.308 load test

[Gtscotty]

I was just curious if there were any glaring issues with your process, that might be introducing variability, but I don't see anything. I've never reloaded precision rifle rounds on my progressive press, but I assume you've had success with .308 target rounds on your 650 in the past? You are using all the same brand and vintage brass right?

 

[murf]

natureboy,

when you have an hour, or two, of free time, read through the "how to reload" section of a good reloading manual. just going over the basics sometimes jars loose an obvious solution.

murf

 

[Nature Boy]

I've had success following the process I outlined using the 650 so there's something that's changed.

Here's what I'll do this weekend.

1. Take all the dies off, clean it real good then put everything back paying particular attention to set up.
2. Take a pervious known accurate load and make a group in progressive mode and a group manually, trickle charging the powder weights.
3. Shoot them over the chrono and see what the data says.

 

[Andrew Leigh]

Another thing to check.

I loaded .308 with a friend and we were having issues. On checking I noticed that the shoulder dimension was changing post forming. We checked and what we noticed was that we had insufficient lube inside the case neck. This was increasing the friction between the expandaball and the case and the results was actually extending the shoulder back out after having bumped it back.

If we lubed the inside of the case neck sufficiently that the expander ball had an easier time of it and the case retained the original dimension at the neck area.

We also noticed that for some odd reason that the .308 did this and we could not replicate this with a 6.5mm or a 30-06. We also noticed that the speed of the stroke mattered and that best results were achieved by slowing the stroke right down when the expandaball passed through the neck. All my brass case forming is now done real slow and for me it has made a difference when compared to the normal up and down stoke.

It is a long shot by worth a look.

 

[Nature Boy]

Excellent advise Andrew. I will process some more brass and pay attention to this

 

[Walkalong]

Are you using an expander ball?

 

[Nature Boy]

I'm using the Dillion sizing die as it comes. The decapping pin has a "ball" at the proximal end that I assume is the "expander ball". Is that correct?

 

[Walkalong]

Yes, and, in general, they are bad for accuracy. Can be anyway. Bushing dies, like the Redding S dies are a much better choice.

Forster will hone out a sizer for you as well.

http://www.6mmbr.com/catalog/item/1433308/1464783.htm

 

[Nature Boy]

Thanks walkalong. I'm learning a lot from this. Can you tell me how to determine through measuing my brass if I'm doing something detrimental to it dimensionally with the expander ball? Is there a way, beyond what I'm doing now, which is using the Hornady headspace gauge with calipers? What else am I looking for?

 

[Walkalong]

Runout can be measured. You can check shoulder position and see if the expander ball is pulling those forward. Lube the ball and it will likely be OK. Basically what A.L. already posted.

I loaded .308 with a friend and we were having issues. On checking I noticed that the shoulder dimension was changing post forming. We checked and what we noticed was that we had insufficient lube inside the case neck. This was increasing the friction between the expandaball and the case and the results was actually extending the shoulder back out after having bumped it back.

If we lubed the inside of the case neck sufficiently that the expander ball had an easier time of it and the case retained the original dimension at the neck area.

Brass work hardened, changing shoulder position/neck tension?

 

[Nature Boy]

I'll also check neck tension when I load some this weekend

 

[Nature Boy]

My first order of business in the morning will be to see if the primer makes the difference since I have Federal 210Ms now. Loaded up 20 each, 210M and BR2


If the 210Ms don't perform as they did, then I'll know it's something else, perhaps the way I processed the brass.

These loads were made from Federal 7.62 M1A brass on their 6th firing. Trimmed to 2.005. They all show neck tension to be .001

I'm using 39.5g of H4895, which previously netted 5 shot groups between 0.55" to 0.35"

Again, if the Fed primers don't show significant improvement over the CCI, I'll come back and reprocess some brass, paying special attention to set up and lubing the expander ball.

Andrew also sent me a load to try that he ran through QuickLoad. I'm going to give that a try as well.

 

[Nature Boy]

Initial results would indicate the primer is making a huge difference, and follows what I was seeing before I ran out of the 210Ms

Targets are 10 shots each. Top two are the CCI BR2s and the bottom two are federal 210M.



Chrono data:

CCI BR2
Average 2574
ES 24

Fed 210M
Average 2576
ES 31

I bet I can tighten that up if I trickle charge the loads. For these I just let the Dillon throw it and I verified +/- 0.1g from the 39.5g target.

Going to process some more brass now

Also: started from a clean bore. Shot the first groups in alternating, round robin fashion. Second 2 were 10 each in a row. The best group was the 3rd one fired

 

[Nature Boy]

I decided to cut one of my brass open to see if there were any signs of thinning but it looks good to me. This is Fed brass that's been shot 7 times

 

[macgrumpy]

Your case is beginning to thin, it's definitely not in immediate danger of failing and when it will crack is anyone's guess. It all depends on how hot the load is, how you resize the case, and how well the case fits the chamber after resizing.

