.17 WSM ammo discussion

[n4ue]

Hi. Thought I'd start another thread concerning the .17 WSM ammo. The contents have been scattered in several threads and thought I'd try to help myself and others.
I've known for may years that .22 lr target shooter weigh/sort the ammo and use head thickness guages, etc.

With the .17 WSM, I've been perplexed by the fact some shooters will get excellent groups with the 20 gr and others like the 25 gr loadings.
I realize this is not an F-Class rifle.... Once I re-floated the bbl, mine shot the 25 gr pretty good, while the 20 gr target looked like it was hit with a shotgun.
So, yesterday, I talked the gf into helping me weigh a couple of boxes of the ammo on my Chargemaster 1500.
Yes, I do know it's not a lab quality scale and the +/- .1 gr 'toggling', is not the optimum set up. I was just looking for surprises. I found some.
Weighed 50 of each, took my time. If the scale couldn't make up it's 'mind', I waited, then reweighed.

On the 25 gr ammo (which MY gun likes) the highest weight was 67.4 gr and the lowest was 67.1 for a delta of .3 gr.

On the 20 gr ammo the highest weight was 63.4 and the lowest was 62.7 gr for a delta of .7 gr.

Of course, this is just extreme spread. I am going to run the weights through a calculator to find the Standard Deviation. However, I noticed that the 25 gr ammo was more consistent through the 'mean'. What does this 'mean' (ha ha).
This is just one measure of ammo consistency. There could be:
- variations in bullet weight
- variations in case weight
- variations in powder weight (which is what I was exploring here).

Being a rimfire, there could be primer issues, OAL, and a bunch of other things to wonder about.

This is certainly not a slam against Winchester. This is just a small exercise for fun.

Your comments are welcome.....

ron

[gsperaz]

Since my rifle went back to savage, I too have decided to weigh and sort ammo. My approach was a little different, by that I mean I grouped weighed ammo by +/- .1 grains. By that I mean ammo the weighed 63.0 grains was grouped with 62.9 and 63.1 ammo weights. It just make it easier to consolidate all the different weights and put them back into the original ammo boxes. All 20 boxes I have are now sorted and labeled by weight.
Whey too much time on my hands...........lol. I just hope it helps the accuracy some.

[n4ue]

gsperaz, yes, this is what I intend to do 'sometime' down the road. I noticed that the weight of the 25 gr stuff was very consistent with some scattering on either side of the 'mean'....
The 20 gr stuff was almost evenly distributed from light to heavy, so the grouping by weight is going to be OK, but will produce a lot of clusters of weights... ha ha

good shootin' and keep us posted if the sorting helps. BUT,if you have it all sorted, you probably couldn't tell!

Of course, you could shoot groups with the light rounds and then again with the heavier. If the groups within each weight are good but the heavier shoots to a different POI, you have accomplished what I'm trying to do. ha ha

ron

[JG26_Irish]

I tried this early on with the 25g ammo (that was all I had at the time). I weighed it in grams just because my scales gave me weights to three decimal points using grams. I also weighed spent brass after shooting and found that even though sorted by weight, the brass often varies also. So, while the biggest variable is likely still the powder charge, sorting by weight still does not eliminate all flyers. In fact, sorting by weight did generate some tighter groups, of three shots each but when attempting to print groups of 5, I almost always got a vertical flyer that was usually lower but sometimes higher as well. There will be variation in brass weight, primer material weight, bullet weight (this is likely the most consistent variable) and powder charge weight. Weighing the cartridges can improve results some, but is not going to result in amazing results either. It take a lot of time, but hey, why not?

I have not tried it with the 20 grain ammo yet, but have finally obtained some, and also found that my gun does not shoot it as well as the 25g ammo. I am a reloader and learned that when I loaded lighter bullets toward the limits of the cartridge, that I often saw increases in the std deviation, and loss of accuracy. This is due to the limits of my ability to measure powder charge was about one tenth of a grain and one tenth grain variation with a lighter bullet causes more variation in velocity than it will with a heavier bullet. So, it is harder to get accuracy when using the same loading process. Therefore, the lighter, faster ammo is almost always going to be less consistent and usually less accurate, unless a certain gun's natural harmonic frequencies happen to match up to the lighter ammo's characteristics.

We found that most 17 HMR guns also shoot the heavier ammo better than the lighter bullets. Likely for the same reason, the heavier ammo has slightly less velocity variance.

Irish

[gsperaz]

N4ue, yes that is my plan, shoot and compare heavy to light loads. It may not help at all or may help some. My gun shoots so poorly every little bit helps. If I ever get it back from savage, the stock issues will have to be addressed as well.

Irish, I have a savage 17HMR BTVSS that will not group 20grain ammo worth a poop. But switch to hornady's 17grain v-max ammo and both my son and I can shoot nickel size groups at 100yd.
Not even the 17 grain TNT hollow points group well, its very particular.
On the other hand my 22 long rifle gun will not group cci stingers, but groups cci velocitors very well at 50yds. So I guess every gun has its preference to ammo, with the WSM being no different. I just hope my WSM comes back and is able to group either ammo better then 3" at 50yds.

[JG26_Irish]

Irish, I have a savage 17HMR BTVSS that will not group 20grain ammo worth a poop. But switch to hornady's 17grain v-max ammo and both my son and I can shoot nickel size groups at 100yd.
Not even the 17 grain TNT hollow points group well, its very particular.
So I guess every gun has its preference to ammo, with the WSM being no different. I just hope my WSM comes back and is able to group either ammo better then 3" at 50yds.

