Barnard action

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agro
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Barnard action

#1 Postby agro » Sun Jul 08, 2018 3:12 pm

With the 6.5x55 cartridge having a non standard case head diameter (.480"), does anyone know of any issues when using it in a Barnard P action with the .308 bolt configuration (.473")??

thx

agro

Matt P
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Re: Barnard action

#2 Postby Matt P » Sun Jul 08, 2018 3:26 pm

Can depend on the brand and batch of brass, but with the right tooling very easy to open the boltface if required.
Matt P

agro
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Re: Barnard action

#3 Postby agro » Sun Jul 08, 2018 3:46 pm

Using Lapua brass??

pjifl
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Re: Barnard action

#4 Postby pjifl » Sun Jul 08, 2018 3:55 pm

I have never had a problem with Lapua 6.5x55 cases used with a standard Barnard P bolt. I think much of the brass is now made to 'US specs' on the case head anyway.

As a matter of interest, you can achieve (139 Lapua projectiles) over 3000 f/s in a 30 inch barrel with 2209. 46 grains 2209 is a max load from my experiments but start lower and work up.
147 Hornady ELDs over 2900 if you want.

Maybe a more sensible load is a touch less. Perhaps 45 grains. 47 grains starts to wreck cases with the batch of powder I have tried.

Peter Smith.

6.5x55ai
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Re: Barnard action

#5 Postby 6.5x55ai » Sun Jul 08, 2018 5:56 pm

My first Barnard P (2006 vintage) was chambered in 6.5x55bjai and the bolt face needed to be opened up to accept the brass (Lapua).
At the time Malcolm at Barnard explained that the earlier actions were held to a very tight tolerance for the 308 family head diameters because that is what was wanted by some American customers at the time. Later Ps did not need to be opened up as Barnard changed the bolt head dimension a tad.
My last 2 P actions will accept a 6.5 Swede case head no problems.
Incidentally my 6.5 Ackley shot 142gr Sierra MKs at 3010 fps (31") with no pressure signs or case life issues. I actually took mine up quite a bit faster and had superb accuracy but decided it wasn’t a place I wished to be. 3k with a 139 in a standard chamber is honking!

agro
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Re: Barnard action

#6 Postby agro » Sun Jul 08, 2018 7:34 pm

thx, 6.5x55ai
What barrel life are you getting with the 6.5x55ai??

6.5x55ai
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Re: Barnard action

#7 Postby 6.5x55ai » Mon Jul 09, 2018 2:43 pm

agro
I have just done some measurements and will need to modify what I said slightly in my previous posting.
My first Barnard was actually an 03 year of manufacture and the bolt face was opened out to 0.483” for the 6.5 Swede. I don’t know the exact measurement of the bolt face prior to it being opened out except that it needed to be opened out.
My last 2 Barnards, 09 and 11, are 0.480” bolt faces. 95% of my Lapua 6.5 SM brass fits nicely into these two bolt faces. 5% doesn’t!
What I have found is the bases on the 95% of my Lapua 6.5x55 brass measures at 0.478”-0.479”. The other cases, the 5%, are oval – measuring from 0.478” to 0.4815”. The cases are still in good knick, the primer pockets are still sound/not expanded. The extractor grooves measure 0.410” on 100% of my brass. The oval shaped heads have no corresponding oval in the extractor groove, they too are 0.410”. I just assume poor quality in the much heralded Lapua brass.
The 5% of my brass with oval head, even though it fits the 03 action’s bolt head without issue I will true up at some stage.
So, even with the 95% that do fit the 0.480” bolt heads that leaves only 1 thou clearance which is cutting it fine.
You would need to measure some new Lapua brass to determine if you will have an issue.

pjifl
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Re: Barnard action

#8 Postby pjifl » Mon Jul 09, 2018 4:13 pm

Interesting thread.

Since I have a box of unopened Lapua 6.5x55 brass, I decided to measure the rims. No idea what year of manufacture.

I used a good micrometer since I trust it more than digital calipers which read about 1/2 thou more. I believe the micrometer more than the calipers which was confirmed with a gauge block.

What I found was all rims were 0.4775 plus or minus 0.0003 max. These were unfired.
Solid but safe loads often expand the rim slightly. After work hardening, as long as the load is not excessive, the rim dimensions should stabilize. If not, you are really overloading.

One factor which I have found often with some other cases is that after FL sizing, large withdrawal forces on the rim can bend and burr the rim edge backward slightly. Since the shell holder is a horseshoe shape, this often throws them out of round. This happens especially with cheaper shell holders which are a poor fit. The SAUM and other magnum cases are a good candidate for this.

I only measured 15 cases out of 100 but they were all very uniform.

Peter Smith.

6.5x55ai
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Re: Barnard action

#9 Postby 6.5x55ai » Mon Jul 09, 2018 6:18 pm

Peter
Out of interest did you measure the extractor groove diameter on your new brass? I'd be interested to know although it may not have a lot of relevance between your brass and mine given different ages lot numbers etc.
That's the ultimate place to measure for head expansion but to do it properly you need a blade micrometer which is what I used to measure my brass. With fired brass I have found you need to take several measurements around the diameter not just 12 o'clock to 6 o'clock and 9 to 3 as head expansion is not always symetrical for some reason.

Sorry agro, getting a tad OT now.

pjifl
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Re: Barnard action

#10 Postby pjifl » Mon Jul 09, 2018 7:21 pm

I do not have any method of measuring the diameter of the extractor groove to the precision we are considering but I must say that I found the rims that I measured had a constant diameter. Which does not exactly prove roundness but it does give confidence.

Peter Smith.

6.5x55ai
Posts: 174
Joined: Mon Mar 18, 2013 4:21 pm
Location: Waikato NZ (Ex Tyabb)

Re: Barnard action

#11 Postby 6.5x55ai » Tue Jul 10, 2018 6:54 am

agro wrote:thx, 6.5x55ai
What barrel life are you getting with the 6.5x55ai??

I never got to “burn out” my Ackley barrel as I mothballed it at 800 rounds and switched to a 284W. At that stage accuracy was still excellent with no random fliers yet occurring.

The bore scope showed erosion, obviously. I have misplaced my throat advancement measurements temporarily so cannot comment accurately on them.

I had my smith examine the throat/barrel, without telling him the round count, and he guessed at 600ish and was surprised when I told him 800. The barrel is a 3 groove Lilja.
I would guess that if I continued to use the Ackley it would give me maybe 200 rounds over similar performing 6.5/284s, but hard to say exactly. Mind you I am aware of 6.5/294s dramatically going west at 1000 rounds and my round count is only 200 short of that with no sign of impending demise.

I did consider taking it up but I no longer have access to the original reamer.

I used only WW760 powder in it to hopefully use the powders lower flame temperature to extend barrel life.

As much as I loved the Ackley I wouldn’t bother again. Too much hassle with brass.


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