First reloads - Interpreting Chrono readings

[Nature Boy]

First time reloader.

I just fired my first 50 reloads on my brand new Dillon 650 in .308 for my M1A/M14.

Loaded light, 38.5g of H4895, 155g A-MAX, 2.800 COAL in LC brass

At 100 yards, shot 10, 5 shot groups with an average 1.05 MOA (pretty happy about that!)

Also crono'd them. I'm just not sure what to do with the data. Here it is:

High - 2492
Lo - 2364
Avg - 2438
Range - 128
Std Dev - 35

What does that data say to you guys? What would you do next? I want to load some more and bump the charge up and see what changes.

 

[readyeddy]

I would probably just stick with the load. Or bump up the charge to see what happens.

Looks like you did a great job!

 

[Old Grumpy]

Your Extreme Spread (Range) appears large but it's only about 5%. The key I always look at is the Standard Deviation. 35 fps is not bad for a rifle round. Like readyeddie said, you can bump the charge up in small steps and see if the SD comes down. Still you're in the ballpark now.

Grumpy

 

[RugerOldArmy]

The ES is a little large. Given that, and the fact that you still got a MOA out of a M1A/M14 rifle, I'd stick with the base components for a bit, and try to get the ES down.

Loading stick powders with a Dillon measure presents some challenges. I've use a dremel and a craytex polishing tool with polish to smooth out the inside of the aluminum funnel. It improves consistency of throws a bit, but doesn't work miracles.

Personally, I would look for a better metering powder. I've not used H4895, only IMR4895, and it metered poorly in my Dillon measures. (Is H4895 shorter cut?) For light bullets in .308 VV N135 is an extruded powder that meters very well in a Dillon...and N140 is similar, and better suited for bullets larger than 155 Gr. AA 4064 (which is much shorter cut than IMR 4064, and is op-rod safe) might be a better metering option.

My favorites in .308 are RL-15, Varget, 4064, and N135 (for lighter bullets). But op-rod consideration matters in your case, and I shoot .308 in bolt-action rifles.

Perhaps you can get a suggestion of other good Dillon-Metering powder, suitable for your gun, from another poster. The VV Powders are expensive, but do meter very well in a Dillon, for an extruded powder.

Another option is ball powders (again, op-rod safe). They'll meter fine (Tac is an example, or 2520)...but I'm not up on the powders suitable for the M1A/M14. My personal experience in bolt guns is getting greater accuracy from extruded powders, as a rule.

 

[35 Whelen]

Your extreme spread likely is so large because your load is so light. You're a fair bit under max by the tune of 3.5 to 4.0 grs.. I bet if you ease the charge up things will come together.

35W

 

[Nature Boy]

Great info guys. Much appreciated. Reloading is all brand new to me so I'm going to lean on you all for feedback.

I'm free this weekend so I'm reloading and shooting my (__) off....if it ever stops raining here in Texas.

I have several Hornady bullet options (150g-165g) and some 125 and 168 SMK. Unfortunately, I only have H4895. Will check with my local reloading supplier to see if he has some of the ones you guys are suggesting.

Thanks again

 

[joem1945]

You might bump the charges up by .1 gr at a time and see if you groups shrink. Do not exceed the max FPS listed in you load books.

 

[Nature Boy]

Thanks Joe. The nice thing about Hornady is their book has a service rifle section and they used an M1A for their testing data. Gives me a bit more piece of mind as I ease into this.

 

[243winxb]

Primer? A mag primer may give better results using starting loads.

 

[Nature Boy]

I'm using CCI 200. I'm rolling some tonight, going to bump up 1g to 39.5g, still well below max.

Also going to try some:

Hornady 165g GMX - LC brass
Hornady 150g SST - Fed brass
Sierra 125g HPMK - Fed brass
Sierra 168g SMK - LC brass

Range report to follow.....

 

[popper]

I'd go ahead and move to 42-43 gr. Your load density is about 80%. ES about 50 is good. Or you could add a pinch of dacron. Love those one piece 6 screw mounts. My AR10 carbine likes the 168 Amax. CCI200 is what I use. 40 gr gives me 2450 avg. with a 170 gr. cast, LC07, as close to MOA as an old guy can get.

 

[Andrew Leigh]

Morning,

camera's are deceiving when it comes to depth perception but you ProChrono looks a little close to the muzzle. 5 yards should do it if you are not already at that distance.

STD deviation is for me a indicator of loading consistency. At 35fps you have the scope for improvement, I am moderately happy at 15fps and ecstatic when in single figures but that is with sorting brass for internal volume, weighing each individual charge etc.

I simulated your load in QuickLOAD using your parameters and indeed you are very close to an accuracy node hence you 1MOA. I have assumed a 22" barrel and a velocity drop of 8fps from muzzle to chrony. QuickLOAD would recommend that you alter you existing load to 38.9gr. to get you to a barrel time of 1.267ms. You are currently loading light and your chamber pressure is simulated at a very moderate 39 127psi and 2 469fps MV.

