RC1 Posted July 29, 2004 Share Posted July 29, 2004 Hi, I am a first year shooter and am preparing for an up coming sectional match. I have been double-checking my load to ensure that it makes major. Got a new batch of powder and have been working with it the last couple of days and I thought that I have got it about where it should be. This morning I tested my results and found that it was shooting just at a 168 PF. That is just what I was trying to accomplish, I went about zeroing my gun and doing a little practice. Before going home I thought that I would crono them again just to make sure. After the gun had been shot a bit and gotten hotter the velocity dropped from 1348 fps to 1326 fps which just makes major. Is this normal? Is there a problem that I don't know about? Should I adjust my load a bit hotter so as to make sure I make major? I would appreciate any help. Thanks Rick Link to comment Share on other sites More sharing options...
short_round Posted July 29, 2004 Share Posted July 29, 2004 What powder are you using? Link to comment Share on other sites More sharing options...
uscbigdawg Posted July 29, 2004 Share Posted July 29, 2004 What's got me curious is that for a 168 PF and a 1348 muzzle velocity, your bullet weight is 124.62 grains. Are you using a 125 by chance? Just curious. If so, at 1326, you're at 165 PF. I wouldn't sweat it. That's 22 fps (i.e. less than 2% drop in velocity) and you're still making major (although barely). My guess is a bad powder charge. If you're really concerned, drop another .2 grains of powder in and you're good to go. However, as short_round (a.k.a. "The Answer" ) has asked what powder? What bullet? What chrono? Rich Link to comment Share on other sites More sharing options...
RC1 Posted July 30, 2004 Author Share Posted July 30, 2004 Thanks I am using 9.3 3n38, zero 125 jhp, wsrp, 1.160 OAL, win brass These were 5rnd groups. Before practice: 1347, 1351, 1342, 1347,1353. SD 4.2 After practice: 1324, 1326, 1325, 1314, 1328. SD 7.7 Thanks Rick Link to comment Share on other sites More sharing options...
tightloop Posted July 30, 2004 Share Posted July 30, 2004 don't be too concerned....read Benos post on chrons...he does 5 strings of 20 shots each and readily admits that sometimes the chrony results are VooDoo.... Keep after it... Link to comment Share on other sites More sharing options...
Yardbird Posted July 30, 2004 Share Posted July 30, 2004 I have seen hot guns chrono slower than cold guns. Very curious. Just make sure you have a bit of a PF cushion just in case. Link to comment Share on other sites More sharing options...
dajarrel Posted July 30, 2004 Share Posted July 30, 2004 Because of the Voo-Doo, I try to load to 170pf. I'm not enough of a connoisseur to notice the difference between 165 and 170 without shooting them back to back and once again, it's all in what you get used to. At 170, I feel pretty comfortable walking up to most any chrono stage and passing with flying colors. technically speaking, (sounds good doesn't it ) when your barrel heats up enough, it will expand which will cause your bullet to actually pass more gas......This isn't going where I thought it would so I will just stop Anyway, as our host and others have said, it's VooDoo dj Link to comment Share on other sites More sharing options...
blkbrd Posted July 30, 2004 Share Posted July 30, 2004 My load with 320 drops about 3-4 PF from a cold gun to a hot gun? Link to comment Share on other sites More sharing options...
RC1 Posted July 30, 2004 Author Share Posted July 30, 2004 Thanks guys for the help. I'll just kick up my powder a tad and call it good. Thanks again. Rick Link to comment Share on other sites More sharing options...
Chriss Grube Posted July 30, 2004 Share Posted July 30, 2004 AET Barrel? Had the same problem with Hornady bullets. Switched to FMJ Zero's and the problem went away. I think the barrel heats up and then the base of the bullet doesn't seal as well since it is totallt enclosed. The FMJ's seem to expand the base of the bullet and gets a consistent seal. Other problem could be sun angle with the Chrono. Now I only use the IR screens. Link to comment Share on other sites More sharing options...
steve223 Posted July 30, 2004 Share Posted July 30, 2004 My AET.Barrel in my open gun drops a few FPS when its warmed up also. like every one said just give your self a little cushion so you dont worry about it. Steve Link to comment Share on other sites More sharing options...
schmitz Posted July 31, 2004 Share Posted July 31, 2004 I have seen hot guns chrono slower than cold guns. Very curious. Just make sure you have a bit of a PF cushion just in case. Curious?? Hotter barrel..more expanded, less friction...curious?? Lower pressure...,??? Fysics??? Henny Link to comment Share on other sites More sharing options...
Vern Posted August 2, 2004 Share Posted August 2, 2004 Interesting! I ussually see a slight increase in velocity as the gun heats up (also on very hot days). I've switched powders and the problem went away. Link to comment Share on other sites More sharing options...
bigg_jon Posted August 3, 2004 Share Posted August 3, 2004 Interesting! I ussually see a slight increase in velocity as the gun heats up (also on very hot days). I've switched powders and the problem went away. I see the same thing. Only my slight increase is like 50-60fps. Powder is W231 in .45acp loads. I'm gonna try a different powder and see what happens. Hopefully I can get this down to about 20fps. -jon Link to comment Share on other sites More sharing options...
RC1 Posted August 5, 2004 Author Share Posted August 5, 2004 I have done some more testing and I am beginning to believe that it has more to do with the sun angle than anything else. Rick Link to comment Share on other sites More sharing options...
J.L. Hardy Posted August 5, 2004 Share Posted August 5, 2004 rick, listen to the advise and load to 170 pf. that gun will shoot flatter at 170 and you won't have to worry about the chrono stage. i run mine at 172 all the time and we are shooting the exact same setup. good shooting, j.l. hardy Link to comment Share on other sites More sharing options...
RC1 Posted August 5, 2004 Author Share Posted August 5, 2004 J.L., Thanks, I did just that and my load setteled out at a P/f of 171.5. Thanks again. Rick Link to comment Share on other sites More sharing options...
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