Pressure Signs WAY before max charge ??

[bubbaonpc]

I've shot/Reloaded 7-08 139-140 gr for 10 years. Trying a 120gr load for Wifey. Using H414, H4350 and RL15. Started LOW/Med loads. I should be able to get 2900 easy and up to 3200. H414 44.2gr, RL15 42gr and 4350 47gr. All are Middle Loads. New Starline Brass, Win Primers and Nosler 120 B-Tips. 4350 gets 2520fps and FLAT PRIMERS....H414 get 2720 and FLAT PRIMERS...RL15 @ 2650 Yea, you guessed it ...FLAT PRIMERS. I'm shooting .02 off lands. What is going on? If I were 400 FPS faster, I'd understand. I have NO heavy bolt lift...or other pressure signs... Seems every load..( 300 BLK OUT...6.5 Gren...5.56 Ect).. I have used Win Primers with the past 6 months has been "HOT"...not in FPS but plenty pressure signs. Has anyone else had issues with Win Primers? Maybe try CCI, Rem or Fed ?? Rifle is a Marlin X7. I'm at 3700' Elevation. Rifle is grouping from 2" down to .75 (Faster the better)
Maybe bad Chrono ?? Showing wrong speed??? Thoughts Please

 

[26Reload]

How clean is you leade...carbon buildup?
Try shorter oal for more speed before bullet hits the lands....
Mag primers or standards...could make difference..

 

[bubbaonpc]

New Rifle, maybe 20 shots.. so no build up. Regular primers. Guess I can try more jump and try different primers. .020 has been a sweet spot for Most loads,,,guess this one will take a little more work. Had a Savage 7-08 that liked .035...never had a load "max out" so quick and have such low FPS....kinda threw me a curve, but that's part of the fun. Thanks for your time !

 

[climb-101]

is the bolt hard to lift? too little pressure can cause signs just like too much pressure.

 

[mbaysinger89]

Whats the change in headspace from new brass to once fired? Its possible the primer is taking the brunt and being pushed out of the case, because the brass is too short your chamber when new.

 

[MagMan]

Silly question but is there any oil in your chamber?

 

[MagMan]

Chamber highly polished? No grip?

 

[nksmfamjp]

Whats the change in headspace from new brass to once fired? Its possible the primer is taking the brunt and being pushed out of the case, because the brass is too short your chamber when new.

this seems most likely. Short CBTD dimension, primer pushes back to bolt face, case head expands back over primer.

 

[bubbaonpc]

The new brass was tight by itself in chamber so I bumped back from .0190 to .0165 and fit well..no slop....shoulder came out to .0175 after firing and it (.0175) would chamber with a little bolt push...nothing harsh. .0190 allowed bolt closure, but was snug. Seems the Marlins chamber is "tighter " than my Savage or TC and needed bump.
Barrel was dry patched before shooting...no carbon build up in New barrel. Double checked price...not jammed in lands.

 

[Rflshootr]

Try your old brass if it's a different brand. I won't elaborate, but I've has some problems with Starline brass in the exact same caliber.
Have any pictures of the case head with the primers?

 

[claybreaker]

Whats the change in headspace from new brass to once fired? Its possible the primer is taking the brunt and being pushed out of the case, because the brass is too short your chamber when new.

I've witness this before, What could be happening is, as stated the primer get pushed out a little at first, then the case moves backward from the pressure, then the primer gets flatten some from the case being pushed back into the breech face with the primer slightly protruded, yielding the flattening. .... That the theory anyway.

 

[LVJ76]

Try your old brass if it's a different brand. I won't elaborate, but I've has some problems with Starline brass in the exact same caliber.

I'm thinking it's the brass as well. Try a different one and see what happens and you should be able to get to 3,000 fps or more

 

[ARKGG]

I've shot/Reloaded 7-08 139-140 gr for 10 years. Trying a 120gr load for Wifey. Using H414, H4350 and RL15. Started LOW/Med loads. I should be able to get 2900 easy and up to 3200. H414 44.2gr, RL15 42gr and 4350 47gr. All are Middle Loads. New Starline Brass, Win Primers and Nosler 120 B-Tips. 4350 gets 2520fps and FLAT PRIMERS....H414 get 2720 and FLAT PRIMERS...RL15 @ 2650 Yea, you guessed it ...FLAT PRIMERS. I'm shooting .02 off lands. What is going on? If I were 400 FPS faster, I'd understand. I have NO heavy bolt lift...or other pressure signs... Seems every load..( 300 BLK OUT...6.5 Gren...5.56 Ect).. I have used Win Primers with the past 6 months has been "HOT"...not in FPS but plenty pressure signs. Has anyone else had issues with Win Primers? Maybe try CCI, Rem or Fed ?? Rifle is a Marlin X7. I'm at 3700' Elevation. Rifle is grouping from 2" down to .75 (Faster the better)
Maybe bad Chrono ?? Showing wrong speed??? Thoughts Please

I've been working up a load for my A-Bolt 7MM-08. Hornady brass, WLR primers, Nosler 120 BT, H-414 49.0 grs. I have not ran into any problems. 44.0 grs Varget is preforming very well in my rifle also. I have a Savage 22-250 that doesn't like Varget In any amount. Sticky bolt, flattened primer. I can put all the H-380 in I want. I have never figured that out. Good luck.

 

[MLN1963]

One thing to check that hasn't been mentioned, neck clearance.

Can you drop a bullet into a fired case?
What is the outside neck measurement of a loaded case and a fired case?

I've seen on multiple occasions where you get pressure signs very early with too little neck clearance. The brass can't fully release the bullet before pressure builds. This has shown me pressure well before it should and slow speeds.