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Old April 10, 2012, 04:49 PM   #1
browninghunter86
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68 BTHP Help

Anyone use this load using IMR 8208 XBR or Ramshot TAC? Needing min and max ranges to start load development but Hornady did not have it nor did Hodgdons/Ramshot website.


Should I just use the Sierr's 69BTHP load data?
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Old April 10, 2012, 05:08 PM   #2
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Quickload tells me that IMR's powder site MAX listing for the 69grSMK/23.8gr/XBR/2.235"
produces at least 3,500psi over that max pressure when using Hornady's 68gr HPBT.

Therefore reduce the charge when using Hornady's bullet by at least ½ grain.
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Old April 10, 2012, 06:30 PM   #3
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The Hornady 68 HPBT Match bullets are longer than the Sierra Match Kings. (Closer to a 75 grain Sierra) My experience with them is using Varget, Reloader 15, H-335, and AA 2015. Reloader 15, and AA 2015 gave the most consistent results. Rl15 was better by a very slight margin. Varget was close to both as well.
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Old April 10, 2012, 08:19 PM   #4
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m&p45: I have H335 but was going to try 8208 for it being less temp sensitive.

but not alot of load data online for it
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Old April 11, 2012, 10:02 AM   #5
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m&p: ever tried 8208 in that combo?
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Old April 11, 2012, 06:48 PM   #6
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Added Scope to my set up

here is my new AR set-up and the reloads ready to go. Can not wait to go shoot it tom



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Old April 12, 2012, 12:02 AM   #7
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Nice photo's Browning.

Now, in picture #1, that box to the left behind your Ar-15. My wife HATES those boxes.
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Old April 12, 2012, 06:58 AM   #8
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grisbald: that is funny. Mine knows I got some good stuff for shooting when it comes
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Old April 26, 2012, 04:03 PM   #9
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OCW Development




DPMS Oracle 16" Carbine 5.56/223 chrome line AR 15 using Ramshot TAC and R P brass and KVB5.56 TulAmmo primers

24.4 appears to be the start of a scatter node and 24.8 appears to be coming out of the settling after scatter node

Any thoughts?

Thanks
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Old April 29, 2012, 02:43 PM   #10
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The center of each group is not shifting much from 23.8 to 24.4, so that is a very good sign for accuracy. 24 grains looks to be where you should be happiest if you can get things to tighten up by playing with seating depth.

It's funny, but 24 gr of powder has been a lot of high power shooters "go to" charge weight with a number of powders...

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Old April 29, 2012, 05:15 PM   #11
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just went out and shot 24.4 and 24.6 gr(supposidly the range Black Hills has in their 68 gr ammo) and here is the results

TAC, 68 BTHP, 2.250" OAL

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Old April 29, 2012, 09:16 PM   #12
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anyone have a box of this Black Hills 68 gr ammo that can tell me what OAL they have?
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Old April 29, 2012, 09:27 PM   #13
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Not to be a jerk, but how are you shooting? I don't normally see horizontal stringing to vertical stringing with just a .2 gr shift in powder charge. Do you have some control ammo that shoots tight in your rifle?

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Last edited by Brian Pfleuger; April 29, 2012 at 09:50 PM. Reason: Language
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Old April 29, 2012, 09:36 PM   #14
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I am not a match shooter or anything but shooting with grip pod on front and bags on rear(although rear bags could be improved) and all this was ontop of a folded beach towel which was ontop of a concrete uneven shooting bench and I was seated ontop of a water jug since their chairs are too short for the height of the bench!! No control ammo to go by.

It was about 90 degrees and gnats were all in my eyes and nose and ears and was sweating horribly but did the best I could.


So never really shot at a nice range with good bench or seat so not sure if this is to blame some for my inconsistancies
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Old April 30, 2012, 07:25 PM   #15
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Ok, that doesn't sound like ideal shooting conditions to me, and it explains the stringing. I also think that parallax is compounding those problems.

Move your target back to 200 (if you have the space) and see how that works out for you. Most scopes are set to be parallax free after 100 yards, but like anything else that number includes a margin of error.

Get a more stable shooting platform (improve that rear bag) and try again at a longer distance.

