Warning

 

Close

Confirm Action

Are you sure you wish to do this?

Confirm Cancel
BCM
Durkin Tactical Franklin Armory
User Panel

Posted: 8/8/2017 1:56:30 AM EDT
[Last Edit: jonathan1994]
UPDATE  9-13-17 WITH TARGET PICTURES BELOW

Well I finally played with my new build.
JP 6.5C barrel, 22", XL gas
JP HP bolt and firing pin
JP SCS standard weight with weakest spring
Fail Zero Bolt Carrier
Aero Enhanced upper and lower
High Speed Match trigger
V seven 57 degree safety
SLR Adjustable gas block
Seekins 20 moa scope mount
Vortex Viper 2.5-10 HS
Silencerco Harvester

I do have a gas problem.  The thing runs with the Harvester at only 2 clicks open on the SLR gas block.  It would have been nice if JP had used a smaller gas port.  2 clicks is not much.  I am using the weakest spring and standard weight buffer though.

I fired one shot without the Harvester, then cleaned it.  Then did the groupings below all with the Harvester on.  Format is best 4 / all 5.
Range is 100 yards,  all 5 shot groups.  Wind was 5-10mph, but the wind was moving ME and the gun.  I could see gusts in the reticle.  Also this was a bad day for my blood pressure.  My heartrate maintained a constant 1/4" wiggle in the reticle so this round was really only a starting point.  I typically fired the first two shots pretty fast to check both magazine feed and lock back.  Then a little cooling for the rest of the shots, but not more than 1 or 2 minutes of cooling between shots.  I was mostly letting the Harvester cool so the heat mirage would die down. The barrel was always cool enough to touch, but too hot to keep your hand there more than a second.  I was shooting off a wooden bench with a bipod front, bag rear.  However, I could not load the bipod at all.  Its feet were completely slick on the wooden bench.  Caldwell $100 chronograph.  Everything is listed in the order shot except the last group of Winchesters.

3 sighters

Winchester Deer Season XP 125 gr - 2850fps on box
2822, 2813, 2812, 2834 fps
first group of the day after sighters 0.81" / 1.38"
Last group of the day to check break in effects 0.97" / 1.16"

Hornady 129gr SST Superformance - 2950fps on box.  I have never had good accuracy with larger Superformance BTW.
2891, 2878, 2922, 2921, 2911 fps and one round did not lock the bolt back.  My theory is Superformance pressures up fast, but drops off towards the end.  Therefore its hard on short gas systems (personal experience), but then short strokes some longer gas systems (also first hand experience).  This "experience" is all with adjustable gas tuned to barely lock back M193.
1.39" / 1.92" - FAR better than my RPR / FNAR / AR10 / 308 Superformance experiences.

Hornady 129gr Interlock American Whitetail - 2820fps on box
2812, 2800, 2783, 2791
0.89" / 1.34" and I know I pulled one, but not sure which one or if it even would have made a difference.

Hornady Black 140 BTHP - 2690fps on box.  Short stroked several times.
2629, 2626, 2629, 3029????? error???, 2773.  I would throw the 3029fps out of course. edit all velocitiesfrom this session thrown out now .
0.64" / 0.87"  NICE.  Must get more of this stuff.

Hornady Hunter 143 ELD-X - 2700fps on box with .625bc
2381, 2404, 2497, 2601 fps - I don't know whats going on here.  Could have been my chrono, but the rest of the day it was spot on.
0.76" / 1.26"

Hornady 120gr ELD-M - 2910fps on box.  Empty brass barely rolled out of the gun.
2852, 2822, 2782, 2844, 2823 fps
0.69" / 0.83" - This is also very nice and lightning fast.

Hornady 120 Amax Match - 2910fps on box.  Also brass barely rolled out of the gun.
2856, 2892, 2879, 2883 fps
0.87" / 1.73"  The flyer was high and I could not tell that I caused it.

Now this was just my first outing with this gun.  I know one group per ammo is not sufficient.  I will clean the barrel and go at it again.  Of note, everything but the American Whitetail and Winchester followed about the same zero.  The 120gr loads seemed to have the least gas for the XL gas system.  143 ELD-X seemed overgassed despite low velocity.    The BLACK ammo short stroked some and I cant explain that unless it was actually overgassed and outrunning the magazine.

