6.5PRC - first run at reloading. Request experienced reloader input

New Avon Arms
zambezi

zambezi

Well-Known Member
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Per the title, I have just started reloading for my 6.5PRC. I can find very little online load data, and none at all for Vihtavouri powders. So any 6.5PRC experience using Viht would be very welcome.

Hornady publish some data for 6.5PRC, and I see that they indicate that Federal 210 primers are appropriate Hornady_6.5PRC_load_data.webp. From web research, it seems that CC1200 primers are equivalents to the Federal 210 Rifle_primer_equivalents.webp

Using GRT as a guide [see below] I built a min-ladder of conservative loads up to 50gr N160. ALL were very accurate. Not sure if that is testament to the rifle or the cartridge, or both. But there seemed to be a sweet spot at 50gr N160 delivering 3088fps. The magnetoscope V3 chrono is registering a 7% higher MV than GRT predicted.

Hornady once-fired brass [FL sized and annealed]
CCI200 primers
Barnes 120gr ttsx [30242]
Viht N160 50gr
COAL/CBTO = 2.950"/2.300"
0.262" inside neck achieved with Hornady bushing die

I will do more testing to confirm, but I would invite any other loaders for this cartridge with data to share to chime in with their wisdom.


1604573042230.webp
 
So, given that they seem to have the same case capacity, what does the 6.5 PRC have that the 6.5-284 Norma does not?

What the 6.5 PRC does NOT have is a 308 Win sized base diameter, so you cannot use a regular 308 Win type "medium" action to shoot it. You have to use a magnum action.

On that point also, the load data for the 6.5-284 Norma should be a good starting point for the 6.5 PRC. And if you look at the Vihtavuori data for the 6.5-284 Norma, they only manage to exceed the 3000 ft/sec. mark using 4.5 more grains of powder than you, in a barrel that is two inches longer. Perhaps more credence should be given to the GRT prediction....
 
borbal said:
load data for the 6.5-284 Norma should be a good starting point for the 6.5 PRC
Click to expand...

Correct. That is exactly where I started. 1604654927455.webp


borbal said:
Perhaps more credence should be given to the GRT prediction....
Click to expand...

As I do more load development, it does seem that the Magnetospeed V3 may be slightly optimistic. But less than 3% out:

It declares the claimed MV of the factory Hornady 6.5PRC Hunter cartridge to be slightly higher but less than 3%. That factory sample was 17 rounds with a declared SD of 21.5. Hornady_Hunter_MV.webp

Magnetospeed V3 and an alternate chrono both declared same MV [to within 2%] for Sako 6.5x55mm factory ammunition [albeit chronos deployed on different days, but same box of ammo].

Previously when the Magnetospeed was claiming higher MV than the load data suggested for my 6.5x55mm, it was simultaneously attended by case over-pressure signs. A form of corroboration.

When next it is feasible for my club to assemble at the range, I will arrange for a Labradar chrono to run in parallel with my Magnetospeed V3 to cross verify accuracy.

Per previous outings, I doubt there will be much in it.
 
More research today on powder equivalents.

I laid the Hornady load data up against a chart that compares the speed of many rifle powders.

All of the powders Hornady trialled for their 143gr projectile have similar burn rates and are slowish.

Applying the rule of thumb that lighter projectiles [in same chambering] require a slightly faster burn rate, it looks like my jack-of-all-trades N540 is in the running for use on 6.5PRC too...

... because I am using a 120gr as opposed to Hornady's 143gr:

Hornady_6.5PRC_load_data_vs_other_powder_burn_rates.webp
 
Per GRT, 44gr N540 will give me MV performance on par with the 50gr N160 results I already have above.

So now to load a ladder of 6.5PRC rounds around 44gr N540. Happy days.

I will also load three more 50gr N160 rounds, but using magnum primers to see if that reduces [hideous] soot build up when firing that powder.

1604673496154.webp
 
zambezi said:
More research today on powder equivalents.

I laid the Hornady load data up against a chart that compares the speed of many rifle powders.

All of the powders Hornady trialled for their 143gr projectile have similar burn rates and are slowish.

Applying the rule of thumb that lighter projectiles [in same chambering] require a slightly faster burn rate, it looks like my jack-of-all-trades N540 is in the running for use on 6.5PRC too...

