7x64 RWS 173 Grain

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9.3x64
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7x64 RWS 173 Grain

Post by 9.3x64 »

(Cartridge) 7x64 Brenneke

(Brand of bullet) RWS

(Weight of bullet) 173 grain TMR Soft Point

(Brand of brass) RWS

(Type of powder) RL19

(Grains of powder) 52 max but no signs of pressure

(Brand, and type of primer) RWS 5341

(COAL) 82.8 mm

(CBTO)

(FPS/MPS) 2318 fps.

(Rifle) Blaser R8

(Barrel Length) 58cm

(Scope) Zeiss Conquest DL 3-12x50 illuminated

(Weather conditions & temp) Moderate winds blowing across target left to right

(Accuracy @ 100 yards/meters) Smallest 3 shot group 8 mm centre to centre, largest 15 mm , average 12 mm. Smallest group in photo.

(Notes)
Hopefully this will be an effective Fallow and Red load.
May also develop a load for RWS 173 Grain H-Mantels at some stage.
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Last edited by 9.3x64 on Thu Dec 29, 2016 9:39 pm, edited 2 times in total.


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Re: 7x64 RWS 173 Grain

Post by Gun Barrel Ecologist »

Is this the TMR bullet or another? :confusion-scratchheadyellow:

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Re: 7x64 RWS 173 Grain

Post by 9.3x64 »

Gun Barrel Ecologist wrote:Is this the TMR bullet or another? :confusion-scratchheadyellow:
Yes.
I also stuffed up the accuracy info. Now corrected.
First post in load data section. :oops:
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Re: 7x64 RWS 173 Grain

Post by secondtry »

Nice. And very sweet to shoot, I'm guessing. :D

I suggest that you try chronoing it, or at least check drop by shooting groups at known distances. 2750 sounds reasonable, but it may well be much less. A bit less speed won't matter to reds and fallow, but unexpected extra drop could matter.

Truth by chrono has ruined a lot of my old loads. :lol:

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Re: 7x64 RWS 173 Grain

Post by 9.3x64 »

secondtry wrote:Nice. And very sweet to shoot, I'm guessing. :D

I suggest that you try chronoing it, or at least check drop by shooting groups at known distances. 2750 sounds reasonable, but it may well be much less. A bit less speed won't matter to reds and fallow, but unexpected extra drop could matter.

Truth by chrono has ruined a lot of my old loads. :lol:
Yes I was thinking of buying a magneto speed just for verification. Then get on the Zeiss website and check clicks for this gun which is my brothers, and then ring number for my Zeiss V8.
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Re: 7x64 RWS 173 Grain

Post by Gun Barrel Ecologist »

Thanks :handgestures-thumbup:

Good to know which bullets you're talking about with the 7mm's as for instance I've found the 175g Hornady SP develops pressure signs 1g lower than the now discontinued RN.

The H mantel and TIG's steel jackets may require tweaking the load - then again the latter might have enough grooves etc to minimise bearing surface :think:

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Re: 7x64 RWS 173 Grain

Post by 9.3x64 »

I only got the estimated velocity from Nicks reloading manual. But the maximum load shoots considerably lower than the factory load. Can I try 53 grains or is that unwise?
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Re: 7x64 RWS 173 Grain

Post by secondtry »

9.3x64 wrote:I only got the estimated velocity from Nicks reloading manual. But the maximum load shoots considerably lower than the factory load. Can I try 53 grains or is that unwise?
A different MPI between two quite different loads, such as you have, is not necessarily an indicator of lower velocity, but it may be.

I am pretty confident with developing loads and chasing pressure up, but I would not usually encourage someone I don't know to do the same. If you are confident with what you are looking for, and with what pressure signs look like and feel like with your components, I would keep working up in .5gn increments. If accuracy deteriorates, or pressure signs appear - STOP.

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Re: 7x64 RWS 173 Grain

Post by 9.3x64 »

Thanks mate,
I would not call myself an experienced hand loader. I did mike the head of the cases, but it's very difficult to measure in 10 thousandths of an inch accurately in my little experience. It very delicate to measure accurately.

How much head expansion is high pressure??
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Re: 7x64 RWS 173 Grain

Post by secondtry »

Case head expansion is much discussed and there seem to be different views on what level of expansion is indicative of a problem.

Many, many years ago, the view was that expansion of .0005" or more was too much. Another view was that any measurable expansion was an indication that the elastic limit of the brass has been exceeded, therefore too much. I have had another view espoused to me that a little expansion is OK, and will stop with repeated firing. Personally I regard the last view as dodgy.

