lowering my ES??

[Bear24]

I am shooting a FN SPR 24" 1:12" twist 308win

I have done a ton of load testing with this rifle and with my best loads I am getting around 22fps ES's. I hear about all these guys getting their ES's down to the single digits and wonder what I am missing in my process.


Brass: FGMM once fired, tumbled, FL resized, Flash hole deburr, trim, chamf/debur (all weigh within one grain of each other)

Powder: Varget, weighed on chargemaster scale without the throwing unit. I dump most of the charge then trickle up until the weight just breaks over to the desired charge.

Primer: Fed 210M

Bullets: Hornady 178g HPBT MATCH, 178g Amax, and 155g berg hybrids.

First is a 22fps ES acceptable for shooting 1 to 2 MOA sized targets out to 1K? If not what am I missing in my process?

 

[jcallan]

I had the most luck by changing primers. Probably not the easiest thing to do with current mark demands but it worked for me. I was using 210M in my 260 and switched to CCI BR2's and got into single digit without changing powder charge. I noticed a slightly slower velocity with the BR2's and I think it was around 15fps slower but better ES.

 

[M1Amen]

One of the guys at the range I belong to frequently competes in the benchrest comps there (and wins). He weighs his powder with a jewelers balance down to 0.01 grains and will even go so far as to use tweezers to add a single kernel of powder. This is too much work for me at this point. A few months ago he was there while I was shooting and walked over to show me the print out from his chronograph. He had a 5 fps ES over 5 fired rounds. He also weighs the brass and sorts his bullets.

 

[Guest]

Make sure your necks are correct, as neck tension is more important than being off a 1/10 or more in charge weight. Next is flash hole uniformity which only comes if the cases are all the same size before you rework the flash hole. I put a cone (inside) in mine when I do the flash holes.

Getting into single digits with a load that exits at mid dwell, is not hard once you know the hows and whys.

 

[milo 2.0]

Prsonally I don't think a 22 ES is all that bad, I've had way higher and still had one accurate load. How many rounds did you chrono? If it was 10, your SD had to be reasonable. Did every shot go through the chrono at the same angle?
Just saying, alot can influence this number, the first shot through mine you may as well disregaard.

Guys can post numbers of 5 ES, .7 as a SD, but they're the guys that get 25mpg out of their F250 with a 460 motor!!!

 

[Bear24]

These were 5 round strings shot several different times with almost the same results with a RCBS chrono and my Magnetospeed.

 

[Aimsmall55]

I had the most luck by changing primers. Probably not the easiest thing to do with current mark demands but it worked for me. I was using 210M in my 260 and switched to CCI BR2's and got into single digit without changing powder charge. I noticed a slightly slower velocity with the BR2's and I think it was around 15fps slower but better ES.

I can vouch for this. The fgm210m are hotter and sometimes give a higher spread. The br2's will bring it wayyyy down.

 

[Enough Said]

In my opinion, you shouldn't be FL resizing once-fired brass. Your brass just fire-formed to your chamber. Neck-size only.
I ream my primer pockets.
Size your neck with competition sizing die. I use a bushing .001 less than loaded cartridge.
Neck lube before charging the case with the load.
Get yourself a great balance-scale. Electric scales vary with the amount of current flowing to the scale.
Sort bullets by bearing-surface length, then by weight.
Load to a Base-to-Ogive length with Competition die.
Check runout
Very low runout bullets only are used for competition or gauging accurate feedback.
Look into crimping lightly

 

[melloyello]

Are you getting your velocities for one day or over many days? Is your ammo temperature the same everytime? Are you shooting through the chrono at the same distance everytime? Are you seating for OAL to tip or ogive?

 

[Rthur]

Neck tension can be a big help. The only means is to measure the neck wall thickness with a ball micrometer. After this you will be surprised how much it can be from one side to another, this would include the high end brass. If a cleanup pass is needed(turning to clean up 60% or so) get a good neck turner in your caliber. While this isn't a requirement it helps with consistent bullet release. I would also add, how is your current load shooting? If it isn't broke don't fix it because the chrono is giving you these numbers.

R

 

[Bear24]

In my opinion, you shouldn't be FL resizing once-fired brass. Your brass just fire-formed to your chamber.

I agree but my brass was not fired from my rifle but I will neck size on the next firing.

 

[Bear24]

Are you getting your velocities for one day or over many days? Is your ammo temperature the same everytime? Are you shooting through the chrono at the same distance everytime? Are you seating for OAL to tip or ogive?

I have gotten almost identical numbers from 4 different days with max 10 degrees diff in temp. I have been using ogive length just measuring tip so it will feed in the mag. I have used a regular chrono at 10ft 3 times and my new magnetospeed once with very similar results.

 

[NoFail]

I have shot Varget with 168 AMAX and Winchester or Hornady brass, Remington #9 1-2 LRP & CCI br2 LRP.
Flash holes deburred and all that stuff.

The ES's with Varget were never great. 20's, 30's ES's.

I've shot exact same load using IMR 4064. Call me a liar but I'm always showing <10 ES using 4064. Usually around ES of 5 to 8.
I use a PACT Chrono & it's newer. Another one with great ES's is CFE223, almost as good as IMR 4064.
H4895 is mostly always in the low teens for me. Those are the 4 powders I've tried for my .308 loads, Varget, IMR 4064, CFE223 & H4895.

I guess YMMV... But whatever I do with Varget the ES's aren't exactly outstanding. Fine for a few hundred yards but further I dunno, I haven't gone very far with it.