... because I am using a 120gr as opposed to Hornady's 143gr:

View attachment 180376
Click to expand...
May I suggest Vit N555 may work with the lighter bullet and give you a better fill. Burn rate is a bit slower than N160 so should work in a 23" barrel? Just a thought.
 
FYI : the tests which I've conducted with my 6.5PRC show the best results in terms of accuracy & speed with RS76 and Vit 565 with monolithics 115, 120 up to 128 grains
 
Use the 6.5PRC for the process of complete testing and validating the monometalic long range bullets TPM-C in 90, 100, 110, 120 and 128 grains.

Objective : V300 higher than 800m/s and if possible V400 closed to this value, without having an excessive Vo (don’t want to be a barrel burner).

Will not use any other bullet.

As previously written the barrel is a 24’’ 1-8’’

The question came up few months ago : which powder …

The reputation of RS and Vitha being both at the top, and as almost nobody is using the PRC, I gave a call to RS experts who told me without hesitation : RS76.

Regarding Vitha, I know the person who created the new line, so I gave him a call and he said that the N565 will do the job. The 160 as well as the 560 could also be OK.

That’s it … I got the information directly from the best experts who know their products.

I could eventually add the IMR 7977 which is also available here and which fits perfectly to the application. More particularly for the light bullets. Have ordered 2 lbs.

That’s all so far for the selection of the powders.

Tests of the powders (stopped at the moment due to the C19) have shown that the RS76 provides the highest speed with the 128 grains, allowing a V400 to be a bit higher than 800m/s. Accuracy 1/2MOA at 100m. The projectile used having a very high BC (G1) is a great help to get thtis performance. The muzzle velocity is 975m/s for a V400 being 785m/s. 62gr RS76.

Comparatively, the N565 delivers speeds being roughly 40m/s lower than the above values. 59 grains N565. The accuracy is comparable.

All the pressures are 400/500bar below the nominal one.

With the 120 grains, the Vo=975m/s for 60 grains of N565 and 1002m/s with 63 grains RS76. There are 2 nodes just below those values (with my rifle) on which I’ll zoom at right after the confinment.

The speeds are in line with the objectives and could even be higher – but from far sufficient for any hunting’s application up to 500 meters. The accuracy is not an issue. The expansion of the bullet is not a part of your question but it is comparable to the standard TPM-C line.

This combo is perfecty suited for any game up to 300kg at the above distances.

The 100 grains (not mentioned yet) is for any game up to 150kg.

Will come back after the current confinment with many more tests and validation results.

Hope it's OK for you :)

Best regards,

equadif68
 
zambezi said:
Per GRT, 44gr N540 will give me MV performance on par with the 50gr N160 results I already have above.

So now to load a ladder of 6.5PRC rounds around 44gr N540. Happy days.

I will also load three more 50gr N160 rounds, but using magnum primers to see if that reduces [hideous] soot build up when firing that powder.

View attachment 180380
Click to expand...

I don’t think n540 will give you the desired case fill, as already mentioned above a slower powder will be better and kinder on your barrel
 
Scooby-3 said:
N160 is slower than n555.

N550
N555
N160

Or so I thought?
Click to expand...

I believe that to be correct. But there is not much in it.

I have highlighted in blue the powders that Hornady suggest be used for reloading the 6.5PRC.

Where the Viht powders burn rates sit in relation to those are highlighted in the left column.

But recall that the Hornady powder selection is for a heavier projectile than that which I will use...so edging towards powders that sit above the range bordered in blue makes sense.

1604914686687.png
 
Scooby-3 said:
a slower powder will be better and kinder on your barrel
Click to expand...

That is not a huge consideration for me. I will not put a huge number of rounds through this barrel per annum...and I am already retired...

Also, I imagine the relative barrel attrition [N160 vs N540] is almost unquantifiable.

N160 has an energy value of 3650J/g, where N540 has a value of 4000 J/g.

If the respective charge weights to achieve the same MV are 50gr vs 45gr [TBC] then energy at detonation is close to parity. [just over 1% difference]

I appreciate that double based powders burn hotter, that pmax using double base powders may be greater and thus stresses on barrel steel instantaneously higher. But in the course of my usage...negligible material difference IMO.
 
Good news!

Lapua will start making 6.5PRC brass from Spring 2021 and Vihtavuori will develop and publish optimum loadings shortly thereafter:



1604920241599.png
 
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