I am going to build a pivoting bipod bumper for the table for the next round.
Link Posted: 8/14/2017 11:20:35 PM EDT
[#1]
I have a similar build except I used the JP 22" barrel in 6mm creedmoor instead of 6.5. Even with the rifle +2 gas length and high pressure bolt, it is over gassed. Only fired 15 rounds today but blew one primer. Factory hornady 6mm ammo.

Accuracy was very good which is interested because when I had called JP about the barrel they said they did not see very good accuracy out of the hornady ammo.
Link Posted: 8/14/2017 11:31:59 PM EDT
[#2]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Lennyo3034:
I have a similar build except I used the JP 22" barrel in 6mm creedmoor instead of 6.5. Even with the rifle +2 gas length and high pressure bolt, it is over gassed. Only fired 15 rounds today but blew one primer. Factory hornady 6mm ammo.

Accuracy was very good which is interested because when I had called JP about the barrel they said they did not see very good accuracy out of the hornady ammo.
View Quote
All my primers looked nice.  What I have though is a heavy BCG/buffer in front of the weakest spring possible.  So this set up does not need much gas and will generate very little BCG velocity.  All this with adjustable gas should mean the pressure has dropped well before unlocking.  However, 2 clicks out on the SLR still sucks badly.  JP REALLY messed up the gas port size on this barrel.  Its like I need 2.5 clicks as 3 is a little....snappy...  I'm sure the gas screw is getting abused.  However, I have not fired this gun without the Harvester yet.  My experience with my 308 AR10 and the Harvester has been that it produces very little back pressure and only makes 1 or 2 clicks difference on a SLR gas block in the 8 - 10 clicks open range.

Accuracy wise, I just cleaned this barrel this weekend.  I hope to get another round of accuracy testing (sans a salt heavy breakfast and windy day) in two weeks.  I now have a box of 140ELDm's and American Eagles to throw in the mix.
Link Posted: 8/16/2017 11:23:45 AM EDT
[Last Edit: ARTNC10] [#3]
jonathan, I'm no super expert here by any means, but on your use of the bipod, I've seen/read and experienced it somewhat myself that bipods do a lot better off the ground instead of tables/shooting benches.  Of course they can be used anywhere, but in cases of really trying to sight-in a rifle or shoot for accuracy off a bench, bags and adjustable precision rests seem to be the choice of most precision shooters...aren't they?

Again, a bipod can be used just about anywhere, but I get the impression that they're more of a field tool where a bench setting is obviously not possible.  And when I say "field" I'm also including prone positions where you may still be at a range.  Bipods are great tools, but to me they jump around a little too much on a bench/table, and most experts...not me...will tell you that it affects recoiling consistency which can affect accuracy.

My precision rifles all use a bipod...just not on the bench for sight-in and/or accuracy testing personal loads or store bought ammo.
Link Posted: 8/22/2017 11:50:58 PM EDT
[#4]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By ARTNC10:
jonathan, I'm no super expert here by any means, but on your use of the bipod, I've seen/read and experienced it somewhat myself that bipods do a lot better off the ground instead of tables/shooting benches.  Of course they can be used anywhere, but in cases of really trying to sight-in a rifle or shoot for accuracy off a bench, bags and adjustable precision rests seem to be the choice of most precision shooters...aren't they?

Again, a bipod can be used just about anywhere, but I get the impression that they're more of a field tool where a bench setting is obviously not possible.  And when I say "field" I'm also including prone positions where you may still be at a range.  Bipods are great tools, but to me they jump around a little too much on a bench/table, and most experts...not me...will tell you that it affects recoiling consistency which can affect accuracy.

My precision rifles all use a bipod...just not on the bench for sight-in and/or accuracy testing personal loads or store bought ammo.
View Quote
You are definitely correct.  I just use a bipod on the bench for convenience as its sort of permanently mounted.  I'll never take it off while hunting.  However, next round I will use bags front and rear.  Once I find the best loads for 100 yds, I will build a 300 yard range at my folks place.  Its too hot for that kind of work now though.  Also, dove season may interfere with my next round of testing.  My 100yd range is ON the field this year.
Link Posted: 9/6/2017 11:52:56 AM EDT
[Last Edit: jonathan1994] [#5]
8-27-17 update, it just took me a while to post. Same rifle but with a Bag up front instead of a bipod, same zero, and I could still never get that last 1/4” of wiggle out of my scope. I did however add a Phase 5 bolt release. I found it too long so I cut the tip section off. This worked great for lining up on the target, then dropping the bolt on the round just before firing.  

