Reloading 6.5x47 Lapua for a Texas babe and pierced primers!

[MCMXI]

I've recently started dating a Texas babe who loves to shoot & hunt, has some cool rifles and certainly shoots well. She bought over a custom 6.5 x 47 Lapua built on an FN action that has a custom 21" heavy barrel and Manners stock. I mounted a Vortex Viper PST 6-24x50mm in Nightforce rings and offered to work up two loads for her, one for target shooting and one for hunting. I have 200 Hornady A-MAX 140gr bullets laying around and ordered 100 cases of 6.5 x 47 Lapua brass along with Redding dies. I have CCI small rifle and small rifle magnum primers and a bunch of suitable powders including Reloder 17, Varget and others. I was pleased to see that N540 is a good choice for the 6.5 since I use that powder for my .375 H&H Mag. Anyway, I looked at VihtaVuori's loading manual and figured I'd put together some loads with 37.0gr of N540, a CCI 400 small rifle primer and an overall length that maintains maximum contact with between the bearing surface of the bullet and the inside of the case neck (~ 2.740"). This load is far from compressed. Here's the first 5-shot group at 100 yards that my girlfriend shot after we zeroed the scope (only took 3 shots). Funnily enough she was disappointed with this group, but I certainly wasn't since I've just started load development. All groups were shot off a bench using a front bipod and rear bag.



I then shot the 5-shot group below. The high shot was the first shot and I will admit that the trigger is too light for me and the first shot took me by surprise.



At this point I noticed that some of the primers were pierced, and even the ones that weren't were heavily cratered.







I loaded up five more rounds with the same 37.0gr and shot over a CED M2 chronograph and the velocities were as follows:

2,670 fps
2,637 fps
2,662 fps
2,675 fps
2,664 fps

These velocities are within the expected range since VihtaVuori's reloading guide shows a max load of 37.4gr of N540 with a 139gr Scenar from a 27-1/2" barrel giving 2,744 fps. So my thoughts are ...

1. The cartridge is over pressure ... but bolt lift is normal and primers aren't flattened (see photos above).

2. Firing pin protrusion might be excessive ... but I measured it at .050".

3. The primer cup is not hard enough.

So does anyone have any other ideas or do you disagree with my thoughts on pressure? The bullet is nowhere near the lands so it has room to move forward during ignition. I plan on trying some CCI small rifle magnum primers to see if the problem goes away since they might have thicker cups. I put together five rounds with 36.7gr of N540 and didn't pop any primers. Thanks for any help.

 

[rcmodel]

I don't know, but check the firing pin tip under magnification for erosion.

If it's damaged now from gas leakage burning it, it will only get worse.

Rc

 

[MCMXI]

That's a good tip ... thanks. I'll check tonight with a 15X loop for erosion of the firing pin tip. She had two slam fires as well so I think the trigger needs adjusting or the sear/cocking piece engagement if the FN trigger has that feature.

I've always been under the impression that CCI primers are fairly hard compared to some other brands but a coworker is going to bring me a number of other small rifle primer brands to test with this load. Also, the whole point of the small rifle primer is to allow for more pressure in the cartridge. .260 Rem and 6.5 Creedmoor use large rifle primers.

 

[243winxb]

36.7gr of N540 and didn't pop.

Your loading maximum with the wrong primer.

 

[MCMXI]

I only shot 5 rounds with 36.7gr, and some loads at 37.0gr and 37.3gr didn't pop so it's a small sample set at this point.

I notice from the 6.5 x 47 Lapua load data on Accurate Shooter that many are using CCI 450 primers.

 

[MCMXI]

One more comment on this from Zak Smith ....

http://www.6mmbr.com/gunweek084.html

"I quickly learned that the pressure limiter in the system would be piercing primers. The AI-AW is set up to be utterly reliable in harsh field conditions and ignite mil-spec 308 primers. In guns built from the ground up for a very high pressure cartridge, it's common to bush the firing pin hole and then control the pin protrusion. I wanted to leave this rifle at the military spec, not to mention that a replacement bolt head from AI in the UK would be very expensive, so I left it and lived with the results. Ignoring the primer issue, even with nuclear loads substantially exceeding my final load, there were never any pressure signs on the case head, nor was the bolt hard to lift."

Hopefully CCI 450 primers will fix this and I can add more powder.

 

[MtnCreek]

You post about a TX babe and then give us pictures of a target and brass. Very disappointing.

RC makes a good point on the firing pin. I pierced a couple primers in an ar (purchased ammo from popular commercial reloader) and the damage from that resulting in piercing of lower pressure loads.

 

[MCMXI]

You post about a TX babe and then give us pictures of a target and brass. Very disappointing.

PM sent!

 

[243winxb]

Remington 7 1/2 primers handle pressure better than CCI 400's for me.

6.5 x 47 Lapua

LIGHT GREY TEXT BOX INDICATES MAXIMUM LOAD - USE WITH CAUTION!
LOADS LESS THAN MINIMUM CHARGES SHOWN ARE NOT RECOMMENDED

http://www.lapua.com/en/products/reloading/vihtavuori-reloading-data/relodata/5/54 Different Component = Different Pressure. Your using a different bullet.

