primers backing out....

J

jaybic

Guest
Hey fellas,

A question for those in the know.....I am beginning my first venture into a full custom rig and I have fire formed the first 50 cases for my brand new 243ai and in doing so I had a number of misfires, maybe 10 (+ or -) most of which fired on the second try but 3 would not go off at all. I also noticed that I had 7 or 8 cases where the primer had backed out of the pocket, the worst of which I measured at 0.019.

At risk of putting my ignorance on display, I have to ask if these are "normal" fire forming faux pas or do I have some sort of legitimate issue that I should be taking it back to my smith for? Excessive headspace?...

In talking with him, he explained that we were going for a crush fit of about 4 thousands of an inch, which as I understand it, is supposed to keep the round from flopping around in the chamber and prevents this sort of thing(I am paraphrasing here) so I don't know...is this supposed to be happening and if not, why is it and what is the proper fix? I think I am in over my head perhaps......

Thanks for your time, I honestly do appreciate it and have a great day.

Jamie
 
"Normal" in the sense that it's common but absolutely NOT RIGHT!.....Your headspace is too long..... waaay too long if you're getting popups of 19thou. While your gunsmith may well talk the talk, he DID NOT walk the walk.

"We were going for a crush fit"

????

Who's WE? He got a mouse in his pocket? Trying to include YOU in the thing???

Nope, HE got the chamber a mile off.

Period.

I've had a dozen .243AI chambers from several different gunsmiths and 5 different reamers and most of them were horribly off. I've never personally had one 19 thou out though! That's HUGE.

Here's what I would most likely do.....

I'm not suggesting YOU do this but this is what I would do. (have done, I still have 3 .243AI barrels) I'd either neck up for a false shoulder or make my cases out of 308 Palma brass and neck them to tight crush-fit and use another gunsmith in future. I won't argue with people who include "we" in discussion of problems, unless I was somehow involved in the work.

Life is short

Keep a close eye on your gapspace, it's the place where the carbon ring builds and you've a monster gapspace going there.

al

Ohhh, and let me go on record here as stating that IMO greasing your cases to try make them slide is a STUPID fix for a problem that shouldn't exist.
 
falseshoulder.jpg
http://www.6mmbr.com/243Win.html
 
Its ideas like these that are exactly the reason I come here for advice.....Thanks a ton fellas.

Now I have a visual on what I need to do and that helps. Can I neck the cases up using a 25.06 die and then using my AI die to slowly size them back down until I can just barely close the bolt on an empty case. Is that what these pictures are trying to visually describe to me? I then pretty much have to re-fire form them and the should be correct in relation to my chamber, right?....or no?

Thanks again,:)

Jamie
 
The cases you previously fire formed, with the backed out primers, may have stretched and thinned
the web enough they are worthless. I personally would start with a batch of new cases, 308 Lapua.
 
kansasvet said:
The cases you previously fire formed, with the backed out primers, may have stretched and thinned
the web enough they are worthless. I personally would start with a batch of new cases, 308 Lapua.
Click to expand...

Ohhh Bravo! Bravo!

I couldn't agree more, NICE CATCH kansasvet

al
 
You mean like "throw them in with the split necks" kind of worthless???? Well, didn't see THAT that coming.....Thanks for pointing that out. I don't want any unsafe conditions but it sucks that 50 brand new cases are junk. That's lame.....

On another note, I took the firing pin assembly out of the bolt and then found some old once-fired RP cases that had been completely prepped for another standard .243 that I have. I got out the Sinclair bump gauge and measure my brand new Lapua cases and the resized RP cases and noticed I had a few longer RP cases. I put some of the longer ones in my rifle and on closing the bolt felt a definite "snugness" to them(almost like the firing pin assembly was still installed and even still a bit tighter). I then chambered the brand new Lapua cases and the bolt closed as if there was no case in there at all so I think I now have an understanding of the "crush" feel that I should be looking for. In measuring them, the Lapua cases were about 4 thou shorter than the RP cases that I could "feel"

Is it reasonable to think that I could take these cases and the rifle back to the smith and just ask him to make the new Lapua cases fit (crush?) like the RP cases? Is it as simple as just screwing the barrel in a little farther?....or is it much more complex that that?

Was this one of those "only one chance to get it right" deals and I have to live with it like this or can it be corrected and made "proper"?

This is turning out to be way more frustrating than I anticipated and thanks again to all of you for your help.

Have a good day fellas,

Jamie
 
If you told him that you were going to use Lapua cases, he should have set the headspace so that you get crush with them, and cautioned you that other cases might need a slight bump before forming. A friend had a very good .22-250 that was properly chambered with the correct gauges. Because of his gun writing, he had factory Remington and Winchester rounds that he used to fire form and make AI cases. One would fire reliably, and the other (I forget which was which.) would fail go go off some of the time, this in a Panda action. The difference turned out to be the difference in the "headspace". Sometimes things are more complicated than they might seem to be at first glance. Your smith may have done everything perfectly "by the book" but sometimes we have to do a bit more. If you want to, section one of the cases to look for any thinning near the head. Sometimes we need to do the expensive thing, rather than what is the most economical and chalk the cost up to education. They may be all right, because the protruding primers are a positive indication that the cases did not stretch back to the bolt face when they were fired. With the false shoulder approach the stretch should be minimized. When you fire them, have lots of neck tension, and seat bullets well into the lands. Those will not work by themselves as well as a false shoulder, but they will contribute to holding the case back against the bolt face.
 