100yds, 80-85F, 0-5 mph wind, dunno the direction. Gun and bore had been cleaned. First group was cold bore and clean bore. I would typically fire the first 2 shots of each group rapid to get the bore fully warm, then single feed the remaining rounds just before firing. Typically a shot every minute. I usually would have to cool the Harvester off with water to mitigate mirage on about shot 4 of each group. The barrel was always too hot to hold, but you could touch it. The gun would get extra cooling between groups as I recorded velocities and changed cartridges/boxes around.

I am also discovering no pattern to what gas setting each round prefers. Most ammo ran on 3 clicks open, but several needed 4. Some were close at 3, but bucked the rifle well off target on 4 clicks. Its like I need a 3.5 click setting. Maybe after the gas rings wear in everything will do good on 4 clicks. JP did use the right gas system (XL), but they made the hole too big IMO. I’ll do groups without the Harvester later to report POI shift and gas settings bare muzzle.

My BC’s are typically the published BC minus about .02. None of my BC’s are recorded – just references.

Format is still Best 4 / All 5. Shown in order shot that day. If anyone wants the Excel Sheet IM me your email addy.

Fedaral American Eagle 140 OTM THIS STUFF IS GOOD. This might be a “pre” federal gold match load.
2623 fps , 18 S.D., 0.56 BC. Runs on 3 clicks of gas.
Cold and Clean bore – 0.57” / 0.80”
0.49” / 0.73”
0.48” / 0.64”

Hornady Black 140 HPBT – very inconsistent velocities. Fine for 100 yds, but the AE is a better choice.
2667 2670 fps , 41 15 S.D. , 0.56 BC. Would not lock back on 3 clicks, felt violent on 4 clicks.
0.91” / 1.25”
0.46” / 0.65”

Hornady 140 ELD-M – My 1000 yard pick should I ever get the chance.
2668 fps , 20 S.D. , 0.626 BC. Trouble on 3 clicks, needs 4 clicks.
0.28” / 0.50”
0.85” / 0.88”
0.60” / 1.07”

Hornady 120 Amax – I’ll never buy more of this.
2878 fps, 13 S.D. , 0.455 BC. Runs on 4 clicks of gas.
1.10” / 1.29”
1.26” / 1.52”

Hornady 120 ELD-Match – My long range pick.
2846 fps , 23 S.D. , 0.466 BC. Runs on 4 clicks of gas.
0.39” / 0.61”
0.48” / 1.03”

Hornady 143 ELD-X - Not getting more of this. If I need heavy lead for brush I’ll use the 308.
2664 fps , 14 S.D. , 0.603 BC , Runs on 3 clicks
0.88” / 1.13”
1.34” / 1.65”

Winchester 125 Deer XP – I will buy another box of this to try at 300 yds. This may be my long range hunting round.
2814 fps, 14 S.D. , 0.52 BC. Runs on 3 clicks
0.55” / 0.86”

Hornady 129 Interlock American Whitetail
2795 fps , 22 S.D. , 0.425 BC , Needs 4 clicks to run.
0.88” / 1.11”

Hornady 129 SST Superformance – I’ll just save the remaining 5 for close range stand hunting, but will not buy more. You think I’d learn my lesson on SF by now.
2916 fps , 25 S.D. , 0.44 BC . Needs 4 clicks to run.
1.05” / 1.34”


Averages of all groups.


All are of 3 separate groups averaged together except only 2 groups for the Hornady 129 SST SF and Hornady 129 Interlock AWT.

