300 yards ... a true 1/4 MOA rifle and load ... 15 shot group in 0.814 MOA.


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1858
October 25, 2010, 03:34 PM
This post isn't an attempt to show off but rather an effort to show what can almost happen when everything comes together during a match. I'd also like to start a discussion on what it means to have a TRUE 1/4 or 1/2 MOA rifle and load. I scored a personal best yesterday at 300 yards with 15 shots in 15 minutes plus two sighters. My rifle is zeroed for 200 yards so I dialed in +0.7 mils of elevation and -0.3 mils of windage and held on center. The first sighter S1 just clipped the X-ring. I made no adjustment for the second sighter, held on center and a wind gust pushed the bullet to the right. Luckily, I realized that the wind had picked up so I made no adjustments for the next 15 rounds but held off to the left slightly and tried to time my shots with the wind. My score was 149-4X with one 9 which was the 14th shot! The scorer told me that the wind suddenly dropped right as I pulled the trigger ... :banghead: I shoot F-TR which means a bipod and some form of rear bag. The conditions were tough with the sun right in our faces and wind gusting from 5mph to 12mph. The wind proved to be a bigger problem at the 500 and 600 yard lines where we had 15mph to 20mph gusts. My overall score was 435-8X (master).

So why do I say a "true" 1/4 MOA rifle and load. Well, I don't believe that you can shoot a 15-shot 1/2 MOA group with a 1/2 MOA rifle and load. Statistically it just isn't going to happen. If you have everything optimized, the vertical deviation is a true indication of your system because wind will mostly affect the bullet left to right rather than up and down. The 15-shot group for score shown below has a vertical deviation of 0.548 MOA. Both sighters (S1 and S2) are inside that vertical spread. Given aiming error and variations in each round, the rifle would have to be capable of considerably better than 1/2 MOA, something more like 1/4 MOA.

Needless to say, I'm very pleased with the target below and doubt that I'll repeat that performance anytime soon.

http://128.171.62.162/hawthorn-engineering/thr/rem700_308win/fclass_tactical_targets/2010/10-24-10/300yard_15shot_group.jpg

http://128.171.62.162/hawthorn-engineering/thr/rem700_308win/fclass_tactical_targets/2010/10-24-10/300yard_15shot_group_zoom.jpg

Here's my string for the 300 yard stage.

S1: X
S2: 9
#1: 10
#2: 10
#3: 10
#4: 10
#5: 10
#6: X
#7: X
#8: 10
#9: X
#10: X
#11: 10
#12: 10
#13: 10
#14: 9
#15: 10

:)

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desidog
October 25, 2010, 03:55 PM
Nice shooting. So what's this boomstick look like? No rock-lock, i take it?

TonyAngel
October 25, 2010, 04:02 PM
FWIW, I agree with you 100%. I don't get the opportunity to shoot past 100 yards very often, so most of my experience is shooting at 100 yards. I just try to make the most of it by shooting at really small targets.

I have shot some pretty good groups, relative to the way that I was shooting a year ago. I can't say that I have "just" a sub MOA rifle, because that would assume that I did everything perfectly every time I pulled the trigger, and I know that is impossible. I would imagine that if I'm able to pull off sub MOA groups, that the rifle is capable of shooting twice as good as the groups I am shooting, if you took me out of the equation.

I can live with this since I build my own rifles and get a sense of self satisfaction knowing that my rifle can shoot better than I can.

SSN Vet
October 25, 2010, 04:19 PM
very impressive!

What's ATC stand for?

FlyinBryan
October 25, 2010, 04:29 PM
very nice (although not terribly suprising coming from you, lol)

i clearly remember being impressed with your work when you competed in one of my ar-15 matches not long ago.

load info?

Dave P
October 25, 2010, 04:29 PM
OK - I am confused.

"... a true 1/4 MOA rifle and load .."



Your max spread is 2.55", which is about .8 MOA (like the software says). A 1/4 MOA group would be about .75".

1858
October 25, 2010, 04:55 PM
OK - I am confused.

"... a true 1/4 MOA rifle and load .."

Your max spread is 2.55", which is about .8 MOA (like the software says). A 1/4 MOA group would be about .75".

