Help. 6.5 Creedmoor loads showing pressure signs??

BulletGuide

BulletGuide

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Full Member
Minuteman
Jun 16, 2017
14
5
73
Monterey, CA
#1
I've been hanging out here for some time, now need some help. I'm just beginning to load for 6.5 Creedmoor, using new Lapua small primer
cases. I seem to be getting a primer crater on almost every load. Here's the specs
Remington 700 24 inch barrel
New Lapua Cases
CCI 400 primers
Loads listed below with photos....

1. Hornady 140 gn ELD with 39.5gn IMR 4350 loaded to 2.80


2. Hornady 123 gn ELD with 36gns of Varget loaded to 2.80


3. once fired Hornady case 140gn ELD loaded to 2.80


All of my loads for my first three range trips with this rifle and brass show some cratering. Is it the CCI 400 primers? I know they have
once of the thinnest top thicknesses of all primers, still it seems a bit strange that I'd get the same or nearly the same primer reaction
on each load. The 140 gn 39.5 did seem to show some gas blow-by too. My Hornady book says 140 gn ELD can go up quite a bit higher
with safety. The grouping for the 39.5 gn load was .4 inch at 100yrds. So it shot pretty well but if I'm nearing a pressure problem I don't
want to continue, obviously. What am I missing here?? Do the Remington bolt face and pin produce these or just mine...
Thanks for any advice.
Bruce
 
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#2
Basically all of what you have chosen doesnt work well together.

If you are shooting a small rifle primer with your stock remington unbushed firing pin then yeah, it will crater every single one. Send the bolt to a smith to bush it to a small firing pin and youll be good to go. Or go with large primers.
Shooting the thin metal 400s over the thicker 450 is only going to make your problems even worse.

Watch the first few minutes of this for a demonstration on small vs large firing pin vs primer. 45 seconds is the example
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#3
Most likely false pressure signs due to the large firing pin and generous clearance in the firing pin hole in the bolt face.
Another suggestion would be to loose the 400 primers and run CCI 450 as they have a thicker cup and handle pressure better and will be less likely to have a pierced primer.

 
#4
Don't see any pics. What is the velocity of the loads? Craters alone do not indicate pressure. Flat primers, ejector marks and heavy bolt lift are better indicators. You can try a BR4, 450 or Fed match primer, they all have thicker cups.
 
#5
Thanks for all the responses. Bushing the firing pin area makes sense, I guess it has to do with how much I want to stick with the
small primer Lapua cases. Then again, it cratered the large primer Horndady brass as well. So, seems like I need to try another primer
or get the work done on the bolt face. I'm going to load up some more once fired Hornady brass and try other primers as I have some choices there where I don't with the small primers, only have the 400's on hand. I have a good supply of BR primers in the large size so
really should try that first. Thanks again. Makes more sense now.
 
#6
My 700 cratered everything, so was never a reliable test for mine. Look for other pressure signs to determine if you’re getting toward the upper end of the pressure spectrum.
 
#7
I have a feeling mine will crater about everything as well, started with 38gns of 4350 and got cratering there. Only difference
at 39.5 was the gas blow-by. I'm not sure this rifle will shoot any primer without the bushing fix. I didn't hear a fee in that video
from Gre-Tan, anybody had him do this or another smith?? Just found the fee on his website, 92.00 and up to 12 weeks. Long time to wait.
 
#10
Thanks for that, I was just concerned that if it takes the long end of the listed time I'd be without the rifle until the new year. Seems too
long to wait for a process like this so I contacted Longrifles Inc and we'll see what they say. Of course I contacted Remington but expect
nothing back from them. Seems like a sloppy tolerance issue and I don't feel than much better about the whole rifle now. We'll see.
 
#14
It seemed that way to me, that's why the cratering had me baffled until I got the info here. I was pretty close to the middle of
the charge range at 39.5, had quite a way to go before hitting the edge of a safe range. I could just keep shooting it I suppose but
the bolt face would take a beating and I'd like to see if I can keep this rifle around without damage for a long while.
 
#15
You can shoot it. The cratering does not cause dangerous damage, minor cosmetics. The bolt face will be fine. I am running a Savage. I changed out the bolt head to a PTG and cleaned up the shape of the firing pin which reduced the cratering. I still have cratering but it is just a cosmetic thing, nothing dangerous. I am running 42.4 of RL16 in Peterson brass and do not have any issues. Shoot it, have fun.
 
#16
I'd like to shoot it, got to get by the obsessive compulsive part of me that is bugged by the primers as I've developed all kinds of loads
for other rifles and never had to see that happen. It would probably take quite a while for the bolt head to get damaged and I may never shoot it enough. Still, if I could find a local smith who was versed in the process I'd do it, just because it would be so easy. We'll see.
Not losing sleep over it, that's for sure. Now that I know what's happening I'm just going to see how I feel in a few days. I appreciate all the great help and comments from this forum, really helps.
 
#18
I’d still prefer you use the magnum ar primers at a minimum just so you are that much further from puncture. Or go large rifle.

Can’t begrudge you doing your thing though.
 
#21
Cratering is caused by a firing pin hole on the order of .080". Contrary to some belief, it isn't a loose fitting firing pin. When a modern high pressure round goes off, the pressure extrudes the brass from the primer into the firing pin hole. It just pushes the firing pin up out of the way.

The force extruding the brass is equal to the product of the internal pressure and the area of the firing pin hole. since area goes as diameter squared, reducing the diameter of the firing pin hole significantly reduces the force acting on the brass. It also reduces the distance that the brass has to span across the hole.

Experience and experimentation has shown that reducing the firing pin hole to .062 from the nominal .080 used on remington and savage eliminates 99.9% of the primer cratering.

I do get requests to bush custom actions that have firing pin holes on the order of .070" that are having cratering problems.

There has also been a high demand for bushing AI bolts.

Pretty much any bolt can be bushed.

--Jerry
 
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#23
Got the bolt back from Jerry today, great job and really quick turnaround. Very good to work with and would recommend him to
anyone. Here's a photo of the bolt face, can't tell much but I suppose that's a good thing.
Thanks to everyone here and for the recommendation. Hope to get to the range this weekend and try the same loads again and load up a few 1 or 1.5 gns. higher if the first ones don't crater....
Bruce
 
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#25

This^^^^

I have been shooting small primer Lapua since it came out and never had my regular size pin in either my Rem 700 or my AX bushed. I’ll see a little cratering and like said above it’s false cratering. Have never had a single issue with blown primers or high pressure issues resulting from it and I’ve went through 4-5 differnt barrels now.

just a little food for thought.
 
#26
Just a follow up on the sleeve repair to my Remington bolt. First is the pre-repair primer with 39.5gns IMR4350 and 140gn ELD,
the second image is today's range trip, same load, sleeved bolt, all other details identical. For the price of the repair (80.00)
and the primes looking better (to me, anyway), I'd say it's a worthwhile repair. Hat's off to Jerry for a great job and quick turnaround.
Will try the 400 primers next. Last photo is 40gns H4350 and 140 ELD, all loads I tried, 39.5, 39.8 and 40 gave sub-minute groups but
you'd expect that with this rifle/caliber and components. Certainly not the shooter. After today I'm starting to believe my Eye Doc
may be right about cataracts. Everything seems bright and glaring, don't even try to drive at night. Felt if for the first time at the range
today and that's enough for me to get an appointment to start the process. Always something it seems.
 
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