Is this a head space issue?
- Thread starter Dr. Matt
- Start date
JSH
Gold $$ Contributor
I got tired of fooling with milsurp crimped primers, I bought 1K of new Starline and have not looked back, no regrets.
I would also like to know who or what primer. Looks awful deep as well. Checking firing pin protrusion is fairly straight forward and easy.
If that brass was not virgin and fired in something else, those marks could be from there.
I had some primer issues a while back. Fellow swore up and down it was high pressure. I fired mine in a different rig, zero issues. It was a protrusion issue along with me swapping primers.
I would also like to know who or what primer. Looks awful deep as well. Checking firing pin protrusion is fairly straight forward and easy.
If that brass was not virgin and fired in something else, those marks could be from there.
I had some primer issues a while back. Fellow swore up and down it was high pressure. I fired mine in a different rig, zero issues. It was a protrusion issue along with me swapping primers.
Thanks for all the replies!
Remington Small rifle 6 1/2
AlNyhus
Silver $$ Contributor
That's likely why the pin indent looks like it does.
Use the Rem 7 1/2. i avoid the CCI 400 Also. Both are good up to 40,000 PSI only. imo. A magnum primer works for me. Thicker cups.
JSH
Gold $$ Contributor
I used CCI 400 for years, no problem, until I did. No more for me.
I am curious about the bolt upper. I look forward to your findings good or bad. Some say it is going backwards. If it is accurate I see it as little different than any other chassis rifle that accepts AR mags.
I am curious about the bolt upper. I look forward to your findings good or bad. Some say it is going backwards. If it is accurate I see it as little different than any other chassis rifle that accepts AR mags.
Coyotefurharvester
Silver $$ Contributor
I'll never run a 6 1/2 or 400's , maybe if I had a hornet,fireball.
Remington is specific that the 6-1/2 IS NOT FOR USE IN 223 Loads. This is a pressure sign and you have developed a load off the lands and when you seat the bullet near/at/into the lands you will increase pressure.
This is incorrect. You reduce pressure as you move away from the lands to a point then the reduced case capacity comes into play. A builet seated near or into the lands does not move until the pressure overcomes the engraving force. The powder burns in a fixed volume for a longer period of time.
I've tested this stuff with a pressure trace system. What I can tell you is that there is no rule written in stone regarding where seating depth makes pressure go up or down. Sounds good and logical but doesn't test nearly as logically.
Ditch the 6 1/2
I would test as many other primers as you can find, one should out perform the rest.
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If that's 100 yards I would consider them all bad groups even for a varmint hunting rifle. The results you see have nothing to do with the primer. I would think you would need at least five shot groups well under .500" to see the difference in primers. The results are due to everything combined, barrel quality, shooter skills, rifle tune, quality of bullets ect.
joshb
Gold $$ Contributor
Yeah, Doom is right. I was writing under a time crunch. The theory is “in the lands” should be the higher pressure and moving off “a little” should drop pressure some. Moving the bullet further back can start to raise pressure from the decreased case volume. Where all that occurs in your gun needs testing.
Closer to 300 with a touch of breeze if I recall correctly, and nearly all the 6.5 primers perched and were never loaded again.
searcher
Gold $$ Contributor
I wouldn't worry about the lines on the brass - as your brass simply appears to be "molding" to the cut lines left in the chamber when it was cut. As others mentioned, I'd get rid of the 6 1/2 primers and go with Federal A/R Match primers, Remington 7 1/2, CCI 450's or Military -type primers offered by various companies. You want thick cups in an A/R for safety due to the floating firing pin, aside from pressure issues. While it is unlikely you would ever encounter a "slam fire", it doesn't hurt to use a proper primer. Nothing likely lacking with your brass, assuming you didn't mess with the flash holes.
Regarding your SD's and signs of pressure, because you are using an expander to get uniform tension, you may not be leaving enough tension, thus allowing bullet slip in the cases when your rounds are stripped off the magazine and when they come to an abrupt stop in the chamber. If this were occurring, the bullets may be actually jamming as they slide forward. Say they were sliding .005" forward in the case, you would not have a jam when setting back off the lands - but when getting within .003", that .005" slide would put you into the lands - potentially causing the pressure spike that you are encountering. You can load up a few dummy rounds with no powder or primer and check this. Measure your dummy rounds from bullet tip (or ogive) to base, then load one at a time into your magazine and pull the charging handle all the way back and let it slam home, stripping off a round. Eject the round and re-measure each these ejected rounds to ensure they are still the same length as before they were chambered. If they are longer, you have bullet slippage. The method you are using with the expander is more commonly used in bolt guns - not so much in A/R's. It will still work - you just need to be sure you still have adequate tension after expanding. A lot of the "off the shelf" expanders will open the case too much to provide the tension you need in an A/R - which is twice what you need in a bolt gun. One last caveat, if you don't anneal your cases prior to each firing (not necessary), there will be some brass spring-back which can take a full day for the significant portion of the spring-back to occur. So, I'd load your dummy rounds at least a day before doing the chambering and re-measuring test. I had re-learned that a few times when using neck bushings not small enough. They tested out O.K. right after sizing - but not a week later.
If there was any bullet slippage, your accuracy will suffer greatly and you will get wide SD's as well.
Regarding loading your rounds .003" off the lands - most A/R's will not allow this, due to maximum length of the loaded ammo restriction imposed by the magazine. Is that a custom barrel?
Good luck getting dialed in.
Regarding your SD's and signs of pressure, because you are using an expander to get uniform tension, you may not be leaving enough tension, thus allowing bullet slip in the cases when your rounds are stripped off the magazine and when they come to an abrupt stop in the chamber. If this were occurring, the bullets may be actually jamming as they slide forward. Say they were sliding .005" forward in the case, you would not have a jam when setting back off the lands - but when getting within .003", that .005" slide would put you into the lands - potentially causing the pressure spike that you are encountering. You can load up a few dummy rounds with no powder or primer and check this. Measure your dummy rounds from bullet tip (or ogive) to base, then load one at a time into your magazine and pull the charging handle all the way back and let it slam home, stripping off a round. Eject the round and re-measure each these ejected rounds to ensure they are still the same length as before they were chambered. If they are longer, you have bullet slippage. The method you are using with the expander is more commonly used in bolt guns - not so much in A/R's. It will still work - you just need to be sure you still have adequate tension after expanding. A lot of the "off the shelf" expanders will open the case too much to provide the tension you need in an A/R - which is twice what you need in a bolt gun. One last caveat, if you don't anneal your cases prior to each firing (not necessary), there will be some brass spring-back which can take a full day for the significant portion of the spring-back to occur. So, I'd load your dummy rounds at least a day before doing the chambering and re-measuring test. I had re-learned that a few times when using neck bushings not small enough. They tested out O.K. right after sizing - but not a week later.
If there was any bullet slippage, your accuracy will suffer greatly and you will get wide SD's as well.
Regarding loading your rounds .003" off the lands - most A/R's will not allow this, due to maximum length of the loaded ammo restriction imposed by the magazine. Is that a custom barrel?
Good luck getting dialed in.
It's not a custom barrel, it a Uintah Wylde 223/5.56 bolt gun on an AR lower. JAM is way out there. I'm using a follower block, so there is not a magazine. I didn't know about the time delay in spring back. I have been shooting, annealing, preping, loading and shooting again. Sometimes the same brass would be cycled 2 times a day. Thanks for the info. Sorry for the delayed reply.
I went with 7 1/2 Rem with much better results. I'll be trying others. This is where I'm at so far at 100 yards.
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