atbarr Posted July 22, 2009 Share Posted July 22, 2009 (edited) I went to the range today. The load was Zero 147 gr JHP. The powder charge is 3.8 gr of Solo 1000, and the primers are Win small pistol magnum. With my M&P FS (4 1/4" barrel), I got 875 FPS. More than enough for minor. In fact, I bet 3.6 gr will make minor. Any thoughts on this? But, with my 5" Trojan, the same load gave 1275 fps. 400 fps more! That is well above major PF. I did not see any problems with the primers. I shot each pistol 5 times through the chronograph. The RO and I was amazed with the increased fps, between the two pistols. Anyway, to get the fps down to 1000 fps, what should I drop the charge to? Would dropping the charge to 3.4 gr be enough? I'm going back tomorrow and thought I'd bring 10 @ 3.4 gr, 10 @ 3.2 gr,and 10 @ 3.0 gr. Does this sound right? Help please. Thanks, A.T. Edited July 22, 2009 by atbarr Link to comment Share on other sites More sharing options...
Dan Hefta Posted July 22, 2009 Share Posted July 22, 2009 Longer barrel + tighter fit = more muzzel velocity. I don't know what else could explain this. Link to comment Share on other sites More sharing options...
Tom E Posted July 22, 2009 Share Posted July 22, 2009 That's too much difference. How close to the chrono were you? Too close and the muzzle blast can affect your reads. Link to comment Share on other sites More sharing options...
BritinUSA Posted July 22, 2009 Share Posted July 22, 2009 My guess is recoil spring. A heavier spring will increase FPS. Link to comment Share on other sites More sharing options...
rvb Posted July 22, 2009 Share Posted July 22, 2009 That's too much difference. How close to the chrono were you? Too close and the muzzle blast can affect your reads. this was my first thought as well. -rvb Link to comment Share on other sites More sharing options...
atbarr Posted July 22, 2009 Author Share Posted July 22, 2009 That's too much difference. How close to the chrono were you? Too close and the muzzle blast can affect your reads. I was right at 10'. A.T. Link to comment Share on other sites More sharing options...
atbarr Posted July 22, 2009 Author Share Posted July 22, 2009 My guess is recoil spring. A heavier spring will increase FPS. The M&P has the stock spring, the Trojan has a Wolff 10 lb. spring. Link to comment Share on other sites More sharing options...
MoNsTeR Posted July 22, 2009 Share Posted July 22, 2009 Has to be a chrono issue, there's no way the difference between two guns could be that much. I would be shocked if you could gain 400fps by going to a 16" barrel much less 5". Link to comment Share on other sites More sharing options...
UW Mitch Posted July 22, 2009 Share Posted July 22, 2009 Shooting an open gun through the chrono I found a bunch of inconsistency due to muzzle blast. Had to stand further back for things to settle out. ~Mitch Link to comment Share on other sites More sharing options...
Tom E Posted July 22, 2009 Share Posted July 22, 2009 That's too much difference. How close to the chrono were you? Too close and the muzzle blast can affect your reads. I was right at 10'. A.T. Try it farther away. 10 ft is iffy, 15' is usually no problem. Link to comment Share on other sites More sharing options...
NoSteel Posted July 22, 2009 Share Posted July 22, 2009 This looks like a muzzle blast issue. Ran into this myself last week. 10ft should be enough distance but with those kinds of numbers it would be tough to believe, sounds like the cases/primers also indicate these readings are false. Just curious, did the chrono have the shades on it?? I was getting erratic readings due to having the shades on when they were not needed. Pulled them off and my readings were spot on... Course, I'm running the cheapest chrono I could find... Link to comment Share on other sites More sharing options...
MikeFoley Posted July 23, 2009 Share Posted July 23, 2009 AT, take another chrono session, at 15' like recommended above. There will be a difference in the two, but not this much. Take your test loads, and take some factory too. Make sure the battery is fresh, and make sure the light is consistent. Zero the memory of the chrono, or write down every shot by hand. Use an aiming point that consistently puts the rounds through at the same height. I think 9 pound ISMI will be a better spring FWIW. Also, don't get hung up on getting the PF too low, you have enough mass, and enough experience to run well above the PF floor, and you may need to run one at 135 PF or so, and the other a bit higher IMO. I think your next results will be much closer. Link to comment Share on other sites More sharing options...
atbarr Posted July 23, 2009 Author Share Posted July 23, 2009 Hello people, that's for all the replies. The shades were on and it was raining lightly. I'll go out tomorrow. Thanks A.T. Link to comment Share on other sites More sharing options...
Tom E Posted July 23, 2009 Share Posted July 23, 2009 Hello people, that's for all the replies. The shades were on and it was raining lightly. I'll go out tomorrow.Thanks A.T. Raining lightly can really screw things up. Not a good time to be trying to chrono. Link to comment Share on other sites More sharing options...
MemphisMechanic Posted July 23, 2009 Share Posted July 23, 2009 Come back and let us know what the difference was the second time! We get tired of cliffhanger threads... Link to comment Share on other sites More sharing options...