0.50” / 0.79” - Hornady 120 ELD-Match - 2846fps - .466BC
0.56” / 0.76” – Hornady 140 ELD-Match – 2668fps - .626BC
0.64” / 0.86” – Hornady 140 Black –  2670 fps - .56BC
0.49” / 0.69” – Federal AE 140 OTM – 2623fps - .56BC
0.74” / 1.08” – Winchester 125 Deer XP – 2814fps - .52BC – first group was the very first rounds out of the gun @ 1.38”, so this raises its average.
0.95” / 1.29” – Hornady 143 ELD-X – 2664fps - .603BC
0.85” / 1.17” – Hornady AWT – 2795fps - .425BC
1.17” / 1.56” – Hornady 129SST SF – 2916fps - .44BC
1.03” / 1.45” – Hornady 120 Amax – 2878fps - .445BC

The stand outs are the economical but good Federal American Eagle 140 for plinking, H 120 ELD-Match for long range paper, and Winchester 125 Deer XP for hunting. Nothing wrong with the H 140 ELD-Match for 1000 yards. In my opinion the NON match Hornady rounds (including BLACK) are inferior to their counter parts.

Now final disclaimer. I am not a good shot. I also could tell no difference between the bipod groups and the bag except for one or two high flyers in the first round with the bipod. My heart beats about 100 bpm while in the sun and the reticle never stops moving in a 1/4 “ wiggle. I have a friend who shot in the state Olympics. I may get him to group this gun with the AE’s for comparison sometime. I might be doing the barrel a great injustice. This fall or winter I might get to build a 300 yd range.
Link Posted: 9/6/2017 4:01:53 PM EDT
[#6]
Well OP seems like this was a good trip for you. You have a shooter!
Link Posted: 9/8/2017 4:51:57 PM EDT
[#7]
Link Posted: 9/8/2017 6:02:15 PM EDT
[#8]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By bfoosh06:
Out of curiosity... have you tried a heavier recoil spring ?

Maybe a Tubbs Flatwire .308 ?

The Tubbs has a decent amount of "closed " weight... and a normal amount of "open" weight.

Here are some spring weight measurements from David Tubbs... just food for thought.

A2 (old) - 7.6lb closed, 14.5lb open
A2 (new) - 9.1lb closed, 16.7lb open
Tubb Flatwire - 10.5lb closed, 16.3lb open
Tubb .308 Flatwire - 13lb closed, 16.7lb open
SpringCo White ? (standard) - 8.3lb closed, 16.3lb open
SpringCo Red (extra) - 10.5lb closed, 18.4lb open
SpringCo Orange (increased) - 13.9lb closed, 24.8lb open
View Quote
A stiffer spring so I can add more gas  would be counter productive. Would mean more bcg velocity.

If I didn't have adjustable gas you would be correct, but then I would be fighting a bcg trying to punch out the back of the stock.
I am just complaining about the resolution of the gas adjustment. I'm in the 3- 4 click Range when most of my other guns run in the 5- 9 click Range.

Had JP drilled the gas port 2 numbered drill sizes smaller I would probably be happier.
Link Posted: 9/8/2017 11:09:22 PM EDT
[#9]
Link Posted: 9/10/2017 3:38:09 PM EDT
[#10]
Thanks for posting your results. Been watching as I am looking at replacing my 18in 260 barrel with a 22in 6.5CM.

Seems JP is a great option since it offers the longer gas port location. What other barrels offer this in a 22in?
Link Posted: 9/11/2017 4:09:47 PM EDT
[#11]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By CSPCRX:
Thanks for posting your results. Been watching as I am looking at replacing my 18in 260 barrel with a 22in 6.5CM.

Seems JP is a great option since it offers the longer gas port location. What other barrels offer this in a 22in?
View Quote
BHW will do extended rifle gas for more money. WOA might. All will be overgassed in a setup like mine without a custom gas port.
If just for paper and steel consider 6 Creedmore. I got 6.5Cr for hunting.
I may get the JP radiator fin now that I see how much heat a casual slow paced grouping session produces. You really need a spray bottle for so many rounds.
Link Posted: 9/11/2017 8:37:45 PM EDT
[#12]
Thanks for the feedback keep us posted on how yours progresses.
Link Posted: 9/12/2017 7:29:16 PM EDT
[Last Edit: jonathan1994] [#13]
Link Posted: 9/13/2017 10:21:41 PM EDT
[Last Edit: jonathan1994] [#14]
MASSIVE frustration over pictures.  I finally got IMGUR figured out.

