View Full Version : My more money than sense MK 262 Mod 1 clone development project.
Digital_Damage
11-17-14, 08:42
Ya... Another one of those threads.
DISCLAIMER! Many of the below figures are over published MAX! Do not attempt a direct copy, always work up your loads!
So I'm starting to get close to finalizing my data capture for my MK262 Mod 1 clone using "premium" components, I have one more range trip to make before I finalize the load and I figured I would share a little of what I have found out to date.
Components
Bullet: SMK 77g HPBT Cannelure #9377
Case: Lapua .223 Match (new Batch) , All Virgin Brass Used.
Powder: Alliant AR-COMP
Primer: Federal 205MAR
General Statistics: Case Length 1.750, Hornady Comparer 2-22 loaded length 1.863
Reloading Tools
Redding Comp Seating Die
Lee Factory Crimp Die
Dillon 550
RCBS ChargeMaster 1500
Redding Comp Neck Die
Hornady Bullet Comparer
Testing Tools
Rifle: KAC LPR (18 inch Kreiger 1/7, Geissele Hi-speed NM, Bushnell HDMR , 250 rounds through it before testing)
Bench: Cement, Lead Sled DFT, 100lb lead shot bags, 100 Yard Lane
Chrono Graph: Shooting Chrony Beta Master (set exactly 10 feet from bore)
Group Calculation: Ontarget Software
Just some notes for now, full result to come later.
I’m going to skip all the minor details and just highlight the major points
1. Every session I fire 10 Black Hills 5.56 mm 77g from the same lot to set my baseline. Pausing 20 seconds before each round. In the three sessions I have preformed on different days I have seen FPS swing from 2763 to 2792 on different days, however within each session the STDEV has stayed within 11 -7. So I can capture a consistent baseline for each session and compare the loads from that session’s baseline. However I cannot cross compare raw figures over all, the comparison has to all be done based on the difference from baseline for that day.
2. I started at 21.8 g AR-COMP worked in increments of .1 (since we are pushing past published max). I roll 5 rounds per each increment. The published max of 22.1 falls 186 FPS short of the baseline with a whopping STDEV of 14! Even with the high STDEV, the load shot just below MOA (.985) I saw similar STDEV (14-16) in the 21.8-22 g range.
3. I have inched up to 23.1 g AR-Comp and I’m within 37 fps of the goal, zero pressure signs. STDEV has dropped to an amazingly low 6. Things are looking very promising, I’ll post a full data dump after my final session.
EDIT 12/6/2014: FINAL SPEED LADDER RESULTS!
I had no issues hitting my goal. The best average I hit was with 23.4 gr. AR-Comp, 15.4 fps over target. Powder was measured to .01 of a gr. using a gem scale.
Baseline: Black Hills 5.56 mm 77gr. OTM
FPS: 2720,2736,2759,2748,2728
Average FPS: 2738.2
STDev: 15.56
.540 moa, 100 yards
30187
30188
Big Money Clone:
Case: Lapua .223 Match
Powder: AR-Comp, 23.4 gr
Primer: Federal 205MAR
Bullet: SMK 77g can
FPS: 2750,2757,2751,2761,2749
FPS Average: 2753
STDEV: 5.18
.600 MOA, 100 Yards
30189
30190
Damn, that's cooking for an 18" barrel. I was getting right at 2,700fps with Varget before I switched to XBR. I thought that was moving pretty fast since Mk262 specs 2,750fps from a 20" barrel.
Digital_Damage
11-17-14, 10:40
Damn, that's cooking for an 18" barrel. I was getting right at 2,700fps with Varget before I switched to XBR. I thought that was moving pretty fast since Mk262 specs 2,750fps from a 20" barrel.
What I have found during this process is to never take the "published" specifications.
I have seen the FPS swing +/-50 in the Factory load through the Crony. However, that swing I have to chalk up to various external parameters (temperature, chrony settings, etc) since the STDEV does not fluctuate during the session very much. That is why I decided to always start with a baseline every session.
I thought that was moving pretty fast since Mk262 specs 2,750fps from a 20" barrel.
I thought they spec'd Mk262 with an 18" barrel.
I thought they spec'd Mk262 with an 18" barrel.
I always thought the same, but according to Jeff Hoffman of Black Hills, it is a 20" barrel. I'll have to chrono a few of the Mk262 rounds I have left if I get EVER get the chance to use my chrono again... :mad:
From the last post (post#55) of the Tipped Matchking thread:
RE velocities of the TMK, we load them the same as the SMK, which typically runs around 2750+ from a 20" gun and around 2650 from a 16" gun. From a 14.5 you are probably in the 2600-2625 range.
As always, this will vary from gun to gun.
