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Possible case head swipe ar15?

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Ccctennis

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I know the vets on here will be able to diagnose and cure my issues!
Hit the range today with my ar15 and two sets of handloads.

1st batch: I KNOW THE ALLIANT WEBSITE SHOWS THIS AS A LOAD. Alliant doesn't state if that is a minimum or maximum
Alliant AR-comp 25 grains pushing sierra match king bthp 52 grain bullet.
I got to round number 11 and it fired but wouldn't extract. Range master came over helped and said it showed signs of over pressure. Case rim was bent and broken off

Switched to 2nd batch: THIS BATCH IS AT THE BOOK MINIMUM FROM HORNDAY
Alliant AR-comp 17.5 grains pushing hornday bthp 75 grain.
1st round went boom and didn't extract.

Got it free and ran 20 factory rounds with no issues.

I will post photos of the cases for your viewing pleasure. Did I miss something here? I went with low book recipes just for range plinking. I didn't crimp anycases and I seated at the suggested OAL.

The reason I think it is a cycling problem is that it occurred with both recipes. Factory ammo worked fine. Is it a cycle problem? If so how do you correct it?
 

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I believe Alliants loads are Max on the website are they not? I think it says somewhere to make your start chg 10% less than their suggestion.

Most times I figure its max if it doesnt say one way or another...dont know if that's right or not:)
 
Thanks

A friend told me the same thing. But the other recipe should have ejected properly. Unless it was under pressured and caused a cycle issue?
 
the primers don't look flattened (although they are not a super reliable way of diagnosing high pressure, they can be useful)
did you work up the load in between firing or go directly min to max?
what's your trim to length?
did you fire steel case ammo before trying out your handloads?
 
Thats not case swipe!
Thats high gas port pressure tearing off the rims!

All Alliant data shown is MAX.
Reduce 10% for the correct starting loads.

They show 25.2 Max with 52 grain.
Starting load would be 22.7.

They show Max with a 77 as 22.1.
Starting load would be 19.9.

They show Max with a 69 as 23.2.
Starting load would be 20.9.

They don't show a 75 grain.

Its possible you are over max in your rifle with the 52 grain load.

Its possible you are under the start load with the 77?

So its possible you are getting strange pressure excursions due to low pressure.

On the other hand?
Its more likely your scales are goofy and you don't really know what charge weights you shot.

Check the scales for accuracy before reloading any more ammo!

rc
 
Thanks

I weigh each charge by hand. I use both manual scale and electronic for extra verification.


The 52 grain load I got off alliant is a rookie mistake as I took it as a minimum or at worse middle recipe.

The other load was directly out of hornady at book bottom.
 
My Hornady #6 manual is dated and does't show. AR-Comp.

But the lowest charge with the fastest powder they do show with the 75 grain bullets is 18.6 grains IMR-3031.

3031 is fast for that heavy a bullet.
Is AR-Comp even faster?

rc
 
When I first read this thread title I thought it said "possible head case swipe at AR-15". I thought it must be discussing Sen. Dianne Feinstein.:eek:
 
Is your ar a factory rifle or a budget build rifle? It looks like the extraction forces are too great causing the case rim to shear off. I would assume that you worked the load up keeping an eye on pressure signs as you upped the charge, If not then thats what you need to do. If only one charge is listed, it is understood to be the max and it's up to you to reduce accordingly.
What is the histoy of the brass you used? Once fired by you? Once fired by someone else in a different rifle? Once fired MAYBE? The reason I ask is lets say the brass was fired is a kit gun that somone put together without checking headspace and chamber dimensions after the build. This guy doesnt reload so he leaves his brass at the range and a scavanger picks it up to sell on the net or a dealer. You get the brass and and run it through the sizer, but since the brass is so blown out, your sizer doesnt size it down quite enough. You then run it through your ar that may have a chamber thats cut tight. This is where a case gauge comes in handy. And if this is the case you may need a small base sizer to size the brass just a little more. The new factory ammo is small enough.
Next what about the rifle. Factory or built? New or well used? I have seen a few budget build ars that the factory actually coated the chamber as well. We meed a little more info from you. Look at it like its a system including the ammo when you have a problem with a gun running with reloads and even more so when you built the gun. Building a gun is more involved than just pushing in some pins when there is a problem or out of spec part. All the details are important
 
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I think I can imagine, but what exactly is "head swipe"?
First time Ive heard that one.
 
Hornady 223 data seems very conservative imho. Especially compared to speer.

i cant explain the missing rims however. Does your rifle have adjustable gas pressure? Brass clean? Chamber smooth? It appears extraction is attempted while the brass is still momentarily fused with the chamber walls.
 
IF you had no problems with the factory rounds (cycling or damage, I assume they were brass), then I would suspect the reloads. I have found manufacture's minimum loads not cycling to be fairly common in rifles and hand guns.
 
More details

The gun is rock river Lef-T elite operator.
It has the chrome bolt group in it.


The hornady bullet wasnt the A-max as it generally is listed as not for semi-auto guns.


We have 2 different problems occuring at one time.

The 75 grain hornady load is at the book minimum. Which it would seem is the primary reason for CHW (case head wipe)

The 52 grain load was from the Alliant website and was max load. and i pulled a rookie move and didnt back it down any.

The gun was cleaned prior to this trip. The mouth of the chamber doesnt have any carbon build up. this particular gun doesnt have a gas adjustment system on it. I will probably replace the buffer spring but not till i work up the 75 grain loads a bit and see what the problem is with them.

I also will drop the alliant load down 10 percent and see what i get.
 
After looking at your pictures, I cant help but think that somthing is causing the cases to stick to the chamber when the extracter is trying to so it's job. How hard was it to remove the cases afterwards? Since you had the same problem with a light and a max load, I am suspect of your sizing die and brass. It takes some force for the extractor to rip the rim off. Try taking some of your loaded rounds and dropping them into your chamber. Then push the bolt group home with finger pressure. Note the difference in the amount of force needed between a sample of reloaded and factory rounds. Also try taking some and dropping them into the chamber and pushing on the case head with your finger. Then invert the rifle and see if the round drops right out. If it hangs then color the case with a sharpie and do the same. The ink will rub off where the case is hanging up.
 
Eam3. Thanks for that tip. I will try that tomorrow for sure. I took a cleaning rod and it only took a couple of light taps to kick the brass out. I bought 3k rounds of alleged once fired brass. I may take a batch of 20 and check them for fit in the chamber and possibly re adjust my die. I used full length resizing die.
 
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