7x64 RWS 173 Grain

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Saugmann
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Re: 7x64 RWS 173 Grain

Post by Saugmann »

Vaughan wrote:I'm not sure if this QL data is helpful or if I've put your data in correctly and I've NEVER loaded this caliber so I could have screwed this up so please be careful with this data!

If you want specific changes, I'm happy to rerun this.....

Hope it helps anyway... :doh: :lol:
Hi again,

I've run the load in QL as well and get similar numbers to Vaughn, for what it's worth.

The difference as far as I can see is that I've used the measured case capacity for my own RWS cases, which is 66.6 gr H2O.

I get an MV with your measurements of 2612 fps.


Regards,

Christian



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Re: 7x64 RWS 173 Grain

Post by 9.3x64 »

Saugmann wrote:
Vaughan wrote:I'm not sure if this QL data is helpful or if I've put your data in correctly and I've NEVER loaded this caliber so I could have screwed this up so please be careful with this data!

If you want specific changes, I'm happy to rerun this.....

Hope it helps anyway... :doh: :lol:
Hi again,

I've run the load in QL as well and get similar numbers to Vaughn, for what it's worth.

The difference as far as I can see is that I've used the measured case capacity for my own RWS cases, which is 66.6 gr H2O.

I get an MV with your measurements of 2612 fps.


Regards,

Christian
Thankyou Christian.
Why would Vaughan get 2660 fps and you get 2612 fps.
What am I missing?
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Re: 7x64 RWS 173 Grain

Post by Saugmann »

Hi,

Of Vaughn's two loads, one is 54 grains and one is 52 grains.

Vaughn's 52 grain load gives a muzzle velocity of 2564 fps. This load is based on the QL standard 7x64 case capacity of 69 gr H2O (4.43 cm3).

My 52 grain load with a muzzle velocity of 2612 is based on the average case capacity I measured for a batch of the RWS cases I use. I measured 66.6 gr H2O or 4.324 cm3.

The reduced volume in my load causes more pressure, which in turn creates faster MV (when the powder charge is the same).

I can't see any other differences between the two loads.


Regards,

Christian

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Re: 7x64 RWS 173 Grain

Post by 9.3x64 »

Very interesting.
I have read many times before that RWS brass is thicker and hence slightly less capacity. Your case capacity measurements support this.

I only chronographed one round of 52 grains on a hot Brisbane summer day and I got 2475 fps in my R8, considerably less than both yours and Vaughans quickload data. :think:

Interestingly RWS claim a velocity of 2624 fps for their factory load and I got a four shot average of 2623 fps for their factory load. :clap:
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Re: 7x64 RWS 173 Grain

Post by secondtry »

I wouldn't regard the difference between 2612 and 2660 as meaning anything much, except perhaps a descent into the anality that is typical of us handloaders :lol:

If your loads are getting within 50 to maybe 100 fps of RWS factory loads in your rifle, with accuracy and sensible pressures, you're doing well. Any velocity beyond that is a plus.

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Re: 7x64 RWS 173 Grain

Post by 9.3x64 »

secondtry wrote:I wouldn't regard the difference between 2612 and 2660 as meaning anything much, except perhaps a descent into the anality that is typical of us handloaders :lol:

If your loads are getting within 50 to maybe 100 fps of RWS factory loads in your rifle, with accuracy and sensible pressures, you're doing well. Any velocity beyond that is a plus.
I think the differance between 2612 and 2660 is completely understandable...differant case capacity of RWS brass :D
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Re: 7x64 RWS 173 Grain

Post by Gun Barrel Ecologist »

Waiting for Oscar to chime in here, but from memory Geco & S&B cases in this round both have vastly different capacities as well.

Looking back at chrony results and noting that n=1 on each charge, the lack of a uniform upward progression in velocity is a worry. In fact when I was last chronying a .45 B load I chickened out on my last 5 rounds with the most powder as the second highest charge wasnt yielding greater velocity than my third highest but the extra half a grain could be felt on the shoulder :think:
9.3x64 wrote: 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.

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Re: 7x64 RWS 173 Grain

Post by 9.3x64 »

Gun Barrel Ecologist wrote:Waiting for Oscar to chime in here, but from memory Geco & S&B cases in this round both have vastly different capacities as well.