After looking at my groups I decided I want to adjust my zero 1/2" down.  On all my composites, I took all 3 five shot groups, and magic markered them 1/2" low on a scrap piece of target.  I chose the 140 ELD-M for my zero until I can try the 147's.  COMPOSITES OF 15 SHOTS FOR EACH AMMO BELOW.


Hornady 140 ELD-M.   I might as well use this for my main ammo over the 120 ELDM.  They are similar at close range, but this is better at longer range than the 120 ELDM.


Hornady 120 ELD-M.  Very nice


Federal American Eagle 140 OTM - very nice groups.


Hornady 143 ELD-X


Hornady 140 OTM Black


NOW INDIVIDUAL GROUPS

Federal AE 140 OTM.  This stuff is good.  Of note, the high group was cold bore and CLEAN bore.  The next group shifted down some (first 4 shots were high, last was the low one).  Third group settled in low.  I figure this was my pattern for barrel fowling from clean bore.  If I had more of this I could have done the MOA all day challenge.  My setup would be legal.


Hornady 120 ELDM


Hornady American Whitetail 129 Interlock on top
Hornady Superformance 129 SST on bottom


Hornady 140 OTM Black.  I should probably just throw ALL the velocities from the first day out and recalculate the S.D..  The 3 good ones are still much slower than the stuff from Round 2 testing even though temperatures were about the same each day.


Hornady 140 ELDM


Hornady 143 ELDX


Winchester 125 Deer XP on top.  This is my pic for deer hunting.  I have another box.  In all honesty the first group was my sight in group and shots 4-8 out of that barrel.  After that low group I turned the scope up 2" and over 1/4".  The second group was actually the LAST group of Day 1 testing and was by my 15 year old nephew.  Hes a good shot, but does not try hard.  The last group that is sub 0.86" is one I shot myself on Round 2 of testing.  I was then out of ammo.  I'll update this round later.
On bottom is Hornady 120 Amax.  This was the worst ammo for this barrel.  Maybe its too far from the lands.

Now maybe this weekend I will try the Hornady 147 ELDM.  If this stuff groups good it should obsolete everything else.  It has a considerably higher BC than the 140 ELDM, but is only 15 fps slower by the numbers on the box.  The chrono will tell that story.  This stuff should be a game changer if it lives up to the match name.  Apparetly people also hunt with the Amax type bullets at range.  That would be awesome.

Also this weekend I will try the Winchester Deer Season XP's out more.  This stuff is pretty amazing IF and I meant IF its very high Ballistic coefficient is for real.  I have no way to test that though.

Also, I may see I can get my friend who is actually and excellent shot to lob a few for me.

Once I decide on my final rounds. I will build a 300 yard range and try that game out.
Link Posted: 9/13/2017 10:36:59 PM EDT
[#15]
Photobucket is dead, your pictures are not showing.
Link Posted: 9/19/2017 11:53:31 AM EDT
[#16]
Update 9-17-17

Not a good range trip. This one left me with more questions than answers. NOTHING ran on 3 clicks of gas today, not even the Winchester 125’s that ran perfect on 3 clicks. Maybe the gas rings are wearing in and now I can just leave the thing on 4 clicks without getting much kick from the BCG. Also, the Federal 130 Bergers flattened all primers, so I need the hives opinion on how to proceed with them. I also should have finished with a group from a known load to make sure the barrel is not just ready for a cleaning. The only good thing is the temperature has been between 80 and 85 every time I have shot the Creedmore so all velocities are compatible.

Today was my first big experience with mirage. I shoot across 97 yards of water. The sun was low in the morning and NO WIND, 30.06 barometric pressure. I had mirage from before ever firing a shot so I cant blame the Harvester. When the wind BARELY picked up from time to time the mirage would go away. I don’t know if this skewed my results, but the first group I fired was sub moa and was through an obvious mirage.

