Another OCW-ish test…. Thoughts

KOPFJÄGER13

KOPFJÄGER13

If people were half as good as they think..
Full Member
Minuteman
Sep 11, 2018
265
53
47
#1
Hey everyone! I recently picked up a CZ 600 Range and it had only 50 rounds through it at the time of the test….. load charges are written on target…. Target was shot at 200y.
I’m looking at opinions on what looks like a solid contender, the more peoples opinions, the more insight, the less chance of me over looking something ….

CZ 600 Range
Petersons SRP brass
155gr Lapua scenar
Fed GMM primers
Vihtivori N540 powder

Thanks in advance!
 

Attachments

  • IMG_0065.jpeg
    IMG_0065.jpeg
    361.7 KB · Views: 109
#2
When I do an OCW type of test I like to look for the groups impacting an a similar location. So, that looks like 43.1 to 44. I would try to repeat 43.7 and start trying different seating depths with 44.7.

Is this a 308 Win?
 
#3
You will want to use some target processing software to help reduce those holes into understandable target results.

Pick one of the many available target processors, they are all pretty good and not that hard to learn compared to everything else in life.

In glancing at your targets, nothing looks like it comes out of the noise in the groups or the centroid shift.

If you are only going to shoot short range and are happy, just pick a level and run. Otherwise, you will need to make choices about your path forward.

You can re-run the same test, you can try a change in the recipe, or you can shoot an Audette Ladder at distance to see if anything stands out.

Good Luck and in for the range report.
 
  • Like
Reactions: Baron23
#4
ShtrRdy said:
When I do an OCW type of test I like to look for the groups impacting an a similar location. So, that looks like 43.1 to 44. I would try to repeat 43.7 and start trying different seating depths with 44.7.

Is this a 308 Win?
Click to expand...
Thank you for the reply, that was also my thoughts…….yes it’s a .308 & that’s .020” jump (at this point), btw, these were shot at 200y
 
Last edited:
  • Like
Reactions: ShtrRdy
#5
RegionRat said:
You will want to use some target processing software to help reduce those holes into understandable target results.

Pick one of the many available target processors, they are all pretty good and not that hard to learn compared to everything else in life.

In glancing at your targets, nothing looks like it comes out of the noise in the groups or the centroid shift.

If you are only going to shoot short range and are happy, just pick a level and run. Otherwise, you will need to make choices about your path forward.

You can re-run the same test, you can try a change in the recipe, or you can shoot an Audette Ladder at distance to see if anything stands out.

Good Luck and in for the range report.
Click to expand...
Thank you for your input, are you suggesting loading more and at different gr weights and reshoot……what would your next move be?
 
#6
KOPFJÄGER13 said:
…what would your next move be?
Click to expand...
That is up to you. This would be determined by your intended goal down the line.
What kind of shooting are you trying to do?

If these results are "good enough" for what you will be doing, then pick any speed you like and roll.

You did well to include a baseline with FGMM 168. Your rig looks decent for a factory rig and factory ammo and should keep you busy out to 600 yards as is.

If these results are supposed to be tighter for your goals, then you have to roll up your sleeves and keep trying with your best efforts.

If you are less experienced, you should re-run exactly what you just did and see how well (or even if) the results repeat. Then you try another different bullet, or another different powder, then you decide if there is more to see or if this is just as good as it will get.

This is a factory rifle, so don't expect it to compete with custom competition rigs and you will avoid frustration. It is more than good enough to learn to shoot to 600 yards as is for informal work. To be competitive in midrange prone matches like F-Class or F-T/R, it would have to hold under 0.5 MOA for 20 shot strings, or very close to it.

If your goal is to go farther down range, then I would also learn to combine this type of centroid shift test with an Audette Ladder. You may find a charge weight that shows better at distance than is evident at 200, or you may find that this recipe has shown all it has.

You can still learn a lot about shooting with the load you have now. Field shooting isn't done from stable rests, and this load will show you plenty as long as you understand the limitations.