The max spread in the horizontal direction is due in part to wind so this is NOT an indication of the rifle/loads potential accuracy. The max spread in the vertical direction is a better indicator of the rifle/loads potential. There is still error, both load and shooter induced in the vertical direction. If you have a rifle/load truly capable of 1/4 MOA grouping, not just for 3 or 5-shot groups but for 10, 15 or 20-shot groups with 1 minute per shot, it's highly unlikely that you'll shoot 1/4 MOA groups. Think of the variables such as the SD of the load, shooters ability to hold on target, wind, parallax etc. In fact, I'll go so far as to say that you need a 1/4 MOA rifle/load to even have a chance of shooting a 1/2 MOA group. Another thing is that S1 was the first shot out of that rifle and #15 was the last over an allotted time of 17 minutes. In fact, I finished in under 15 minutes. There is no significant difference in the POI as the barrel fouls and heats up. Another indicator that this is an excellent rifle.


What's ATC stand for?

Average distance to center of the group. The software calculates the center of the group (centroid if you like) which I find useful since I use that average group center to check my scope adjustments. The Off V: value tells me how low or high the average group center is compared to the point of aim on the target. In this example, the group center is less than 1/2" low at 0.436". With 0.1 mil adjustments, if I come up 0.1 mil, that would move the group center 1.08" up which would put me over 1/2" high. Basically, the comeup of 0.7 mil is as good as it gets at 300 yards. If the scope had 0.05 mil ajustments I would make a change but 0.1 mil is as fine as it gets.



load info?

Thanks ... here's the load info ...

178gr A-MAX
CCI 200 primer
44.2gr of Reloder 15
Lapua brass fired three times



So what's this boomstick look like?

Sort of like the photo below but with a Premier Reticles Heritage 3-15x50mm scope on it. I'm very pleased with the Seekins rings that I have on the PRH. A few months ago I took the PRH off after using it for a course and some F-Class matches. I wanted to try the Mark 4 again so I removed the PRH with the Seekins rings still on the scope. A couple of weeks ago I put the PRH back on and didn't even check the zero before yesterday's match. First shot (sighter) at 300 yards was an X ... now that's my idea of a repeatable zero after removal and re-installation!!

http://128.171.62.162/hawthorn-engineering/thr/rem700_308win/photos/rem_700_308win_4.jpg

:)

JDGray
October 25, 2010, 05:17 PM
Great shooting!! And I'm happy with 5 shot groups that size:D

USP45T
October 25, 2010, 05:21 PM
is that a 1.5" x-ring? nice of your scorer to give you an X for S1. I wish they'd score me like that where I shoot. There's usually money involved. lol

1858
October 25, 2010, 05:28 PM
JDGray, thanks ...

is that a 1.5" x-ring? nice of your scorer to give you an X for S1. I wish they'd score me like that where I shoot. There's usually money involved. lol

Actually, the X-ring is 1.40" and the 10-ring is 2.85" in diameter. S1 clearly breaks the X-ring but it doesn't help since S1 and S2 don't count for score. At the 500 yard line, S1 and S2 were both 10s, but my first shot for record was a 9!! :banghead:

You have to shoot either .223 Rem (5.56x45mm NATO) or .308 Win (7.62x51mm NATO) in the F-TR class, but I don't know anyone that is competitive that shoots .223 Rem. The bullet diameter would put you at a disadvantage in terms of breaking the X-ring or 10-ring, not to mention wind drift at 300, 500 or 600 yards.

:)

Walkalong
October 25, 2010, 05:33 PM
Great shooting, but what is the distance center to center of the two furthest shots? That is the group size, and it would have to be .75 or less to be 1/4 MOA.

Dr T
October 25, 2010, 05:35 PM
Very, very impressive shooting.

As a probabilist, I must agree with you. I am not sure what the term would mean mathematically. If you assume that your shot placement has a two dimensional Gaussian distribution, by saying that a rifle is a true 1/2" MOA, does this mean that 95% of the shots would land in a circle of radius 0.25"?

The calculations can get complicated (see http://en.wikipedia.org/wiki/Multivariate_normal_distribution).

Perhaps it would be better to use the CEP (circular error probable) like is used for targeting heavy ordinance (see http://home.earthlink.net/~loganscott53/Circular_Error_Probable.htm )

Personally, I prefer to reduce things to a univariate case. I look at the axis of extreme spread that you have highlighted. What ever that distance is, I call it the group size.

USP45T
October 25, 2010, 05:41 PM
Thanks for the info. I guess I don't see too clearly. Nice shooting. A 1/4 moa rifle is a joy to shoot.

wanderinwalker
October 25, 2010, 07:21 PM
Nice shooting! Mid-range prone shooting is hard enough, those F-class targets are just diabolical. Must have been drawn up by some kind of sadist. "They want to shoot scopes? Then check THIS out!" :eek:

taliv
October 25, 2010, 07:27 PM
Nice shooting!

