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Discussion Starter #101
Here are my conclusions and lessons-learned from this test and associated data.

• First, using velocity decay from LabRadar data inside 100 yards accurately derives bullet BC for that specific velocity range. BC (G1) may change some as velocity decays down range but the BCs derived using the Lab Radar get me on-target.
• Bullets must be fully stabilized with enough twist to achieve their full BC potential. Either the Sierra advertised BC of 0.600 (G1) requires a faster twist (or velocity) than 1:6.5 to achieve its full potential or its BC is less than advertised. Note, their 90 SMK fell way short of advertised BC even when fully stabilized. As temperatures rise, the 95 SMK may become more stable and see a BC improvement.
• A trajectory drop analysis for the slowest and fastest bullets within each group provided interesting results (min-max MV delta). You can see that this muzzle velocity variation accounted for the vertical spread of the ELD-M and SMK showing the importance of achieving a low standard deviation for your handload's muzzle velocity. (How is it that MV Std Dev was directly related to vertical spread at 1000 yards?) The 85.5 Berger Hybrid was not a close match like the other two. It was shot last. The wind had picked up slightly and the heat waves/shimmer was a bit more noticeable which may have contributed to its increased vertical dispersion compared to its muzzle velocity variation. There is more to learn here and a retest will be forthcoming.
• I need to go back and continue load development for the 88 ELD-M and 85.5 Hybrid. I wasn’t expecting these results with the 85.5 Hybrid. It has been the most accurate inside 300 yards compared to any other of my handloads. The 3-shot group sizes when zeroing at 100 yards were; 85.5 Hybrid (5/8"), 88 ELD-M (1 1/4"), and 95 SMK (1"). Berger recommends a minimum twist of 1:8 for their new 85.5 Hybrid. I’m interested to learn if the 1:6.5 twist is too fast for the 85.5 Hybrid (maybe stabilized too much to let the nose fall through after its apex). I’ll have an ARP Valkyrie barrel with 1:7.7 twist to compare with shortly.

For the short-term, I will use the 95 SMK as my go-to long-range round for now. I have to go back and rework my loads for the 85.5 Berger Hybrid and 88gr Hornady ELD-M to provide better accuracy and consistency. I enjoy testing like this so I have more fun in-store for me.

Please share your observations, comments, and conclusions. It is always helpful and insightful.
 

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I assume this is your "long freebore" model? BTW, it doesn't take much to snap those tips off if the bullet nose hangs on anything at all on the way in from a magazine. Even if your hand-feeding and dropping the bolt it can still hang on something. I've long thought about making a bolt gun with a savage barrel for 224 valk and dispensing with the dynamic AR feed altogether to see what difference that might make. Hornady finally rolled out their .224 version of the a-tip match--I'd take a hard look at that.
 

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XMan, as always you create a very scientific data-driven approach to optimizing cartridge selection. The time you put into all of this alone is amazing. Thank you.
I was at the range yesterday chronographing a 80SMK 224V load developed for me by a custom ammo shop since I don’t load myself. I actually brought the factory Hornady 88ELD and the Federal Gen2 90SMK to get more data on as well. While I haven’t shot out to 1000 yds with the intent to measure MOA, I have found the cartridge with the lowest SD to be most consistent at 100 yds also.

This is the same WOA Shilen barreled 18” 1:7 twist AR I’ve used for previous posts. 62 degrees F with some wind yesterday. Warmed up the barrel/fouled with 10 shots of the Federal Black 75g BTHP which I don’t like and didn’t measure. Then measured 20 shots of each, pausing to write the velocities and get back on target.

Custom 80 SMK 224V
2824 fps SD 18

Hornady Match 88ELD 224V
2596 fps SD 23

Federal 90 SMK Gen 2 224V
2550 fps SD 25

Federal 90 SMK Gen 1 224V (recorded last year)
2620 fps SD 16

This is a pic of the custom 80 SMK cartridge at 100 yds. 5 shots.



This is a pic of the 88 ELD approx 13-15 shots at 100 yds. What’s interesting with the ELD is I always get a flyer out of a 5-shot group and I think the SD and this pic demonstrate it very well.



