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Post by rangeball on Dec 6, 2011 12:40:36 GMT -5
Say you were looking for a .50 load for a 250gr bullet and wanted the most FPS possible while keep pressure as low as possible to ensure consistent ignition and temp stability.
What would you use?
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Post by edwardamason on Dec 6, 2011 13:05:30 GMT -5
Say you were looking for a .50 load for a 250gr bullet and wanted the most FPS possible while keep pressure as low as possible to ensure consistent ignition and temp stability. What would you use? Im going to be curious about the responses you get too. Ive been experimenting around with some of the light loads listed on this site. Vitavori n110 34 gr to be exact and getting excellent groups. I am told this load is getting probably around 1900 FPS but no way to tell for sure without a Crony. I would love to know what someones guestimate/estimate is on the pressure of this round. Ive also been told Rel 7 gets more FPS with lower pressure traces. Going to have to test that out this weekend. |
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guppy
8 Pointer
hunting buddy
Posts: 191
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Post by guppy on Dec 6, 2011 13:13:01 GMT -5
RB did a trace with 70 and 81gns of H322. It is in the tips and hints section under powders and Pt's. 2450@81gns and 30kpsi it was only 20kpsi @ 70 which he didn't think was reliable for consistent ignition. Maybe a good low pressure load to duplex??
oh, and sorry rangeball. The package I was supposed to send to you got lost in my wife's purse. It is on it way now.
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Post by rangeball on Dec 6, 2011 14:20:10 GMT -5
RB did a trace with 70 and 81gns of H322. It is in the tips and hints section under powders and Pt's. 2450@81gns and 30kpsi it was only 20kpsi @ 70 which he didn't think was reliable for consistent ignition. Maybe a good low pressure load to duplex?? Thanks. Duplex is fine if someone wants to offer some suggestions. No problem, sounds like our wives shop at the same store  |
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Post by jdmax on Dec 6, 2011 15:02:30 GMT -5
I am using 65gr n120 with knurled 250 barnes tmz with supplied yellow sabot. In 70 degree weather it gets 2566fps and great accuracy. In 30 degree weather it gets 2518 fps. Going to try to work up in colder weather this winter and see what happens.
JDMAX
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Post by rangeball on Dec 6, 2011 15:05:53 GMT -5
jdmax, any idea what pressure it's generating?
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Post by jdmax on Dec 6, 2011 15:15:28 GMT -5
No, I was going off of RB's powder by bullet weight post. He suggested 65-69grs of n120 With 250gr bullets. I have never had sabot problems with load. This load in my 50 is the most consistent shooter of any guns I own. 7/8" at 100 with 3 shots and no poi change.
JDMAX
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Post by TGinPA on Dec 6, 2011 16:17:08 GMT -5
Rangeball: I tried briefly to look at this for my 45cal barrel. IMO, one has to look at it for each specific bullet weight in terms of psi/fps. Since May, on most of the traces I have posted, this number can be calculated. And so for a while, I did. From a excel spreadsheet looking at 65 loads of N110, N120, 4759, 5744, RL7, RL10x,H4198, H322, IMR4895, and 4227, I recorded the following:
For a 200gr bullet, RL7 65gr was “best” (lowest psi/fps ratio) at 10.7 psi/fps (range: 10.7-15.7), (Mv=2620 PeakP=28000). Also for 200gr bullets a duplex 4759/RL7 11/57gr gave 10.9psi/fps (second best),(MV=2781, PeakP=30350). For a 250gr bullet, the “best” was a load of RL7 65gr giving 9.2psi/fps (range: 9.2-16.1), (MV=2400, PeakP=22000). For 300gr bullets, the “best” was a load of RL7 which 65gr, gave 16.6psi/fps (range: 16.6-20.9) (MV=2522, PeakP=41845). I concluded the following:
1) Singles, particularly RL7 generally have the lowest psi/fps ratio.
2) As a rule, duplexing increases psi/fps ratio.
3) With light for caliber bullets, some of the highest velocity most accurate loads are duplexes. That suggests that maybe a low psi/fps ratio is not necessarily a very good indicator of the factors comprising the best loads, at least in some cases.
4) 65 data points with so many possible different bullet/powder combinations is way too few. IMO, to make sense out of this, literally thousands of simultaneous recordings of pressure and velocity would be necessary. After looking at this for a while, I decided looking at the psi/fps ratio wasn’t a productive use of my time and quit.
TG
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Post by rangeball on Dec 6, 2011 16:24:52 GMT -5
Thanks. I did go through your past PT threads but nothing for the .50 jumped out at me.
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Post by Dave W on Dec 6, 2011 17:32:15 GMT -5
Which bullet?
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Post by edwardamason on Dec 6, 2011 22:50:04 GMT -5
I would've interested in the xtp 250 |
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Post by rangeball on Dec 7, 2011 9:59:56 GMT -5
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Post by Dave W on Dec 7, 2011 12:42:59 GMT -5
For the 250 TEZ, I would try a 13/62 N110/H322 ratio. Velocity with a Har LB and a very tight knurl resulted in nearly 2700fps. Accuracy sub 3" @ 200yds IF it did not blow sabots, may need to alter the ratio in your gun.
