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OK just got back from the range and started to notice that the first shot of 4 is almost always slower then the next three . I work up loads in 4 shot increments cus thats what my mag holds . I noticed today My loads ES and SD were high-ish like most of mine are . No big deal , just something I need to work on I guess right ? hmm maybe not . So a guy comes over to me and ask if I'll shoot his rifle and loads through my chrono , I say sure bring it over . He brings over a Rem 700 with 4 different loads . He tells me he has never shot the loads through a chrono or any loads for that matter and just wanted to confirm some things . I shoot the first sting with a ES of 4.8fps and SD of 2. something . The next three were for the most part the same thing but one load had a SD of 8 fps . I'm thinking to my self this guys got it going on and I am doing something wrong . I then start looking at my data and could see that most of my loads are about the same as his if you throw out my first shot . The first shot of almost all my loads including the ones I came home and looked at as well , all clock slower then the rest buy 20fps-ish . That is throwing my spreads off ? or not if that is what it is and is normal ? I'm thinking it's one of two things . The barrel warms up and I get higher velocity's or the chamber is hot and that intern warms up the ammo . I do not chamber the next round until I'm ready to fire the next shot but it can take me 10 to 20 seconds to fire . Sometimes I lock in quick other times I readjust and sight again . I do not run a patch down the barrel between groups or do anything to the barrel at all . In fact I clean the bore very little . Maybe a quick boresnake every 150 to 200 rounds and a good cleaning every 4 to 5 hundred . What do you guys think is going on ? I'll give you the numbers if you want but I have no dwell times for how long the rounds stays in the chamber before firing . I really don't feel like I take a lot of time but I'm going to start clocking that as well . | ||
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Are you feeding from the magazine? If so maybe the rounds are being pushed back into the case, causes higher pressure = higher velocity most of the time. Consistency comes from many things with reloads, powder choice primer choice neck tension, and yes seating depth. Work to make all the little things the same, the chronograph will follow your efforts.  Member NRA, SCI- Life #358 28+ years now! DRSS, double owner-shooter since 1983, O/U .30-06 Browning Continental set. | |||
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308 Sako : Yes you are right and I will not discount it but the issue is consistent with the first round only . I have used 5 diferent powders ,3 bullets and 4 different cases in many diferent load combo"s . The fact I have used all of those different components but only get it the lower vilocity on the first shot seems odd to me . It is not 100% of the time . More like 70% . I just got the remote for my chrono and used it the last two times I shot . Now that I am cycling through all the data I notice the issue . It was there in my old notes but I had not broke it all down yet Now going back and looking at previous data I see I was getting the same thing . | |||
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The first shot in a COLD barrel will often be slower than consequent shots in a WARM barrel, this is due to tolerence differences in the steel, normally caused by inadequate heat treatment. If you find it a problem, take some fouling rounds with you. I do not understand, even from an earlier post of yours, why you do not clean your barrel for 4-500 rounds, as you lay all that carbon over copper etc, etc, it will be very difficult to remove and probably eroding the throat of that rifle prematurely. The copper deposits in the throat will be very thick after 500 rounds. Explain the purpose of this in terms I can understand, please. Thanks. | |||
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I think 416 R H is right about the barrel being the culprit, maybe it is ever so slightly loose, a few 10,000ths just enough to close up with some heat. Perhaps try cooling the barrel with ice after the first shot and some time for the chill to take effect. Then see how the numbers fall. I would also compare that to several other rifles in similar strings of fire. Member NRA, SCI- Life #358 28+ years now! DRSS, double owner-shooter since 1983, O/U .30-06 Browning Continental set. | |||
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First shot from a clean barrel is often slower. Once fouled velcity should settle. If you suspect that it's temperature try shooting shots 5 mins apart. | |||
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It happens, due to heat; especially with light barrels, but my question is; "how does it shoot?". You need not be concerned with that small of a variance. Clean your bore with some copper remover once in a while. | |||
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416 : Lets see If I can explain this better and find the video I got the idea from . Everybody has heard of shooting a few foiling shots through a clean bore . There must be a reason right ? Well it's my understanding it is to fill in any inperfections in the bore and that will get your rifle shooting more like it will from shot to shot . What I want is my rifle to shoot the exact same from the first shot of the day to the last shot . I then want to be able to put the gun up for a day , week , month what ever . When I take out and fire that first shot . I want it to shoot as close as the last time it was fired . That will not happen if I cleaned it in between outings . Now I understand that if weather and other conditions are not the same the next day , week , month the bullet will fly different .I'm ok with that as long as I know the rifle is the same , I can correct for the rest as long as I keep detailed notes . I also keep notes on ambient temp , bullet/cartridge temp and barrel temp It's kinda like the old military saying . ( yes I have 1000rds through my rifle why would I clean it now. I'm pretty confident the 1001 shot will fire . If I clean it I'm not sure if that first one will . )If you clean the rifle you now have disturbed just about every aspect of the rifle and who knows what it's going to do. So the theory is at some point you are removing almost as much fouling as you are leaving behind . Every rifle , bore , caliber will be different . Just making up numbers here . lets say your rifle is good and seasoned at 50 rounds . Why would you go home and clean it ? It's going to take you another 20+ shots to get it shooting it's best again . Now once you hit that 50rd mark you will be removing as much fouling as your leaving in the bore for another 100 rounds . For those 100 shots your rifle should shoot the same from shot 51 to shot 151 . and that is the copper equilibrium theory . I think this is the video but did not watch the whole thing to be sure , It talks about it about 8:30 min into the video https://www.youtube.com/watch?v=_KRUAv3Byp4 | |||