So, what I would do next depends on what type of shooting you plan for this rig/ammo and your goals.
 
  • Like
Reactions: straightshooter1 and supercorndogs
#7
I would call myself a novice…. This gun will shoot 10rnds in under an inch with FGMM. It’s very consistant for what it is, I feel…… I’m only interested in 100-600y with this rifle….. example: I have a shoot coming up that is a poker chip shoot at 200y, shoot till ya miss, just a club shoot….so I need a load that’s consistently 1.5” or better at 200y….. thanks again I really appreciate the feedback
 
  • Like
Reactions: ShtrRdy and RegionRat
#9
Do you know what the SD’s ES’s for these groups are? If the 43.7 grain group has a good SD and ES, I would run a seating depth test. It does often make a remarkable difference.
 
#11
KOPFJÄGER13 said:
Hey everyone! I recently picked up a CZ 600 Range and it had only 50 rounds through it at the time of the test….. load charges are written on target…. Target was shot at 200y.
I’m looking at opinions on what looks like a solid contender, the more peoples opinions, the more insight, the less chance of me over looking something ….

CZ 600 Range
Petersons SRP brass
155gr Lapua scenar
Fed GMM primers
Vihtivori N540 powder

Thanks in advance!
Click to expand...
One of the things that helps with interpreting someone's OCW test is the chrono numbers that go along with it. Because, if your velocity ES and SD's are high, then that could explain why there's so much noise from one load to another making it hard to interpret the differences from one group to the other. If you tend to get good velocity SD's and ES's with your reloading process, then these groups suggest to me a different bullet and/or powder . . . or maybe even different primer might be in order.

Otherwise, you should probably test around that 43.7 grs to see if you can repeat something like you you have there. Like, try loading 43.5, 43.7 and 43.9 and see what you get. If you can't repeat a group that's like that 43.7, then decision(s) should be made for making some changes.

A lot depends on what you're expectations are. 🤷‍♂️ :giggle:
 
  • Like
Reactions: RegionRat
#12
1717538336527.png


I assumed it was 6" spacing between the black vertical lines.

From 43.1 to 44 gr, the POI center from group to group is roughly within 0.05 MRAD of each other even when including the fliers.

Triangle is what the software (Gordon's Reloading Tool shot group analysis) assumes is a flier.

Option 1 (favoring velocity) - Choose a velocity you like, then retest +/- 0.3gr to see if the center POI remains within 0.05 MRAD of each other (including fliers).

Option 2 (favoring group size consistency) - Retest all and if the group size SD remains similar, choose 43.1 to 43.4gr as they have the smaller group size SD variation compared to 43.7 to 44.
 
Last edited:
  • Like
Reactions: RegionRat
#13
KYAggie said:
Do you know what the SD’s ES’s for these groups are? If the 43.7 grain group has a good SD and ES, I would run a seating depth test. It does often make a remarkable difference.
Click to expand...
I haven’t got them yet….that will be step #2 once I seem to find a group
 
#14
Evintos said:
View attachment 8432065

I assumed it was 6" spacing between the black vertical lines.

From 43.1 to 44 gr, the POI center from group to group is roughly within 0.05 MRAD of each other even when including the fliers.

Triangle is what the software (Gordon's Reloading Tool shot group analysis) assumes is a flier.

Option 1 (favoring velocity) - Choose a velocity you like, then retest +/- 0.3gr to see if the center POI remains within 0.05 MRAD of each other (including fliers).

Option 2 (favoring group size consistency) - Retest all and if the group size SD remains similar, choose 43.1 to 43.4gr as they have the smaller group size SD variation compared to 43.7 to 44.
Click to expand...
It’s 4” spacing actually, the spots are 1” ( actually 15/16”)…. That’s awesome software!
 
#15
An interesting thing about POI of the 5 groups is that I put a straight edge in center of 43.1 & 44.3 and the line went straight through the 3 tight ones in 43.7…. Not sure if that’s significant……?
 