 

[Nature Boy]

Thanks Mcgrumpy.

I keep feeling around in there with a bent paper clip, thinking I'm "feeling something". Now that I cut one open I realize that I'm not. This gives me a good base line for future reference. Even with thin spot it looks like I've got a few more rounds of life left in this batch.

I'm generally not loading hot and only bump the shoulders back .002-.003. Primer pockets are still tight.

 

[macgrumpy]

Absolutely, I'd guess that you'll average around 10 to 15 loadings at least. I load .308 for gas guns and I can get 7 to 10 times out of Lapua brass with my light loads, with my hot loads I'm lucky to get 5 times out of the brass.

I quit using the paper clip scraper method to check for thinning and I started checking my brass visually with a small pen light. You can actually see the thinning as a hollow inside the brass. When the brass shows thinning around 50% or more of the case then I toss them. This is easy to do with 30 caliber and larger bottle-necked cases but it gets difficult with the smaller calibers.

For the last several years I've been using the tightness of the primer pockets as a flag indicating that the brass is done. In fact, I've come to the point now where I no longer bother looking inside the brass for thinning, culling based on primer fit seems to eliminate the brass before the thinning becomes a problem. I use a .210" diameter pin to gauge the size of the pockets, when the pin fits in the pocket I toss the brass. Using this method I've not had a problem with cracked brass. It also prevents bolt face wear because the primers fit tight enough to prevent flame cutting of the bolt face. I've also found that having consistent primer fits help reduce those unexplained flyers.

 

[Nature Boy]

Ahhhh, you didn't tell me lose primer pocket = flyer.

Here's a question. Your .210 pin gauge is a go-no go, correct? If it fits the pocket you toss?

 

[larryh1108]

It's amazing what we can learn here if we keep our mouth (fingers) shut and our ears (eyes) open. Great stuff you guys. The more you learn the more you realize that you don't know jack... lol.

 

[macgrumpy]

Ahhhh, you didn't tell me lose primer pocket = flyer.

Here's a question. Your .210 pin gauge is a go-no go, correct? If it fits the pocket you toss?

Yes, I use the pin as a go, no-go gauge and if the pin fits then the brass is tossed out.

Flyers can be caused by a lot of things but over the years I've noticed that mine seem to lessen when I pay attention to the primer pockets and the head-space dimension. I suspect that gasses escaping around the primer and variations in the usable case volume changes the flame front and burn characteristics of the powder. I can't prove these as being fact with any kind of test proof but over the years I've adjusted my reloading process to prevent problems in these areas. Of course, the rifle and the shooter can be part of the problem too. Loose mechanical fits can cause flyers and most often I've seen poor stock fit and mechanical fasteners being the source. Recently I found contact between a washer and a gas system part as the cause for a flyer issue that I chased for months. On a bolt action like yours the mechanical fit of the recoil lug in the stock and it's contact with the receiver can cause a lot of headaches. A rough bore and extreme fouling can cause flyers too.

 

[Nature Boy]

Thanks again Mcgrumpy. Pin gauges ordered for both small and large rifle

 

[Walkalong]

Another option.

http://ballistictools.com/store/exclusive

http://www.sinclairintl.com/reloadi...swage-gage-primer-pocket-gauge-prod71030.aspx

I use pin gauges to check the ID of case necks, before and after sizing, for .308.

 

[Nature Boy]

Thanks walkalong. I just ordered 2 runofthemil pin gauges from Amazon.

Question regarding the neck. When I measure neck tension (neck OD after seating - neck OD before seating) I get a consistent .001. Is that correct and is that OK?

 

[Walkalong]

Should be fine.

I "feel" neck tension by being aware of the pressure it takes to seat a bullet myself. Nothing scientific about it.

From my load sheet:

Neck OD of the sized brass: .3375 to .338
Neck OD with bullet seated: .338 to .3385

Lapua brass (4th reloading) and Sierra 168s.

 

[Nature Boy]

With primer issue resolved, I checked all primer pockets and all were still in spec. Now I'm focusing on runout. Picked up the Hornady concentricity tool and started measuring. Everything is between .0005 and .0035. The Hornady tool allows you to correct the runout so I did that to some but I left a batch as I found them to see the affect on accuracy.

The box on the left shows how they were distributed (.003 on the left, .002 middle and .001 on the right). As you can see, the bulk fall in the .001-.002 range.


The results seem to indicate that runout could be causing some of my flyers. (.003/.002/.001)