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Old April 11, 2010, 05:36 PM   #1
riverwalker76
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Need Help With Identifying Pressure Signs Part 2 *pic*

Ok, so I took some of your advice, and went out to test another batch of ammo today. My question is two fold, so please bear with me.

Could you all please look at these, and tell me if the primers are showing any pressure signs? I know that the primers aren't always a good indicator, but the brass all ejected fine and looks ok.

Also, why did the groups settle in, open back up, and then settle back down to the best group yet?

I'm using the Battlesight Theory that if my AR is sighted in at 25 yds. it will be the same zero at 150 yds.

Barrel: 16" Wilson Combat M4, 1:9" twist, 5.56 NATO Chamber
Brass: Lake City
Primer: CCI #41
Powder: Accurate 2230
Bullet: PRVI 62 gr. Full Metal Jacket Steel Core Boat Tail


Lot #3 pictured from left to right.

1) 21 gr. ~ accurate to 25 yds w/ .5" group

2) 21.5 gr. ~ group opened up to 2" @ 25 yds.

3) 22 gr. ~ group stayed at 2" @ 25 yds.

4) 22.3 gr. ~ group settled to .25" @ 25 yds.

5) 22.5 gr. ~ opened up to 2 1/2" @ 25 yds.



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Last edited by riverwalker76; April 11, 2010 at 05:42 PM.
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Old April 11, 2010, 06:01 PM   #2
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They still look good to me. Can you make out any ejector marks? I didn't see any clear ones.

The group size changing is the normal thing that happens as the barrel time for the load moves in and out of sweet spots based on muzzle vibration. Read Chris Long's web site on Optimum Barrel Time. If that gets more technical than you'd care to, just use Dan Newberry's method and 0.2 or 0.3 grain charge increments to fine tune them.
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Old April 11, 2010, 10:04 PM   #3
snuffy
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Quote:
I know that the primers aren't always a good indicator, but the brass all ejected fine and looks ok.

Also, why did the groups settle in, open back up, and then settle back down to the best group yet?
Wellllll, you have a mixed lot of LC cases from 5 different years,(covering 18 years), so the appearance of the primers is immaterial. Then you say primers are poor indicators of pressure, then ask us to read them?

Next, why are you shooting an AR @ 25 yards? Way too close to tell anything useful Some bullets re NOT fully stabilized that close to the firing point, especially a steel core boat tail FMJ. ( Steel core is a misnomer, it's really a steel jacketed LEAD core).
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Old April 11, 2010, 10:23 PM   #4
riverwalker76
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Quote:
Next, why are you shooting an AR @ 25 yards? Way too close to tell anything useful Some bullets re NOT fully stabilized that close to the firing point, especially a steel core boat tail FMJ. ( Steel core is a misnomer, it's really a steel jacketed LEAD core).
And the point of your post was what?

FYI .... I'm using the U.S. Marine Corps 25-Meter Zeroing Procedure to determine my zero with these bullets. What I was trained to do at PISC.

Another thing .... these bullets are actually a Copper Jacket over a Steel Penetrator with Lead slug. SS109 Lake City copy to be exact.

SOmetimes I wish they had an IGNORE button for some people.
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Last edited by riverwalker76; April 11, 2010 at 10:35 PM.
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Old April 11, 2010, 11:10 PM   #5
snuffy
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Quote:
And the point of your post was what?

FYI .... I'm using the U.S. Marine Corps 25-Meter Zeroing Procedure to determine my zero with these bullets. What I was trained to do at PISC.
I don't care what gimmick you were trained to do. 25 yds. is too close to tell anything about groups.

Quote:
S0metimes I wish they had an IGNORE button for some people.
So you come here seeking advice, then when someone gives you some, you want to ignore it? Fine, go right ahead onward blindly, I'm finished offering any! That ignore thing works two ways ya know.
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Old April 11, 2010, 11:33 PM   #6
Jim243
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Simmer down, river, just like a butt hole everyone has an opinion, not always the prettyest.

From the information you have provided - Every barrel when fired will wip up and down. You and I can not see it unless we are using REALLY high speed video cameras, but EVERY barrel will do it. What is happening is that the bullet is exiting the barrel at different stages of the barrels rise and fall base on the FPS you are achiving with your powder loads. What you want is for the bullet to leave the muzzle just as the barrel in nutural in it's vibration.

From the data you have provided that would be with 22.3 grains of 2230 powder. Now this will change if you change the bullet weight or shape or any number of conditions effecting the bullets travel through the barrel. Each combination of elements needs to be balanced to get the proper accuracy load.

