Question for chamber Guru's

6

6.5mag

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I have a question and will try to explain without getting to long winded. I put together a new rifle with a prefit barrel using a Rem nut. Headspaced no issues. Closed on the Go easy. Won't close on the No Go. I loaded some rounds normally. Full length resized, primed, charged, and loaded. I tested a few to make sure there was no chambering issues with my loaded rounds. I took some loads out to test and the rifle shot great except I started getting heavy bolt lift about two grains before I thought I would. My rifle is a 6.5 Rem Mag chambered 700 Long Action, 28" 8-twist barrel. 140 A-Max at 3.00" COAL started at 58gr. IMR 7828SSC. At 59.5gr. I encountered slight heavy bolt lift and small extractor mark on the case and stopped there. Groups were best at starting load, but not bad at all with other loads. I had some primer cratering with my first load at 58gr. thru 59.5, but it was not severe and generally don't freak out on primer flow without other things saying back off.

Now for my issue. In looking at my fired brass it has no visible issues, but if I try to insert a bullet into the case mouth of a fired case it will not slide in. I cannot force it in by hand. I have never seen a once fired case that will not accept a bullet slid into the case mouth and most of the time the bullet will just fall through the case mouth. Is there a chamber issue? Could a tight chamber be why I saw heavy bolt lift 2 grains before I thought I would?
 
Okay on the neck turning advice, but this was a no-turn chamber I'm sure. I did take a fired case and used the press to seat a bullet. Not near enough neck tension to secure a bullet so I might have jumped the gun on this. So can't start bullet by hand, but press definitely shows not enough resistance while seating a bullet in a once fired case. I am ordering a neck size only die tomorrow. Also I think I have determined I was to far into the rifling at my 3.00" overall length. I did some test with the once fired case with the low neck tension and seated bullet. I'm thinking now I need to back down to 2.97" and try the load that gave the slightly heavy bolt lift again at that shorter COAL. Thoughts?
 
If you are getting primer cratering on your starter load, back off. That was the most accurate load, you said.

Loading manuals are GUIDELINES not the final word on all chamberings and combinations.



EDIT- According to QuickLoad, your starter load is at 72 KPSI anyhoo!!

.
 
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6.5mag said:
Okay on the neck turning advice, but this was a no-turn chamber I'm sure. I did take a fired case and used the press to seat a bullet. Not near enough neck tension to secure a bullet so I might have jumped the gun on this. So can't start bullet by hand, but press definitely shows not enough resistance while seating a bullet in a once fired case. I am ordering a neck size only die tomorrow. Also I think I have determined I was to far into the rifling at my 3.00" overall length. I did some test with the once fired case with the low neck tension and seated bullet. I'm thinking now I need to back down to 2.97" and try the load that gave the slightly heavy bolt lift again at that shorter COAL. Thoughts?
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Neck size die won't help! If you can't drop a bullet in the neck of a fired case, your chamber neck to case dimension is too tight. Like a previous poster said, turn your necks. If you don't want to do that, open up the chamber neck. Or, get a chamber cast done to compare the chamber neck diameter to the loaded round size.,
 
Getting a print of the chamber reamer print sent to me. Maybe that will tell me something about what's going on. Thanks for all the advice.

Oh by the way yes I know the neck sizer won't solve problem. I should not have confused the issue by mentioning I plan neck sizing only.
 
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chamber cast.
find out what the neck actually is...screw the print.
 
You did not say if a loaded round would chamber easily with a stripped bolt. Your loaded rounds could have just about .001 clearance, allowing yout to chamber and shoot, but not enough chamber neck clearance to compensate for the spring back of the neck after firing.

Pay no attention to the primer crater. Remington's are notorious for having a generous amount of firing pin to firing pin hole clearance. DO, I repeat, DO pay attention to the tight extraction, and most of all, that shiny ejector mark on the case. When that shows, you are moving metal. That means you are getting into the 60,000+ psi pressure range.

Measure the OD of a fired neck. They will generally spring back at least .001 on the first few firings. That will give you a indication as to what you neck actually is.
 
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6.5mag said:
Getting a print of the chamber reamer print sent to me. Maybe that will tell me something about what's going on. Thanks for all the advice.

Oh by the way yes I know the neck sizer won't solve problem. I should not have confused the issue by mentioning I plan neck sizing only.
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Neck sizing only? Maybe 1 time with what you are telling us. Keep your full length die handy.
 
Unsized case .293. Sized case .292. Loaded case .294. Once fired case .296.
 
6.5mag said:
Unsized case .293. Sized case .292. Loaded case .294. Once fired case .296.
Click to expand...

Then I think Jerry hit it in post 5. You're load is too hot. The .002" difference between loaded and once fired rounds, if those measurements are accurate, should not be causing pressure problems like you describe.
 
6.5mag said:
Unsized case .293. Sized case .292. Loaded case .294. Once fired case .296.
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"loaded case .294. Once fired case .296"

I submit that you've plenty of room, you just need to clean up the factory casemouths using the liddle double-ended inside-outside chamfering tool.

Sounds to me like you've three thou clearance
 
The insert bullet into a fired case test is just the first part. If it doesn't go back in there are several things that could be happening. 1. obviously overall neck clearance. 2. overall case length and being crimped in the chamber. 3. How were the cases trimmed to length by the manufacturer. One manufacturer has a rim rolled out at the case mouth. Chamfering inside and out made it look good but the cases still had a lip which I've seen raise pressures. Insert a bullet and see if it pivots at the case mouth. If it does pivot get more aggressive when you outside chamfer.
 
Based on experience, and given the additional information, it looks to me like you have enough clearance. I normally figure that fired necks have sprung back about a thousandth from what the chamber neck is, which, from the numbers that you have given would give a loaded round clearance of about .003.

The other thing that I get from your information is that you may not have a handle on the ogive to head dimension that at which your bullets are just touching the rifling. I would look into this subject in detail.

Finally, there is the matter of your expectations vs the reality of where your rifle wants to shoot more accurately. Listen to your rifle, and stop trying to tell it what is should like.

Finally there is the matter of pressure signs. How does your bolt lift for your hottest loads compare with that of the lighter ones?

You have nothing to gain from going to a neck die. Make sure that you know how to properly set up your FL die. Manufacturers instructions are often not where you want to go. I am amazed that in many cases they still instruct users to turn them down till they touch the shell holder and then past that point a fraction of a turn.
 
There does seem to be a problem that you might figure out over time. The loaded round neck diameter is .294 and the fired case neck diameter is .296. That indicates some clearance but the bullet will not slide into the case using your fingers. Clean the neck of a fired case, carefully. then measure it right at the case mouth....or see if a bullet will slide in. You ain't got but .001 all around and that's not much. You'll have to watch really close at that clearance to maintain some space. I'd shoot it right there if it were me but recommend that you turn another .001 or so off the neck to save having to check them each time you load. The only reason I'd shoot it there is that I'm really lazy.

Make sure your case necks are not too long as well. Sacrifice a case and trim it way too much to see if that makes a difference. Pretty sure if you do the above you'll eliminate this effort but we all measure differently and were talking .001 here.

If you continue as is...be sure to check your bullets from lot to lot to make sure they are the same diameter or less.
 
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