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Old April 30, 2012, 09:17 PM   #16
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will try to build more homemade bags for the rear using sand. Never shot at 200 so I don't know how that will go but worth giving it a try.

SOmeone else suggested shooting prone but never done that either....


The scope is a Nikon Prostaff 4-12x
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Old May 2, 2012, 11:43 AM   #17
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Yeah, your scope is set for parallax at 100 yards. Not saying that your is a "plus" on the tolerance, but in my experience there is some wiggle room.

And since you are loading BTHP bullets, going back to 200 will start getting you ready to shoot long distance.

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Old May 3, 2012, 03:12 PM   #18
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68 BTHP bullets tumbled at 25 yards with my highest 2 charges. Vertical tears in cardboard target. Other loads were straight clean holes. Does that mean too fast velocity or what? Can post pictures if needed


Thanks
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Old May 3, 2012, 06:31 PM   #19
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Yes, pics please.

Too high velocity won't cause keyholing if other charges under that bullet don't, so something else must be going on.

You are having some issues, this is interesting.

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Old May 3, 2012, 07:53 PM   #20
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I really am confused with all this and not getting groupings and strange stuff happening




Shots right under tuck tape were the 23.4 and 23.6 gr

Do bullets need further distance to stabalize?

Maybe this could be why only 2 shots out of 5 hit paper with the highest load if it was doing this wierd stuff


Brass was trimmed to 1.751" and headspace was 1.453. OAL of round was 2.250 with NO crimp. Cases were chamferred/deburred with LE Wilson tool


thanks jimro for the help with this.
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Old May 4, 2012, 03:46 PM   #21
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They can't recover stability once they've turned that far.

The JBM blllistics site includes a gyroscopic stability factor calculator. Most experts say gyroscopic stability factor values of 1.4 to 1.7 are best for high accuracy work, while Sierra, specifically, recommends 1.3 to 3.0 as best for hunting accuracy. When I run the 68 grain Hornady with a 9" twist at 2700 fps (guesstimated velocity for your loads) I get a stability factor of just 1.25. That is not normally outright unstable, but it's too low for good accuracy. Why most of your bullets fly OK but some don't is probably individual to the gun's characteristics. The short barrel will produce relatively high muzzle pressure and resulting muzzle blast, and if a bullet comes out imperfectly aligned, that extra blast may push it over the edge.

Under the same atmospheric conditions, the same calculator shows the 69 grain Sierra will actually be much more stable with GS of 1.658, so it will shoot better. It's about the same weight, but it is 0.085" shorter, and that turns out to be a critical difference in the velocity and twist rate you are operating in. I'd expect it to shoot fine and not be so hard to tune to an accuracy sweet spot.
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Old May 4, 2012, 04:44 PM   #22
Jimro
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What Unclenick writes is true, sometimes in ballistics a higher powder charge weight simply means more muzzle blast due to not all the powder getting burnt....

But marginal stability should show up more often, of course there is an exception to every rule (including this one). I've never shot the Hornady 68's through a 16" 1:9 twist, but you aren't the only one reporting problems with that combination. Over at thehighroad one guy was trying to get them to shoot with a charge of Win748 powder and couldn't get tight groups.

But, if you can't get a handload to work for you, change a single component at a time until it does. If you have a bunch of those 68gr bullets I'd start by changing the powder.

Do you have any old standby powders available like 4895, Re15, or 4064? I'd try those to see if you get different results. Actually any results is a good thing for you, tighter groups is good, same groups is good, and worse groups is good as it give you something to compare with your current load.

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Old May 4, 2012, 07:27 PM   #23
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unclenick: thanks PM inbound

Jimro: all I have is varget and 8208 Xbr and H335. have a full box of 100 less about 20 bullets from last range test
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Old May 4, 2012, 07:52 PM   #24
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I've been shooting Hornady 68BTHP in my 1/9 twist 16" barreled AR @ 100 yd (most I can shoot at my range). Not a problem. Nice small groups.
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Old May 4, 2012, 07:54 PM   #25
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cherokeet: mind sharing your load with us? Having some big issues with this load so far
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