Please school me on POI

[vaalpens]

I tested my first 9mm reloads this week and found good and bad results.

I loaded 124gr Xtreme RN using AutoComp with 4.8/4.9/5.0/5.1gr at COL 1.154".

The results I saw at 10yards were average groupings of:
4.8gr 1.22"
4.9gr 1.27"
5.0gr 1.29"
5.1gr 2.28"

The lower charges gave me the best groupings, but I also found that the brass landed inside 3ft at the lowers charges, and the POI was also higher. The POI was better at 5.1gr, but still not where I expect it.

There are two changes I can make. I can work my load up from 5.2gr to 5.4gr and see if I get better grouping than 5.1gr, and also a better POI. Or I can start at 4.8gr again, and lower the COL to the published 1.150" and see if it improves my POI and retain the good grouping.

As a footnote I can just add that I also load AutoComp for 40S&W 165gr RNFP at the lower load levels and has no issues with weak brass ejection or high POI.

As always, any advice will be appreciated.

 

[rcmodel]

As a footnote I can just add that I also load AutoComp at the lower load levels and has no issues with weak brass ejection or high POI.

not sure I understand your post?

Was the 'No Problemo' load with the same bullet brand & weight?
Or something different????

Low pressure, lower velocity loads will shoot higher, because the bullet is in the barrel longer.
Giving the gun more time to rise in recoil.

rc

 

[vaalpens]

not sure I understand your post?

Was the 'No Problemo' load with the same bullet brand & weight?
Or something different????

Low pressure, lower velocity loads will shoot higher, because the bullet is in the barrel longer.
Giving the gun more time to rise in recoil.

rc

The hearing and eyesight are gone, and now the mind. Thanks for catching the omission of the different bullet brand & weight. I edited my previous post.

Thanks for confirming that low pressure and lower velocity will cause a higher POI. I have to say it was a consistent higher, which made me realized that it wasn't my aim.

Do you have any suggestion where to start trying to bring down the POI?

I can change the COL to 1.150 from 1.154, but I'm not sure it is going to give me much more in pressure. Currently I am leaning towards working loads from 5.2gr to 5.4gr to see if it brings to the POI down to the POA, and then evaluate and see if I can maybe increase the COL to improve the grouping if the grouping suffered. I can work up to 1.169" if needed since I have tested dummy rounds at 1.169" COL.

Thanks again for the feedback.

 

[Potatohead]

1.15 to 1.154, That's probably not even an eyelash.

I guess you don't want to get to awful short, but any opposition to loading shorter? I like to try a lot of different OALs, after Ive started low and ensured that the load is safe enough to move it around.

 

[vaalpens]

1.15 to 1.154, That's probably not even an eyelash.

I guess you don't want to get to awful short, but any opposition to loading shorter? I like to try a lot of different OALs, after Ive started low and ensured that the load is safe enough to move it around.

I can probably go shorter in the COL, but I'm not sure how much shorter since I don't have a chrono. I will all have to be done based on feel and obviously what the bullet allows. I can't shoot in my backyard to test it out, so I will probably have to do a few with lower COL, and then some using more powder, but still within the maximum.

Thanks for the advice.

 

[Potatohead]

I think 1.10-1.16 is probably safe if you're not running max IMO, and always start low of course. Might be getting a little short with a round nose @ 1.10. Cant recall if Ive seen RN that short in data but I do bet you have some wiggle room.

 

[moxie]

I run 124 RN (FMJ & lead) at 1.116 oal. Works for me with 4.3 Bullseye.

 

[vaalpens]

I think 1.10-1.16 is probably safe if you're not running max IMO, and always start low of course. Might be getting a little short with a round nose @ 1.10. Cant recall if Ive seen RN that short in data but I do bet you have some wiggle room.

The load data I was using was for 124 gr BERB HBRN TP, which is a hollow base bullet. I don't know what the length of the bullet is, but I should be able to go to 1.15" minus the difference in length between the Berry's bullet and the 124gr I use, which has a length of 0.5875"-0.5900". I will also see what the bullet bearing surface allows and then work up from there. I am at the low end of the powder weight and it definitely feels like bunny farts, so I should be safe. The key for me will be baby steps at a time.

Thanks again for the advice.

 

[vaalpens]

I run 124 RN (FMJ & lead) at 1.116 oal. Works for me with 4.3 Bullseye.

Thanks for the information. Looks like 1.10" COL should be ok with my low end powder load, but I will work slowly down to it.

 

[JamieC]

Maybe I missed something, can you adjust your sights? If you want to go up in powder till max, just to see if the groups improve, why not? I guess it depends on what you want, if these are just plinking rounds, why go higher if lower gives you better groups. Save the wear and tear on your gun, hand, wallet.

 

[vaalpens]

Maybe I missed something, can you adjust your sights? If you want to go up in powder till max, just to see if the groups improve, why not? I guess it depends on what you want, if these are just plinking rounds, why go higher if lower gives you better groups. Save the wear and tear on your gun, hand, wallet.

That is a good point, but I have fixed sights. All other ammo I have the POI is at POA, except for this load I am working up. I will work with the COL and load and see much I can bring it down. Thanks for the suggestion.