Need help dialing in a load...

Hi everybody.
I've been working on a new rifle project. It's basically an AR15 in 358win short X 1.71".
I've been working with Hornady 200 FTX and Speer 180s
I pulled the tips off the FTX bullets so I could seat them out farther to get closer to the lands.
I'm getting some good results, but a flier will pop up and ruin the targets. I'm not sure where the fliers are coming from or what to do to fix it.
I'm getting good velocities with 1680. I ran the powder charges up and down and picked the best one, 35.5gns @ 2391fps, now I'm varying seating depth.
Attachment 323406
This was tonight's targets.
I did not get any velocity measurements as the sun was getting low and that always messes with the chrony.

I tried some Lee 358-200 and they went everywhere except the middle of the target. Pattern was like 18" at 25yds.

Thoughts?
Suggestions?

Might try changing out the scope.

I assume all the cases are one headstamp and about the same number of firings?

Yes, all Winchester brass, fired twice now.
It's a new Bushnell scope.
I may have a Leopold 2x7 sitting around.
Good thought on the scope...

What is the barrel twist of your rifle?
what yardage are you shooting at ? 100 yds ??

have you tried any 158g ? if the 200 do not work try some thing lighter

try at 50

are you over stabilizing or under stabilizing[/QUOTE]

try at 50

are you over stabilizing or under stabilizing

Which shot in the string is the flyer, or is it random?

I remember reading of first shot flyers from handguns back in the 1980's and 90's. I couldn't shoot a handgun well enough then to prove or disprove the theory. Now I can't see well enough.

Robert0

If you haven’t found the issue, I would weigh each case. If the weights are off by more than 3 grains, investigate why. Seems another fella had trouble with inconsistent neck diameters in that caliber that required reaming to correct.

Twist rate? What other powders do you have in in that range?

I would also ask basic things first.

What range was that? How well can you shoot other guns/cartridges? Which round in the group was the flier? Did you shoot from a rest, standing unsupported, bags? What length is the barrel and what twist did you use?

"...358win short X 1.71"."
I would look into the forming for residual neck thickness and bullet tension.

Quote:

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Originally Posted by TurnipEaterDown

"...358win short X 1.71"."
I would look into the forming for residual neck thickness and bullet tension.

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Excellent point.

If you are using a traditional lube, they may be over-lubed, causing fliers due to lube purging.

Hi guys, I guess I forgot to include the pertinent information.
18.5" stainless barrel from Deadshot barrels in Oregon.
It's a 14 twist,
I'm shooting from a sandbagged
rest at 75yds.
The rifle was warmed up.
The fliers seem to be random.
The previous velocity was 2391fps with the 200FTX. I tried seating them touching the lands and then backing off a little bit each time.
I did not chronograph the velocities of those targets as the sun was getting low and the light seems to give funny chrony readings late in the day.
I've tried Speer 358 180 and Hornady 358 200 FTX so far.
I've shot the FTX with and without the flex tips.
I can usually shoot fairly well.
My Ruger AR in 450bushmaster I can put 5 in under .5" at 75yds.
My 7.62x39 AR Pistol will do 3/4" all day long.
I'm trying to shoot slowly with 2-3 minutes between shots.
I have a lot of powders to choose from. My next thought was going to be cfe-blk. I tried rl7 and RL10X, but the velocities were way lower...
Groups were similar also.

It's all Winchester brass, chopped at the neck shoulder junction, then formed in a cut down 358 Win sizing die and trimmed to 1.710". The neck is .015" thick. a loaded dummy chambers and extracts smoothly. Any other brass gets the necks turned to .015".
Winchester seems to have the most internal capacity, so that's what I went with trying for more performance from my project.

The chamber was cut with a standard 358Win reamer and was just run in 1.710". Headspace was set with a case that I sent along with the bolt to DeadShot Barrels.

Loading dies are Lee that were cut down about .3" and seem to be doing fine.
Brass is formed in one pass with Imperial Sizing wax.
The case capacity is 47.5 gns of H2O which is slightly more than 360 Buckhammer.
I have Quickload, but with Buckhammer data availible from Hodgdon, I'm comparing the two and verifying results with a chronograph.

Attachment 323458
I put a new Weaver scope on. I need to pickup something better.
I shot the same load again.
This is 8 shots.
It looks like it wants to shoot, but the random fliers are still there.

Attachment 323459
I took a rough stab at the 200 Hornady spire point.

If you have a muzzle device on, take it off.

Look closely for copper colored strike marks on the inside of the device.

Don't ask me how I know.