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Depends on your particular bore as to how much fouling it will retain. Clean it and shoot a couple of fouling shots and it might do better. When you first break in a barrel you are supposed to shoot, clean, shoot,clean, for 10 shots; that will fill in the pores and smooth the barrel like you said. From then on, it will not retain much copper, theoretically. If you like how your barrel shoots now, do not clean it. And don't be concerned about the velocity variation either. Every barrel is different. I never heard that old military saying; we always made the soldiers clean bores, both small arms, MGs and tank cannons, every time they were fired. Not with copper remover though. I personally, just oil my hunting rifle barrels and never clean them with copper remover. Just remove carbon soot and keep them from rusting. | |||
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Yeah I don't think it's really a military saying . Not sure why I put it that way . To late on the don't clean your rifle . I just spent 45min cleaning the bore to bare metal . Just thought I'd start over . The funny thing about that is . Someone just said some chrony's use the first shot to calibrate :-@ . I do not see that in my instructions but that would explain alot . I have a Chrony F1 Master and I have been turning off and turning it back on between groups . | |||
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If you feed the first round by hand and the rest from the magazine try firing the rifle in the single shot mode for all rounds. It could be that recoil is shifting the loads to the front of the case. If you do not want to feed single shot, point the rifle at the ground muzzle down while loaded to move the powder toward the base of the bullets. After that if it is possible at your range, point the muzzle at the sky for each round and compare results. If the variation is not position related clean the barrel between each round and give it 15 mins to cool. Once you duplicate each round shot to shot you should be able to duplicate the variation. If you can't it might be the phase of the moon.
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Chrony's don't rely on a shot to calibrate themselves; it calibrates when you turn it on and it reads some letters; I forget what they are. Anyway, just shoot and have fun. | |||
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sneak up 20' closer    | |||
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I think thats what i'll do , only for the first shot though . I'll belly crawl back to my FFP | |||
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I have a Chrony that usually gives the lowest velocity of a string on the first shot. Shooting an Oehler 35P does not give this result with the same ammo. I usually shoot 10 to 15 shot strings, and turn off the Chrony between strings to conserve the battery while I get ready for the next string. When I leave it on, the subsequent shots show normal dispersion. Unless it is close to the other readings, I throw it out and shoot another round to make up for it. I think the muzzle blast from the first shot wakes it up like a slap in the face. This is sometimes needed with lazy electrons. (You can't fix stupid) Falls of Rough Ky University Our victory cry is FORK U! | |||
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LOL Funny!!  R-WEST Load smart. Load safe. Triple check everything. Never use load data from the 'net without checking against known, pressure tested load data. Typo's happen!! "the spotlight of truth will cause the cockroaches of deceit to run for cover every time" Rush Limbaugh "just because you're paranoid doesn't mean they aren't following you" "never turn on a blow dryer while holding a cat" "genius has limits, stupidity does not" | |||
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Update . Went to the range and checked the chrono again . I did not have a bunch of ammo to play with so my results don't have a lot of data to them . I shot a total of 13 strings . Of those 13 , 7 were 4 shot strings and 6 were 10 shot strings . 4 of the 7 shot strings had the first shot lower then the rest by 20fps-ish . only one of the 10 shot strings had the first shot being the slowest by 22fps of the ave , by looking at all ten velocities it appears the ave came from large group that came in with a 10fps spread .That spread was 18 to 30fps faster then the low velocity . I did try the fire a shot through the chrono first then shoot my 4 shot string . I did that 4 times . 2 of the 4 had the first shot slower then the rest by 20fps-ish . So what I get out of this is pretty much nothing . Although the issue seems to have a pattern with it happening on the first shot . It is not consistent enough or I have not tested enough to see what the issue is . It happened on the first string I shot from a cold very clean bore using Federal GMM and it happened well in to the day after having at least 40rds down the pipe . I've been keeping things as consistant as I can . The 10 shot group was done in 3 min or less , the 4 shot groups are under a min for sure . I've been keeping track of my ammo temp and my barrel temp before each string . I never start a string with the barrel more then 10* hotter then the ammo . The ammo tends to never be more the 2* off the ambient temp so that means the barrel is never more then 12 degrees hotter then it is outside when I start . There was a day when the temp was 96* and the barrel would not cool down fast enough so I shot it when the barrel was a little hotter . On that day it would take up to 30 min for the barrel to cool to the outside temp . ( always shooting from a covered shooting area ) | |||
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