definitely check for overcharging.

 

[johnfkingmatrix]

it was the first round and like 70 degree F
round chambered quite smoothly. the case prep involved liquid tumbling with soap, no ss pins or media. then i trimmed case to specs and deburred. the only thing i could imagine being IN there is a little bit of brass shaving.

im afraid to shoot any more of them.. and yeah i thought load was fine too.. thats why im so confused/unsure where to go from here.

and yes the case has a MASSIVE swell line right above the base. , looks more like the case was smashed backwards as opposed to being caused by outward pressure, since its a paper thin brass ridge, as opposed to a balooning of the case. hopefully thats clear in pic. also the extractor shape is completely engrained in the base of the case.. like the case was forced backwards.. idk if ramrodding it did this or if it was done upon firing ..

the only obstruction i could think of is if a little loctite dripped into the scope mount threads.. i just mounted a scope and had pulled /cleaned the bolt. but i checked it pretty good and the action operated smoothly prior to firing. so i doubt its this.

i guess the most likely culprit is that somehow the scale wasnt correct and i put too much powder in.. would this honestly explain the case being forced backwards/crumpling upon itself at the base , but having no other obvious signs of swelling /the depth the firing pin went into primer? its seriously like half a millimeter at the base of the case just accordioned in on itself , imprinting the ecact outline of the extractor on the bottom about 1mm deep. the case went backwards HARD.. but didnt seem to swell *confused*

 

[rijndael]

Any chance the neck tension was too light and the bullet was set back on feeding?

 

[JB10]

That looks like a federal case not Winchester, just by head stamp. Had you just cleaned the rifle? I ask because i see black markings by the case base. If still had some lube or cleaning solution in bore could cause high pressures. Just a thought.

 

[Bill Norris]

That looks like a federal case not Winchester, just by head stamp. Had you just cleaned the rifle? I ask because i see black markings by the case base. If still had some lube or cleaning solution in bore could cause high pressures. Just a thought.

Doesn't actually look like any Win case I've seen. And the Fed would definitely be a thicker case from all measurements I've seen.

 

[johnfkingmatrix]

i did full size case then light de burr so i dont think it was too loose?i guess i should chamber a few from batch then re measure and see.

yeah i lubed the bolt pretty liberally but didnt touch barrel.

yes u r correct there were some federal cases, my mistake.

just to be clear, the deformity of case IS absolutely a sign of pressure? i guess im just surprised that it isnt "swollen" but instead accordioned backwards about <1mm
this is what always happens?

fwiw case was held in extractor pretty good too, had to wiggle it out

 

[JB10]

I would say high pressure. I have left some oil in before and caused pressure spikes on a known good load. Left black markings arround base. You say none got in barrel area but what about arround bolt face? I have 2 6.5 cm rifles. With one of them i use hornady brass. Same load i used nosler brass. Blew primer right out. Was not as bad as yours. I was still under max published charge. Still shoot same load with hornady just fine.

 

[Texas10]

You mention it was the first shot of the day, any possibility that you left oil or cleaning fluids in the chamber after cleaning? Looking at the collapsed case, i suspect it was hell bound to get out of that chamber as pressure built.

Very interesting pics. I tried 4451 in my 6.5 Cm when H4350 was unobtainium and as I recall, i was using around 40 grs with no pressure issues with a 142 SMK.

 

[johnfkingmatrix]

holy crap. ya i feel like a moron tbh i didnt even kno i had to worry about that...i basically doused the bolt then stuck it back in lol.

learned a ton
.ill wipe it off then test a factory round. still pretty scared to shoot them.. maybe ill just have gf shoot one of the reloads , in case something goes wrong.

 

[KMart]

I need to clear up something in my mind.
Was this the first round you ever fired in this rifle or the first round that day?
Have you fired factory ammo in this rifle?

This is picking nits and has no bearing on your problem but you stated it is Winchester brass. The photo shows an FC headstamp which is Federal

Added
I was writing while you were posting. Be sure to dry the chamber with some denatured alcohol after wiping it out with a swab.