 

[Casey Simpson]

The issue is whether rounds impact within the capabilities of the rig and shooter in vertical dispersion at longer distances, say 600+. Rounds' impacts from a one minute rifle would expect to be within 1moa in vertical dispersion (6" top to bottom of group) unless there is a gun or ammo problem, despite es, though wide es tends to suggest unacceptable vertical dispersion will occur.

 

[jwp6114]

start annealing if you are not, every other shot... you will thank me... and neck turn (not completly, just clean off high spots) case necks.

Low ES's are a a product of consistant neck tention(anneal)/seating depth(measure cases with ogive comparitoor)/bullet bearing surface length(can be measured and sorted)/ powder charge(i trickle from a redding beam scale... another tip, having 95% or more of the case volume filled with powder helps. I.E. less air in case.

i have 1-1.5" verticle spread prety consistantly with my 243AI, at 600 yards.

 

[NoFail]

About neck tension. I never turn necks. I always though my necks sucked. Then I started SS media tumbling. All the sudden my necks got real smooth and consistent. The SS tumbling seems to be honing the necks. Now my necks don't suck anymore & they measure and feel very consistent now.

 

[Bear24]

That's very interesting, after I fire all my 500 pieces of brass I plan on sending them out to have them SS tumbled and annealed. Hopefully with that and only neck sizing i will have better results.

 

[NoFail]

Yeah, that was an unexpected result when I first started the SS tumbling. It solved a lot of bullshit. I'm pretty happy about it.

 

[MTyotehunter]

Out uf a FN 22fps may not be bad.... however... so you have heared alot about neck tension which could help, switching primers can make a big differance, but how your seating your primers is super important. make sure they are bottomed but DONT CHRUSH THEM. good luck!

 

[CoryT]

22fps is within the margin of error of the device. IF the ES IS actually 22fps, there is nothing at all wrong with the load, as the SD (which is the number you should actually be concerned with anyway) would be less than 5, which would be hardly likely.

There are a number of problems here. First, a 5 shot string is basically meaningless when is comes to predicting future velocities, there is simply not enough data to form any kind of impression at all, except bad. If you fire 5 rounds and the ES is 125 fps, it's possible you have a load which is not optimum. It's also possible you had one flaky chrono reading.

20 shots in a string will provide fairly good confidence level data, and if you show an SD of < 15 you are probably fine. More important would be the results of the OCW or ladder test to see if you have minimal vertical dispersion. Even an SD of 15 can deliver good results at 1000. A .308 175 load with -30 FPS from the average would be about .25 mil low, and considering the average hold error, you might not even notice. Two shots in succession with the maximum variance, +45/-45 would impact .55 mil apart or so, given a perfect repeat hold, which would make for some 18", but that would represent an ES of 90 FPS between 2 shots.

Anyway, ignore the ES, look at the SD over at least a 10 shot string, and if the OCW test and resulting downrange performance is good, leave the chrono at home and don't worry about it.

 

[1lnbrdg]

For me, it's always been easier to get SD down by shooting heavier bullets.

For my .223 with 80gr bullets, I'm lucky to get under 50 max deviation but the group on paper at 600yds is 3.5".

For my .308 with 190gr Noslers, max deviation is running 14fps for a 20-shot string.

I think it has a lot to do with the recoil of the rifle after talking with others. How much shoulder is limiting the recoil possibly, pushing the velocity spread a bit. That makes sense if you think about the light impulse with .223 versus the heavy impulse with .308 with heavy bullets.

I haven't got the neck-sizing figured out yet, I always get unexplained flyers when I neck-size. I don't see those with full-legnth resized brass.

 

[jwp6114]

About neck tension. I never turn necks. I always though my necks sucked. Then I started SS media tumbling. All the sudden my necks got real smooth and consistent. The SS tumbling seems to be honing the necks. Now my necks don't suck anymore & they measure and feel very consistent now.

can SS media be used in a standard vibratory tumbler? and where do you purchase suc hmedia?

 

[X-fan]

can SS media be used in a standard vibratory tumbler? and where do you purchase suc hmedia?

No its too heavy and will burn out the motor

 

[NoFail]

SS media you need something like a rotary rock tumbler. Water is used in the tank so more weight and the water is important for SS media cleaning to work anyway.

Everything you wanted to know about SS media cleaning right here;

http://www.snipershide.com/shooting...34722-stainless-steel-media-testimonials.html

 

[Rust]

.308 is a little tricky getting low ES/SD numbers for. As mentioned above, switch to CCI primers as they are less hot than the Federal primers. I believe that the federal primers were originally optimized for 30-06 case (or not, heard it both ways) and may be a touch too hot for the smaller .308 case. At any rate the .308 seems to respond positively to milder primers.

IMR 4064 has been a go to powder for many, may years. IMO some of the older single base powders are much more consistent shoot to shot than some of the new wonder powders. I'll give up some velocity for consistency any day of the week. IMR 4895 works for me too with lighter bullets.

I always uniform primer pockets in other than Lapua brass using the Sinclair carbide uniformer. Seating primers uniformly is critical. Any case where primer seating feel is too much different gets set aside and never put back in the "good" batch. They make useful foulers.

Annealing is a must. Especially with used brass. Uniform neck tension contributes to uniform ignition pressures.

Powder is weighed and charges are within .1 gr.

All that said since I don't use anything for match shooting except Lapua brass, I don't turn necks (neck thickness is checked), don't chamfer flash holes (they are inspected), don't weigh cases, don't weigh bullets (do inspect every one for deformities/damage). Tried it all, never noticed a bit of difference with either chrono results or the target.

Word has it that the small primer Lapau brass can give better numbers but haven't tried it myself yet as I have quite a bit of large primer Lapua. Might try it this year.