6.5 CM , low velocity and primer cratering ?

Rewulf

Well-Known Member
Just started loading for the Creed, Im fairly proficient in 223, but Im hitting some snags.
Rem 700 24 inch barrel 1.8 , nearly new, has a Evo mod on. Ive never put any factory ammo through it)

Started off with N550 and 143 ELDX , Im also using 95 g Vmax with CFE but I dont have any problems with that at the moment.

Large primer , new Hornady brass, started at vhit base line of 34.5, 2.79 OAL , was getting 2300fps , so went up in .5 increments.
Got to 38g , which is over max for SRP and barely reaching 2500fps.

Got some RL16 , as I wasnt happy with the 550.
Started out at 41g , and it just about got to my target speed of 2700 fps at 41g and 2.8 OAL (I do want to try higher , but slow steps)
Cratering primers straight away, and a very slightly heavy bolt lift, certainly not willing to continue.

Now, Ive just got some new Lapua SRP brass, the only issue is , I cant get hold of any Magnum primers in either LRP or SRP , Ive been using CCI 200 and some BR2 s tried also.
The question is , is the Lapua brass going to make much difference ?
Are standard SRP s going to be OK ?
Apart from the cratering, and slight heavy bolt lift (which may be the primer) there are no marks on the case , and the case even fits quite nicely into the head space checker afterwards , so Im pretty confident theres no head space issue.
You hear of 2800+ fps quite easily achieved from this combo , so Im a bit stumped ?
If its just the combination of LRP and being non magnum, then fair enough, Ill just use the Lapua for the ELDs and the Hornaday for the 95s.
 

baguio

Well-Known Member
Do you know how far you are off the lands? Could you be touching and therefore creating a pressure spike?
Why would you need magnum primers?
 

Rewulf

Well-Known Member
Do you know how far you are off the lands? Could you be touching and therefore creating a pressure spike?
Why would you need magnum primers?
2700 fps isn't low velocity BTW.
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 !
 

Rory

Well-Known Member
Looking at Vhit data for 143 ELDX, you're nearly 100fps over their max load for 550, they're only hitting over 2700fps with 560 and 565.
I don't think magnum primers have a harder cup, just more 'brisance'.
 

paul o'

Well-Known Member
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 .
 

Rewulf

Well-Known Member
Looking at Vhit data for 143 ELDX, you're nearly 100fps over their max load for 550, they're only hitting over 2700fps with 560 and 565.
I don't think magnum primers have a harder cup, just more 'brisance'.
Max load for 550 is 37.7 g for 2628 fps (SRP) Youre supposed to reduce the load for LRP.
Im 38g for 2500 fps.

The 2700 fps figure was with 41 g RL16 which is what I have the pressure signs with
 
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Rewulf

Well-Known Member
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 .
Good to hear, no issues with CCI 200 cratering ?

Im quite hopeful for the SRP lapua brass to sort it out, so I can press on.
Ive had to widen the flash hole though :oops:
 

stubear

Well-Known Member
Did you size the brass before you loaded it or just use it from new right out the bag? I've generally always sized it just to make sure I'm happy before I use it.

It might also be worth putting some factory through it, seeing what speeds you get and then using that brass for your home loads.

I would think standard LR200 primers would work just fine for 6.5CM, I dont think you'd need magnum for it.

It might also be worth trying RS powders - they have a more controlled burn and a moderate pressure curve from what I have read. If you have a look at their site you'll see there are a number of powders you can use.
 

Rory

Well-Known Member
Max load for 550 is 37.7 g for 2628 fps (SRP) Youre supposed to reduce the load for LRP.
Im 38g for 2500 fps.

The 2700 fps figure was with 41 g RL16 which is what I have the pressure signs with
Ah yes seen, missed the powder crossover. Might be worth trying it with regular large rifle primers, see if that works perhaps? Just plain old CCI 200's?
 

Rewulf

Well-Known Member
Did you size the brass before you loaded it or just use it from new right out the bag? I've generally always sized it just to make sure I'm happy before I use it.
Yes FL sized , and also tried some fireformed after the first attempt, made no difference.
It might also be worth putting some factory through it, seeing what speeds you get and then using that brass for your home loads.
When I can get hold of some !
Very limited choice around here.
Might be worth trying it with regular large rifle primers, see if that works perhaps? Just plain old CCI 200's?
Tried 200s as well as the BR 2 s, no difference.

