Min. Number of shots to create a trend

[Pripyat]

I'm ready to start altering stuff in my reloading as well as my rifle setup.

What is, in your opinion, the minimum number of shots required to assign an MOA to a batch?

Also what barrel considerations do you take? Clean barrel and shoot three foulers per test? Or three foulers then a couple tests back-to-back? Too many variables!

 

[gamestalker]

I'm no expert, but I like to fire a foul shot, then I will print several groups of 5 over the chrony. After the first group, I will let the barrel cool for about 15 minutes, run a swab only down the throat, and then another 5 shot group again. This is if I'm working with a green load.

For checking an already documented load, I fire 1 foul, and then print over the chrony one 3 shot group to make sure the new powder and bullet lot didn't drastically change things.

GS

 

[PapaG]

In statistics, two points do not establish trend. Three are better and five better yet. For a true statistical examination, short run style, 21 points (or observations) are needed. Way too deep a subject to go into here.
Best is using statistical process control......21 points (groups of three, for example), finding mean, standard deviation, and then plotting plus 1,2,3 and minus 1,2,3 s.d. from the mean for the whole sample. You can then predict what may happen and see what changes to your input (load) produce.

 

[Pripyat]

I've found my rifle performs best with a cold barrel. Are some weapons just going to suck at back-to-back shots or is there a load out there that I'm yet to find? I want to play with free float vs tip pressure and bedding vs pillaring. It is going to be difficult to replicate the temperatures on different days without letting the barrel cool between shots.

 

[Otto]

What is, in your opinion, the minimum number of shots required to assign an MOA to a batch?

(4) 5 shot groups that can be identified on target or (1) 10 shot group.

Alternatively... a target using 10 or more 1/2" dots with one individual round on each dot for a minimum of 10 shots.

Group shots outside of 2 MOA from POA is considered a miss.

 

[Lee S. Forsberg]

What rifle are you talking about and what stock are you using?

 

[Walkalong]

A rifle that can shoot 1 MOA every time out unless you screw it up. 3 shots for a hunting rifle and 5 for a target/casual target rifle. Naturally we expect more than just 1 MOA from a target rifle. Start with a lightly fouled barrel.

 

[Pripyat]

First test subject is a howa 1500 / vanguard. Reports on the web are all over the place. Some people say they need tip pressure, others say free float is the ticket. Others say the rifle will never shoot sub moa if it didn't come out the box doing it.

I have never seen the rifle shoot less than 1.5" 3-shoot groups. I picked up a Boyd's laminate stock to experiment with. I want to start with a couple of the same load with each stock. Then compare with the laminate stock once it is bedded. Eager to see where this all leads.

 

[edfardos]

First is a fluke.
Second is coincidence.
Third is a trend.

 

[Walkalong]

I like that.

 

[Lee S. Forsberg]

Are you doing the bedding? If so you might consider bedding the barrel and action solid from the rear tang to the tip of the fore-end. That includes the front and back of the recoil lug. Tape off the bottom of the recoil lug. Use a Torque Wrench in inch pounds to tighten the guard screws till it shoots correctly then leave it alone. Record Torque setting for the guard screws. Not exactly load development but a good place to start.

 

[jr_roosa]

I find that 5 shot groups don't help me. If I get one flyer, is that me or is that the load?

When I use 10 shot groups I get much better info. I also make sure the data are repeatable on a different day. The only down side with 10 shot groups is that you get a slightly larger number for your group size. As long as you are comparing 10 shot groups to 10 shot groups, it's fine. It also makes testing large numbers of combinations somewhat difficult.

For example, I tried three different 10-shot loads last week. The best group was 1.7 MOA, I made another 10 rounds with that load and it shot 1.4 MOA today. It verifies that 1.4 is about as good as I'm going to get with that bullet and powder, and that the one good group wasn't a fluke. It holds the 10 ring, though.


Untitled by jr_roosa, on Flickr

After that string, I shot three more loads trying out another bullet and I got 5 MOA, 3.5 MOA, and 2.4 MOA groups...terrible. On the other hand, it's reliably terrible and it shows me that I didn't just get a couple of flyers, and I should try something different next time.


Untitled by jr_roosa, on Flickr

These aren't as sexy as a three-shot bughole, but they are much more helpful with load development.

If anybody cares, these are .30 cal holes on 100yd reduced 600yd slowfire targets, shot at 100yds prone with a sling and iron sights. They're a little off center. As for procedure, I shoot a clean barrel, 5 sighters to get relatively centered, and then shoot groups until I'm done. I throw in a few more sighters when I change components. I don't care about cold bores because I shoot highpower matches where you are always shooting for score after a few sighters, and you a shooting about 1 round per minute. If I was working on a hunting rifle or if I was a sniper or something, I would have a different procedure to focus on a cold bore zero.

-J.

 

[smokey262]

When I do load development work with all unknowns I even use two shot groups after fouling shots. If they aren't less than an inch or so for two at a 100 yards it doesn't matter to me what follows.