Should you want to increase speed then your next accuracy node would be found at 1.196ms which would take 40.7gr and would have you with a chamber pressure of 44 327psi and 2 576fps MV.

The next step would be 1.095ms and this will take 43.2gr and will come in at an estimated 55 000psi and give circa 2 750fps MV. The burn rate of powder alters as the charge increases so we would need to re-tweak this load probably.

Continue with the CCI200

 

[243winxb]

Primers and Starting Loads

Mysteries And Misconceptions Of The All-Important Primer http://www.shootingtimes.com/ammo/ammunition_st_mamotaip_200909/

We tested loads at both maximum normal pressures and at the starting loads (some labs calculate start loads—we shot them). Standard primers caused no ignition issues at the max load but posted higher extreme variations in pressure and velocity in the lower pressure regimes of the start loads. In extreme cases, the start loads produced short delayed firings—probably in the range of 20 to 40 milliseconds but detectible to an experienced ballistician. Switching that propellant to a Magnum primer smoothed out the performance across the useful range of charge weights and completely eliminated the delays.

I dont think this would be an issue with H4895??

 

[Nature Boy]

Awesome info Andrew! Headed to the range with 40g loads

Also going to make sure the crono is further out.

 

[Eb1]

keep the same load, but try changing to a Winchester Primer. I have found that CCI200 primers give random velocities like you have seen, and the Winchester Primers have brought the groups together and the spread way, way down.

 

[Nature Boy]

Funny you say that. As I was loading last night started getting CCI 200 primers sticking in the pick up tube and primer magazine. After (gingerly) clearing 2 jams, I switched to Winchester LR and made 50 A-MAX 168g rounds with no issues. They also insert into the primer cups A LOT easier.

I'll have a good comparison between the two now.

 

[Eb1]

I have shot the same bullet/brass/powder/charge in a test, and the only difference were the primers. The worst accuracy were the Federal Gold Match for this load, then to the CCI200, then the CCI250, and the winner was the Winchester Large Rifle Primers.

This was in a .25-06. Since I have done this test in the 30-30 and the .303 British, and the Win primers always shoot the tightest on the Chrony and in groups.

 

[Andrew Leigh]

Not 40 but 38.9 or 40.7g ...... trust me on this one.

 

[Andrew Leigh]

It is unlikely that a case filled to 86.3% will result in pre-detonation as this seems to be the criteria rather than load.

By the way could anyone point me to any good links where pre-detonation has been conclusively proved. I cannot seem to find any.

 

[Andrew Leigh]

Hi EB1,

your comments on primers is of most interest to me. The local powder manufacturer in their reloading guide lists a primer as being not crucial for accuracy quoting that primers are generally all superbly made.

For many years I used the so called Russian / Wolf / Murom primer with great success but these were withdrawn from our market which caused me to shift to CCI200 and CCI250's.

German Salazar conducted fairly exhaustive research on primers. In the statistical firing test the "Russian" primers showed least SD and ES closely followed by RWS primers. In physical accuracy tests as determined by vertical displacement at 600 yards "the RWS were at 5.9" followed by the Win LR at 6.1" and then the Russian primers at 6.2".

I found this out after buying 1000ea of CCI200 and 250's. I am a hunter so the accuracy is acceptable and I am sub MOA on all rifles so all is well.

 

[243winxb]

detonate

Sunray, H4895 is used for reduced "Hodgdon Youth Loads" Its not going to detonate. Some magnums may produce secondary pressure spikes under odd conditions. Here is one >http://thefiringline.com/forums/showthread.php?p=4928827

[/URL][/IMG] But anything is possible i guess??

 

[Andrew Leigh]

Why are there no signs of powder blowback if this is the case? I can get those marks when F/L sizing with too much lube on the neck.

I have searched, many claim pre-detonation but I have not yet read one paper where anyone has been able to create pre-detonation under controlled conditions and then repeat the result. This is of great interest to me and I would really like to get some info.

 

[243winxb]

powder blowback from same link above.

 

[Andrew Leigh]

Aha, thanks for that.

 

[Nature Boy]

Range Report #2

So I bumped up my charge weight to 40g and used that charge for 3 different size Hornady bullets. I think I added too many variables to make this effective but it's been raining cats and dogs over the last week so I made bullets. Next time I'll stick with one bullet and pivot off of that.

Accuracy was abysmal. My best 5 shot group was 1.7" at 100. I think Andrew is on to something. If there's a sweet spot I was definitely in the sour spot.

All loads were 40g of H4895, cases trimmed to 2.005"

Here's the chrono results

Hornady 168g A-MAX, LC brass, Win LR primers
Hi - 2599
Lo - 2510
Avg - 2555
ES - 89
SD - 25

Hornady 150g SST, Fed brass, CCI 200 primers (worst accuracy)
Hi - 2635
lo - 2564
Avg - 2602
ES - 71
SD - 17

Hornady 155g A-MAX, LC brass, CCI 200 primers (best accuracy)
Hi-2614
Lo- 2525
Avg - 2567
ES - 89
SD - 20

So I'm going back to the 155g and work off of that bullet. After I have that nailed down I'll move to a different bullet.