G-ManBart Posted July 23, 2009 Share Posted July 23, 2009 With my M&P FS (4 1/4" barrel), I got 875 FPS. More than enough for minor. In fact, I bet 3.6 gr will make minor. Any thoughts on this? I sure have thoughts on it. 128PF isn't enough and it definitely isn't enough if the sample size is only 5 shots. I like 10-20 shots per string, do more than one string each time, test on different days, in different temps and lighting before I really trust a load. My normal Open Major load went between 173 and 175PF at three or four major matches last year. The exact same load, same batch of ammo, same everything went 166.1PF at Nationals With Minor, if you don't make it, you're shooting for fun and that would be no fun at a big match. Bump it up to somewhere between 130PF (minimum) and 135 and enjoy not worrying....you shouldn't feel any difference at all. There was some sort of chrono/lighting issue when you tested the Trojan....no way it'll gain that much. 100fps after factoring in the longer barrel and individual variation between guns would be reasonable, not 400fps. R, Link to comment Share on other sites More sharing options...
G-ManBart Posted July 23, 2009 Share Posted July 23, 2009 My guess is recoil spring. A heavier spring will increase FPS. Have you tested that extensively to get solid data? Like chrono a hundred rounds with one spring, swap springs and run another hundred rounds...or something along those lines? I'm just curious how much difference it could actually be since all the high speed video I've seen has the bullet leaving before the slide has moved more than a tiny bit. I'm not saying it won't make a difference...just wondering if you/anybody has ever tried to quantify it. R, Link to comment Share on other sites More sharing options...
atbarr Posted July 23, 2009 Author Share Posted July 23, 2009 Hello people, it was the cloud cover and the light rain that was causing trouble. Today, the 3.8 gr in my 1911 had an average of 910 fps, and the M&P had an average 895 fps. 3.6 gr had a average of 865 fps, so I'll go with that for USPSA and IDPA. Thanks for all the replies and help. A.T. Link to comment Share on other sites More sharing options...
Dan Burwell Posted July 23, 2009 Share Posted July 23, 2009 AT, I am going to have to pile on with G-man here; an average PF of 127 isn't good enough. I don't like to go by averages, I go by my lowest. My lowest has to be 130. That way if I hit chrono and by pure $hitty luck they fire my 3 lowest rounds I will still make it. I acutally take a bit further and find out what condiditions makes my PF drop and wil make sure even under those my lowest isn't under 130. Link to comment Share on other sites More sharing options...
atbarr Posted July 23, 2009 Author Share Posted July 23, 2009 AT,I am going to have to pile on with G-man here; an average PF of 127 isn't good enough. I don't like to go by averages, I go by my lowest. My lowest has to be 130. That way if I hit chrono and by pure $hitty luck they fire my 3 lowest rounds I will still make it. I acutally take a bit further and find out what condiditions makes my PF drop and wil make sure even under those my lowest isn't under 130. To be honest, I've only loaded maybe 150 rounds on my 550. I agree, a PF of 127 is pushing my luck. In October, my club is having the "Battle in the BlueGrass", I will have a load worked up to get a 130 PF. Many thanks, A.T. Link to comment Share on other sites More sharing options...
MemphisMechanic Posted July 24, 2009 Share Posted July 24, 2009 If you're going to be shooting in weather any warmer than the day you chrono... You might be in trouble. Someone on here mentioned that Solo1000 is reverse temperature sensitive (loses velocity as temperature RISES, not as it gets colder) and I decided to test it. It's true. My chrono results are in post 28 over here: http://www.brianenos.com/forums/index.php?...st&p=966545 Link to comment Share on other sites More sharing options...
atbarr Posted July 24, 2009 Author Share Posted July 24, 2009 If you're going to be shooting in weather any warmer than the day you chrono... You might be in trouble. Thanks, I'll watch for that. Today it was in the middle 70's, when it does get above 90 (not often ), I'll chrono again. so damn much to learn. Stay Safe, A.T. Link to comment Share on other sites More sharing options...
G-ManBart Posted July 24, 2009 Share Posted July 24, 2009 Hello people, it was the cloud cover and the light rain that was causing trouble. Today, the 3.8 gr in my 1911 had an average of 910 fps, and the M&P had an average 895 fps. 3.6 gr had a average of 865 fps, so I'll go with that for USPSA and IDPA.Thanks for all the replies and help. A.T. You're going to get burned with a 127PF baseline in theM&P....910-930 is more like it. It may not happen immediately, but it's gonna happen. Link to comment Share on other sites More sharing options...
atbarr Posted July 24, 2009 Author Share Posted July 24, 2009 yeah, I plan on getting around 910 fps out of my 1911 and the M&P. And then, whenever it gets above 90 degrees, I'll chrono those loads again. Many thanks to all, A.T. Link to comment Share on other sites More sharing options...
scheirere Posted July 24, 2009 Share Posted July 24, 2009 I've had a similar situation arise while chrono'ing ammo on my CED M1 chrono using the infared screens. Recently I was verifying ammo on my G34. 147 MGB typically ran ~900-910 fps. Occasionally I'd get a reading of 1300+ fps. But the recoil seemed the same. Usually I would just disregard the reading and continue. This time it started happening a lot. So a freind brought out another chrono (pro-chrono?). Same thing was happening with his. We finally figured out it was the way the sun was hitting the chrono. It was getting late and the sun was getting low behind us. We were able to setup some shade on my CED and it worked consistantly after that. Let's just say that now I have a better understanding of why they use the chrono boxes at big matches!! Link to comment Share on other sites More sharing options...
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