The Federal 90 SMK cartridge just frustrates me and not even worth posting a pic to discuss. I’m over it. I may attempt another custom load with the Berger Hybrids but at this point I am very satisfied with the Hornady ELD and the 80 SMK for whatever I want to do with this platform from 100 to 1000 yds. I have to qualify on the 1000 yd range to access it so that’s in the works this year, but wanted to start with a platform that would be capable in an AR15 format. That was the original intent of 224V right?!
I will say anecdotally, the 224V cartridges really foul up the BCG vs other cartridges I use (.223, 5.56, 6.8, and .308).


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Discussion Starter #104
Hornady finally rolled out their .224 version of the a-tip match--I'd take a hard look at that.
At a $1 per bullet, I've got a lot more learning to do before I am worth of launching that precious metal downrange.
 

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Discussion Starter #105
Hurricane, thanks for sharing your results. Your barrel looks like a great shooter. That Custom 80 SMK is "keeper"! I don't suppose they share with you what their load details and powder are? Strange how the 88 ELDs have fliers that cover the entire 360-degree range. Almost like it was done on purpose/design.

It is sad that the Valkyrie had a bad start. The chambers weren't right because of the drawing/reamer error. The bullet they designed the chamber after (90 SMK) was flawed. It has so much more potential.

BTW, what APP are you using to do the group size calculation shown in the first target?
 

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At a $1 per bullet, I've got a lot more learning to do before I am worth of launching that precious metal downrange.
LOL, I get what mean--it's kinda relative in some cases, sometimes the extra cost is made up for when you consider how much money can be used on trying dozens of other combinations. I'm not exactly sure why--but 90 grs. bullets have always been difficult for me in 224 valk.
 

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Hurricane, thanks for sharing your results. Your barrel looks like a great shooter. That Custom 80 SMK is "keeper"! I don't suppose they share with you what their load details and powder are? Strange how the 88 ELDs have fliers that cover the entire 360-degree range. Almost like it was done on purpose/design.

It is sad that the Valkyrie had a bad start. The chambers weren't right because of the drawing/reamer error. The bullet they designed the chamber after (90 SMK) was flawed. It has so much more potential.

BTW, what APP are you using to do the group size calculation shown in the first target?
Thanks X. I thought you would find the 88 picture interesting and I have to believe it is something to do with the SD and the twist and the plastic tip. I don’t know...I’m not a physics guy but it looked like a pattern to me and explains in a larger sample that the fliers I get are happening for a reason. Not trigger pull or breathing or hold, etc.
“SubMOA” app. A little quirky when first using. First set your session details, then start a “new group” then measure your squares for reference with the app, then plot your POA and impacts and it does the rest. Pretty neat, uses bullet diameter and it matches right up with the size of the holes.


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I will take that 95gr load any day of the week. Amazing vertical.
There could be several ways to look at and analyze these results, however, there are a lot of variables involved. I found that the data aligned and the results made sense when the 88 ELD-M was used as the benchmark and the analyzed kept relative to the ELD-M. Note, this is collected data/real-world results but this doesn’t mean that your rifle will have the same outcome with these bullets. View attachment 60424 View attachment 60425
 

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Discussion Starter #109
I went to the 1000-yd range and repeated the same test as last month with 8-shot groups. Long story short, the results were consistent with the last session (previous image below for reference). All three bullets, when vertical dispersion was averaged, were within 2" of trajectory calculations using the measured BCs listed from last month. Both the 85.5 Hybrid's and 88 ELD-M's vertical dispersion improved with corresponding MV SD reduction. However, horizontal dispersion for these two bullets were significantly greater than what the 95 SMK was - again, similar with last session. The wind was pretty consistent so I don't have an explanation. It also get the feeling that the 85.5 and 88 drift further left than the 95 but will watch this further.

Bottom line, I'm done with Berger's 85.5 Hybrid. It did very well inside 300 yards but I'm not going to spend any more time using that bullet at longer ranges. Fortunately, I had not opened the box of 500 I just bought and they are being returned. The 95 SMK will be the primary bullet going forward, the 88 ELD-M as secondary. R17 and 2000MR may be giving higher velocities but W760 is giving the lowest SD so will be the powder of choice. I just received an 8-lb jug of 760. It's power potential is not as great as the 10-year old W760 I had, loosing 75 fps for the same charge weight. This explains why I was over pressure before reaching the max load using Sierra's published load data. I will rework the loads with the newer W760.

Let the fun begin!!

