Troubleshooting my troubled shooting

[wyrmzr]

I've managed to get my AR to quit moving it's POI as it warms up; however, I'm now trying to work up a load using H335 behind Hornady's 55gr FMJBT bullet, I think it's #2267(?)
The interesting part with this bullet and powder combination is the variation in powder charges posted in the reloading books, and in several places online. Hodgdon currently lists no data for this particular bullet, but their latest books seem to indicate a load of 21.4 to 23.4, or something similar. Older Hodgdon books had a max load of 25.4 for this bullet. Other loading manuals are showing up to 27 grains.
Here are my results from today's range time, working up this load:
135493
The above is 22 grains of H335, seated off a bipod.
135494
This is the same round, fired into the same target again, but off a rifle rest.
135495
Here's 22.5 grains, seated, supported with a bipod.
135496
Again, 22.5 grains from the rifle rest.
135497
23 grains from the bipod.
135498
23 grains from rifle rest.
135499
24 grains from bipod.
135500
24 grains from rifle rest.
135501
25 grains from bipod.
135502
25 grains from rifle rest.
As of yet, I don't see any signs of high pressure. No flattened or leaking primers, no blown primers, no stuck cases, etc. Has anyone got experience that tells me I need to load even hotter than this? I'm firing a bull barrel with a 1:8 twist. I'm used to making jagged holes at 100 yards, so I know I'm capable of better, but I don't want to push my luck in the event that somehow this gun just isn't capable of tight groups for whatever reason.

*edit*
As an added note, I am sorting my LC brass from the commercial types. Perhaps I should be sorting it all by brand?

[wyrmzr]

OK, after browsing several other forums, I'm thinking I'm going to start from scratch, with Hodgdon's newer data, and work up. I may actually be running too hot to be accurate.

[Sticky]

Always a good idea to start from scratch with any load, but.. fwiw, you may want to try a different boolit other than a fmj. They are not inherently accurate, but many other 55gr jwords are. I shoot a 55gr Vmax or Zmax in front of 25.3gr of H335 and it is submoa. One of my go to groundhog loads. The polymer tipped boolits are inherently accurate and cheaper than match boolits. ;)

I have also had very good luck with W748 and light 223 factory boolits, here is a 40gr Nos BT (note on target was wrong, not Vmax) shot at 100yds last week. 5 rounds to the right were sighters after shooting a different load, clicked a few to the left and rattled off 20 rounds pretty quickly, from a bench with a bipod. This was using a bull bbl'd AR tho, so it handles the rapid fire pretty well. ;)

135513

[Sticky]

It also helps to have a chrono so you can see the velocity increases as you run through the loads. As the velocity plateaus, you are nearing your max load and accuracy will start to often fall off (or primers are getting flattened.. lol)

[country gent]

Unless your dead set on a 55 grn bullet. give 69 grn 77 grn sierras a try alnog with the 75 grn hornady match bullets. 1-8 twist may be over stabilizing the shorter 55 grn bullets. I have a 1-7.7 twist that loves 75 grn hornadys and 80 grn JLKs. The faster twist ussually shine with the heavier longer bullets. Also if the rifle has a clamp style gas block make sure its not to tight causing a barrel restriction or a slight tight spot. Same if it has a flask hider over tighting can cause the muzzle to constrict. Another thing is to plot the shots as they are fired to see if there is a "pattern" to them.

[wyrmzr]

I do wish I had a chrono, or at least could borrow one from someone, but it's not easy finding someone who's willing to loan one out, and I'm on a very low income for now. So, it's going to be a gradual work up.
I was previously shooting sub 1" groups at 100 yds with this rifle, but that was with a different powder (I think H322). I picked up this 8 lb. jug of H335 because it was one of the few rifle powders available locally at the time, in any kind of real amount. So for now, I'm hoping to work with this, and am on the lookout for other powders, but having to be cautious about what and when I buy.

[Sticky]

I have had good luck with H335 and fwiw, those groups with the 40gr and my 55gr loads are all being shot from a 1:8 twist barrel with excellent results. I have loaded some heavier, but not really wrung them out well yet, as this is primarily a varmint rifle and I like blowing their heads off.. lol

[lefty o]

you cant overstabilize a bullet!