 

[MCMXI]

I received a PM from another member who pointed me in the direction of a primer chart. It looks like the Remington 7-1/2 and the CCI 450 are both .025" thick, which is .005" thicker than the CCI 400 primer. The member in particular has had good success with CCI 450 primers. That's what I'll be using.

http://www.accurateshooter.com/technical-articles/primers-and-pressure-analysis/

 

[stubbicatt]

I made sure for my 6.5x47L that I got a small firing pin. It is likely that if you had yours turned down and bushed properly you would not receive that sort of problem at the loads you are using.

 

[Jim Watson]

I would be nervous about those blanked primers. Note that they are not just pierced, the metal of the indent is GONE.
Possibly due to use of a Mauser action for such a hot little round. You/she could have the firing pin bushed down, although I don't know where to get that done on a Mauser.

 

[Walkalong]

The edges of the primers are nice and rounded, as if the pressure is OK, but you have the primer trying to flow into the firing pin hole around the primer. Poor firing pin fit? Weak firing pin spring? Both?

Might want to pull the firing pin and spring and look for the missing primer cup material.

 

[MCMXI]

Thanks for the excellent feedback from stubbicat, Jim and Walkalong. I loaded up five more rounds when I got home last night. I used CCI 450 primers (small rifle magnum) and 38.0gr of N540. I wanted to push it a little to see if the primers would hold up. Accuracy was decent at five shots under 0.5 moa but one of the five primers was pierced. It's obvious from the photo that the primer is cratering and flowing around the firing pin. The primers still have a nice radius on them. At this point I'm not sure as to the best way to proceed. I might try 37.5gr and shoot them over the chronograph. If velocity is around 2,700 fps or better and no pierced primers I might call it good for this particular bullet. I plan on ordering 130gr Berger bullets since the gunsmith who built the rifle gave me his 1,000 yard load which he says will shoot one hole at 100 yards. He uses Varget and CCI BR2 primers.

 

[MCMXI]

Here's the rifle in question.

 

[Edarnold]

Time to go back to the gunsmith that built the gun and have him fix the faulty firing pin, before one of those pierced primers lets enough gas loose to reduce that expensive stock to firewood. On a new gun it is not your responsibility to fix the builders mistakes.

 

[Offfhand]

Classic example of "biscuit cutting" weak firing pin spring, or internal firing pin drag. Install new, correct spring.

 

[MCMXI]

Classic example of "biscuit cutting" weak firing pin spring, or internal firing pin drag. Install new, correct spring.

This is interesting. I have a lot of experience with Kimber rifles which have a similar bolt to the FN shown above. However, with a Kimber bolt, if you push the safety from the middle position to the fire position you'll need a lot of force and a solid edge to push the firing pin back (via the cocking piece) enough to capture it with the safety. When I was measuring the FN firing pin protrusion yesterday, I moved the safety forward to allow the firing pin to move forward. I thought I would have to go through the same steps to get the firing pin captured with the safety but I was able to turn the cocking piece by hand very easily. I figured there was a difference between the Kimber design and the FN design but would it be indicative of a very weak spring?

 

[rcmodel]

Yes.
You shouldn't be able to 'easily turn the bolt shroud by hand' and recock a 98 Mauser without pulling the striker back on something.

(Unless you are a lot stronger then I am?)

She had two slam fires as well so I think the trigger needs adjusting or the sear/cocking piece engagement if the FN trigger has that feature.

It sounds like that rifle needs to go back to the gunsmith who built it for problem solving.

The rifle in it's present condition is not safe.

rc

 

[MCMXI]

It sounds like that rifle needs to go back to the gunsmith who built it for problem solving.

The rifle in it's present condition is not safe.

It's complicated so that's not going to happen. I will however work on the trigger which is far too light for my liking. I will check sear engagement and trigger pull weight and take if from there. I will also replace the firing pin spring with a new part to see if that solves the pierced primer issue. Speaking of that, my interpretation of the issue with a weak firing pin spring is that the expanding primer is able to push the firing pin rearwards which allows the metal to flow excessively. Agree?

 

[Walkalong]

Checked my FN SPR and it takes a bit of pressure to re-cock the spring (Certainly not what I would call easy, but it isn't hard by any means.

Here are a couple of pics of the primers fired in it.

Lapua .308 brass. 44.8 Grs RL-15 (Work it up in your rifle folks, not a recommendation), 168 Gr SMK @ 2.800, Fed 210 primers, for 2715 ish FPS from a 24" tube.

 

[taliv]

i can tell you the AI actions are notorious for piercing primers in 260rem and the various 6xc type cartridges in medium pressure loads. bushing the firing pin hole is the fix. pm inbound on who to talk to. best of luck.

nice looking rifle btw

 

[MCMXI]

taliv, thanks for that. Here are a couple of photos of the bolt face and firing pin. I just ordered a few thousand CCI BR4 primers and Berger 130gr Match VLD Target bullets to test out the load, that according to the gunsmith who built the rifle, will put five shots into one hole at 100 yards without piercing primers.