Measuring heads with a normally anvilled mike is very hard, if not impossible. Rims can be measured, but this has not been, for me, any where near as precise or as usefull as measuring the actual head immediately in front of the extraction groove. Some grind down the anvils. Some years ago I bit the bullet and bought a blade mike specifically for checking case heads. A bonus is that the graduation scale is very coarse, and although the mike is metric, the coarse scale lets me easily read down to the metric equivalent of.0002".

When I get measurable expansion on that mike, I back off.5gn to 1gn. My old Speer manual says back off 5%, but in my experience (and ONLY my experience) 5% is unnecessarily conservative. I can tell from my components, my chrono, and my rifle that the loads with measurable expansion are definitely getting up there, although MAYBE still quite safe albeit hard on brass. When I refer to the chrono, I am not usually referring to the raw velocity, but to how things are reacting as the charge increases.

I use only ADI/Hodgdon and do not usually hunt in hot places, although I have used my loads in Charters Towers in February with no issues.

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Re: 7x64 RWS 173 Grain

Post by 9.3x64 »

secondtry wrote:Case head expansion is much discussed and there seem to be different views on what level of expansion is indicative of a problem.

Many, many years ago, the view was that expansion of .0005" or more was too much. Another view was that any measurable expansion was an indication that the elastic limit of the brass has been exceeded, therefore too much. I have had another view espoused to me that a little expansion is OK, and will stop with repeated firing. Personally I regard the last view as dodgy.

Measuring heads with a normally anvilled mike is very hard, if not impossible. Rims can be measured, but this has not been, for me, any where near as precise or as usefull as measuring the actual head immediately in front of the extraction groove. Some grind down the anvils. Some years ago I bit the bullet and bought a blade mike specifically for checking case heads. A bonus is that the graduation scale is very coarse, and although the mike is metric, the coarse scale lets me easily read down to the metric equivalent of.0002".

When I get measurable expansion on that mike, I back off.5gn to 1gn. My old Speer manual says back off 5%, but in my experience (and ONLY my experience) 5% is unnecessarily conservative. I can tell from my components, my chrono, and my rifle that the loads with measurable expansion are definitely getting up there, although MAYBE still quite safe albeit hard on brass. When I refer to the chrono, I am not usually referring to the raw velocity, but to how things are reacting as the charge increases.

I use only ADI/Hodgdon and do not usually hunt in hot places, although I have used my loads in Charters Towers in February with no issues.
Very very interesting and thankyou for the detailed post.
When you say say blade mic, do you mean caliper?
I already have a Mitutoyo digital caliper.
Is that suitable?
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Re: 7x64 RWS 173 Grain

Post by secondtry »

A blade mic. is a micrometer with the two opposing anvils resembling thin screwdriver blades. This lets one measure in very narrow places, such as a case head in front of the groove, but still behind the point at which the case body expands.

A caliper would let you get into the same place, but I do not think would be sensitive enough in it's measuring capability.

Some trickery in the construction of the blade mic.means that the two blades do not spin when the mic. is wound in and out, and stay aligned with each other during measurements and adjustments.

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Re: 7x64 RWS 173 Grain

Post by 9.3x64 »

secondtry wrote:A blade mic. is a micrometer with the two opposing anvils resembling thin screwdriver blades. This lets one measure in very narrow places, such as a case head in front of the groove, but still behind the point at which the case body expands.

A caliper would let you get into the same place, but I do not think would be sensitive enough in it's measuring capability.

Some trickery in the construction of the blade mic.means that the two blades do not spin when the mic. is wound in and out, and stay aligned with each other during measurements and adjustments.
Thanks Iain.
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Re: 7x64 RWS 173 Grain

Post by 9.3x64 »

Well. I had a very interesting day at the range today. I took Corjacks lead and also bought a strap on. What a wonderful bit of gear it is.
It turns out that my above load is not shooting anywhere near 2750fps as listed in Nick Harveys reloading manual. A four shot average was only 2318 fps!
This is a maximum load in this manual but was extremely soft to shoot in my brothers R8 and showed absolutely no signs of visible pressure or measured case head expansion.
So I tried one shot of each of the below.
52.5 - 2428 fps
53 - 2392 fps
53.5 - 2430 fps
54 - 2480 fps
54.5 - 2475 fps
I took my time with my brother and double checked each case. There was absolutely no case head expansion to .0001 and primers look the same as all the other lighter loads.
We would like a load that equals the factory load which we also measured today at 2623 averaged over four shots.
If we watch closely for signs of pressure can we try another .5 -1 grains?

Also why would a reloading manual list a 52 grain max for 2750fps and we are only getting 2318?
Thankyou in advance
Allan.
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Re: 7x64 RWS 173 Grain

Post by 9.3x64 »

Has anyone else noticed such an extreme differance between published maximum loads and chronographed loads when loading for their R8?

2318 fps vs 2750 fps seems pretty extreme to me?
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