OK, one thing I feel compelled to ad..... While I've got A TON of opinions on this pertickler subject I feel It would be remiss not to mention this.

It is my strong opinion that you get ONE CHANCE to blow your brass out correctly. And that once blown out you cannot fix the result.

Brass work-hardens when it's folded/spindled/mutilated

al
 
I am gonna toss all that brass just to be on the safe side. I don't want the thought wandering around in my head that that brass thinned out near the web and it is worst case, unsafe or just end up with case head separation at a critical moment and all the PITA that goes with it.

The 'one chance to get it right" that I was talking about was in reference to my barrel. I am trying to figure out if the barrel can be set back or fixed somehow to gain the correct crush fit that it should have....



Jamie
 
jaybic said:
I am gonna toss all that brass just to be on the safe side. I don't want the thought wandering around in my head that that brass thinned out near the web and it is worst case, unsafe or just end up with case head separation at a critical moment and all the PITA that goes with it.

The 'one chance to get it right" that I was talking about was in reference to my barrel. I am trying to figure out if the barrel can be set back or fixed somehow to gain the correct crush fit that it should have....



Jamie
Click to expand...

I understood you Jamie.... my reference wasn't tied to yours, it was simply my thoughts.

I don't think you should toss the brass, you should just mark it, bag it and set it aside with an explanation/date. IMO you can check for incipient casehead separation once you've a full understanding of the process and then you'll be able to shoot these cases against properly formed cases, baseline, etc. It's still all good fun :)

I'm serious about making cases from something else being easier and less heartache than asking for a fix...... the next major argument comes in at "well if you wanted it SHORT-CHAMBERED you should have been more specific!" And the fix will definitely cost the gunsmith more than the original work. Especially since you did find some brass that fits....

al
 
alinwa said:
"Normal" in the sense that it's common but absolutely NOT RIGHT!.....Your headspace is too long..... waaay too long if you're getting popups of 19thou. While your gunsmith may well talk the talk, he DID NOT walk the walk.

"We were going for a crush fit"

????

Who's WE? He got a mouse in his pocket? Trying to include YOU in the thing???

Nope, HE got the chamber a mile off.

Period.

I've had a dozen .243AI chambers from several different gunsmiths and 5 different reamers and most of them were horribly off. I've never personally had one 19 thou out though! That's HUGE.

Here's what I would most likely do.....

I'm not suggesting YOU do this but this is what I would do. (have done, I still have 3 .243AI barrels) I'd either neck up for a false shoulder or make my cases out of 308 Palma brass and neck them to tight crush-fit and use another gunsmith in future. I won't argue with people who include "we" in discussion of problems, unless I was somehow involved in the work.

Life is short

Keep a close eye on your gapspace, it's the place where the carbon ring builds and you've a monster gapspace going there.

al

Ohhh, and let me go on record here as stating that IMO greasing your cases to try make them slide is a STUPID fix for a problem that shouldn't exist.
Click to expand...
d


And thank you for the vote of support!!! I am the guy that did his chamber. It is done with .004" less headspace (tighter) than the 257 Roberts. We have determined that the problem lies with the brass he is using! He does not get primer back out when he uses new W-W brass but he does with Lapua brass. I have already advised him to neck his cases up and then size down to the false shoulder.

So, stick your comments up your ass until you know what the hell the problem really is!
 
It sounds like I have resolution in regards to this issue. I am going to drop the rifle and some brand new Lapua cases and the barrel is gonna be set back one turn and rechambered to get a correct crush on them. I little extra gas money and a few hours drive time to have the piece of mind that I don't have any issues is MORE than worth it......

Feel free to chime in if I am missing anything so I don't screw this up a second time.....

Thanks fellas and have a great day!

Jamie
 
I think the words "off at the gunsmith" are missing from the first line of the above post....
 
hmmmm, and here I thought you were going to bang the butt on the ground and get 'er to slip one t'read.....
 
Close Al, I good sharp rap on the muzzle with a large maul should do it.....either that or I am gonna park my car on it and give'er a good spin with a pipe wrench and leverage bar....I think that will git'er dun....

Jamie
 
Using factory new brass to headspace a barrel may make for a short chamber. Standard 243 AI dies may not size the brass enough?? Ok if you getting custom dies to match. Many Savage owners screw the barrel in to headspace on new factory brass and have this problem.
 
so instead of being to long, it would end up too short? how do I prevent this from happening?

Jamie
 
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