Looking back at chrony results and noting that n=1 on each charge, the lack of a uniform upward progression in velocity is a worry. In fact when I was last chronying a .45 B load I chickened out on my last 5 rounds with the most powder as the second highest charge wasnt yielding greater velocity than my third highest but the extra half a grain could be felt on the shoulder :think:
9.3x64 wrote: 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.
That is a very useful observation GBE.
The only thing I can say is those velocities were one shot velocities and not three shot averages.
However after reading what you have said I think I will start my next load development session at 54 grains again and work up from there measuring velocity from a three shot average and checking for signs of pressure on three cases not just one.
Thankyou.
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Re: 7x64 RWS 173 Grain

Post by secondtry »

I also noticed the lack of any uniform progression in the velocities as the charge weight was increased, BUT in these circumstances, I think it more likely to be an indication that pressure was insufficient to get a uniform burn, rather than that max is approaching, or has been reached.

Lack of progression can be an indication that things are getting up there, but your data does not conclusively suggest that to me.

I have experienced similar behaviour to what you report under similar circumstances, in a range of calibres, when initial loads have been very soft. Then as the charge has been increased, progression has started. I have also experienced exactly what GBE has described at the top end, although usually, I see progression over a wider window than what you are reporting before velocity flat lines.

If you follow your plan in .5gn steps, chronoing and measuring as you have been, you should quickly and safely find out if you have room to move past 54/54.5 or not.

Some projectiles also seem to me to build pressure over a narrower window than some others. I have no experience with the projectile that you are using, but this may also be a factor at play.
Last edited by secondtry on Fri Jan 06, 2017 8:08 pm, edited 1 time in total.

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Re: 7x64 RWS 173 Grain

Post by 9.3x64 »

secondtry wrote:Then as the charge has been increased, progression has started.
It will be very interesting to see if this happens with small increments in powder.
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Re: 7x64 RWS 173 Grain

Post by 9.3x64 »

Blaserbuds is a great forum.
So much expirience from all over the world freely shared without all the bullshit and arguing of many other forums.
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Re: 7x64 RWS 173 Grain

Post by secondtry »

You should see it with .5g steps, although it may not be as marked as with bigger increments.

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Re: 7x64 RWS 173 Grain

Post by Vaughan »

9.3x64 wrote: I only chronographed one round of 52 grains on a hot Brisbane summer day and I got 2475 fps in my R8, considerably less than both yours and Vaughans quickload data.
It's obvious, I know, but it is worth remembering QL is calculating aid to reloading, a very good one I believe, but just a tool and the pressures and velocities are based on equations not exhaustive physical measurements for all calibers and combinations.

I find it very useful for selecting starting powder and projectile combinations and figuring out initial loading ranges etc. It rarely comes in on the money with respect to MV. The exception there seems to be my 6br, for which it seems to calculate MV with surprising accuracy. For my 9,3, not so good (always a good deal higher than actual).

I also find it to be fairly conservative. My old 308 loads based on Hodgdon data and working up etc should have detonated my R93 if QL and the internet was to be believed. After buying QL from Pigeon I backed those loads off a bit even though I did not believe they were dangerous in my rifle. I figured it didn't hurt to be careful. QL seems to match up OK with Norma factory data in the 6br and 9,3.... This drivel being a long winded way of saying I'm not too surprised by those differences.

One thing that you might not think of (apologies if its obvious) - if you are getting up toward max pressures be very careful with messing about with seating depth. If you're near max pressure and you shorten your COAL you can push your load over safe limits fairly easily.
/Vaughan

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Re: 7x64 RWS 173 Grain

Post by Vaughan »

Others have mentioned this before but one other thing to ask yourself when pushing for those last 100 or 50fps - is the deer going to notice?? In my own limited experience, the answer to that question is usually an emphatic NO. So if the velocities achieved produce an accuarate round that enables the bullet to perform as designed in the game you target at the ranges you will shoot - is it worth pushing your rifle to its max specs? I'm not saying you shouldn't (or that I don't) but you should at least ask yourself that question before pushing your kit hard.
/Vaughan

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Re: 7x64 RWS 173 Grain

Post by 9.3x64 »

Vaughan wrote:
One thing that you might not think of (apologies if its obvious) - if you are getting up toward max pressures be very careful with messing about with seating depth. If you're near max pressure and you shorten your COAL you can push your load over safe limits fairly easily.
Thanks Vaughan.
Certainly a piece of advise worth keeping in mind..
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