 

[ColtPythonElite]

I do what everybody else on the internet does: Fire a 5 shot group, throw out then 2 fliers and then proclaim she shoots groups you can cover with a dime or is a real tack driver. I also do this at a guesstimated 100 yards, which probably is closer to 75.

 

[Otto]

@ jr_roosa
Those may not be the best looking groups but at least they're "honest" ones....

 

[Pripyat]

My intent was to do the bedding myself. Still torn on whether or not I should pillar the stock when I bed it. Seems like a lot of wasted time breaking it out into two steps.

BTW thanks for all the input. I feel like I'm on the right track.

 

[mdm]

Tight groups are nice but with a scoped rifle I'm pretty much just concerned with the first shot out of the barrel. If there is a need for additional shots, it likely won't be on the same target anyway. If it is on the same target, it will have probably moved so grouping is pretty meaningless.

Once I have what I consider a good load, I want to know where it will hit out of a cold barrel with no fouling shot. I am also interested in where additional shots hit as the barrel gets hotter. I'm not interested in covering 10 shots with a dime at 500 yards. I'm interested in killing what I'm aiming at.

 

[Poper]

Pripyat,

The Weatherby Vanguard/Howa 1500 will often shoot groups better than the shooter is capable of shooting. I think you will like it.

My .30-06 Weatherby Vanguard at 100 yards; cold, clean barrel, 2 3-shot groups back-to-back at 100 yards from a sandbag rest. Group #1 measured 0.303" center-to-center. Group #2 measured 0.525" center-to-center.
This action is in a Boyd's Prairie Hunter walnut pre-finished stock. The action is not bedded nor is it pillar bedded. It is just placed into the stock and the screws torqued. Scope is a Redfield 2x7x33 in Warne rings on a Warne 1 piece base.

The load is 155 grain Berger Hunter, 53.5 grains IMR 4350, RP case (new, unfired, fully prepped), Winchester LRP, COAL: 3.220". Very shootable load as it is not much above a starting load and is clocking in the 2780 fps neighborhood.

Poper

 

[Pripyat]

Thanks for the post. I actually have that exact stock but a different color. I have front and rear rests and the trigger is really sweet on the Howa. I was getting super frustrated at the range the other day as my shots were all over the place and I was trying to do load development. I was really finding out that some loads suck slightly less than others. Next time I make it out to the range I'll try the weapon free floated in the laminate stock and see how it does. If it shoots under 1MOA I'll probably never touch the rifle again except to shoot and clean it.

I really want to bed the rifle even if it doesn't make a difference with accuracy - The 30-06 is just too much gun for me to shoot back-to-back in a lightweight rifle. Any weight I can add is a positive in my opinion. My shoulder doesn't have enough meat on it to properly cushion my bone. 10 shots and I'll be hurting for two days.

 

[Poper]

The 30-06 is just too much gun for me to shoot back-to-back in a lightweight rifle. Any weight I can add is a positive in my opinion. My shoulder doesn't have enough meat on it to properly cushion my bone. 10 shots and I'll be hurting for two days.

I often hear this from people.

When I was 19, I went into the USAF and was stationed at GFAFB, ND. I grew up hunting waterfowl, so ND was fine with me. I used a H&R 10 gauge single shot. Oh, did I tell you I was 5'-8" & 119 lbs with a 29" waist?
It is not what your body provides in mass to absorb the recoil of a fire arm, but the proper mounting of the gun and being able to move with it that makes it possible to shoot heavy recoiling guns without pain or injury. I often shoot 20 or 30 .30-06, .308 and .300 WSM from the bench, sometimes more, without painful results. Now I'm 5'-8", 155 lbs and a 33" waist.

Poper

 

[PPS43]

https://github.com/lstange/mcgs lists CV for various group sizes.

 

[Pripyat]

A lot of my problem is stance. The benches at my local range are too tall for the chair. I am only slightly larger at 130#, 5'9". I have never had issues with recoil before now. It almost had to be my stance.

 

[edfardos]

Don't count the first clean cold bore shot either.

 

[Andrew Leigh]

@ ColtPythonElite



I am afraid you are near 100% correct. It is with amusement that I see people discounting "flyers" and claiming wonderful groups. I have seen my mate discount a shot in the three shot group of 1.5" and claim .3" for the two that were cutting, I told him he was delusional.

To be a little contentious, I personally don't believe in flyers, flyers for me are an excuse for me not to improve my marksmanship. If I "call" a flyer then I am simply admitting to having made a poor shot and I take this into consideration when evaluating groups. If I have an established load and am at 100m then so called flyers are simply due to operator control.

Getting back the the OP. I saw an interesting statistical model which postulates that a 4 shout group would statistically be the best to shoot. The larger the number of rounds fired in a group the more chance you have for poor shots to expand the group size. the article is here;

http://www.the-long-family.com/Group size statistical analysis.pdf

Cheers

 

[ColtPythonElite]

You gotta get the shooter's lingo down, too. If you have a witness to your poor shooting, you need to know how to authoritatively say something like, " I'm still dialing her in."