6.5 CM , low velocity and primer cratering ?

[User00040]

There is a whole industry built around 'bushing' Rem 700 firing pin holes, totally pointless and waste of money IMHO.

Ejector brass flow marks are a better warning sign. If you are shifting brass at the base of the case head, be careful.

 

[andyk]

Ejector brass flow marks are a better warning sign. If you are shifting brass at the base of the case head, be careful.

For me this is the biggy, along with a stiff bolt (usually caused by the same thing). If you're getting that - stop!

Primers strike me as very unreliable, too subject to the thickness of the cup. I've also heard it said that if they are seated deep, i.e. behind and not flush to the case head, they can flatten themselves when they are propelled backwards into the bolt-face, it isn't so much pressure flattening them as the speed at which they strike the bolt.

 

[Chikentikka]

primer flow is worse with remmy actions, i wouldnt worry about it, as others have said, concentrate on what the brass tells you.

 

[Selous]

I suspect you have an undersized firing pin in a generous sized hole! My remmie was the same

 

[Rewulf]

I suspect you have an undersized firing pin in a generous sized hole! My remmie was the same

Looks pretty snug to me, and no shamfered edge like in some of them?

 

[palo]

My remington action 204 does the exact same.
I wouldn't worry about it as its quite common with remingtons.
Just keep an eye out for other pressure signs and you should be OK.

 

[samdk]

Ive made a spilt case to try and gauge how far off I am , and dont believe Im any where near at 2.800, I was going to work on that once I had found a node ?

Magnum primers have a tougher cup I believe ?

2700 fps is around where I want to be for now, but 2800 would be better once I start getting into it, you hear of some hitting 2900, but that sounds like a barrel burner.
However , even at 2700, cratering isnt good for my piece of mind !

There was a very useful post on here somewhere about the CCI primers specs and differences, I believe that the magnum SRP and BR-4 SRP both have a stronger cup.

I shoot 6mm creedmoor with Lapua SRP brass and use CCI BR-4 and have yet to see any primer cratering (even when I have experienced extrusion into the extractor), so would highly recommend them!

Sometimes if the firing pin hole in the bolt face is quite large with excess space around the firing pin it can cause cratering so that could also be worth checking.

Sam

 

[Rewulf]

There was a very useful post on here somewhere about the CCI primers specs and differences, I believe that the magnum SRP and BR-4 SRP both have a stronger cup.

I shoot 6mm creedmoor with Lapua SRP brass and use CCI BR-4 and have yet to see any primer cratering (even when I have experienced extrusion into the extractor), so would highly recommend them!

I found this when I was searching for possible answers.

 

[samdk]

I found this when I was searching for possible answers.
View attachment 212128

Good find!

Sam

 

[Rewulf]

Found some Federal 215 (M) LRP and some CCI 450s to try, Ill update when Ive tested them.
Im dubious about the firing pin hole slack , in mine anyway, but Ive bought a box of factory ammo to test , see if that does it too.
Ive dismantled one round , and put my powder and bullet in, Im covering all areas

 

[samdk]

Found some Federal 215 (M) LRP and some CCI 450s to try, Ill update when Ive tested them.
Im dubious about the firing pin hole slack , in mine anyway, but Ive bought a box of factory ammo to test , see if that does it too.
Ive dismantled one round , and put my powder and bullet in, Im covering all areas

Let me know if you want to try some BR-4’s and I will sort you some out.

Sam

 

[Rewulf]

Let me know if you want to try some BR-4’s and I will sort you some out.

Sam

Cheers mate , will do

 

[hedge hunter]

Just started back on the path 6.5 cm first load R16 41.5 GR 130RDF Bullet CCI 200 primers the brass is new Lap L/P fps @2780 sd 9 , col set at 2.825 standard, with a 0.402 group . the best group was with 40.0 gr R16 with an sd 6 but its only runny at 2640 fps thats lower than the S&B 140 factory I run it in on with an sd of 12 @2677 FPS.
With the N555 I only pushed it to 41.5 gr starting at 39gr and it was like a shot gun over 1" feel I need to pack more in to a max nr 44.5 to get the best of it .
In short the R16 is at this time giving me better results .

Wot length barrel have you got Paul o

 

[paul o']

Its a standard 610 cm feller and has that MRR 1-8 twist

 

[hedge hunter]

I'm just sat reloading with some reloader 16 are you happy with the powder ect paul .anything too watch out for.im loading for a creedmoor

 

[paul o']

Looks to be ok , not sure i'v got the best out of it but at 41.5 gr seems to be the best SD on my first outing with it ! I think C.O.L is my next move with this load . .
with the N555 iam going to do some more testing as soon as I can .

 

[Rewulf]

I'm just sat reloading with some reloader 16 are you happy with the powder ect paul .anything too watch out for.im loading for a creedmoor

I'm struggling to get more than 42 gn of RL 16 in a lapua SRP case, with a 143 eldx and an 2.8 oal, it compresses slightly, but it needs to be at least 2.840 with damaging the bullet.
No issue with LRP.

 

[turner.jc1]

I'll chip in my experience in case it's of interest.

I have a 6.5 CM and use RL 26 with 143 ELDX/147ELDM, Lap SRP brass and CCI mag primers @ 2850/2820 (24" barrel). Both can go well over 2900 with no pressure signs, this powder is a perfect combo for 140s+ in this cartridge. RL 26 has displayed the best, or equivalent to, accuracy I've seen. Shoots bug holes.

I've found RL 16 to be too fast burning for 130gr+, or maybe it just produces low vel generally. QL predicts at least 100 fps+ faster than real life for RL 16 in my rifle with 100gr ttsx and 130 sierra tgk's. So realistically it's 100/150 fps behind optimal powders unfortunately. It was very uniform in accuracy, every load about 3/4" in testing.

RS70 is another good option for the 140/130s, I hit the same 2850 node in my rifle with the 143 eldx. It also produces top velocity and accuracy with 130 tgk @ 2950fps. RS 70 shot 1/2" with either. You can't get enough RL26 in the case with the 130's unfortunately.

For what its worth ive tried RS 60 and RL16 with the 100ttsx, neither produced adequate accuracy. I don't think the 1/8 twist barrel I have is conducive to accuracy for these short bullets. RS 60 got them to 3400 fps though which is fun.