I take it you don't have pit service and paste targets between shots? Your scorer determines the value from behind the line?

Uncle Mike
October 25, 2010, 07:43 PM
Nice, Nice, Nice!

1858
October 25, 2010, 07:56 PM
Great shooting, but what is the distance center to center of the two furthest shots? That is the group size, and it would have to be .75 or less to be 1/4 MOA.

Walkalong, I'm not claiming that the group is 1/4 MOA ... clearly it is not. What I'm saying is that given the 0.5 MOA of vertical spread for 17 shots which is largely independent of wind, and given the human and load error, the rifle and load together would have to be a lot better than 1/2 MOA.

Dr T, thanks for the links. I need to read up on the statistical part and figure out how to sum all of the errors inherent to the system to make sense of this.

:)

1858
October 25, 2010, 07:59 PM
I take it you don't have pit service and paste targets between shots? Your scorer determines the value from behind the line?

We do have pit service and we take turns pulling the targets. We typically have three relays, one shooting, one scoring and one pulling targets. We use pasties but they're of low quality and are easy to remove after the match when we get our targets back. We tape up a new face center for each shooter over the correct high power target.

:)

taliv
October 25, 2010, 08:27 PM
cool. We do the same, but when i put the spotter in the hole it usually makes the paper tear slightly different and our pasters hold pretty well except in august when my hands are sweaty

1858
October 25, 2010, 08:42 PM
We use golf tees with a 1" rubber washer painted white on one side at 300 yards. We use a regular 3" spotter at 500 and 600 yards. The 1/2" small round pasties are junk but the 3/4" larger square ones are very good. I cut them in half when I'm pulling the target so that I don't obscure the rings. I was just looking at the national records for 300 yards (15 shots). The open and civilian record is 150-7X. Nancy Tompkins holds the women's record with a 149-5X. I was 1X behind her and given that she's a phenomenal shooter I feel good about that. The national record for the mid range prone course is 442-27X! :what: I have a long, long way to go with my best so far being a 435-8X.

:)

52grain
October 25, 2010, 09:13 PM
Very, very impressive shooting.

As a probabilist, I must agree with you. I am not sure what the term would mean mathematically. If you assume that your shot placement has a two dimensional Gaussian distribution, by saying that a rifle is a true 1/2" MOA, does this mean that 95% of the shots would land in a circle of radius 0.25"?

The calculations can get complicated (see http://en.wikipedia.org/wiki/Multiva...l_distribution).

Perhaps it would be better to use the CEP (circular error probable) like is used for targeting heavy ordinance (see http://home.earthlink.net/~loganscot...r_Probable.htm )

Personally, I prefer to reduce things to a univariate case. I look at the axis of extreme spread that you have highlighted. What ever that distance is, I call it the group size.

I think both the univariate and the bivariate treatments. The math isn't that bad. If I didn't have other things to work on, I'd make a Matlab routine to handle it.

Walkalong
October 25, 2010, 10:00 PM
largely independent of wind, and given the human and load error, the rifle and load together would have to be a lot better than 1/2 MOA.In that case, every group I have shot with my bench gun would be a zero, cause the rifle is capable. :D

Seriously though, that's good shooting. My last 300 yard group (I shot one with an unknown load the other day and haven't shot at 300 in years) was double yours. I loaded two more loads to try in the .222 Mag. I am going to try it at 100 & 300 one of these days. I am almost out of the Hornady bullets that this gun will shoot 1/4" groups with (if (big if) I do my part), but Hornady changed the bullet. I am trying some 52 Gr A Max bullets to see if I can find a combo they like in this rifle. The 50 Gr V Max is next. Even with a rifle and load that is capable of shooting 1/4 MOA, it is difficult to actually do. I would be most happy to shoot a group like the one posted using a factory rifle.

You are right. The rifle/load must be able to shoot much better than that group, to be able to shoot that group, given human error, wind etc. We only wish we could shoot to our rifles potential. Well, sometimes we do. :)

1858
October 25, 2010, 10:24 PM
the rifle/load must be able to shoot much better than that group, to be able to shoot that group, given human error, wind etc. We only wish we could shoot to our rifles potential. Well, sometimes we do.

Exactly!!!

:)

p5200
October 25, 2010, 11:55 PM
Great shooting and a very sharp looking rifle! :)

TexasPatriot.308
October 26, 2010, 12:00 AM
money, money, money.....