[Cmm_3940]

The hornady FMJBTs have decent accuracy, but nothing stellar. I've shot a lot of them. As others have posted, there's better ones out there. Then again, they also cost more. I shoot the Hornady FMJBT from two different ARs with different twists, so I really don't see a point in trying to fine tune the load down to the tenth of a grain when I'm shooting the same ammo in two very different rifles. I've settled on 25 grains of H335 as my standard load with the 55gr Hornady FMJBT, seated so a light roll crimp is just under the top edge of the cannalure. It shoots well in both my 16" 1/9 and my 20" 1/8. If I remember correctly, this load is very close to being a duplicate of M193.

Regarding brass, I sort all commercial (and foreign military) by headstamp, as different brands are often very different internally. LC gets sorted into "similar" groups; not strictly by year, but by the different "patterns" the headstamps have gone through over the various generations, if that makes any sense... EVERY piece of brass goes through the trimmer on EVERY reload, since they don't seem to stretch consistently, even within the same headstamp.

[Garyshome]

Got a chronoy?

[wyrmzr]

Yes, I've also been trimming my brass consistently, as the bull barrel I'm using does NOT like any brass with a length much more than 1.760 inches. 1.763 will not feed in this barrel, and all the brass I've fired through it seems to stretch to no more than 1.751. That's a far cry from my Savage Axis, which will chamber and fire brass that is 1.770 inches in length. So, the 5.56/.223 bull barrel is obviously made to some pretty tight chamber specs. I've tried firing brass that I made for the Axis in this AR barrel, and there's no way it will fully feed. Hitting the forward assist only jams the brass in the chamber, and makes it that much more difficult to extract.
So, 1.750 is best, with 1.760 being the high end as far as I'm concerned.
My only other spec to really try and tamper with is the OAL of the cartridge. I'm going to see if the recommended 2.220 is preferred by this gun, or whether I can go longer and get better accuracy. So far, crimping on the cannelure seems to be the ticket, and that ends up being around the 2.220 recommended by Hodgdon.
I'm not dead set on the 55 grain, but I have had sub MOA accuracy with it in this gun. I've tried Armscor 62 grain, but they just don't want to group so far. I'll look at trying heavier bullets, so long as they'll fit in the magazine; that seems to be one of the limiting factors for the AR, is that the mag can only handle so much length.

[WineMan]

I have used the H4198 load and it really works. From Fr Frog's web page:

http://www.frfrogspad.com/ar.htm

"If you want to test the accuracy of your AR, there is a simple, consistent load that originated with Wally Hart of benchrest fame that can be used. Use the Sierra 52-gr. or 53-gr. benchrest bullet and 22 grs. of H4198 or IMR4198; or alternately 23.5 grs. of H322, and anybody's match primer, in whatever brass you have, but sorted by make or arsenal and year. Seat to 2.26" OAL. DO NOT exceed this charge with 4198, as this is a fairly fast burning powder for this case. As for the H322, this surplus powder varies from batch to batch, and while the 23.5 gr. charge suggested to me was a mild load with the lot used, others may run faster, so please be careful."

I have a Bushmaster DCM upper (1:8 and heavy barrel with a float tube) and with any kind of rest at 100 and iron sights I can usually get five shot groups within an inch and sometimes under a quarter coin size. I trim my brass to 1.745 and use a RCBS X Die. Too short is usually not a problem.

Dave

[Artful]

you cant overstabilize a bullet!

:veryconfu - Right - or understablize either huh

[lefty o]

you cant over stabilize a bullet! under-yes.

[Artful]

you cant over stabilize a bullet! under-yes.
Think about it - you can do either
- if you don't give enough spin it won't be stable and like a poorly thrown football will wobble thru the air.
- if you give the jword or cast boolit too much spin you will exheed the material stress limits and
it will start to come apart.
Look up 220 swift and light jacketed bullet usage - you will find that instead of nice holes you
will force the jword too fast for the jacket to hold together and you'll get a little comet on
the target of if you really push it - just a puff of lead/jacket on the way to the target.
Been there done that.

[lefty o]

thats a bullet failure, that aint "overstabilized". what happens when you throw your football with a tighter spiral, yup it flys better, if you spun a football fast enough, it would come apart too. bullets and footballs alike dont become unstabilized by being spun faster. they dont magically start wobbling again. a bullet spun faster continues to fly straight and smooth, or if spun too fast it fails.

