interesting artical

[littlebuf]

found this while doing some research on standard deviation of FPS. little long but worth a read for those relaoders on here

 

[Sam Millard]

Thanks for posting! He did an excellent job explaining SD and gave me another reminder of why I ignore it!

MV and ES rules for long range work...

 

[littlebuf]

Would you mind explaining MV and ES. Thanks

 

[Sam Millard]

MV= Muzzle Velocity, the average velocity in a string. Baseline number used for input into a ballistic program.

ES= Extreme Spread, the spread between the fastest and slowest shot in a string.

My long range rigs run loads that keep the ES in the single digits to high teens. During load work up, I check it by shooting 4-5 strings of 5 shots, each one started with a cold bore shot (fouled). I then check it randomly throughout the year (surprise inspection!). Of course, when shooting out at distance, high ES shows up as vertical dispersion on target.

If you use ES as your standard, you know what the high and low will be. SD just gives you a statistical deviation from average, depending on sample size.

 

[littlebuf]

haven't really worked much with velocities in reloading up until recently. always reloaded for accuracy and the hunting i did with a rifle was generally 400 yards and under. my needs/desires have changed a bit and am starting to stretch it out a bit. heres where im at with my 300 win mag. currently working up a load for some 185 Berger hunter classics out on my tikka. it seems to want to shoot around 3000fps the best. just finished up a load yesterday that im pretty happy with. average speed of 2981 with an average three shot group size of .4785. pretty good shooting but now you have me thinking of the extreme spread. in that load its 73fps. i can get that a lot closer at higher velocity's for example at a average speed of 3255fps i had a ES of 15 but a 2 inch group. seems the faster i go the closer the velocities in this rifle but the larger the group. any advice?

 

[mtswampfox]

Thanks for posting! He did an excellent job explaining SD and gave me another reminder of why I ignore it!

MV and ES rules for long range work...

Think sometimes we have too much information . Used to work on sd and it will drive you nuts. The reason of some sd is the accuracy of the chrono which for the consumer market is going to have a spread as well. The real proof is the group size for me and an average over ten shots or so for velocity.

 

[Sam Millard]

haven't really worked much with velocities in reloading up until recently. always reloaded for accuracy and the hunting i did with a rifle was generally 400 yards and under. my needs/desires have changed a bit and am starting to stretch it out a bit. heres where im at with my 300 win mag. currently working up a load for some 185 Berger hunter classics out on my tikka. it seems to want to shoot around 3000fps the best. just finished up a load yesterday that im pretty happy with. average speed of 2981 with an average three shot group size of .4785. pretty good shooting but now you have me thinking of the extreme spread. in that load its 73fps. i can get that a lot closer at higher velocity's for example at a average speed of 3255fps i had a ES of 15 but a 2 inch group. seems the faster i go the closer the velocities in this rifle but the larger the group. any advice?

Unfortunately, accuracy and low ES don't always coincide with each other. As you know, there are a lot of variables in the hand loading process. The author of the article you posted claimed to have stopped measuring every powder charge because the SD told him it wasn't worthwhile. I can tell you from a lot of personal experience that it won't fly for LR ammo. Every charge needs to be weighed within .1 grain for consistently low ES. You can throw charges that are very loose from throw to throw and still get great 100 yard accuracy.

Having said that, perfectly weighed powder charges won't guarantee anything if the rifle doesn't like the load! I don't know what your process is or what components you are trying, but here are some general things to consider:

Neck tension- consistent neck tension is important. I have found that .001-.003" works the best. Anything over that starts degrading accuracy and ES.

Seating depth- EVERY bullet needs to be exactly the same distance from the ogive to the lands. If you don't get this perfect, you are spinning your wheels!

Powder and primer- use a powder that gets you the most energy in the most efficient manner. Having unburned powder spit out the end of the barrel is not good for the process. H1000 is a powder that not only drives the heavies in a 300 to an acceptable velocity, but also does it efficiently. It has the added bonus of being temperature stable, so the load you work up now will shoot the same this summer when it's 90 degrees or more. It is not the only powder that works, but it's tough to beat for a LR load that you don't have to worry about changing from season to season. Primers all burn a little differently. Changing primers can have a dramatic effect on accuracy and velocity numbers. Keep in mind though, changing primers can also drastically change pressure, so the powder charge needs to be backed off into the middle somewhere and ramped back up incrementally.

Bullet- your barrel might not "like" the bullet you are trying when it is shot to a velocity that gives good ES numbers. LR shooters have been having good luck with 210 and 215 Bergers, as well as the heavy SMKs and 208 AMAX. I would not waste any of your barrel life messing around with light bullets for a LR rifle.

 

[littlebuf]

i dont agree either with not weighing every load, i use a scoop and trickle to get exact loads every time. the brass im using to work up the load is at the end of its life span. my next step is buying some new brass to finish the process. you think 185 is too lit? i was shooting 200gr accubonds but after working with these 185 bergers my groups have gotten consistently tighter. powder im using right now is magpro

 

[littlebuf]

im going to go ahead and hijack my own thread cuz Sam seems talkative on here and i want to pick his brain. so here goes. current load ive found with the best accuracy (sub 1/2") is as follows in regards to ES

High- 3009
Low- 2949
average out of 12 shots- 2981

running some number through a ballistics program and setting my maximum range for this rifle (factory tikka) at 800 yards heres wht i come up with

drop @ 800 in inches
high FPS- 137.4
low FPS- 144.2
doped to average FPS- 140.5 difference from average +/- 3.5"

as far as click on the scope go the difference from average are roughly 1.5 clicks up or down respectively.

im going to work more with this load to get as much ballistic information as possible but ive burnt a fair amount of powder so i know right around this FPS is where this rifle/bullet want to shoot. what do you think for the range (not extreme long distance) im looking to accomplish on game?

 

[Sam Millard]

I wouldn't run the load, but if you are tired of messing with it, go for it! Shoot it out to the distance you want to be able to hunt and see how it does. You are basically losing 1/2 moa or more of accuracy by having the ES that high through vertical dispersion. Half of that ES would be my maximum for 800 yards. 1 MOA will work at 800, but I hold myself to 1/2 MOA at that distance.

Find a spot with rocks you can shoot at or hang some 10 or 12" steel plates out there and bang away You will quickly figure out if your ammo and sighting system will work! 100 yard testing is necessary but monotonous...plus it only tells half the tale. LR shooting should be fun! Keep notes on hits and misses so you can come to some conclusions on what will work for you.

From a "most bang for your buck" standpoint, learning to shoot in the wind with the ammo you have now, is better than getting frustrated and wearing out barrels at 100 yards trying to build perfect ammo No matter how much experience you have or how well your equipment works, everybody needs more wind practice!