I have a Tromix Linear comp on it.
It has a .375" hole in the center.
I'll take it off and reshoot a target.

also go over rifle with fine tooth comb...dont only check the scope rings..check the plurry bases too...has caught me out twice and three other blokes I know of....strangely both mine were after gunsmith visit!!!
to some degree your shooting in the dark as dont have a baseline to go with..EG a federal blue box factory load....am I better or worse than can do with that....
recheck the crown... reclean bore,try it clean then leave it alone for say 30 rounds then try it again..it might like to be dirty.
worst case its still a good up close gun..but be very disapointed being a new build.

At this point, you are wasting time and money. Let’s eliminate a variable, is it the gun or the ammunition? Take a single case and load and fire it five times or as many as you want. That will tell you if it’s something with the gun or the ammo.

Powder position may be the issue. Is a filler used? If not, try the method Larry suggested in the past where you hold the cartridge at a 45 degree angle (nose up) and tap the base slightly on the table while rotating it. Then load gently so the powder is at the location last tapped.

Good luck and happy shooting. A bad day at the range is still better than a good day at work.

Slim

Quote:

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Originally Posted by slim1836

Powder position may be the issue. Is a filler used? If not, try the method Larry suggested in the past where you hold the cartridge at a 45 degree angle (nose up) and tap the base slightly on the table while rotating it. Then load gently so the powder is at the location last tapped.

Good luck and happy shooting. A bad day at the range is still better than a good day at work.

Slim

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It's a compressed load, so powder position shouldn't be an issue.
Thanks for the thought though.

Quote:

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Originally Posted by slim1836

Powder position may be the issue. Is a filler used? If not, try the method Larry suggested in the past where you hold the cartridge at a 45 degree angle (nose up) and tap the base slightly on the table while rotating it. Then load gently so the powder is at the location last tapped.

Good luck and happy shooting. A bad day at the range is still better than a good day at work.

Slim

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point at sky,give wee shake then lower and shoot does same thing easier LOL....

Attachment 323517
Okay, so I changed several things, so I'm not sure what was wrong, but I am happy with today's limited shooting.
I put a Vortex scope on, took the center out of the Tromix Linear Comp, and switched to CFE-BLK.
I can use the same loads tomorrow with the Linear Comp put back in to see if that has any effect on the groups.
The velocity was lower with CFE-BLK. I think there's still room to go higher. The bolt wasn't locking back all the time.
I ran out of prepped brass, so I didn't load anything higher than 36.5gns.

Lar45 - how did the repeat go?

BTW: 200 @ 2300-2400 Seems peppy for what is in practical terms a 35 Rem AR, though do realize you likely are targeting higher operating pressures. 2-300 fps seems quite a gain over the 35 Rem.
Have you run an analytical model to guesstimate the pressures? Have you done a water capacity comparison w/ 35 Remington?

BTW - I know 680/1680 is a good powder in the 357 Herret, but when I gave it a go in 35 Rem some weird things started rearing their head for me. Perhaps try something marginally slower like 4198?

I read or watched somewhere about dialing in a load using increments of 3% of your first good group as you progress up or down the ladder. I hope my post makes sense.

Hello, I reshot the same loads with the center piece of the Tromix comp and got essentially the same groups.
A friend suggested maybe shimming the comp out to try and tune the barrel. Kind of like the BOSS systems on the Browning rifles...
I shimmed out progressively to .0060" in 20thou steps and at 60 got some really nice tight groups.

I noticed that my round is very close in case capacity to the 360 Buckhammer, it has around 1.5gn more capacity at 47.5gn of H2O. So I've been comparing Hodgdon's data with Quickload to come up with a reasonable max load.

This barrel seems to be real touchy as to what it's fed, but I think it's shooting great for a home built AR in a hot 358 short cartridge.
I was going to take it Hog hunting this weekend, but my buddy's dog got hurt and needs bandages changed twice a day for 2 weeks...
So I'll go in 2 weeks...
Maybe in the mean time, I'll see if I can get the Speer 180s to shoot.
I took a stab at the Lee 200 and they were all over the place at 25yds :(
I think I'll slow them down and load with 2400?

Thanks everybody for the help :)

I suspect most of the issue is the comp. As you noticed it can change things dramatically.

I'd start over with a good ladder test. You will waste less ammo and find the node for your barrel. If needed you could then look at changing seat depth and comp shims. Change one thing at a time.

The cast bullets running that fast need some special attention. Be picky about any flaws and weight sort the bullets. Make sure they fit your bore. You also might want to seat them so they lightly engage the rifling. If you load them down too far you will run into powder position issues. Tipping the barrel up between shots will help that.