60908
 

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I went to the 1000-yd range and repeated the same test as last month with 8-shot groups. Long story short, the results were consistent with the last session (previous image below for reference). All three bullets, when vertical dispersion was averaged, were within 2" of trajectory calculations using the measured BCs listed from last month. Both the 85.5 Hybrid's and 88 ELD-M's vertical dispersion improved with corresponding MV SD reduction. However, horizontal dispersion for these two bullets were significantly greater than what the 95 SMK was - again, similar with last session. The wind was pretty consistent so I don't have an explanation. It also get the feeling that the 85.5 and 88 drift further left than the 95 but will watch this further.

Bottom line, I'm done with Berger's 85.5 Hybrid. It did very well inside 300 yards but I'm not going to spend any more time using that bullet at longer ranges. Fortunately, I had not opened the box of 500 I just bought and they are being returned. The 95 SMK will be the primary bullet going forward, the 88 ELD-M as secondary. R17 and 2000MR may be giving higher velocities but W760 is giving the lowest SD so will be the powder of choice. I just received an 8-lb jug of 760. It's power potential is not as great as the 10-year old W760 I had, loosing 75 fps for the same charge weight. This explains why I was over pressure before reaching the max load using Sierra's published load data. I will rework the loads with the newer W760.

Let the fun begin!!

View attachment 60908
 

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I arrived at the same conclusion a while ago (you and I embarked on more or less the same development journey due to the long free-bores). Rumor had it for a while that federal was coming out with 100 gr bullet--hasn't happened AFAIK. I have a 22-250 so the lighter weight bullets in the valk don't interest me that much.
 

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Discussion Starter #112 (Edited)
My last range session was not a good one. Insightful but not what I would call positive. First, as stated above, I've been working with 3 long-range, VLD bullets. The 85.5 Berger Hybrid, the 88 Hornady ELD-M, and the 95 Seirra Match King. I have returned all my 85.5 Berger Hybrids because their great accuracy inside 300 yards was not maintained at 1000 yards. I've had some great groups at 1000 yards with the 95 SMK and Win 760 powder but the new batch of 8# of W760 has not been friendly. I've been getting a good grouping for 3 out of 5 shots but the other two would be well off to the sides.

So this last range session was all upside down. First problem - I was shooting the 95 SMK and getting similar results as before with 2 grouped tight and 2 off to the sides. When I shot the 5th round, I saw no impact on the paper. When I went down to the target, I checked to see if it went through one of the other holes when I caught sight of a gash in the back board. The 95 SMK had gone unstable.

61215
 

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Discussion Starter #113
Next I shot 5 rounds of 88 ELD-M that I had loaded with the new W760 powder to see if they might do better than the 95 SMKs have been doing. I dropped the hammer on the first round .... it was a no-fire. I went to extract the round and the bolt was jammed. I tapped the butt on the shooting table while pulling the bolt back and out came the round ... without its plastic tip. I found the remains of the tip up in the bolt extension and fished it out. I shot the four remaining then launched the one without the tip for no good reason.

Ok, what's going on here. Two rounds lost their tips in a month's worth of shooting. Not so fast. I noticed the velocity decay was almost double without the tip. Hmmm ... I had two out of 8 rounds miss my 6-foot board at the last 1000 range session. Could it possible be ... yeap, the LabRadar data showed two bullets with excessive velocity decay. So I've shot 58 round of 88 ELD-M with 4 tip failures in the last month. Hornady's response was yes it happens, but rarely. They don't see it as a problem. Well I sure do ... anyone want some 88 ELD-M bullets?

What's next ... I've got some 90 grain Berger VLDs on the way and I'm going to see how fast I can get the 95s in Federal brass.
 

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Xman--I seriously doubt even the missing tips are knocking your accuracy off that much or causing a random bullet to go completely sideways like that if the rest are otherwise "acceptable." I'm probably one of the few (only?) people that have a set-up just like your's--I have the long-throat and I also machined the channels to get 2.35 cartridges to feed (geniuses--or whackos--think alike, I guess ; ) ). My opinion is that these high SD 224 bullets are so easy to introduce even minute asymmetry to; and that even slight asymmetry will show up as a significant group dispersion immediately. I've found I have to be "ultra-attentive" to normalizing everything. The mere fact your getting damage to the tips tells me you're likely having feeding issues, again I know your set-up, so my money would be on your cartridge nose catching--especially if you're using the PRI mag with front cut-out and going all the way near the max COL. If you single-shot hand fed them, then that would be a bad sign for sure. ; )
 

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Discussion Starter #115 (Edited)
overPressure, thanks for the comments. I've been shooting this longer-than-mag-length configuration now for 7 years and have had no issues with any plastic tip breakage on a long list of .224 and 6.8mm bullets out to 2.410" COAL. I have not had any issue with the 75 A-Max tips but they are a different plastic. I did have one tip break off a ELD-M prior to ever reaching the rifle. Have you had any tips break off?

