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WTF am I doing wrong.

Megalodong

Supporter
Supporter
Full Member
Minuteman
Mar 13, 2022
116
114
Denver
I feel like I’m about to be a little bitch and give up on reloading. As soon as I think I’ve got something figured out it all goes to shit.

Have a 6.5CM gun. Wanted to switch mags from magpul to the poly/metal MDT ones. So had to shrink my COAL to 2.8”

Range day one:
40.2 gn (12 SD)
-2755
-2745
-2769
-2742

40.5 gn (5 SD)
-2778
-2772
-2765
-2772

40.8 gn (12 SD)
-2770
-2801
-2789
-2785

Range day two:
40.5 gn (12 SD)
-2818
-2797
-2785
-2801
-2775
-2810
-2787
-2784
-2795
-2800


This is a gun with 400-500 rounds on it. Cleaned it before range day one and fouled with 10 factory rounds. Exact same sorted Hornady brass, same box of 210M primers, same jug of H4350, different lot of 140 ELDMs (?), exact same reload process two days apart. No change in weather during reloading or shooting.

I get that the first day was a smaller sample size, but wtf happens to cause a 24 fps change in average velocity??? If I load up 150 this afternoon wtf velocity are they going to come in at??

Partial rant, partial hoping someone has suggestions to help me understand this.
 
Fuck this. Disregard. I have bigger issues. Range day one the 40.5 load printed a .6 MOA 5 shot group. Today it just shot a 1.7 MOA 10 shot group.
 
Assuming everything else is squared away in the reloading room…

Something to keep in mind is Barrels will typically gain speed as bore conditions change with rounds fired

If the barrel is brand new, it’ll speed up, then settle somewhere in the first 100-300 rounds (usually)

Then as it fouls more and more if you don’t clean, it’ll speed up more and more

Clean out a very dirty/fouled barrel and the velocity will typically drop with the same ammo, it’s also likely to speed back up to the normal speed over the next 10-20 rounds

The cleaning process also has to be effective, just because some patches are pushed thru with a solvent, doesn’t always mean it did much

Edit to add: forgot to wrap the thought up, but all said…rounds fired/bore condition/cleaning cycles all need to be considered, especially when pinning down velocity changes of < 50 fps, which in reality, doesn’t take a whole lot of difference to occur
 
Last edited:
I feel like I’m about to be a little bitch and give up on reloading. As soon as I think I’ve got something figured out it all goes to shit.

Have a 6.5CM gun. Wanted to switch mags from magpul to the poly/metal MDT ones. So had to shrink my COAL to 2.8”

Range day one:
40.2 gn (12 SD)
-2755
-2745
-2769
-2742

40.5 gn (5 SD)
-2778
-2772
-2765
-2772

40.8 gn (12 SD)
-2770
-2801
-2789
-2785

Range day two:
40.5 gn (12 SD)
-2818
-2797
-2785
-2801
-2775
-2810
-2787
-2784
-2795
-2800


This is a gun with 400-500 rounds on it. Cleaned it before range day one and fouled with 10 factory rounds. Exact same sorted Hornady brass, same box of 210M primers, same jug of H4350, different lot of 140 ELDMs (?), exact same reload process two days apart. No change in weather during reloading or shooting.

I get that the first day was a smaller sample size, but wtf happens to cause a 24 fps change in average velocity??? If I load up 150 this afternoon wtf velocity are they going to come in at??

Partial rant, partial hoping someone has suggestions to help me understand this.
Temperature sensitivity and condition changes?
 
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I feel like I’m about to be a little bitch and give up on reloading. As soon as I think I’ve got something figured out it all goes to shit.

