3 shot or 5 shot groups to test loads?

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Rugdoc

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How many shots do you use to test a load?

I want to try shooting some 175 grain bullets in my 7x57 using 43, 44, 45 and 46 grains of H4350 and though I have done this before with both three and five shots, I was wondering what is normally done.
 
I do "rough" tests with 3 shots. Then I move to 5 to get more reliable information to differentiate more precisely between loads that may be "close" in potential.
 
If I was zeroing in a hunting rifle, likely 3 shots. I only need to be so accurate, and given that hunting rifles are not target rifles, things start to heat up and bend after 3 shots, throwing group sizes off.

If I am shooting target type rifles, for load development, then 5 is usually OK, and generally the standard. 5 is a large enough group to tell you how accurate the load is.

If I was super serious about that particular load(s), then at least 7, if not 10. Generally the larger the sample size (# of shots per group) the more accurate your estimation of group size (or average velocity, or extreme spread, etc.)
 
I always do 5 , and then I measure the 5 shot group as well as a 4 shot group with the worst shot removed, record all group measurements on a spread sheet.

You would be surprised what you can over look in a trend from the occasional flier making you second guess. ;)
 
I read somewhere that statistically speaking, 7 rounds is the most you need to fire in order to determine precision. Can't recall where though.
 
Some rifles are incapable of firing 5 accurate shots due to barrel stress and or bedding.

3 shots will give you velocity and pressure indications and are enough to prove a load does not work, and to suggest what might work.
 
Any hunting rifle is good to go for normal hunting distances (to about 300 yards) if it will give you consistent 3 shots groups of under 2MOA. yeah, we all want sub MOA 3 shot groups, but the reality is even deer have a pretty big kill zone and 2MOA will do it. Most factory rifles these days will shoot 3 shot 1.5 MOA groups or less to that distance. Depends if you want to hunt or win shooting competitions.
 
Kelly Timoffee said:
I always do 5 , and then I measure the 5 shot group as well as a 4 shot group with the worst shot removed, record all group measurements on a spread sheet.

You would be surprised what you can over look in a trend from the occasional flier making you second guess. ;)
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Same here. Playing with the sort orders of 5 and 4 round groups in the spreadsheet really helps sometimes. I find shooting less than 5 is useless for me. It doesn't take flyers and operator error into account. I can't see how guys can do it with 3. They must be perfect shooters shooting in perfect conditions!
 
When hunting if you hear one shot, it might be a hit. If you hear two - it is a maybe and three is a miss.
Those shots will come in quick succession.
For hunting purposes, three shots, evenly spaced will give you a fair idea as to the ability of the shooter and the rifle.
When shooting benchrest, five shots for score with sighters in 7 minutes would be evenly spaced.
Many good three shot groups are wasted by shooting a 4th or fifth shot while accomplishing nothing in a hunting rifle.
 
horseman2 said:
When hunting if you hear one shot, it might be a hit. If you hear two - it is a maybe and three is a miss.
Those shots will come in quick succession.
For hunting purposes, three shots, evenly spaced will give you a fair idea as to the ability of the shooter and the rifle.
When shooting benchrest, five shots for score with sighters in 7 minutes would be evenly spaced.
Many good three shot groups are wasted by shooting a 4th or fifth shot while accomplishing nothing in a hunting rifle.
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X2!! This man speaks wise words...listen to him!!
Eagleye
 
I make 6 rounds of a given load. With 3 round groups I shoot through all my loads, then start over shooting the rest in 3 round groups. I shoot all my individual loads into the same groups, ending up with 6 round groups. Hope that made sense... I've seen this method called "round robin". I believe it accounts for what my rifle is doing while shooting (fouling, etc.). This has given me the best results so far.
 
Unless you're into target shooting anything over 3 shot groups in a hunting gun doesn't much matter. Harold
 
I always prove loads with 3 cold bore shots (read: 10 mins or more apart) for hunting guns. Once I have a load that I'm happy with under that criteria, I will check how the load works for 3 quick shots... I've rarely found a problem.

For target guns I like 5 shots fired at a leisurely pace: make shot, check out brass, have a look at the wind, take your time... that sort of pace.
 
I may be alone thinking that but for me the epitomy of accurate precision is a 10 shots group in a small cluster, when achived, i rest my case... JP.
 
caramel said:
I may be alone thinking that but for me the epitomy of accurate precision is a 10 shots group in a small cluster, when achived, i rest my case... JP.
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You're not alone, but the OP asked about testing loads. Once I've got a good load, no problem going for 10 shot groups (although clay pigeons at 4-500m are more fun.)
 
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