I believe the shank on the plastic tip for the ELD-M is too small in diameter compared to other ballistic tips and is why they are the ones failing or maybe I got a bad lot. I read your comments a couple of time and using them to re-evaluate. The flaring on the feed ramps was not perfect but there was nothing to catch on but I still touched them up. I have been using the Hornady concentricity tool which applies pressure to the bullet's tip if I apply a correction force. I will stop using the correction capability and use the few rounds that are more than 0.002" out for close in work. Thanks again for you insight.

BTW, there is a dramatic difference between the ELD-M bullet's velocity decay with and without the tip. With the tip, the deceleration rate is about 39 fps every 25 yards. It was 72 fps without the tip.
 

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I've had tips come off every now and then with other makes than eld's--but I'm sure in every case it was because the nose tipped on something on the way in. The eld's seem to use some come kind of garnular composite as opposed to a rubbery/plastic like tip. Mine usually crumble as opposed to break off in one piece. The bullet may have a decayed trajectory--but I haven't seen them go totally key-hole sideways like yours as a result of the tip missing alone. If you're getting 2.410 COL--than you MUST have taken down some of the barrel's extension as well--I wasn't quite brave enough to go that far. ; )

When I was messing with 90 gr vld's I did get some key-holing with my bullets. This was after successfully developing the 95 gr MK load that shot under .5 MOA if I did my part well enough. I called H and talked to him about it, it was a bit perplexing that a lighter bullet traveling faster was key-holing when I got a bigger slower one not to. Tried various seating depths and finally found one at the right velocity that didn't key-hole, but it still was a "depended what kind of mood" the bullet was in on a particular day and the slightest variation would touch off instability again. So that's when I came up with my "theory" that bullet entry into the lands could easily be non-concentric under certain circumstances and that asymmetry "printed" into the very long and soft body of the projectile. Sounds dubious, I know, but other than hitting something in the bore or muzzle I don't know what else could account for that consistent level of key-holing (the twist and velocity seem within acceptable parameters). It would be interesting to see if a high SD monolithic bullet also key-holed like this, I haven't found one yet. Somehow, I believe the behavior of the bullet while jumping the long freebore is the stage where "bad mojo" happens when a valk load goes haywire. If the cartridge is perfectly concentric itself--as well as to the chamber/throat, then very good things happen.

The PRI mags that cavity back cuts out--and I've cut out magazines of my own--eventually will swell and that changes the stacking of the cartridges and how they "behave" on feeding in my experience. When I get "bad behavior" I switch to hand feeding to isolate whether or not it's a feed issue. I'm guessing you know all this and forgive me if I seem to be talking "Mr smarty pants." ; )
 

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Discussion Starter #117
I appreciate the comments. The only thing I would point out is the ELD-Ms did not keyhole without the tip. It was the 95 SMK that keyholed.
 

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My apologies, senior moment I wasn't paying attention to your picture. At first glance my impression is that you are borderline velocity with that load to keep the 95 gr bullet stabilized--I think the load I developed is significantly faster than that. I'll see if I can find it--though I know I posted the full "formula" on this forum some place when I first started messing with the valk.
 

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Discussion Starter #119
while checking the rifle over more after thinking through overPressure's feedback, I found the adjustable gas block was locked-up. It had only been 125 rounds since I last ran the set screw with CLP on it. Further inspection found the BCG had significant carbon deposits, more than I've experience on my other ARs. There are only 783 rounds down the tube so I'm going to have to be more diligent in my cleaning. Beside a thorough cleaning of the rifle, I'm prepping brass for what I'm considering ....

Phase 2: I've got Berger 90 VLDs and Hornady 90 A-Tips coming this week. I feel re-invigorated and ready to start anew after thinking through minor details to improve my situation. I will keep the thread updated.
 

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I certainly hope you get to the bottom of it. I'm interested in how it goes with the a-tips and other 90 gr bullets, I haven't really gotten consistent stellar results in that weight. To this day my best results have been with 88 eld's and the 95 MK's.
 
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