Have a 6.5CM gun. Wanted to switch mags from magpul to the poly/metal MDT ones. So had to shrink my COAL to 2.8”

Range day one:
40.2 gn (12 SD)
-2755
-2745
-2769
-2742

40.5 gn (5 SD)
-2778
-2772
-2765
-2772

40.8 gn (12 SD)
-2770
-2801
-2789
-2785

Range day two:
40.5 gn (12 SD)
-2818
-2797
-2785
-2801
-2775
-2810
-2787
-2784
-2795
-2800


This is a gun with 400-500 rounds on it. Cleaned it before range day one and fouled with 10 factory rounds. Exact same sorted Hornady brass, same box of 210M primers, same jug of H4350, different lot of 140 ELDMs (?), exact same reload process two days apart. No change in weather during reloading or shooting.

I get that the first day was a smaller sample size, but wtf happens to cause a 24 fps change in average velocity??? If I load up 150 this afternoon wtf velocity are they going to come in at??

Partial rant, partial hoping someone has suggestions to help me understand this.
1) Is the brass on Range Day 2, the same brass that was fired on Range Day 1? If so, did you anneal after resizing? That will effect neck tension which will effect velocity.

2) Are you using thrown charges from the measure, or are you trickling to charge weight? H4350 is an extruded powder, and extruded powders don't meter consistently. It's better to trickle to final weight.

3) Were Day 1 and Day 2 at the same COAL, or was one day at the PMAG length and the other at the MDT mag length? Seating depth will affect group size and velocity.


Those are the biggest variables that I can think of. Another possibility is that you just got lucky on day 1 and the larger string on day 2 showed the true nature of the load.
 
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Fuck this. Disregard. I have bigger issues. Range day one the 40.5 load printed a .6 MOA 5 shot group. Today it just shot a 1.7 MOA 10 shot group.
Hang tough. Reloading is not always a rewarding endeavor, but with time and effort your proficiency will improve along with your methods.

Try to find an experienced reloaded in your area who can show you their process and fill in the knowledge gaps wherever they may be.

The hide is an incredible resource and wealth of information but you may not be to that degree of controls and knowledge that is available to be gleaned. It comes with time and experience. Most of the lessons learned are what does NOT work.
 
I’ve got 300ish pieces of Hornady brass that are on their 2-3rd firing. Barrel has 400-500 on it. It’s a barrel nut prefit , straight taper 24”, on a Howa 1500. Velocity from magnetospeed.

Powder emptied into jug after session. Loaded 48 hours apart.

Prepping brass.
Hand decap
Tumble in walnut for 30 min
Anneal on AMP
Hornady one shot lube
Hornady 6.5CM die with expander ball removed
Then a 21st Century mandrel
Tumble in walnut for a couple hours
Trim/champfer
Hand prime using Frankfort perfect seater
Drop powder with a super trickler over AD120
Seat with Hornady die.
Use an area 419 Zero


This was a fairly consistent gun at 40.5 gn loaded to coal to fit in magpul mags, ~2.86. But feeding sucked and the velocity wasn’t what I needed. It ran ~2715 for a few hundred rounds. Consistent mid to high single digit SD, good groups at 100.

Switched to MDT and a 2.795 coal and the same powder charge is what you see above, 80ish fps more.

I guess next step is going back to the magpul mags and bumping powder to try and get to 2750.

I usually do everything CBTO, but since I was trying to work around mag constraints I was doing oal.


Just leaving the outdoor range, figured I’d dump the last 20 on steel and see. Use AB custom curve, which has worked well with this gun previously and its solutions were .2 high at 400, .3 high at 560, and .7 high at 1000. Adjusting still didn’t really instill confidence.
 
How far do you need to get away from the target before 35 fps makes 0.1mil difference?
 
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That's fair, I may just need to adjust my expectations. Running this through the calculator, a 40 fps ES results in a .1 mil difference at 500y.

A lot of this is self inflicted. Its a Howa in a MDT LSS, hence not being able to use my metal mags. It's a NRLH gun, so that's why I need it to be ~2750 fps for power factor. The game is find/range/engage, so a lot of tolerance stacking going on. Figure targets on average .5 mil in size, slight errors in ranging, maybe not building perfect positions on the clock, a gun that's +/- .1 mil in elevation.