  • Like
Reactions: ShtrRdy
#17
KOPFJÄGER13 said:
It’s 4” spacing actually, the spots are 1” ( actually 15/16”)…. That’s awesome software!
Click to expand...
1717541880738.png


Updated to reflect 4" spacing for reference distance. The group to group POI center variation shrinks (improves) to roughly +/- 0.03 MRAD horizontal and/or vertical for 43.1 to 44gr.
 
Last edited:
  • Like
Reactions: RegionRat
#20
Evintos said:
View attachment 8432098

Updated to reflect 4" spacing for reference distance. The group to group POI center variation shrinks (improves) to roughly +/- 0.03 MRAD horizontal and/or vertical for 43.1 to 44gr.
Click to expand...
I’m sorry if I don’t understand what you’re telling me…is that good or bad and which load would you work with…. This is very interesting to me
 
#21
KOPFJÄGER13 said:
I’m sorry if I don’t understand what you’re telling me…is that good or bad and which load would you work with…. This is very interesting to me
Click to expand...
The theory of OCW is to achieve a powder charge weight that results in a POI that is insensitive to powder charge or environmental induced variations (mainly temperature) or minor variations in powder lots. More powder = higher velocity, less powder = less velocity. For temperature sensitive powders, higher temperature mimics higher powder charge, lower temperature mimics lower powder charge.

Looking at only POI differences, your results are good. The combo you have has a very large and forgiving window. Most scopes can't dial 0.03 MRAD, so theoretically you'd never have to readjust your zero once set if you choose a powder charge somewhere in the middle of 43.1 and 44gr. Of course you should retest the entire range just to confirm that the center of the groups remain true to your initial test.

If you just want a wide range window of powder charges that you don't have to mess with adjusting your zero, you can choose exactly 43.55gr of powder, which is in the middle of the 43.1 to 44gr range which allows you to have a powder charge variation (crappy powder measure, sloppy loading, etc) that is +/- 0.45 grain of powder or have temperature swings that mimic +/- 0.45gr difference in velocities, and you theoretically will have no more than a 0.03 MRAD center of group shift from your original zero.

Now this doesn't mean your results will give you the smallest overall group sizes nor does it give you the most consistent group.

For consistency in group sizes, you look into group size SD (Variation) as well as the group size mean. The smaller the differences between charges in a range the better. For your results, that is 43.1gr to 43.4gr, with a SD variation of about 0.34" and a mean difference of 0.172" (43.4gr with a mean of 1.26" minus 1.088" which is the mean of 43.1gr) .

If you wanted to choose this range, to confirm, you would load 43.1, 43.25, and 43.4gr and retest for similar center POI (of primary importance in OCW), consistency in group size mean and SD. If confirmed, you would aim to load 43.25gr of powder every time and your charge variance allowed is +/- 0.15gr.

If you take a look at 43.7, yes it produced the smallest group mean, but on either side (43.4 or 44), the groups grow larger by roughly 0.45". So theoretically any change that is equivalent to +/- 0.3gr of powder (temperature extreme or otherwise) from 43.7 will result in your group size increasing by up to 0.45".

It all depends on what you want to accomplish. If you need velocity for external ballistics reasons, you select the powder charge that gives you the velocity you need but also is resistant to changes in point of impact, however, it might not consistently have tight groups.

If you want consistency in group sizing and not have to wonder why one range session your groups are 0.4 moa but your next session you can't get better than 0.6 moa, then you potentially select a narrower window which provides little to no POI shift and has consistency in group sizing. Your ability to consistently load ammo with good quality components and using temperature insensitive powders is paramount to achieving consistency with a narrower range. Any variable that induces changes that puts you out of that narrow window and your results may end up unacceptable to you.
 
Last edited:
  • Like
Reactions: Genin, RegionRat and simonp
#23
Evintos said:
The theory of OCW is to achieve a powder charge weight that results in a POI that is insensitive to powder charge or environmental induced variations (mainly temperature) or minor variations in powder lots. More powder = higher velocity, less powder = less velocity. For temperature sensitive powders, higher temperature mimics higher powder charge, lower temperature mimics lower powder charge.