It is Soooo true that every gun has its own preference for ammo. The bbl is like a tuning fork and when you get it right, it makes a big difference. With rimfires, we lack the ability to reload and find a load that is just right for our gun. That is a big handicap in my opinion. With my centerfire long range rifles, a good hand load is usually able to tighten a group by half. Example is my 700 Rem 223. It shoots premium varmint factory ammo with nosler or hornady ballistic tips in 0.50" groups at 100yds. It shoots my hand loads using the same bullets in groups that are closer to 0.25" with a best of 0.152" c-c. It typically is able to group 0.50" at 200yds using the same hand loads but is lucky to group under 1" using any factory ammo at the same distance. From what I can tell, the only real difference is my getting the OAL right and the powder charge to be very consistent. I am usually using a hodge podge of mil-spec brass of all different head stamps. I am not a bench rest shooter. I am a varmint shooter and never found much value in buying one brand of unfired brass for my rifles. I do use a full length resizing die and trim every casing to the same OAL. I use a taper crimp as that seemed to get better results for my guns. 22lr match shooters usually test many brands of ammo and once they find one their gun like, they will test many lots of the same ammo to find the one that is best for them.

I have a Savage 93R BRJ in 17HMR. It likes the Hornady 17g BT's and the Federal 17g HP's the best so far. It hates the Winchester 17g ammo. So far the only 20g ammo I could find was also Winchester. It shot these OK but not better than the others. The CCI 20g 17HMR ammo has been impossible to find here in recent months. It is reported to shoot the best in most of the HMR's. Both my HMR and my B-Mag have printed very nice 100yd and 200yd groups from a bench on a not too windy day. The HMR did 0.850" at 100yds and 1.30" at 200yds. The B-mag has done 0.687" at 100yds and 1.250" at 200yds. Typical is closer to 1" at 100 and 1.5-2.0" at 200. Still that is not too shabby for low priced rim fire rifles with cheap scopes on them. If your gun is not able to do that, I would start by checking a few things like:

1.) Is scope mount tight and secure?
2.) Is the bench you are shooting from stable? It is amazing how much better you can shoot from a solid rest and how poorly from a less than solid platform.
3.) Are you using good sand bags and getting the gun bedded in well?
4.) Wind? If there is any, groups will open up.
5.) Is bullet dispersion horizontal or vertical or random? Horizontal is usually due to either technique/trigger pull or wind and vertical is usually due to ammo or the bench or rest is moving. Sometimes a "U" shaped dispersion is due to the bbl contacting the stock somewhere. My B-mag does this sometimes.
6.) Is trigger adjusted to the lightest pull? The Savage trigger is not great. It is OK, but creepy. Better than a lot of modern guns, but not match grade.
7.) Choice of tgt? A good tgt is easier to consistently aim at the exact same way each shot.
8.) What power is your scope and what type of recticle are you using? Is the recticle fine enough to get good precise aiming point every time? My HMR uses a 3-12x scope with a duplex and my B-mag a 6-24 scope with a mil-dot. The better scope/recticle combo on the B-mag makes it consistently more accurate, especially at the longer ranges where the cross hairs can cover the aiming point. The lower powered scope on the HMR makes it the better hunting gun for deep woods where field of view is more important than ultimate precision.

Irish

[gsperaz]

Thanks for the suggestions Irish, but all have checked, adjusted and bench fired from stable bags , scope is 4-16x the same as on my 17HMR. The shot string was vertical with little wind on a 6'' shoot & see target at 50yds. At 100yds I could not keep 5 rounds in the 6" target with either ammo.
Thinking back I don't recall where the bag was resting under the forend of the stock. With so much stock flex and a none free floating barrel this could account for some of the accuracy issues I experienced if the bag was too far forward. I had to return the Bmag for warranty work anyway so I did not mess with the stock. Its nice to hear there are a few folks who's Bmag's shoot well.
Hope to get it back by Dec 1, opening day of Fox season here in GA. If not I will use my BRJ in.22mag another good shooter !
I also have a savage in .223 for long range stuff. It also shoots under .3/4''at 100yds with cheap 50 grain v-max ammo, American eagle brand I believe.

[JG26_Irish]

I doubt anyone would do this, (but I did), that is to rest the B-mag barrel onto the front sandbag. I did that one day and was shocked to see how much it affected the point of impact. The barrel is very flexible. Point of impact was 4" above POA at 35yds. I thought my scope was broken until I moved the gun to a proper rest.

Irish

[J.Baker]

It's not that the barrel is flexible, it's that you effectively shortened the barrel as far as wavelength is concerned and thus totally changed the harmonic characteristics of the barrel. This is why you don't ever rest the barrel itself on anything when shooting and it's why most all precision rifles have a free-floated barrel these days.

[davemuzz]

n4ue, short of setting up a spreadsheet for just plopping in numbers to get the standard deviation (Ghee, I wonder who would do that?) here is a web site (scroll down just a tad when you get there) where you can enter your numbers and it will do the number crunching for you. Of course, if you just Google "Standard Deviation" you will get a few other choices. This is just the one I have used in the past.

FIWI………..http://easycalculation.com/statistic...-deviation.php
Dave