7mm STW OCW test help

[Ccctennis]

I went to the range today to do a OCW test for my 7mm STW. I had some issues and knew some of the vets here could help point me in the correct direction
The test recipe range and specifics:
168 grain Nosler Accubond Long Range
H1000 Powder
Winchester Large Rifle Magnum primers
Powder Range 77.4-79.5 grains
Seated to 3.600

I started the round robin and got to the 79.2 rounds and the 1st 3 of them didnt go off. They have powder and the primers were struck. I also had a couple of the 79.5 and one 78.0 that didnt go off either. I am not sure if it is bad primers or no ignition or what?
Below are the pictures. I don't think any of these initial charges proved much so far.
What say you? I appreciate any and all feedback.

 

[Ccctennis]

Here are 3 other targets.
The one with no writing were 3 fouler shots with 78.0 grains.

 

[cape cove]

I think I would use a Mag primer other than Winchister. There have been many reports of misfires with them. I developed 3 loads for a friend's 7mm STW a few years back.
175 Hornady Spt interlock
83 grs H-1000
RP case Fed 215 primer
OAL 3.673
Vel-3035 ft/sec
Accuracy with this load was .725 for 3 shots at 100 yds.

175 gr Hornady Spt
77 grs RL-22
RP case Fed 215 primer
OAL 3.673
Vel-3064 ft/sec
Accuracy with load was .330" for 3 shots at 100 yds.

!75 gr Nosler Part
76 grs H-450
RP case Fed 215 primer
OAL 3.673
Vel 3047 ft/sec
Accuracy with this load was .550 for 3 shots at 100 yds.
These were 3 great loads that my friend used to harvest several moose.Hope this somehow helps.you in your load dev.

His rifle was a Rem 700 with a 24" barrel. All of these loads were safe in this rifle but should be reduced and reworked if tried in another rifle.

 

[dok7mm]

As far as misfires, it seems to be either bad primer lot, primers fouled with lube, or the most likely ---- primers on faulty rounds were not seated fully and consistently.

 

[Ccctennis]

Thanks for the feedback. After more digging it seems as there was some cases not fully dry sonic cleaning. I'm going to pull the bullets tonight and dump the powder. I also will try and conduct another OCW test with this powder but I'm going to start at 78.0 and also try 79.2 again as well. I also have retumbo to try and 7828

 

[Rich Coyle]

If you can use some Federal 215 Magnums you can then switch to other primers without starting over with a lower load. Switching primers is the last thing I do once I like the pressure and over all length of a particular bullet load. I have seen groups cut in half with nothing more than changing primers.

 

[WildRose]

As far as misfires, it seems to be either bad primer lot, primers fouled with lube, or the most likely ---- primers on faulty rounds were not seated fully and consistently.

Or a dirty/iced up firing pin. The only truly bad primers I've seen were one lot of CCI's a few years back that were too thin and too hard and the firing pin was punching a hole straight through them without igniting them.

 

[WildRose]

Thanks for the feedback. After more digging it seems as there was some cases not fully dry sonic cleaning. I'm going to pull the bullets tonight and dump the powder. I also will try and conduct another OCW test with this powder but I'm going to start at 78.0 and also try 79.2 again as well. I also have retumbo to try and 7828

It's always best to shake each round out well to get as much of the liquid out as possible and then put them in the oven on a cookie sheet on low for a half hour or hour to ensure they are completely dry inside and out.

 

[WildRose]

Here are 3 other targets.
The one with no writing were 3 fouler shots with 78.0 grains.

78 and 79.2 seem to show some promise.

Are you shooting these from a bench? Prone? Rear bag? Bipod or bags on the front?

I ask because it looks like maybe some of the problem is form related rather than load related. No insult intended at all but there seems to be a lack of consistency because in between those two and just above 79.2 there's not really much of a "group".

Are you taking your time between shots or just pretty well shooting as quickly as you can reload and get back on target?

 

[Ccctennis]

No offense taken. I shot this test with front and rear bags. I shot 6-7 rounds and let the barrel cool between strings. Most of my rifles I shoot sub MOA easily which is why I was confused by these results. I too was pretty surprised that I got no real "groups". I was doing a similar test with my 257 roberts and 243 Wssm and shot tight groups all over the place.

 

[WildRose]

No offense taken. I shot this test with front and rear bags. I shot 6-7 rounds and let the barrel cool between strings. Most of my rifles I shoot sub MOA easily which is why I was confused by these results. I too was pretty surprised that I got no real "groups". I was doing a similar test with my 257 roberts and 243 Wssm and shot tight groups all over the place.

Try this. Shoot 3 shot groups with no more than one shot per minute and no more than 3 shots in five minutes. Yes it gets boring but if there's a bedding or floating issue that should eliminate it.

While we're looking for clues give the crown a good look and make sure it hasn't been damaged.

 

[Ccctennis]

Sounds good. I will give that a shot this week. Thanks for the advice. Stay tuned. I will post my results

 

[WildRose]

Sounds good. I will give that a shot this week. Thanks for the advice. Stay tuned. I will post my results

Good luck, we'll be watching for the results.gun)

 

[Ccctennis]

Sounds great. I will also be conducting a OCW test for my 6.5-284. Trying to find something that works with these Accubond long range pills. Need both guns dialed in for Elk in October.