Most scopes can't dial 0.03 MRAD, so theoretically you'd never have to readjust your zero once set if you choose a powder charge somewhere in the middle of 43.1 and 44gr. Of course you should retest the entire range just to confirm that the center of the groups remain true to your initial test.

If you just want a wide range window of powder charges that you don't have to mess with adjusting your zero, you can choose something exactly 43.55gr of powder, which is in the middle of the 43.1 to 44gr range which allows you to have a powder charge variation (crappy powder measure, slopping loading,, etc) that is +/- 0.45 grain of powder or have temperature swings that mimic +/- 0.45gr difference in velocities, and you theoretically will have no more than a 0.03 MRAD center of group shift from your original zero.

Now this doesn't mean your results will give you the smallest overall group sizes nor does it give you the most consistent group.

For consistency in group sizes, you look into group size SD (Variation) as well as the group size mean. The smaller the differences between charges in a range the better. For your results, that is 43.1gr to 43.4gr, with a SD variation of about 0.34" and a mean difference of 0.172" (43.4gr with a mean of 1.26" minus 1.088" which is the mean of 43.1gr) .

If you wanted to choose this range, to confirm, you would load 43.1, 43.25, and 43.4gr and retest for similar center POI (of primary importance in OCW), consistency in group size mean and SD. If confirmed, you would aim to load 43.25gr of powder every time and your charge variance allowed is +/- 0.15gr.

If you take a look at 43.7, yes it produced the smallest group mean, but on either side (43.4 or 44), the groups grow larger by roughly 0.45". So theoretically any change that is equivalent to +/- 0.3gr of powder (temperature extreme or otherwise) from 43.7 will result in your group size increasing by up to 0.45".

It all depends on what you want to accomplish. If you need velocity for external ballistics reasons, you select the powder charge that gives you the velocity you need but also is resistant to changes in point of impact, however, it might not consistently have tight groups.

If you want consistency in group sizing and not have to wonder why one range session your groups are 0.4 moa but your next session you can't get better than 0.6 moa, then you potentially select a narrower window which provides little to no POI shift and has consistency in group sizing. Your ability to consistently load ammo with good quality components and using temperature insensitive powders is paramount to achieving consistency with a narrower range. Any variable that induces changes that puts you out of that narrow window and your results may end up unacceptable to you.
Click to expand...
wow very good info! I’m actually chasing 1.5” groups at 200……I have a poker chip shoot that’s at 200y in few weeks, I want it to be consistant…. Also the test was shot round robin not just sitting on 1 dot, which is rough for me sometimes as apposition to just 1 dot, idk…..what would you do to reach this goal?
 
#24
918v said:
Might wanna try 2.800-2.810”
Click to expand...
That’s .020” jump. Once I feel I have a solid powder charge I was thinking trying .010,.015 & .025…… something else I have to consider is this is new factory sized brass, my help when neck sized only on next firing
 
#25
KOPFJÄGER13 said:
wow very good info! I’m actually chasing 1.5” groups at 200……I have a poker chip shoot that’s at 200y in few weeks, I want it to be consistant…. Also the test was shot round robin not just sitting on 1 dot, which is rough for me sometimes as apposition to just 1 dot, idk…..what would you do to reach this goal?
Click to expand...
If it was me, I'd explore 43.7gr, +/- 0.2gr (so 43.5, 43.7 and 43.9). If POI is the same between those 3, and group sizes average (mean) remains around 0.867" (even with a flier), then I would move on to a seating depth test to see if I can squeeze a bit more performance out of it. Depending on results, I would be willing to accept a +/- 0.1gr window.

I also have the powder dispensing equipment that resolves within 0.02gr so that is also a factor in my willingness to accept a narrow window.
 
