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Hi All! I've been loading for a .300 Win Mag, Mod. 70 Winchester Classic Sharpshooter. It's a target gun I'm using to shoot steel with in a Sporting Rifle Match here in NM. I also do some 1000 yard stuff at our club. The load I've developed for the gun is good and I think the accuracy has topped off for this factory gun. My question has to do with vertical dispersion at longer ranges due to velocity differences from shot to shot. I've chrono'd the load and the lowest velocity is at 3000 fps and the highest is 3050 fps. I know that with a difference of 50 fps between shots can make the bullets print on paper at 1000 yards poorly with a low velocity shot printing low and a high velocity shot impacting high. How can I get more consistant velocity and eliminate vertical stringing? I'm loading 75 grs. of Winchester 780 and just the Winchester large rifle primer. I was thinking of trying the magnum primer in hopes it was just an ignition problem. Make sense? Is 50 fps on a 3000 fps load pretty significant or is it normal? I carefully weigh every powder charge, so it's not a powder measure variation problem. If you can noodle this problem out and give me some suggestions, I would be greatful! | ||
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RCA, just thinking out loud - if you could tweak the load so that the lower velocity shots shot higher, you might be able to compensate for the increased drop. If I may ask, just how much vertical spread do you actually get? It may be worth asking the black powder folks how they do it. They are shooting 45-70's to 1000yds and doing very well indeed with no vertical stringing! I am thinking of trying long range cast and paper patched shooting with my Lee Enfield so your problem is very relevent to me! Oh - aren't BR primers supposed to be more consistent? Best of luck!  Regards 303Guy | |||
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Velocity IS consistency @ 1000, generally speaking. (Vertical stringing with velocity variation is the norm.) I assume you are prepping the cases- using single lots of cases, powder and primers, etc. (Are you neck reaming or turning, uniforming the flash hole, sorting by weights, checking for concentricity, using a comparator, bushing style seating die, etc) ( I know it sounds a bit Obsessive-Compulsive-- but consistent prep yields consistent target impacts) DuggaBoye-O NRA-Life Whittington-Life TSRA-Life DRSS DSC HSC SCI | |||
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Nice to hear from you, 303! I'm not sure how I could tweak the load to make the low velocity shots shoot higher. I chose the load that shot the tightest groups, so I guess that problem gets solved during the development process? At 1000 yards on Sunday, the distance between the high and low shot was problably 18". I didn't measure it; it's an estimation. | |||
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Yes Duggaboye, I outside neck turn, am using Nosler brass so it's weight sorted, flash hole de-burred. I don't ream the necks, check concentricity, use a comparator or use a bushing style die. I use an RCBS die set and only partially neck size till the shoulder needs to be bumped. I realize I could get really anal about case prep as you suggest. Do you think it could make that much difference? What do you think about changing the primer to the magnum? | |||
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Every change makes a change--good, bad- or indifferent. The WLRM's are considerably warmer than the WLR's (in fact , to me they indicate to be warmer than the 215Gm's I routinely use) It's worth a trial run; 780 might light more uniformly that way. I have gone to the competition bushing dies with better results than the "std" neck sizers on my LR rifles,and have improved consistency. (I am not going to the level of case and bullet prep or using Wilson dies as on my BR rifle though.) DuggaBoye-O NRA-Life Whittington-Life TSRA-Life DRSS DSC HSC SCI | |||
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Thanks, trying the WLRM was the next thing I was gonna try simply because I have them. My idea was like you state, it may ignite the powder more uniformly from shot to shot. The Lyman reloading manual uses the LR for their data and that's why I did the development with it. I've read that with big powder charges (over 70grs.) it's better to use the magnum primer. I also just read about shooting in mirage and that it can give vertical flyers by tricking you to aim where the bullseye isn't. There was mirage on Sunday and may have caused some of the problem. | |||
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That TOO DuggaBoye-O NRA-Life Whittington-Life TSRA-Life DRSS DSC HSC SCI | |||
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You say you are weighing your charges. What type scales and what tolerance do you allow? What bullets are you using? Are you weighing them and to what tolerance? Are you uniforming the tips of the bullets? Do you know where your seater bears on the bullet? Have you compared the measurements of your loaded rounds from the base of the cartridge to the ogive? You need to be able to answer these questions and address them to get rid of some of your vertical. Butch | |||
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I find compressed loads give lower SD in vel. You might try IMR7828 & see if yo ucan get your spreads closer. LIFE IS NOT A SPECTATOR'S SPORT! | |||
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Hey guys, excuse me if I back up a tad here. My understanding of the cause of vertical dispersion between shot to shot is totally due to velocity deviations. As I understand, barrel harmonics and the time it takes a bullet to exit the barrel are the culprets. The reason velocity is important is that you want the bullet to exit the barrel at exactly the same time during its movement. When you have loads that vary as much as 30 fps, they exit the barrel at different times, and at these different times, the barrel is pointing at a different place vertically. Now Butch and Duggaboye, do things like concentricity, uniform bullet tips, and case prep effect velocity? | |||
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I think an extreme spread of 50fps is excellent. Plus you are talking about a 300 Win Mag. That is one heck of a lot of powder to burn. Incidentally, having competed in a number of 1000 yard matches, postional error, the windage call, are going to move the bullet a lot more than a 50fps difference in velocity. | |||