WNTFW
October 26, 2010, 04:16 PM
For a small piece of paper it carries a lot of weight
Oh, that mean, mean, mean, mean, mean green

Almighty Dollar!

Sorry, Texas Patriot had me go to O'Jays mode.


Nice 1858. The difference between shooting just above 1/4 moa and just below 1/4 moa is about as hard as it gets. Even at 100yds with no wind.

Afy
October 27, 2010, 12:10 AM
Good shooting.

FLAvalanche
October 27, 2010, 09:24 AM
Guy puts up an impressive group and you guys nitpick half an inch at 300 yards? Wow.

Tell you what...put up a target even relatively close to this and then you can bitch about his math.

SpeedAKL
October 27, 2010, 11:00 AM
Nice! Is that rifle a build you put together yourself or did you have a custom shop like GAP do it?

wankerjake
October 27, 2010, 11:29 AM
Seriously good shooting!

1858
October 27, 2010, 08:18 PM
Thanks for the kind words guys. FLAvalanche, I should have been clearer in the thread title since it is a bit misleading. The point I was trying to make, and that I think most here understand, is that the rifle and load have to be a whole lot better than the group on paper ... particularly at 300 yards where any error will reveal itself in short order.

Nice! Is that rifle a build you put together yourself or did you have a custom shop like GAP do it?

If you have a minute or two .... this is a good lesson in incrementalism (avoid at all costs!! :D)

The action is from a Remington .308 Win that I bought about 15 years ago. I spent days looking on Krieger's web site and finally chose a stainless steel 26" fluted, MTU #10 contour barrel. I sent the action with the factory barrel to Krieger, had them true the action, then chamber, crown and install the barrel.

While waiting four to five months to get the action and new barrel back, I ordered an AICS stock, AICS bipod, Jewell trigger, Leupold Mark 4 6.5-20x50mm scope, Leupold Mark 4 rings and a Leupold Mark 4 one-piece base. I then upgraded the base to a Badger Ordnance one-piece base because it has a recoil lug and it extends further forward on the action. After shooting 300 or so rounds through the new rifle, I decided to upgrade the bolt to an oversized and fluted PT&G bolt with a Sako extractor. I was having extraction issues during rapid fire drills and wanted a tighter bolt ... the PT&G solved both problems. I timed the new bolt and welded on the bolt handle from PT&G but ended up bending, cutting and welding a 5/16" bolt to make an aesthetically more pleasing bolt handle.

The new PT&G bolt changed the headspace so I had a local gunsmith (now "my" gunsmith) remove the barrel and cut a new chamber to get the correct headspace. His match reamer didn't match Krieger's reamer so rather than have a transition in the chamber, I asked him to cut a new chamber. I lost 3/4" off the barrel so now my barrel is 25-1/4" long. At my request, he also installed a thicker Badger Ordnace recoil lug, and recrowned the barrel. I machined a wider notch in the AICS to accept the thicker lug. I grit-blasted and painted the action and barrel myself using GUN-KOTE 2400 from KG Coatings. I then upgraded the trigger to a CG X-Treme two-stage trigger, upgraded the Leupold scope to a Premier Reticles Heritage 3-15x50mm with Seekins 34mm rings. The other thing I "fixed" is the sling attachment that is sandwiched between the butt pad spacers and the stock. I welded the attachment to a piece of steel plate with holes for the butt pad screws and painted the part with GUN-KOTE. It's very rigid now. So that's what I have at this point and I'm very happy with the rifle. The only thing I should have done is have my gunsmith thread the end of the barrel for a suppressor.

So as you can see, I've had work done by Krieger and a local gunsmith but I've also done some things myself. I've learned a number of valuable lessons from this process.

:)

kis2
October 27, 2010, 08:38 PM
a true love story. very nice work, both in shooting and building.

1858
October 27, 2010, 08:48 PM
a true love story. very nice work, both in shooting and building.

More of a horror story when I think of the learning curve :banghead:. My latest build is going a whole lot better ... albeit rather slowly.

:)

Double Naught Spy
October 27, 2010, 08:57 PM
Nice shooting!

The max spread in the horizontal direction is due in part to wind so this is NOT an indication of the rifle/loads potential accuracy.