#26
Evintos said:
If it was me, I'd explore 43.7gr, +/- 0.2gr (so 43.5, 43.7 and 43.9). If POI is the same between those 3, and group sizes average (mean) remains around 0.867" (even with a flier), then I would move on to a seating depth test to see if I can squeeze a bit more performance out of it. Depending on results, I would be willing to accept a +/- 0.1gr window.

I also have the powder dispensing equipment that resolves within 0.02gr so that is also a factor in my willingness to accept a narrow window.
Click to expand...
I will do exactly that! Was kinda my first thought…… I’ll be at the range again Monday, I will let ya know my results….. thank you for the insight…… something else to consider is this is factory sized brass, neck sizing on following reloads may improve also…. Thanks again!
 
  • Like
Reactions: Evintos
#28
MarkyMark007 said:
dont waste your time and components for a such a lousy groups. just pick your charge and OAL and go shoot.
~0.040'' jump and low charge will have optimal group.
Click to expand...
Lousy groups? I wouldn’t think sub-moa @ 200y out of factory everything including rifle is lousy….. that’s a cool comment regardless of what or who you think you are, I’ve been respectful and just posted to learn something….which is nice to do here, there are some people on “the hide” that are incredible to pick there brain and take something away from it………. Then there are people like you, way to keep it classy….thanks for the response that didn’t help anything but make you look like a douchebag……
 
#30
Doom said:
OCW is about barrel harmonics. Shooting at 200yds tends to muddy the picture especially if you are not the best shooter. 100yds works best. I think you have a "node" in the 43.4 to 43.7 range. That is based on average point of impact remaining consistent.
Click to expand...
Thanks for the reply, I’m curious as to why 200 muddies up the test, does it not exaggerate the results? Doesn’t that make it clearer….. serious question…just trying to understand…. Thanks again for any clarity you may offer
 
#31
KOPFJÄGER13 said:
That’s .020” jump. Once I feel I have a solid powder charge I was thinking trying .010,.015 & .025…… something else I have to consider is this is new factory sized brass, my help when neck sized only on next firing
Click to expand...
Try 5,10,15 at 43.7, it’s definitely the node center. I used to shoot 155 scenars with n140 all the time. Your next node should be around 45.0 gr and you should be able to get there with no pressure. Take the best seating depth from your test with 43.7 and shoot 43.7, 44.8,45, and 45.2. That should finish your load development

I also second shooting at 100 over 200. Wind and any hold inconsistency will be greater at 200 and could muddy the results.
 
#32
KOPFJÄGER13 said:
Thanks for the reply, I’m curious as to why 200 muddies up the test, does it not exaggerate the results? Doesn’t that make it clearer….. serious question…just trying to understand…. Thanks again for any clarity you may offer
Click to expand...

Environmental's, especially wind, become more of a factor and larger velocity variations start to show up. In OCW the barrel harmonics are what is important so that you find the point where the barrel is releasing the bullet on the same trajectory. There is a tendency to think that the "nodes" are powder nodes but they really are velocity nodes where the barrel is pointing at the same departure angle and moving slowly so that the POI variation is minimized.
 
#33
jsthntn247 said:
Try 5,10,15 at 43.7, it’s definitely the node center. I used to shoot 155 scenars with n140 all the time. Your next node should be around 45.0 gr and you should be able to get there with no pressure. Take the best seating depth from your test with 43.7 and shoot 43.7, 44.8,45, and 45.2. That should finish your load development

I also second shooting at 100 over 200. Wind and any hold inconsistency will be greater at 200 and could muddy the results.
Click to expand...
Thank you, I can do that!
 
#34
Doom said:
Environmental's, especially wind, become more of a factor and larger velocity variations start to show up. In OCW the barrel harmonics are what is important so that you find the point where the barrel is releasing the bullet on the same trajectory. There is a tendency to think that the "nodes" are powder nodes but they really are velocity nodes where the barrel is pointing at the same departure angle and moving slowly so that the POI variation is minimized.
Click to expand...
Gotcha, makes sense!!!
 