Winchester 125 Deer XP. After 19 shots the velocity is 2,812fps with 14 SD. Only the first group looked good today.
0.53” / 0.81” cold bore
1.03” / 1.72” ouch…
0.70” / 1.20”

Hornady 147 ELDM 2,664 fps, 24 SD. Not as accurate as I had hoped. The 120 & 140 ELDM’s are better. I’ll buy no more of this.
1.04” / 1.30”
0.73” / 1.15”
1.34” / 1.50”

Federal Gold Match 130 Berger Hybrid 2,857 fps HOT, 10 SD CONSISTENT. However, it was not accurate and COMPLETELY FLATTENED ALL PRIMERS. This is the first load I have tried that showed any pressure issues. The firing pin was not cratering though. Should I put the rest up or give them another try after cleaning the bore? Why were these so bad? Are they the wrong distance from the lands for my gas gun (OAL issue)? Are they just too hot and that degrades accuracy? Is this just a fowling issue and the next groups might look fine? Will Prime be close enough to this that I should NOT order any prime to try?
1.14” / 2.28” by my hand. Fouling issue? OAL issue? Dirty Bore?
1.29” / 1.41” by my nephew as I had wrote the ammo off after the first group. Whole group shot in about 1 minute – 15yr olds patience level and end of the day.

My plan is to go out next time with the American Eagles or 140 ELDMs and see if they group good. If not I will clean the bore and try everything again. If AE and 140 ELDM do good I’ll write off everything from this post and just hunt with the 140 ELDM’s.

OR

Should I just clean the bore and then shoot the rest of each box from this post? It has now gone 125 shots since cleaning.

Is the Federal GM 130 Berger load unsafe to shoot or are the flattened primers just a sign of a dirty bore?
Link Posted: 10/16/2017 9:50:05 PM EDT
[#17]
Another round on the books.  140ELD-M  was 3/4". 147ELD-M was not good and federal 130 hybrids were still bad and flattened primers.
Link Posted: 10/18/2017 6:51:39 AM EDT
[#18]
When shooting 130 FGMM, the majority of cases demonstrate flattened primers.  I had a blown primer get lodged between a chambered round and the receiver.

We've seen sticky cases out of bolt rifles too.

I think they're loaded too hot.
Link Posted: 10/24/2017 9:08:14 AM EDT
[#19]
This is great reporting. Thanks for all the info. I just finished a similar rifle;
Genesis billet 80% lower/upper receiver kit,
MI 15" G2 Keymod rail,
Ballistic Advantage 22" stainless barrel,
APA Gen2 Little Bastard
SLR Rifleworks adjustable gas block,
JP Compensator,
Aero Precision melonite bolt carrier group,
BCM Gunfighter charging handle,
Geissele SSA-E trigger,
Magpul trigger guard,
Magpul MOE grip,
A2 stock,
JP silent captured spring/buffer assembly,
Magpul 10 round magazine.
Cerakote OD green
USO LR17 on Badger mount
I've only had it out once and put 40 rnds through it. I don't have the data you have, but here's the best group:



This is with Hornady Match 140G AMAX. First shots rifle wouldn't cycle...realized I hadn't opened the gas block. I just opened it about a half turn at a time till the BCG would lock back. I don't remember feeling any clicks on the gas block adjustment. In the end I snuck up on the adjustment about 1/4 turn at a time. I have no idea how far out it is, and I'm not shooting through a can. I was shooting prone off an Atlas bipod and a rear bag. Wind was at my back, probably 5-10 mph, and it was 32* @ 6500' agl. I had several groups that were just about identical and one decent "hurried" ten shot group with some flyers. All in all, I just love this rifle. Really looking forward to "getting to know it".

Link Posted: 10/24/2017 9:14:40 AM EDT
[#20]
Have you ever looked at Dan Newberry's method for working up a load? I wonder if you could apply it to just trying different factory loads?
Link Posted: 10/29/2017 12:44:39 AM EDT
[#21]
I built my AR in 6.5 creedmoor, Used a Shilen 22 inch barrel 1:8 twist, I didn't measure port size. Used a JP adjustable gas block and standard 308 rifle buffer and spring. Rifle runs great on Hornaday Match 120 grain ammo.
Close Join Our Mail List to Stay Up To Date! Win a FREE Membership!

Sign up for the ARFCOM weekly newsletter and be entered to win a free ARFCOM membership. One new winner* is announced every week!

You will receive an email every Friday morning featuring the latest chatter from the hottest topics, breaking news surrounding legislation, as well as exclusive deals only available to ARFCOM email subscribers.


By signing up you agree to our User Agreement. *Must have a registered ARFCOM account to win.
Top Top