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6.5 STW with peak strain measurements
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<grkldoc>
posted
I just received my fabrique scientific peak strain meter and tried this out on some of my loads. This is quite an interesting gadget and when combined with QuickLoad information makes wildcatting a much safer affair.
With todays polished chambers sticking is less common. Primer morphology, I have found, doesn't indicate pressure well when less than 65000psi. At least I couldn't see any difference in the following load data. This makes it difficult to understand how hot a load is especially a wildcat with little loading data available.
Quickload is of some value but you never know when its going to be way off. I have seen it under represent pressure by as much as 15000psi. Therefore, some measure of relative pressure is invaluable. Here are my initial results.

Materials:
Action: Win M70
Barrel: Pac-Nor SST super-match grade, 28",#7 contour
Chamber: 6.5 STW, 98.3 grains of water, neck.296
Cases: Remington OAL= 3.500(.020 off the lands)
Bullet:120gr. Nosler Ballistic tip
Powder: H870
weight Vel MOA Peak Chamber pressure
82gr 3127 .336 51000psi
84gr 3238 1.298
86gr 3279 1.928
88gr 3330 .532
89gr 3397 1.180
90gr 3506 1.904 62700psi
The last value is 1500psi less than that predicted by QuickLoad. Next I will try 91 grains H870 hoping to improve the accuracy(there is definitly a trend here). That should top me off at maximum.

More to come later(I'm going to check out the lost river ballistics 120gr hunting bullet Ballistic Coefficient 0.687).

[This message has been edited by grkldoc (edited 03-16-2002).]

 
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<grkldoc>
posted
Here is some more information for anyone interested in this type of wildcat:

120 gr Nosler Ballistic tip OAL 3.520
H1000
76gr 3377fps 62500 psi poor accuracy
78gr 3500fps 67500 psi poor accuracy

H870
91gr 3575fps 65500psi poor accuracy

WC860 (.008 off the lands)
83gr 3019fps 44000 psi
89gr 3267fps 51000 psi
92gr 3547fps 66300 psi .64" group (6 shot group)

H50BMG
80gr 50000psi
84gr 3410fps 64000psi
85gr 66500psi

120gr lost river ballistic J36 solid bullet design BC=.687 OAL= 3.595

H870
85gr 3430fps 55000psi
86gr 3485fps 59000psi
87gr 3505fps 60500psi
88gr 3521fps 63000psi
89gr 3597fps 66000psi .52" group 4 shots

H50BMG
86gr 3550fps 73500psi .8" group

140gr Hornady AMAX OAL=3.585
WC860
80gr 3136 fps 56000psi
84gr 3205 fps 60000psi
86gr 3255 fps 62500psi

[This message has been edited by grkldoc (edited 01-28-2002).]

 
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<grkldoc>
posted
Here are the ballistics for the 120 gr. Lost River Ballistics bullet with 89gr. of H870. Muzzle Velocity=3608fps Muzzle energy= 3470foot*pounds. Ballistic data from quick target/quick load

Trajectory
100 200 300 400 500 600
0.4 0.0 -3.6 -10.7 -21.6 -36.8
3.1 5.3 4.4 0.0 -5.8 -15.5

Velocity
100 200 300 400 500 600
3452 3303 3156 3016 2880 2748

Energy
100 200 300 400 500 600
3176 2906 2656 2425 2211 2013

This bullet-powder combination has more retaineed energy than many maximum 338 magnum loads at 600 yds (Nosler reloading manual). The recoil is negligible in comparison.

[This message has been edited by grkldoc (edited 02-05-2002).]

 
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one of us
posted Hide Post
grkldoc, how much are the fabrique scientifique peak strain meter and where can I purchase one? Are you doing any more research with different cartridges?
 
Posts: 1935 | Registered: 30 June 2000Reply With Quote
<grkldoc>
posted
Sorry for the wait but I havn't checked the board for a while.

www.fabriquescientific.com

They will get it to you in 3-5 days. Its pretty easy to set up. You will have to "crazy glue" a strain gauge to your barrel. Make sure the gauge is completely glued down without air pockets. Use some "Glad" cling wrap or similar product to protect your finger. You'd rather not leave skin on your barrel.

I have used this set up on my 25-06 as well with good results. Keeps me out of trouble.

The cost of the meter is around $150 strain gauges with the connector wire soldered on already is $14 per gauge. I think 5 gauges and meter with software was about $220. For me well worth it.

[This message has been edited by grkldoc (edited 03-16-2002).]

[This message has been edited by grkldoc (edited 03-16-2002).]

 
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<Aussie Hunter>
posted
grkldoc,
This Lost River 120gr projie. sound very cool.
How long is the proj. and what shape is it?
Do you have a dig. photo (or one off a flat-bed scanner. That is one hell of a BC!
I have a 260 Rem, and I am always looking for new proj. to experiment with. Even if I have to hand feed them into the chamber.
Thanks,
Aussie Hunter
 
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<grkldoc>
posted
You can find a description of these Lost river ballistics bullets on their website. www.lostriverballistic.com. You will find many different calibers available with outragous BC's. They are expensive but for long range game hunting you don't need too many.

Have fun!!

 
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