#35
Update….. today I shot 5 more groups with 43.7 gr at 5 different seating depths ranging from .005”-.025”…….2 things… after shooting the 3rd group I realized my bipod mount was bumping my rest under recoil so I moved rest out towards end on the other side of the mount, rookie mistake……4th and 5th group I dialed scope in to zero, so yes the POI moved on to the target…… however it seems 43.7gr @ 0.010”-0.005” jump looks pretty good……
 

Attachments

  • IMG_0541.jpeg
    IMG_0541.jpeg
    163.4 KB · Views: 13
  • Like
Reactions: simonp
#36
Original session 43.7gr (0.020" depth?) - Horizontal 0.092 mil, Vertical 0.116 mil from POA
1718047458204.png


Today's session - Assuming it's 4" spacing and 200yds -

From 0.015 to 0.025" Center POI - Horizontal average - 0.068 mil, Vertical average - 0.132 mil

Difference from session 1- horizontal 0.024 mil, vertical 0.016 mil, which is around the same size as the center dot on a lot of mrad reticles.

From 0.005 to 0.010" Center POI - Horizontal average - 0.005 mil, Vertical average - 0.0295 mil
Difference session 1 horizontal 0.087 mil, vertical 0.0865, around 2.5x the line thickness of a lot of reticles

Average (mean) group size for all of them (including fliers) - 0.5278 in

1718046504861.png
 
Last edited:
#37
Evintos said:
Original session 43.7gr (0.020" depth?) - Horizontal 0.092 mil, Vertical 0.116 mil from POA
View attachment 8435784

Today's session - Assuming it's 4" spacing and 200yds -

From 0.015 to 0.025" - Horizontal average - 0.068 mil, Vertical average - 0.132 mil

Difference of - horizontal 0.024 mil, vertical 0.016 mil, which is around the same size as the center dot on a lot of mrad reticles.

From 0.005 to 0.010" - Horizontal average - 0.005 mil, Vertical average - 0.0295 mil
Difference of horizontal 0.087 mil, vertical 0.0865

Average (mean) group size for all of them (including fliers) - 0.5278 in

View attachment 8435759
Click to expand...
Today was at 100y, and yes the spacing is 4”, spot being 1”…. Once again wow on your analysis…. Could you dumb it down a bit so maybe I can wrap my head around your findings, thank you!
 
#38
1718048840480.png

New pic to reflect 100yds for session 2.


'A' - 0.015 to 0.025" - Average Horizontal 0.139 mil, average Vertical 0.2616 mil

'B' - 0.005 to 0.010 - Average Horizontal 0.025 mil, average vertical 0.041 mil

Average POI shift for all - 0.0924 mil horizontal, 0.1734 mil vertical
Average (mean) group size at 100yds - 0.4288 inch

For 0.015 to 0.025" the difference from session 1 vs session 2 is 0.047 mil horizontal center POI, 0.1456 mil vertical center POI

For 0.005 to 0.010" the difference from session 1 vs session 2 is 0.067 mil horizontal center POI, 0.075 mil vertical center POI

Difference between A and B - 0.114 mil horizontal, 0.2206 mil vertical

Original session was horizontal 0.092 mil, Vertical 0.116 mil from POA

If you were to use the combined averages for POI shift and compare with session 1, there is basically 0 difference for all of the seating depths when it comes to horizontal POI shift and 0.0574 mil vertical POI shift difference which I also count as basically no difference since many reticles have a line thickness of 0.03 mil. Was the POI center basically repeated?

If you were to compare the group size average of .4288 inch at 100yds, it basically matches the session 1 group size of 0.867 inch at 200yds, if you were to multiply 2 times 0.4228 = 0.8456 inch. Was the group size result basically repeated?

Analysis and opinions will vary but just based on what I see, it doesn't look like seating depth changed group size average nor center POI shift despite the visually appealing group with 0.005 to 0.010" depth.
 
Last edited:
#39
Evintos said:
View attachment 8435835
New pic to reflect 100yds for session 2.


