Secret to lowering es and sd on a ar10?

[Kansaswoodguy]

My SD is 0 but I shoot 1 shot groups

I couldn't resist

In my AR-15 I get around an SD of 15. I use a Redding powder drop 75gr bthp match Hornady bullets and CCI 400 primers 22.1gr IMR 8208 there is a second node at 23.2gr but it is right at max book maybe higher or slightly lower depending on your firearm. I shoot to 700yards with boring regularity with the 22.1gr load and can get to 1000 yards with 23.gr Get some 8208 for heavy bullets in 223 you will like it.

 

[Pdvdh]

My SD is 0 but I shoot 1 shot groups

Ha ha... good one!

 

[jca57jd]

I have no reason to lie. Just trying to help a brother out. the gun is pretty consistent. Here is a copy of the spreadsheet from my magnetospeed. Only 5 shots on this one but somewhere I have others

6mm ar turbo 40 lapua brass br4 primer H4895 28.6 gr lapua scenar L 105 grain Series 1 Shots: 5 Min 2818 Max 2829 Avg 2822 S-D
4.2 ES 11 Series Shot Speed 1 1 2820 ft/s 1 2 2820 ft/s 1 3 2829 ft/s 1 4 2818 ft/s 1 5 2823 ft/s

And the results are here

What exactly is your 6mm turbo ar compared to my ar10 243 Winchester?

 

[rcoody]

What exactly is your 6mm turbo ar compared to my ar10 243 Winchester?

It fits an AR-15, 243 should get higher velocities,

6mmAR Turbo 40 Improved

 

[rcoody]

Yes, I remember that you prefer to weigh powder charges down to 0.02 gr. I've read your posts on other Threads about weighing powder charges. I'm not critical of that practice. Look at all the time I've spent on 3,500 casings. It's a hobby. I'm glad you shared your approach, and perhaps weighing powder to +/- 0.02 grain would be the additional effort that would drop my ES from 45 down to less than 10. Still not going to do that. I can live with ES 45 in this AR15. It's a plinker.

Here's my perspective. I don't weight powder charges down to less than +/- 0.1 grain for any of my other rifle cartridges, and I rarely experience ES exceeding 100 fps as I have in my AR15, even with the worst load combination tested. And I don't have great difficulty getting ES down to less than 45 fps with a reasonable amount of load development effort.

I've got more time, components, and rounds fired into this effort to reduce ES/SD with my AR15 than I typically expend on any bolt action rifle, and I'm still at ES=45 over 10 rounds fired. The only reason I've put this much time and effort into it was because I was curious. Anyhow, ES = 45 took me a lot of effort, but it's good enough for my intended use of this rifle.

this thread was about reducing ES and SD. I just posted what works for me.

Personally I don't worry about them during load development. I find a load that works and then I run it over the croney. Not all my accurate loads have low SD's.

and I only weigh and trickle during load development and for long range loads

For normal use I use my Harrell powder measure. Try to find one of those 0.3 grain accuracy nodes and just drop charges. So much faster than any other method.

this is the magnetospeed data for my .308 and this load is a one holer

Series 4 Shots: 10 Min 2687 Max 2719 Avg 2701 S-D 10 ES 32 Series Shot Speed 4 1 2702 ft/s 4 2 2719 ft/s 4 3 2687 ft/s 4 4 2708 ft/s 4 5 2693 ft/s 4 6 2703 ft/s 4 7 2698 ft/s 4 8 2704 ft/s 4 9 2691 ft/s 4 10 2713 ft/s

 

[Apollo]

For my AR-10 I shot a ladder test moving up .5 grains each shot. I loaded up two batches of ten, right around the highest speed node. One batch was .5 grains higher than the other.

My extreme spread with the more accurate batch was 4 fps. I was getting a lot of the same numbers repeating so in a perfect world I'd say it was almost perfect. I'd attribute that to picking a very stable powder (Varget), and shooting a slightly compressed load. Hand trickling your powder helps too. It shoots sooty as all heck but the accuracy is there even at long range. Hope that helps.

 

[Canadian Bushman]

I think its important to specify how many shots you are gathering your velocity spreads from. 2-3 shots is not reliable.

I focus on sd and pretty much ignore es in most regards. I think SD is a better representative of your loads consistency. Es can be more barrel and action dependent and only really has good definition over a longer shot string, or from day to day.

Where i get stung trying to reload for ar's is the mv average. I get a load shooting with decent numbers and the next week i test and the avg is 20fps different.

I think it might have something to do with the bolt and how its maintained. I know that the LR match shooters that really get their ar to shoot are all shooting them single shot.

 

[jca57jd]

Well I got my es down to 12 with some h4831sc over a 6 shot spread. 4 of them were within 3 fps of each other. It still resulted in a 4" group at 300 yards. Frustrating! Trying to get this gun shooting at least .5 moa with consistent sd and es. I've been shooting 105 amax's in my 243 ar with 1-8" 26" Kriegar barrel. I guess I will step it down and try some 95gr smk's and see what happens. Mabe this barrel doesn't like 105's. I've tried the 105 amax's and Berger hybrids with neat her shooting good with a low es and sd. Thanks for all the advice!

 

[Kansaswoodguy]

I think it might have something to do with the bolt and how its maintained. I know that the LR match shooters that really get their ar to shoot are all shooting them single shot.
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Those guys are running 80-90gr bullets that can't be mag loaded. I've done it some to 1000yards it would be fine for competition but I like mag length ammo

 

[Canadian Bushman]

I think it might have something to do with the bolt and how its maintained. I know that the LR match shooters that really get their ar to shoot are all shooting them single shot.
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Those guys are running 80-90gr bullets that can't be mag loaded. I've done it some to 1000yards it would be fine for competition but I like mag length ammo

Some are shooting heavies but the 300,600yd guys also do it and so do some of the across the course guys.

They could shoot 90gr bullets at mag length, but they dont.

Mag length ammo is also probably part of the equation. Not being able to tune with seating depth could surely have negative consequences regarding velocity spreads.

 

[Kansaswoodguy]

I would be very interested to see a 90gr bullet loaded mag length for an AR-15 please provide photo's. I don't own a 1-6.5 twist barrel so I don't have any 90's laying around.

 

[Canadian Bushman]

I would be very interested to see a 90gr bullet loaded mag length for an AR-15 please provide photo's. I don't own a 1-6.5 twist barrel so I don't have any 90's laying around.

Any 90 with a bc worth using wont, and if you could it would eat up so much powder capacity that it would be soooo slow it wouldnt be worth using.

Thats beside the point im trying to make, which is ar's that ive seen shot with the gas system off, even with light bullets, have seemed , to me, to be more accurate.

Agree or disagree i dont care. Ive done lots of testing with this stuff either take my info or leave it.

 

[Pdvdh]

Thats beside the point I'm trying to make, which is ar's that I've seen shot with the gas system off, even with light bullets, have seemed, to me, to be more accurate.

You mean ARs outfitted with an adjustable gas block, which can seal off the gas tube?

 

[Canadian Bushman]

You mean ARs outfitted with an adjustable gas block, which can seal off the gas tube?

Yes.