Just trying to take all the variables out I can. If I had shot range day 2 and those 10 rounds for velocity had an average somewhere from 2765-2775 and a 10 SD, then shot a .8 MOA 10 shot group, I woulda been happy and ran with it. Just the huge change in results makes me lose all confidence.
 
Part of what is going on is you are comparing two very small sample sizes and then comparing the sample means and expecting them to agree and the probably of this happening is small. You also have the added variable of different lots of bullets which likely have different bearing surfaces. When analyzed the two means are statistically different but that can be due simply to sampling or you did change something in between your reloading sessions.

Understand that even if you loaded the rounds identically (which is impossible as the components vary on every shot) that it is likely to yield different sample means. The smaller the sample size the greater the likelihood that any two sample means will differ, sometimes by a significant amount.

What I would take from your original testing is this. 40.5 gn of powder will give me somewhere between 2750 and 2800 fps. This is anecdotal evidence. I would ignore any of the standard deviation numbers due to small sample sizes but I would conclude that there doesn't appear to be any significant issues with the reloading process. Again, anecdotal evidence not based on statistics.
 
I feel like I’m about to be a little bitch and give up on reloading. As soon as I think I’ve got something figured out it all goes to shit.

Have a 6.5CM gun. Wanted to switch mags from magpul to the poly/metal MDT ones. So had to shrink my COAL to 2.8”

Range day one:
40.2 gn (12 SD)
-2755
-2745
-2769
-2742

40.5 gn (5 SD)
-2778
-2772
-2765
-2772

40.8 gn (12 SD)
-2770
-2801
-2789
-2785

Range day two:
40.5 gn (12 SD)
-2818
-2797
-2785
-2801
-2775
-2810
-2787
-2784
-2795
-2800


This is a gun with 400-500 rounds on it. Cleaned it before range day one and fouled with 10 factory rounds. Exact same sorted Hornady brass, same box of 210M primers, same jug of H4350, different lot of 140 ELDMs (?), exact same reload process two days apart. No change in weather during reloading or shooting.

I get that the first day was a smaller sample size, but wtf happens to cause a 24 fps change in average velocity??? If I load up 150 this afternoon wtf velocity are they going to come in at??

Partial rant, partial hoping someone has suggestions to help me understand this.

Hang in there man. Been reloading since 2012 and it is always tough to bounce off the wall. I have done it many times. The key is to bounce and not go splat….. sometimes a small break is a good thing too.

All the normal issues are exacerbated by the price of components, and the somewhat scarcity. It certainly adds to the level of anxiety when something comes up.

One thing I’ve learned in reloading, the times that I’ve had the most trouble and hit the wall, have been the times when I have learned the most…..
 
This is another very good example of what can actually happen with small sample sizes. This isn't something that won't happen at a decent frequency.

Your loading process seems g2g unless there's something going on that we'd only find if we were there in person.


If you put all 14 velocities together, you end up with Avg 2788, SD 15.5, ES 53. Which is fairly normal when using Hornady Brass with multiple firings.

When you look at it this way, its pretty easy to see how you could have easily gotten 4 shots on the low side of your ammo's overall velocity spread.
 
That's fair, I may just need to adjust my expectations. Running this through the calculator, a 40 fps ES results in a .1 mil difference at 500y.

A lot of this is self inflicted. Its a Howa in a MDT LSS, hence not being able to use my metal mags. It's a NRLH gun, so that's why I need it to be ~2750 fps for power factor. The game is find/range/engage, so a lot of tolerance stacking going on. Figure targets on average .5 mil in size, slight errors in ranging, maybe not building perfect positions on the clock, a gun that's +/- .1 mil in elevation.

Just trying to take all the variables out I can. If I had shot range day 2 and those 10 rounds for velocity had an average somewhere from 2765-2775 and a 10 SD, then shot a .8 MOA 10 shot group, I woulda been happy and ran with it. Just the huge change in results makes me lose all confidence.
If you trim the metal AICS magazine back about 1.5mm and down about 5mm at the leading edge it will engage fully in the chassis/action.