6.5x47 Lapua, when will I see pressure???

[tonyb]

This is for all of you experts out there. I am wandering when I should start seeing pressure. Here are my specs:

Defiance action
Brux 8.5 twist @29"
.175" freebore, .292" neck
.005" into the lands
.289" loaded round diameter
.001" neck tension
Varget powder, CCI-BR-4 primer

I am at 39.7 grains with the 123 Scenar
I am at 39.2 grains with the 130 Berger hunting VLD

I am not seeing any cratering around the primer, there is no ejector marks, and the bolt lifts just fine.

What say you?

Thanks in advance,

Tony.

 

[B Mize]

Im no expert on anything..........
Your probably not going to see primer cratering with the fitted / small firing pin hole.
With my rifle I saw ejector hole mark on the brass face.
Primers were still round on the edge and bolt lift was normal.
Also I don't shoot varget. With the long barrel you need to try H4350.

Good luck.

 

[Patch700]

I would agree with the above mentioned... to add to that you have 2 other things working in your favor , the 175 throat and the 8.5 twist..

I would say a chronograph would also lend a bit of insight on the matter as well.

 

[AusFclass]

Get a BRAND NEW case from the same batch and load it up with your load and fire it. Reload it and fire again. Repeat until your primer pocket becomes loose.

If your getting 3 firings your probably need to back off .5gr. If you get over 10 you might be able to go up .5gr.

You may need to full length size during this process but I find it gives me the best indication of how hot that load is in my chamber with my barrel and my lot of powder.

You can take pre weighed charges to the range in medical vials or even fired cases with a plug in the top. Just size prime and seat at the range.

 

[Scott Harris]

None of my Defiance actions crater primers no matter how hot the load. I had a load so hot it blew out the primer pocket such that the primer just fell right out....but it never cratered... so don't use that as a pressure sign. The only real way to figure it out short of a strain gauge is to see how long the primer pocket lasts over repeated firings as mentioned earlier.

 

[ChrisNZ]

Bear in mind that case can hide a lot of pressure.
If you have an action with a bit of clearance round the firing pin, the first observation might be a gas cut bolt face :-[

 

[LCazador]

IMHO, primer cratering is not a good indicator of pressure. Measure head diameter when new and then again after fireforming. When you see head expansion of more than .0008"(that's 8 ten thousands), that's a good place to stop.

 

[X-Caveman]

IMHO, primer cratering is not a good indicator of pressure. Measure head diameter when new and then again after fireforming. When you see head expansion of more than .0008"(that's 8 ten thousands), that's a good place to stop.

I agree ^^^. I find this to be the case with 6.5x47 and the .308 Palma brass. I'll add to make sure you measure in the same place every time. Otherwise the taper will give you trouble.

 

[AusFclass]

IMHO, primer cratering is not a good indicator of pressure. Measure head diameter when new and then again after fireforming. When you see head expansion of more than .0008"(that's 8 ten thousands), that's a good place to stop.

That's true but if it's not measured correctly using the same case across the same axis every time it can be hard to get a meaningful measurement.

 

[tonyb]

Thanks for all of the responses.

Tony.

 

[280man]

If you are using BR-2 primers the pockets might have already expanded a bit :

 

[tonyb]

If you are using BR-2 primers the pockets might have already expanded a bit :

LOL, yea, I would imagine so! BR-4's, sorry.

Tony.

 

[fourpower]

I have been loading 40gr h-4350 with 140 berger hunting bullet and it gets 2835fps. I am now on my 29 loading and primer pockets still tight and have not had to trim yet! I am using forester dies with no expander plug and I turned the necks. most accurate gun I own bar none. fun to load for!

 

[280man]

I tried to find the article but failed. Bob Jensen and German Salazar did a bunch of pressure testing to prove just how inaccurate primer flatness represented pressure. It was a great article and if I recall it was published in Precision Shooting Magazine.

 

[Drop Port]

This is for all of you experts out there. I am wandering when I should start seeing pressure. Here are my specs:

Defiance action
Brux 8.5 twist @29"
.175" freebore, .292" neck
.005" into the lands
.289" loaded round diameter
.001" neck tension
Varget powder, CCI-BR-4 primer

I am at 39.7 grains with the 123 Scenar
I am at 39.2 grains with the 130 Berger hunting VLD

I am not seeing any cratering around the primer, there is no ejector marks, and the bolt lifts just fine.

What say you?

Thanks in advance,

Tony.

Probably not until you feel bolt lift or blank a primer.

With the 29" barrel and .175" FB I would look into a 140 Hybrid and some H-4350. Depending on what type of shooting you are doing the long FB and barrel will benefit from the slower powder and heavy bullet. I run a 28" with 198" FB and 140 hybrid at an upper node and no other combo can touch it at long range out of that cartridge.

 

[Eric Leonard]

I have shot several bullets and powders and they all shoot so well it is hard to choose,,but I have settled on the 123 Scenar and 39 grs RL15 CCI BR4 primers loaded to 2.720 with a .020 jump

Stiller Tac 30 action with small firing pin,,28.25 inch 5R 8 twist Bartlien barrel,

this setup is so strong it could get a man in trouble,,it will hold a lot of pressure and I am afraid when you finally get hot enough to see pressure you may really see a lot of pressure,,

I have been at 41 grs H4350 and 140 Hybirds and 39 grs Varget and 130 VLDs and have decided to shoot the most accurate load with the 123 Scenars and 39 grs RL15,,brass is on 8th cycle using .288 bushing and havent lost a primer pocket yet,,