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Yes, Velocity can vary because of seating depth. The BC of the bullet is important and uniforming the tips help with the BC. He asked about 1000yds., not 100. It is a different ballgame. Slamfire, if you are laying on your belly to shoot, it is important to have good shooting techniques. I understand that, but we are talking about accuracy. We will deal with that after his rifle is shooting. The things that I pointed out and the things Duggaboye mentioned are what the long range guys practice. If you don't want to do the things that we mentioned he will have to be satisfied with a 50FPS spread. The successful long range shooters have single digit ES. Butch | |||
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Wow! Single digit extreme spreads in velocity! Thanks Butch and Duggaboye............ I may have to be content with the 50 fps spread as I just can't see that I will have the time or inclination to get that detailed and meticulous with my loading. Maybe I need to get a better set of dies or at least a really good competition seating die? | |||
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I have had some loads with double ditget sd and they shot better groups.Don't know why just saying.Good Luck | |||
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What is your powder-weighing regimen? I ain't much of a marksman (1/2-moa is all I can get), but I use a trickler to get to where my target weight just clicks up on the read-out of my RCBS Rangemaster 750 scale. Considering there is 1/10-grain in every display, I am of the mind I am at the "lower" limit of that 1/10 grain. Best we can do with that graduation. I use 65 grains of powder in my 300WSM loads. I would have to think 1/650th of the total load is close enough... | |||
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Have a look at this link. http://castboolits.gunloads.co...owthread.php?t=64433 Check out FPMIII's post. Thats with black powder and cast bullets and no scope!   Regards 303Guy | |||
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The idea is that if you are lucky, the load that produces a vertical spread 100yd group also happens to be putting the slower shots higher. I have never tried it so I don't know that it can be done. It could be fun trying though!  Regards 303Guy | |||
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303 guy, The rimfire guys can do it on a regular basis with their tuners. The slow load is leaving the barrel as the vibration is rising and vice versa for the fast loads. I don't think you will see it at 1000 yds. Butch | |||
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What is the Standard Deviation of the load? | |||
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Thanks homebrewer..... Yes, that is exactly how I measure powder. I even have the same scale! 303, something may be going on with the load; it may need some adjustment somewhere. When I developed it, it grouped 5 shots at .75" at 100 and 5 shots at 1.17" at 300. It has never duplicated that since........ Buliwyf, I calculated the standard deviation from some of my measured velocities and it's 20.74 I don't know what is considered acceptable. | |||
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R, You want single digit SD for the work you are doing. I pay close attention to brass preparation consistancy. | |||
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Thanks gents, looks like I've got some more work ahead. | |||
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My Favorite “Blacksmith” Always Speaks the Truth!! I will not even consider using a rifle in a match that I cannot get the ES down below 20 in real world conditions. When I have gotten a lot down to single ES’s I am giddy!  !!Butch—you going to the ACGG Show this year? | |||
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Was that NEW brass, once-fired, same lot ,etc-- If you are going to try to replicate-- you need to record info. It sounds picky--but, if you are not pickily consistent-- the results vary. I have created new loads in new brass and have gotten good results-- just never as consistent results as fired and meticulously prepped rounds. You can get good rounds by less obsessive measures than we have indicated-- just do not expect the consistency of the more meticulously prepped rounds- Example- years ago did a test for grouping of : 1.)LC M 118 , 2.)a copy of the M 118 made as close as possible, with identical new components and 3.)a hand prepped version-- weight sorted(case and bullet) tips uniformed, flash hole, primer pocket necks, ogive to base, runout, etc etc all as identical as possible. Consistency in groups and size of groups : was 3., 2., 1., by ALL 3 shooters and weapons involved. Good prep works--period. Not to belabor the point DuggaBoye-O NRA-Life Whittington-Life TSRA-Life DRSS DSC HSC SCI | |||
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The brass was brand new Nosler, neck turned. I developed the load with Winchester Brass. Maybe the change of brass caused inconsistency? I'll try re-developing the load with the fire-formed brass; small adjustment around the Winchester brass load, or just going back to the Win brass. | |||
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R, Start by weight sorting your brass and keep brass within 2 grains. Then, keep your brass preparation procedure consistant. | |||
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The weight of the brass has nothing to do with the volume of the case which has everything to do with the pressure curve generated during ignition. | |||
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Sort the brass after prep as you will remove more from some and less from others. I think you will need to uniform the brass to within .2grain. Do not use a digital scale to measure you loads. Use a beam scale. If you are serious you might want to buy some RWS brass. You will have to use custom bullets and then segregate them. You need to make sure your seater stem does not touch the meplat. These things are not necessary for a 300yd hunting rifle, but they are necessary if you want an accurate 1000yd. rifle. Butch | |||
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I think you mean SD, not ES. I have never, seen ES in the single digits for a magnum case. It may be possible, I just have never seen it. SD yes, I have achieved that many times. LIFE IS NOT A SPECTATOR'S SPORT! | |||
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fredj338, My sucessful 1000yd Buds said ES is not too good of a statistic. Said it gave you the 2 worst bullet speeds only. If you sampled 10 rounds and only shoot 3-5 for group then you do not have a true picture. They say that 15-20fps is worst though. SD does mean more and yes they want low single digit SD. I stand corrected. Butch | |||
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Well, I can only go by what folks tell me.
