Help with 22lr ammo test in a new GM bull barrel

keyrock

keyrock

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Good day fellow firearm enthusiasts,
For some time now I have been stock piling a fair amount of different types of 22lr ammo from various manufactures in different quality categories.
I'm looking to perform a test of different ammo to see which one my new free floated 20" Green Mountain Bull barrel on my SR-22 will like the most.
I have tried to search out the best methodology to performing this test to no avail...
It seems that most of the articles has a different approach to performing this test and there is little consensus among them.
Keeping in mind I'm looking to perform this within one day at the range in order to minimize variations in other external factors.... temperature, wind, humidity, etc...
I'll be running this on sandbags for stability and I've recently performed a trigger job to reduce creep and over travel and brought the pull weight down to 2.2 lbs.
I've decided to group the ammo types into three categories for testing purposes: bulk, mid-range, and high end.

Here's some of the questions that have come up that I would like clarification for...

How many rounds per grouping would provide a reasonable spread of data?
Is it necessary to clean the barrel between each ammo type?
Is it necessary to prime or hone the barrel each time a new type of ammo is tested through it, and if so how many rounds should be fired?
How to mitigate barrel overheating during the testing process? Since I have around 20-25 different types of ammo and I'm estimating I'll fire 15-25 rounds of each type. Or will that not amount to much variation in accuracy over the testing process?

Is there anything else that I've missed? Or are there any other helpful pointers that could help me in this testing process?
Please let me know.
Thanks in advance!
 
If I were you and wanted to acomplish this for data purposes.

I would shoot the whole box and clean between ( just a wet patch soak for 2min and 2 dry ) and shot 10 5shot groups. You should see a pattern of groups shrinking after first 2.
I would use last 5-8 groups for data depending on when they start to "shoot in" with new lube down barrel.

Wouldn't worry about heat, just stay consistent time between groups. I usually load the next mag inbetween so 45sec-1min.

And a scope with parallax adj will help you out a bunch.
 
I think tuffbuff's recommendations are good. A couple of other points. First, make sure you're doing this on a calm day. If you're shooting rimfire in wind, your tests will be inconclusive, and keep in mind that wind can change in direction and intensity during the course of a day. Since different ammunition brands/lines have different lubrication, it is important to clean between the different ammunitions you are testing. In other words, you would start with Ammo A; shoot 10 5-shot groups, and then clean the barrel (as suggested by tuffbuff) before beginning shooting 10 5-shot groups with Ammo B, and so on. You could use the last 9 groups with each ammunition/line to assess group size. Compute the group size, center-to-center for each group, and record the average and standard deviation.

A better plan would be to break up the ammos and groups as follows as the day progresses. Say you're testing 4 different ammunitions/lines:

1. Order of shooting: Ammo A - 5 groups; 2. Ammo B - 5 groups; 3. Ammo C - 5 groups; 4. Ammo D - 5 groups (cleaning between ammunitions/lines), then

2. Same order as above, cleaning between ammunitions/lines (or you could reverse or otherwise change the order).

This plan would reduce somewhat any daytime and shooter-fatigue effects that may be at play. You could consider the last 4 groups in each set of 5 as ones you will use for recording group size. This would give you 8 groups of each ammo. The average group sizes should reveal which of the 4 ammos is best. As for barrel heating, by cleaning the bore between ammos, there will be some cooling from that, but in addition I'd perhaps let the barrel cool for 3-4 minutes between groups shot with each ammo. Barrel heating won't be much of a problem with the heavy barrel you have, but I'd still let it cool a bit between groups. The ambient temperature on the day you're doing the shooting will have a bearing on this.

There are other factors to consider (such as bench setup and technique) that I'll leave for others to cover.
 
I had a 20” stainless green mountain on a 10/22 it shot cci blazer into a 5/16” group at 100 yards and I lost my marbles when I saw the group. Had a buddy there to witness it. Cci blazer shoots insanely good in my cz 452 varmint
 
Thank you gentlemen for your informative replies. I will be incorporating all this information into my testing session. Another quick question. Instead of using sandbags, would a shooting rest work better to mitigate shooter fatigue over the course of the day?
 
A shooting rest would be better as you can set it to a comfortable night for you, plus it is alot more consistant then sand bags that can move around easaly.
All my reading and research says that you need to shoot atleast 20 rounds of one ammo to season the barrel to that particular ammos lube. I have used this method and have seen my groups shrink constantly over the first 4-5
5 shot groups. Stick with 5 shot groups any more then that and you start shooting through a BIG hole in the target so you have no idea if it is getting smaller or bigger.
 
Could you please post the result after the test? I have a GM 20" barrel in a Troy Chassis, Would like to know your test result.
 
The average of five, five-shot groups should give you a pretty good idea of how each ammo type performs. I would shoot maybe ten fouling shots of each type before shooting for groups.
 
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