I like the way you present data. I am going to start presenting data based on the potential of my rifle and load and not what I actually shot. So I take my best group and then reduce down to the next quarter inch. Hell, I might just cheat and reduce it to the next half inch...it is potential after all! :D

Can I extrapolate to hog weight as well?

kis2
October 27, 2010, 09:12 PM
haha, well there is a fine line between horror and love stories. the difference is in the end, and your groups speak to a good one.

and at least your in the building phase! i'm still in the 'learn the fundamentals' phase IMO. one day I'd like to build a nice 338 lpmag. one day I'd also like to be able to afford to shoot it.

again, nice job. now I have to go try a 15 shot group.

1858
October 27, 2010, 09:15 PM
I like the way you present data. I am going to start presenting data based on the potential of my rifle and load and not what I actually shot.

The problem though is what is the potential of our rifles and ammunition? For most of us, it's hard to know. Benchrest shooters approach the mechanical limitations of their systems more than most of us, so for them, they probably have a better idea of what is possible. I have no idea how accurate my rifle is but based on last Sunday, I'm starting to get some idea of what it's capable of under fairly arduous conditions. Members here often state that their rifle is a sub moa rifle or their load is a sub moa load but at what distance, and for how many shots, and at what rate of fire? These are the interesting questions for me.

:)

1858
October 27, 2010, 09:18 PM
one day I'd like to build a nice 338 lpmag. one day I'd also like to be able to afford to shoot it.

No kidding. I have a rifle that is virtually identical to the one shown in this thread but it's chambered in .300 Win Mag. After this current build is complete, I'm going to start planning something in .338 Lapua Mag. It may be a turnkey system such as an AI AWM or a Barrett 98B.

:)

Walkalong
October 27, 2010, 09:33 PM
Oh yea, almost forgot, beautiful rifle 1858. :)

blackops
October 28, 2010, 02:06 AM
1858,been a while. I see you have made considerable progress in your load development! I would expect nothing less from you. Was it the neck turning that improved your accuracy? I also noticed you switched from the PR to a MK4, I’m curious as to why? I’ve always like that rig, nasty rifle. Good work man, you’re really progressing with that rifle.

blackops
October 28, 2010, 02:36 AM
Members here often state that their rifle is a sub moa rifle or their load is a sub moa load but at what distance, and for how many shots, and at what rate of fire? These are the interesting questions for me.

I want to share my theory on this and would like your opinion, as I‘m sure that I‘m most likely not fully correct.

I think 8-10 shots is enough to establish an accurate MOA. Beyond 10 (that’s ten within a few minutes) personally, my barrel becomes too hot. This is the result of a factory heavy barrel, thus resulting in a sporadic POI. On the contrary, this ultimately results in a loss of accuracy when you compare to a Krieger or Shilen etc. So if you factor in more shots in a short time frame, does that make another rifle more accurate? Yeah, I guess it’s safe to say it is. For those first 8-10 though I can hang! :)

I also believe a 100yd test is the truest way to fully understand the potential of one’s rifle. While doing so you eliminate more human or atmospheric error. In my mind there is no reason one’s rifle shouldn’t consistently hold the same MOA with additional yardage as long as the atmospheric conditions are properly accounted for and equipment (glass, trigger, etc) allow you to.

Bonesinium
October 28, 2010, 03:51 AM
I like seeing posts of how well people shoot. It gives me something to shoot for. I just wish I could shoot as well at 100 as you do at 300! If I could shoot 17 shots in a grouping even close to that without at least one floater I'd be happy. Well done.

1858
October 28, 2010, 03:58 PM
I see you have made considerable progress in your load development! I would expect nothing less from you. Was it the neck turning that improved your accuracy? I also noticed you switched from the PR to a MK4, Iím curious as to why? Iíve always like that rig, nasty rifle. Good work man, youíre really progressing with that rifle.

I haven't done any neck turning yet but I did correct the problem that I was having with inconsistent neck tension. Also, I used the AI bipod which seems to work better for me than the Harris bipod. I had the Mark 4 on the rifle, then the PRH, then the Mark 4 again and now I'm back with the PRH. I shot the target in this thread with the PRH mounted. Obviously I prefer the PRH scope being front focal and mil/mil, but the Mark 4 is still an excellent alternative. Once Leupold starts offering the M5 retrofit I'll be sending some Mark 4s to them.


I also believe a 100yd test is the truest way to fully understand the potential of oneís rifle. While doing so you eliminate more human or atmospheric error. In my mind there is no reason oneís rifle shouldnít consistently hold the same MOA with additional yardage as long as the atmospheric conditions are properly accounted for and equipment (glass, trigger, etc) allow you to.

I agree that 100 yards is a good test of the rifle but not of the ammunition or the optics.

Bonesinium, thanks.

:)

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