In addition as your barrel heats up, the conditions (Point of Impact) will also be effected. One way to get around this is a Cryo treatment to the barrel to align the steel molucles to make a stronger type barrel.

Since I believe you mentioned that you are using a Wilson Combat barrel, I would believe that it is chrome lined. The heat of repeated or rapid fire will affect the conditions as well, as opening your groups up, most compitition rifles use non-chromed steel for their barrels. Shorter life but more accurate.

It would appear you have a good load worked out with your .25 MOA results. Just load them up with 22.3 grains.

Jim


Sorry, your .25" groups would be a 1.00 MOA since MOA is measured at 100 yards. Again sorry.

Jim

Last edited by Jim243; April 11, 2010 at 11:56 PM.
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Old April 11, 2010, 11:56 PM   #7
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does your rifle has regular hand guards or is it free floating ?
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Old April 12, 2010, 12:54 AM   #8
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Sorry, but I'm not going to simmer down. When someone goes off on me half-cocked then I'm going to give it back. Plain and simple. What's good for one guy is good for the other. If he shells it out he'd better know how to take it.

Then he comes back and has the nerve to say that the USMC range course at PISC is a 'gimmick'. I mean ... what kind of stuff is he smoking?

FYI Snuffy ... In all actuality ... if you really want to get technical ... the M4 was designed for CQB and was never meant to be a 300 yd. weapon. I've never personally exchanged fire in any situation further than 75 yds.

So, to answer your question ... I AM concerned about the 25yd to 75 yd. range. Anything past that is impractical for my purposes. I'm not going to be using my M4 for shooting deer or coyote. I have a bolt rifle for that! Anything past 150 yds. and I'll use my .308 .
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Old April 12, 2010, 01:00 AM   #9
Jim243
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Back to your question about the primers. It is hard to tell from a picture straight down. You need to look at them from an angle.

From left to right - your #1 primer looks under pressured and was not pushed back all the way into the case.

Your # 2 & 3 primer look normal.

Your #4 & 5 primer looks flattened, but it is hard to tell from the photo.

Since they are all Nato cases they had to be swedged before you put new primers into them. It could be a case of a really tight primer because of the swedge or could be a pressure sign.

The real concern is the indentations in case #1, 2 and 3 this appears to be markings from a ejector rod in the bolt. But since the marks on case #3 is in three places, I would guess this case has been used 3 or 4 times. Also the Nato markings are kind of washed out on cases 2, 3 and 4.

I would suggest that you use new unused cases for your test, load them one shoot at a time, recover the cases and check again.

Not what you want to hear, but what would give you the best results.

Jim
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Old April 12, 2010, 01:10 AM   #10
riverwalker76
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JIM243 ... that's exactly what I was looking for! I need to be able to read my primers, and see what they might be telling me.

As for the cases ... they are once fired Lake City, and I have a feeling that some of them are M249 SAW brass. I can usually tell a case that has been fired through a SAW, because those weapons are really hard on brass. Whereas, the M16 and M4 rifles are a little more gentle with them.

The problem I am running into is that the range for Accurate 2230 load data is literally all over the board. Accurate suggests I load MIN. @ 20.4 & MAX. @ 22.8. Then Sierra says not to load BELOW 23.5 which is ABOVE Accurate's MAX. Then Lee is right in the middle. So, needless to say .... this is a head scratcher for me. Sierra is saying that their accuracy load is 23.5 gr. which is .2 grains below Lee's Max, and Sierra's Max is at 24.5 gr. which is ALMOST 2 full grains above the powder manufacturer's (Western Powder) Max load.
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Old April 12, 2010, 02:44 AM   #11
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Closest bullet is the Speer 62 Grain FMJ-BT #1050 (BC = 0.307 COL = 2.255 SD = .177)

Load Data is 22.5 gr AA2230 Min to 24.0 gr AA2230 Max.

Since LC brass is smaller (thicker walls) than standard I would set the Min powder load at 21.4 gr Max powder load at 22.8 gr

I would use your best results 22.3 gr and set the OAL for the load at 2.250, 2.255 and 2.260 (max for mag).

Test these OAL's first to see if they tighten your groups.

Jim
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Old April 12, 2010, 09:01 AM   #12
riverwalker76
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Thanks. I'll try that today, and post the results later.
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Old April 12, 2010, 09:58 AM   #13
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I gotta agree. 25yds might be a good indicator of a 22LR's accuracy, but for the 223Rem, you need to be shooting groups at 100yds.
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