'A' - 0.015 to 0.025" - Average Horizontal 0.139 mil, average Vertical 0.2616 mil

'B' - 0.005 to 0.010 - Average Horizontal 0.025 mil, average vertical 0.041 mil

Average POI shift for all - 0.0924 mil horizontal, 0.1734 mil vertical
Average (mean) group size at 100yds - 0.4288 inch

For 0.015 to 0.025" the difference from session 1 vs session 2 is 0.047 mil horizontal center POI, 0.1456 mil vertical center POI

For 0.005 to 0.010" the difference from session 1 vs session 2 is 0.067 mil horizontal center POI, 0.075 mil vertical center POI

Difference between A and B - 0.114 mil horizontal, 0.2206 mil vertical

Original session was horizontal 0.092 mil, Vertical 0.116 mil from POA

If you were the combined averages for POI shift with session 1, there is basically 0 difference for all of the seating depths when it comes to horizontal POI shift and 0.0574 mil vertical POI shift difference which I also count as basically no difference since many reticles have a line thickness of 0.03 mil. Was the POI center basically repeated?

If you were to compare the group size average of .4288 inch at 100yds, it basically matches the session 1 group size of 0.867 inch at 200yds, if you were to multiply 2 times 0.4228 = 0.8456 inch. Was the group size result basically repeated?

Analysis and opinions will vary but just based on what I see, it doesn't look like seating depth changed group size average nor center POI shift despite the visually appealing group with 0.005 to 0.010" depth.
Click to expand...
I appreciate your analysis a lot….. it’s intriguing….. so what bullet would you build? Seems solid with any seating depth tested and powder charge is decent based on poi…. My next test will be velocities….. thanks again!
 
#40
Seating depth wise, I'd just load long (0.005) which gives you room to account for throat erosion.

As for powder charge, if you wanted to see if the analysis holds true for average group size, you can repeat the charge weight test of session 1 at 100, and if the group size averages hold true, then a charge weight around 43.7 still will give smallest groups. You can also measure velocity while doing this test at 100.
 
#41
KOPFJÄGER13 said:
Update….. today I shot 5 more groups with 43.7 gr at 5 different seating depths ranging from .005”-.025”…….2 things… after shooting the 3rd group I realized my bipod mount was bumping my rest under recoil so I moved rest out towards end on the other side of the mount, rookie mistake……4th and 5th group I dialed scope in to zero, so yes the POI moved on to the target…… however it seems 43.7gr @ 0.010”-0.005” jump looks pretty good……
Click to expand...
Keep in mind, it's NOT the jump that's important. It's the seating depth that's giving you that jump. Measure your CBTO and maintain it as the jump increases as the throat erodes.
 
#42
Evintos said:
Seating depth wise, I'd just load long (0.005) which gives you room to account for throat erosion.

As for powder charge, if you wanted to see if the analysis holds true for average group size, you can repeat the charge weight test of session 1 at 100, and if the group size averages hold true, then a charge weight around 43.7 still will give smallest groups. You can also measure velocity while doing this test at 100.
Click to expand...
Thanks again!!!!! Learned a lot here…
 
You must log in or register to reply here.

Similar threads

Milirad
Rifle Scopes Burris Eliminator 6 Accuracy Range Test Review
Replies
19
Views
5K
Eric B.
E
Halfnutz
CMP M1 Advanced Maintenance Course-Build your own "Expert Grade".
Replies
8
Views
644
Halfnutz
Halfnutz
pangris
Battle Arms Development barrels and customer service – Caveat Emptor
Replies
15
Views
628
JS8588
J
Glassaholic
Vortex Impact 4000 GB First Impressions
Replies
23
Views
5K
Glassaholic
Glassaholic
Glassaholic
Rifle Scopes Steiner T6Xi 3-18x56 Review and comparison with NF ATACR 4-16x42, S&B US 3-20x50 and March 4.5-28x52
Replies
128
Views
10K
Jojo417
Jojo417
Top Bottom
Back
Home
Forums
Merch
Alerts