Loading up the Lapua SRP now with CCI 400 s , try and get out to test later on in the week.
 

Rewulf

Well-Known Member
Update.
The SRP brass seems less liable to crater the primer, which is fairly expected , but seems to leave a 'washed' ring around the pocket , there are no other marks on the case head, and it doesnt do this with LRP.
Ive got up to 2600 fps with the 143 s , and also put some 123g scenars through with the same 41.5 gn load of RL16, produced a highly accurate 2800 fps (pretty much 5 rounds through the same hole)
The 95 vmax recipe was upgraded to 3000 fps, with no issues.

Ive managed to find some Federal 210 LR primers , but interestingly , the RFD asked if it was a Rem 700 ?
I need to check the firing pin clearance on the bolt hole, as he has had issues with primers cratering on them ?
Anyone else heard of that , and a possible fix ?
 

andyk

Well-Known Member
Yes, it is a known reason for cratering if the firing pin hole is oversize/firing pin undersized (whichever way you want to view it). I have seen photos knocking about online which try to show the difference between a crater caused by pressure and one caused by a loose firing pin.

Personally, I wouldn't pay too much attention to a cratered primer if it doesn't coincide with other signs. If it was with a flat primer, hard bolt lift etc then I'd certainly be worried but not if all else looks well. I have heard it said by a number of people that primers are not the best indicator of pressure.

I would add that I find CCI 200 'tougher' than Fed 210. I find that modest loads can flatten the Feds, to the point that I don't pay much attention to it if it is the only sign, but the CCIs tend to take more pressure before flattening. Of course, that is my own experience so please don't ignore flat Fed primers just because!

I also think the Feds are slightly 'hotter' and found in .270 that they gave a little extra velocity than CCI. For that reason I started to use Feds over CCI for that. Of course, the .30-06 type cases are on the margin of where you might want a magnum primer (I tend to think about 60gr of powder) so the hotter standard primer makes sense. I tend to use CCI for anything .308 based as where I am they are easier to source.
 

Rewulf

Well-Known Member
Personally, I wouldn't pay too much attention to a cratered primer if it doesn't coincide with other signs. If it was with a flat primer, hard bolt lift etc then I'd certainly be worried but not if all else looks well. I have heard it said by a number of people that primers are not the best indicator of pressure.
Agreed , but I did get slight heavy bolt lift at first , I thought this might have been caused by the primer getting a little 'stuck' around the firing pin ?
Having said that , it didnt feel so bad last night, so it might be loosening up a bit !
The SRP you can feel the raised cratering on your fingertip, visually theres not much to see.

I keep measuring the brass with micrometer and head space checker, and its barely moving from spec, Im going to go forward with fireformed and neck sizing.

Noted about the Fed primers , Ill just try 100 and see if theres any improvement, Ive also found some Magtech SR that are supposed to be OK .
 

Rewulf

Well-Known Member
Lapua SRP with 143 eldx at 2600fps

Hornady LRP with 123 g scenar at 2600 fps

Way below any hot load.
 

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andyk

Well-Known Member
If that was my case, I wouldn't be too worried as the primer isn't being flattened and I tend to think that high pressure would start to squash it.

It may not help, but you could try firing an empty case without powder or bullet but a primer. If there is no cratering, I'd ignore it entirely but if you do that would point towards the firing pin being the cause.
 

Rewulf

Well-Known Member
If that was my case, I wouldn't be too worried as the primer isn't being flattened and I tend to think that high pressure would start to squash it.
Im coming round to that way of thinking too.
The calibres new to me (Ive had it all of 2 weeks) so discretion was the better part of valour !
This sort of confirms what youre saying Primer cratering on all loads

It may not help, but you could try firing an empty case without powder or bullet but a primer. If there is no cratering, I'd ignore it entirely but if you do that would point towards the firing pin being the cause.
Excellent idea , Ill try that .
Cheers .
 
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