DODAC AA53, MV measured 15 feet from muzzle.
10-inch barrel 2350
M4 2600
16-inch Recce 2700
MK12 2740
M16 2770
Submariner
11-19-14, 00:49
DODAC AA53, MV measured 15 feet from muzzle.
Why 15 feet from the barrel?
How far from the barrel does Black Hills measure velocity and why?
I'm going to follow along on this one. I purchased some ar comp when that was all I could find so I am interested in the results of this.
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This is interesting to me too. I'm doing some load dev with arcomp in a few hours actually.
I can't bring myself to buy any Alliant powders. I know AR comp is supposed to be less temp sensitive, but still can't get the notion of Alliant being the red headed step child of gun powder out of my head.
Digital_Damage
11-19-14, 07:30
I have the last ladder rolled up (23.2-23.8 ). Unfortunately I'm prob not going to get to the range today, I hope to by Fri.
Once I hit the velocity to match (if no pressure signs). I'll load up 25 and begin 5 * 5 accuracy testing (if early indications hold true these will be in the .6-.7 range from the SR-15 LPR) and keep reloading the same lot to see how long the cases hold up.
Why 15 feet from the barrel?
How far from the barrel does Black Hills measure velocity and why?
The gases/unburnt powder can throw off the chrono readings. I use 10' personally.
The gases/unburnt powder can throw off the chrono readings.
That's true. But I remember M193's spec being X velocity at some oddball disance like 75 feet or something.
Digital_Damage
11-19-14, 08:06
The gases/unburnt powder can throw off the chrono readings.
This, 10 feet is the suggest min from Crony. Otherwise you could get a bunch of err readings.
I finally got motivated to set up my press to use this stuff. I have never used Varget so I can not give a comparison but the AR Comp is metering very well. I have the poor man setup with the Lee adjustable charge bar and it is within +\- .1 grain with each throw. I am measuring with a beam scale as well as a digital. These are my first rifle rounds so I am having some issues fine tuning the process as some of my bullets are not seating straight but that is my fault I'm sure. I have heard this is a very accurate powder so I am excited to get out and shoot some of these.
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Digital_Damage
11-26-14, 13:30
I have not given up on this, the weather has been less than ideal this week. I hope to get final numbers this weekend.
So I've loaded consistent sub 0.5 MOA match ammo before ...
But my ARcomp failed terribly. 6" 10 shot group at 100yds. Factory SWA 77gr SMK ammo through the same barrel right after got an easy .75" group.
So I've loaded consistent sub 0.5 MOA match ammo before ...
But my ARcomp failed terribly. 6" 10 shot group at 100yds. Factory SWA 77gr SMK ammo through the same barrel right after got an easy .75" group.
You couldn't give me Alliant gun powder. The temp probably went up 1 degree and the velocity doubled.
You couldn't give me Alliant gun powder. The temp probably went up 1 degree and the velocity doubled.
Yeah, I was getting crazy mv fluctuations. I'll post some data later.
2.260" coal, 77gr smk, cci primers, 22.1 gr AR Comp that gave me the 6" group:
2721
2666
2656
2692
2754
2672
2683
I have not given up on this, the weather has been less than ideal this week. I hope to get final numbers this weekend.
Where are you at? It's been beautiful here just outside of Houston, but the wind as put everything on hold. I have like 5 different loads I still need to test out.
Digital_Damage
11-27-14, 12:34
Where are you at? It's been beautiful here just outside of Houston, but the wind as put everything on hold. I have like 5 different loads I still need to test out.
In central Florida, lots of rain and high wind all week.
Digital_Damage
11-27-14, 12:37
Yeah, I was getting crazy mv fluctuations. I'll post some data later.
2.260" coal, 77gr smk, cci primers, 22.1 gr AR Comp that gave me the 6" group:
2721
2666
2656
2692
2754
2672
2683
Bazar, so far my testing has not shown any of that.
I have not shot a group larger than 1.2 from 22 - 23.2
Bazar, so far my testing has not shown any of that.
I have not shot a group larger than 1.2 from 22 - 23.2
I was getting popped primers at 22.5 gr too. Idk what's going on.
Digital_Damage
11-27-14, 13:03
I was getting popped primers at 22.5 gr too. Idk what's going on.
Has to be something else then, I'm up to 23.1 with no pressure signs what so ever.
the CCI are not magnum are they?
Has to be something else then, I'm up to 23.1 with no pressure signs what so ever.
the CCI are not magnum are they?
No, regular small rifle, CCI 400. But I thought the only difference was hardness of the primer?
Digital_Damage
11-27-14, 16:27
No, regular small rifle, CCI 400. But I thought the only difference was hardness of the primer?
#41/450 is a magnum.