[Artful]

thats a bullet failure, that aint "overstabilized". what happens when you throw your football with a tighter spiral, yup it flys better, if you spun a football fast enough, it would come apart too. bullets and footballs alike dont become unstabilized by being spun faster. they dont magically start wobbling again. a bullet spun faster continues to fly straight and smooth, or if spun too fast it fails.

take your football which isn't perfectly balanced and spin it up watch what happens - it doesn't fly straight the imperfection of the projectile which is barely noticeable when not overly spun causes it to make a non-linear path - it diverges from normal path due to imbalance. And while we have come a long way from toward more perfect bullets we are not there.

take a rifle which can shoot a light weight and heavy weight boolit that you cast
shoot the light weight boolit as fast as you can - when it reaches above the rpm threshhold it will start to make enlarged groups - if you increase the speed more causing more rpms it will ultimately come apart.

[country gent]

After watching the bullets "trace" going down range in a spotting scope at long ranges its obvious whats goping on. There is a range of projectile length to a given twist rate. Shorter bullets can sometimes be gotten to perform in a faster twist by loading to a lower velocity. 5o grn SX bullets in my swift blow up at around 50-75 yds in full power loads. Loaded down to around 3300-3500 they shoot and stay together but little penetration. Any balance or imperfections are magnafied by over stabilization. If bullets cant be over stabilized why are there twist rates in 22 cal from 1-14 to 1 - 6.5 why isnt 6.5 being used for everything? In 6mm the range is 1-12to 1-7. 30 cal is 1-16-1-7.

[Gtek]

What if somebody threw out the term RPM Threshold? :popcorn:

[Artful]

What if somebody threw out the term RPM Threshold? :popcorn:

Oh, you said it! :shock:

[Dan Cash]

you cant overstabilize a bullet!

I beg to differ but I doubt that is the OPs problem.

[lefty o]

What if somebody threw out the term RPM Threshold? :popcorn:

i did, without using those exact words!

[wyrmzr]

Right now I'm planning on picking up some more 60 gr. bullets over the next few days. I did have good luck with some Nosler polymer tipped bullets in this barrel, so I'll see whether it still likes them. The 55 grains may be set aside for the Savage Axis if that's the case, and it still leaves the AR as a good coyote gun with 60 gr ballistic tips.
I'm currently waiting on a new scope mount, as the Axis doesn't like the Redfield Revolution scope (it's too short). As an added bonus, if the 55 grains work fine in the Axis, I'll go through bullets a lot slower than if I was plinking with the AR. It's way too easy to go through 100 rounds with any semi auto.

[CHeatermk3]

I had an HBAR Colt that was a 1/7 twist and had the devil of a time with it. Varmint bullets like the Hornady 50 vmax would come apart and it definately did not like the 77gn sierras. It liked the 69gn sierra MK and did surprisingly well with the winchester 64gn pp bullet; they held together and were accurate. They are also available with and w/out cannelure; are also available in bulk for lots less than either SMKs or HDY vmax.

BTW I personally don't think overstabilized is a useful term I like "overspun".

Also bullets don't fly in a straight line they spiral thru the air in a helical path to the target.

For coyote shooting the win 64 power point would be great if it shoots in your gun.

[W.R.Buchanan]

It looked to me like your 24 gr load was the one. this load is not even close to too hot.

My standard .223 load is 25 gr of W748/BLC2 with a Hornady 55 gr FMJBT. It is not close to hot either.

I'd go with what you've already got. I'd also find some W748/BLC2 as it meters better in a Powder Measure .

Randy

[303Guy]

Why is there a difference in group pattern between the the two rests? Wouldn't this indicate something other than the ammunition is going on? One of my rifles changed from a loose group to a wild vertical and narrow string when I fitted a too tight fore-end to it. If I could get the same vertical spread as the horizontal it would have been pretty accurate.


BTW I personally don't think overstabilized is a useful term I like "overspun".My thinking too. Over-stabilized means the bullet will maintain muzzle orientation down range instead of line of flight orientation which might not be good for long range accuracy. That wouldn't apply here.

Would over-spinning cause groups to change shape with different fore-end support?