That's a 45-110 loaded with black powder. It has a stack of wads between the charge and the bullet.
The owner of the pic did not not say but these black powder folks are traditionalists and don't use scopes! Regards 303Guy | |||
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I can only tell you what works for me. The last 6 shots from my 338RUM were 3191, 3182, 3182, 3189, 3189 and 3197. The last 6 shots from my 6.5 rem mag were 3072, 3086, 3072, 3072, 3072 and 3072 (I thought the chrono was stuck except I was shooting other guns in between with different velocities registering). This is happening with a corresponding stabilization of seating depth. I have loaded as many as 50 bullets at a time with no more variation in seating depth than .002", this with a 130 gr Scirrocco in the 6.5 rem mag. The reason both the velocities and seating depths have stabilized is because I have taken total control of the inside of the neck as far as finish and dimensions go. I also outside neck turn because both of these are tight necked chambers. The trick is what you do next. For sizing in the 338RUM I use a Redding bushing die for .003" bullet grip and in the 6.5 rem mag I use a Lee Collet with a .261" mandrel for a .003" bullet grip also. Then I scour the inside of the neck with Scotch-brite  next with steel wool  This does not really polish the inside of the case but does get rid of the scratche and burrs and leaves a matte finish. The matte finish then picks up the mica I dip them in      Then use a Competition Seater and you can decrease your seating depth variation. Neither of these 2 loads (6.5 rem mag and 338RUM are crimped). Once you have set your seating die then leave it alone. You can chase seating depths back and forth with your comparator but that has been counterproductive for me. If you have done a good job of prep and bought good bullets then your variations should minimize on it's own. ____________________________________ There are those who would misteach us that to stick in a rut is consistency - and a virtue, and that to climb out of the rut is inconsistency - and a vice. - Mark Twain | Chinese Proverb: When someone shares something of value with you and you benefit from it, you have a moral obligation to share it with others. ___________________________________ | |||
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My process is similar to woods. I use a K&M Tappered Reamer Tool to lightly clean up inside neck burrs after chamfer bevel. I use Redding bushing die for .002" bullet grip. | |||
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Thanks Woods, I have been using standard RCBS dies that I've had for years. I thought that the seating process with those dies could be improved, so yesterday I ordered a Redding Competition seating die. From researching, I think that it's the way to go and may solve some of the problems. My chamber is factory so I would have to do some calculating to determine bushings needed for bushing die set up. I did find that by loading freshly annealed cases that then were only partially neck sized gave me the great groups the gun shot. I noticed while loading those cases that even with my primitive seating die, the OAL was right on the money and that the seating pressure or resistance I felt while doing the seating seemed to be uniform from case to case. With the amount of love you are giving your loads I can see why you have attained virtual perfection! | |||
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The overall length doesn't matter. If you are truly looking for top accuracy you need to measure from the base of theloaded round to the ogive of the bullet. Butch | |||
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Granted. But if you know the most accurate overall length, won't it be the same thing since the ogive of the bullet will be in the same place? I'm shooting the A-Max. I would think that from the ogive to the tip would be very consistent. If not the bullets suck. Also, as Woods stated:
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Actually, even the best bullets vary somewhat in ogive to tip distance. The only way to be consistently off the lands a specific distance is to seat by ogive and maintain the base to ogive distance as precisely as possible. DuggaBoye-O NRA-Life Whittington-Life TSRA-Life DRSS DSC HSC SCI | |||
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So while seating, slip the comparator over the bullet and measure each round's base to ogive measurement and make adjustments for each round to insure the optimal length is exactly the same for every shell? | |||
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Regards 303Guy | |||
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