205MAR is just a smidge harder than 205.
I have never had much luck with CCI 400's, however those issues were lots of pierced primers not popped.
The Standard Dev in 22.1 was 14 for me, They did not tighten up until 22.7, 23.1 got down to 6.
I'm going to assume you are using lake city?
#41/450 is a magnum.
205MAR is just a smidge harder than 205.
I have never had much luck with CCI 400's, however those issues were lots of pierced primers not popped.
The Standard Dev in 22.1 was 14 for me, They did not tighten up until 22.7, 23.1 got down to 6.
I'm going to assume you are using lake city?
Random brass. Lake city or pmc.
Digital_Damage
12-06-14, 13:09
Updated to show final speed testing, now onto accuracy testing and case longevity testing. I'll be working up 25 rounds to do 5X5 testing and reloading the same 25 to find the failure rate.
I will also be working up 100 rounds to take with me to Northern Arizona in January to test temperature sensitivity.
Digital_Damage
12-06-14, 13:13
Random brass. Lake city or pmc.
I cant say what is or what is not going wrong with your loads using this powder.
I know their are some on here that swore mixed brass does not matter much, but I have always stuck with the same lots in brass, powder and bullets with my loading.
The largest group I could muster (21.8gr-23.5gr) with these powder, cases and primers was 1.2 MOA and that was very early in testing.
I cant say what is or what is not going wrong with your loads using this powder.
I know their are some on here that swore mixed brass does not matter much, but I have always stuck with the same lots in brass, powder and bullets with my loading.
The largest group I could muster (21.8gr-23.5gr) with these powder, cases and primers was 1.2 MOA and that was in a very early in testing.
I'm going to try again later, I was getting easy sub moa with the alliance recommended load. Then I moved... Everything changed.
I don't have any chrono numbers yet as I have just done the OCW test. The results are promising with Ramshot TAC. Group 2 is 4 shots. I suspect velocity of the upper node is pushing 2800fps.
DD 18" CHF S2W barrel
LC virgin brass, matchish prep
FGMM primer
77SMK
2.245" OAL
LFCD
30391
Well I finally got to try my rounds today. Due to weather and time I was only able to shoot at the local indoor range. I made up 12 different loads and these were the best two. I will make up more of these two and give them a go at 100 yards. These were fired from my 14.5 BCM with an aimpoint t1. I have no chrony right now but hope to get one before I try them at longer ranges. Given the fact that these were my first rifle rounds I was just glad my gun did not blow up. 👍
Edit to add data
Photo on right is a mid charge of 21.3gr ar comp
Photo on left is 22.1gr ar comp which I believe is Alliant's max
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Digital_Damage
12-22-14, 20:13
Well I finally got to try my rounds today. Due to weather and time I was only able to shoot at the local indoor range. I made up 12 different loads and these were the best two. I will make up more of these two and give them a go at 100 yards. These were fired from my 14.5 BCM with an aimpoint t1. I have no chrony right now but hope to get one before I try them at longer ranges. Given the fact that these were my first rifle rounds I was just glad my gun did not blow up. ��
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Details my good sir, need details.
I have to check my book and see exactly which loads these were. This was with AR Comp, pmc brass, Remington primers and mag length OAL. I used 77gr SMK's with a light Lee factory crimp as Markm has suggested. I had no pressure signs of any kind and no feeding issues either. I felt pretty good for a rookie.
I will add that I used these targets to zero another aimpoint I have and when I confirmed the 100 yard zero it was dead on. The way these targets work is to use the colored part as your POA and adjust for POI on the gray circle. What I am wondering is this rifle was zeroed with xm193's and some of the lower charge loads grouped well on the colored section, which is exactly POA. So I want to see the difference POA/PoI of these and the 193 stuff at 100. Not sure if that makes sense or not but basically as the charge increased these loads came more inline with the zero of the rifle which is a lot lighter bullet, 25 yards just may not be far enough to get much of a difference.
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Here is an example of what I was referring to, this is a 20.5gr charge and a so so group that is exactly POA/POI. When compared to the above photos it is easier to see the POI shift as the charge goes up.
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This is max published load (22.1gr) at 50 yards using the mag as a rest with an Aimpoint micro 2 MOA dot. These 11 shots were with a cold barrel and only a short pause between shots. I used the Nosler 77gr for this group.
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I don't have any chrono numbers yet as I have just done the OCW test. The results are promising with Ramshot TAC. Group 2 is 4 shots. I suspect velocity of the upper node is pushing 2800fps.
DD 18" CHF S2W barrel
LC virgin brass, matchish prep
FGMM primer
77SMK
2.245" OAL
LFCD
30391
Did you see any pressure signs with these loads?
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