For the XTP, a similar ratio to the TEZ, possibly 14/61 N110/H322, velocity will likely be close to 2600fps. I prefer a 70gr duplex with the 250FTX @ 2600fps, likely slightly higher pressure, but less affected by temps than the 75gr duplex.
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Post by rangeball on Dec 7, 2011 12:45:25 GMT -5
Dave, any idea of the psi of those loads?
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Post by Dave W on Dec 7, 2011 13:03:42 GMT -5
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Post by rangeball on Dec 7, 2011 14:14:58 GMT -5
Thanks Dave, very helpful |
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Post by TGinPA on Dec 7, 2011 16:36:49 GMT -5
Pressure Traces: 50cal, N110 and 250xtp Edwardmason: Here are a few traces with a 250xtp .452in (hrcr, fed209 primer) and varying loads of N110 in the range you requested. The PT setup has been completely described in earlier threads. On T3, maybe due to bad light, I didn’t get a velocity. Calibration of the gage on my 50cal barrel is still a work in progress. Comparing these traces with RB's data, they may be 1-2kpsi lower than some of his. As he stated, some of his traces of the same load varied by this much depending on gage placement on a barrel and less than perfect measurement of barrel dimensions. These loads were safe in my barrel but may not be so under other conditions. For more velocity, your best bet is to go to slower powders either as singles or duplexes with 250gr bullets as suggested above. Next, I may try to trace RL7 with 250gr sabotted bullets in 50cal. TG  |
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Post by edwardamason on Dec 7, 2011 16:41:43 GMT -5
Pressure Traces: 50cal, N110 and 250xtp Edwardmason: Here are a few traces with a 250xtp .452in (hrcr, fed209 primer) and varying loads of N110 in the range you requested. The PT setup has been completely described in earlier threads. On T3, maybe due to bad light, I didn’t get a velocity. Calibration of the gage on my 50cal barrel is still a work in progress. Comparing these traces with RB's data, they may be 1-2kpsi lower than some of his. As he stated, some of his traces of the same load varied by this much depending on gage placement on a barrel and less than perfect measurement of barrel dimensions. These loads were safe in my barrel but may not be so under other conditions. For more velocity, your best bet is to go to slower powders either as singles or duplexes with 250gr bullets as suggested above. Next, I may try to trace RL7 with 250gr sabotted bullets in 50cal. TG Man thats exactly the information I was looking for. You do man. Please let me know what you find out with the Rel7 as I am wanting to see how that pans out for you. |
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Post by edwardamason on Dec 7, 2011 16:59:41 GMT -5
Looking at some of the previous posts it seems dropping down from 44 gr to 39 gr lowers the PSI considerably without much loss of FPS. Maybe even less than 100 FPS depending on what the reading would have been with T3.
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Post by Dave W on Dec 7, 2011 20:23:58 GMT -5
Thanks TG, any chance you could do a comparison of a 75 vs 70 gr duplex in the 50 cal?
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Post by TGinPA on Dec 8, 2011 17:23:05 GMT -5
Pressure Trace: Two N110/H322 250ftx duplexes. DaveW:Not only is there a chance - here it is. This is a PT comparison of 70gr and 75gr N110/H322 duplex loads, both achieving 2600fps with a sabotted 250ftx bullet. Both may be near pressure levels at which sabot disruption might occur. So, neither may necessarily do well at high temperatures without reduction in powder volume. Also, it might be useful to see comparisons of relative velocity loss of each duplex at low temperatures to determine which is best for that use? TG Gage and Module Manufacturer = RSI Bluetooth model Trigger Sensitivity = 5, Strain Gage Voltage =5.096 Gage Factor =2.11). Rifle Stand: Caldwell Lead Sled. Altitude: 450 ft Chronograph: Chrony Alpha Model 8 ft from muzzle. (13 fps added to all recorded velocities to correct for distance of chrony from muzzle.) Barrel Type: Savage 50cal Cal Muzzleloader Barrel OD = 1.03 in Barrel ID = .502 Breech Plug:Savage Std. (screw-in ventliner) ventliner orifice .032 in. Sensor dist fm BP=.58in Bullet Diam.= .452in. Bullet Type = Hornady .452 250gr ftx unknurled. Sabot: Harvester RCR. Powder: Trace 1:N110/H322 14/64gr. Trace 2:N110/H322 23/47gr. Primer: Fed209A Shot fm dirty barrel. This load seemed safe in my barrel under the test conditions but may not be so in other conditions.  |
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Post by Dave W on Dec 8, 2011 18:39:26 GMT -5
Thanks Ralph, much appreciated.
Velocities are pretty close to my results also.
I checked my notes and the last two times I timed the 70 gr duplex, averaged 2585fps@ 70* and 2575fps@ 17*.
It does flare the sabot bases pretty severely, but no failures.
Thanks again.
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