Primers Backing Out ???

Craig67

Craig67

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Montreal , QC.
Rifle: Spanish Guardia Civil M1916 small ring Mauser, cal. 7.62 NATO

Load: 38 gr's IMR 4895
WLR primers
150 gr FMJBT seated to the crimp grove and crimped
Range picked brass (Win and RP)

I'm getting primers backing out and I'm not sure why. The best explanation that others have given me is that the powder might be detonating instead of burning.Now I know this is a light load, but I don't want to exceed 45,000cup.

Any ideas ?

Thanks,

Craig
 
Where the pockets loose when you seated them?

go to imrpowder.com and check out the 308 loads. You can try a different powder than the 4895. Also try Federal 210M primers, they are actually recommended over WLR. I ran across an article where they were testing different primers for pressures and Winchesters were the hottest, creating the highest pressures. I will see if I can find it for you.
 
check the manuals I as I do not know this powder and my manuals do not list loads for 7.62NATO :)confused: ). However, backed out primers can be a sign of under-pressure, where the primer does not get re-seatet or so I have read...

there does not seem to be much load data lying around for 7.62x51 on the internet, or at least I have grown tired of searching. I don't load for it so I can't advise you. I would also expect other more experienced handloaders will chime in and give you advice. But unless there are some pressure signs other than the primer, you might be a little bit too much on the light side. Proceed with caution , someone will be around here shortly to fill in the blanks :)
 
go to imrpowder.com and check out the 308 loads.
Click to expand...

is it not adviseable to stay at lower pressures of 7.62NATO on the small-ring FR7 (this is what you have Craig67 yes?) .308 seems to be much higher pressures, maxing at 57,700psi according to my load data for this powder!
 
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Thats what I just read on a google search. Slightly under pressured. I think I have some data on the Nato round, I will PM you.
 
Here is the Data from Hornady manual

Nato 7.62 x 51

155 Grain bullets

IMR4895
Primer WLR
Strarting load 37.6grs
Max Load 43.4

You might try bumping it up to maybe 39 or 40 grs. The test rifle was a M1A, so the pressures should not be that high.

By comparison 308 loads are listed from 37.7 to 46.4
 
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is it not adviseable to stay at lower pressures of 7.62NATO on the small-ring FR7 (this is what you have Craig67 yes?) .308 seems to be much higher pressures, maxing at 57,700psi according to my load data for this powder!
Click to expand...

The rifle is the predecessor to the FR-7 and yes I want to stay below 7.62 NATO pressures. I do not want to exceed 40 gr's of IMR4895 as that would put me over 45,900 cup.

Where the pockets loose when you seated them?
Click to expand...

I don't think so. I'm going to try some other cases to see if I get the same problem.

I don't think I'm getting too much pressure as the recoil is pretty light. Correct me if I'm thinking wrong though.

Thanks for the info mylesrom and Proutfoo, I'm still looking for an explanation though.

Craig
 
Proutfoo said:
is it not adviseable to stay at lower pressures of 7.62NATO on the small-ring FR7 (this is what you have Craig67 yes?) .308 seems to be much higher pressures, maxing at 57,700psi according to my load data for this powder!
Click to expand...


7,62 NATO is specc'd in CUP and the 308 is specced in PSI. They're different scales (think farenheit vs celcius), and to the lawyers that makes the rounds incompatible. In reality, they both run almost exactly the same pressures (the 7.62 burning SLIGHTLY less powder to do so due to thicker brass and lesser capacity)
 
Here is some data from IMR its for the 308 winchester, but the pressures should be close to the same for the nato round with the same amount of powder

150 GR. NOS BT IMR 4895 .308" 2.800" 42.6 2631 42,300 PSI 47.3C 2920 57,700 PSI

--------------------------------------------------------------------------------

155 GR. SIE HPBT IMR 4895 .308" 2.775" 43.5 2664 45,100 PSI 47.5C 2897 58,200 PSI


PLEASE NOTE THESE PRESSURES ARE IN PSI AND NOT CUP
 
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Craig67,
It sounds like your loads are too light, and the shot-start pressure isn't high enough to reseat the primers. It happens all the time with reduced loads. I've should hundrdeds of pounds of light cast bullet loads and have seen this alot. My Nosler manual (Which is on the conservative side) has 40.5 gr of IMR4895 as the starting load with 150s. You're way off the bottom.
Here's something to think about. After these loads are fired, the headspace is increased for the next firing because the shoulder has been set back from the firing -pin strike. That's fine with the mid-range and squib loads, BUT here's the glitch; using those same cases in full power loads can give case head separations on the next shot. You don't even get the normal warning signs of incipent separation like the shiney ring or internal groove because for that firing it does not exist. The NRA did a big write-up on this years ago in an article on light loads. The upshot was to keep those cases segregated, not always the easiest thing to do. There is a reason why there are minimum loads as well as Max.
Dogleg
 
Primers backing out is a shure sign of excessive headspace or short brass(from shoulder datum), if the headspace is still within limits the way to eliminate this is to fireform your cases with the bullet making solid contact against the rifling, proper OAL will have to be established of coarse, once you have your fireformed cases in hand, load them carefully and don't push the shoulder back by full length resizing them do a partial sizing, at this point you can seat the bullet at any OAL you wish without experiencing primers backing out.
bigbull
 
Dogleg and Bigbull,

that's the info I was looking for, Thanks !!!

Ok, this experiment is going to come to an end. I'm going to crush those cases and start with a fresh set of data and cases.

Thanks again,

Craig
 
I'm getting primers backing out and I'm not sure why. The best explanation that others have given me is that the powder might be detonating instead of burning.Now I know this is a light load, but I don't want to exceed 45,000cup.
Click to expand...
NO detonation here! If the powder charge detonates, the barrel bursts into several pieces..........end of story.
Bigbull and Dogleg are in the X-ring.
 
Well - you could consider partially resizing the brass such that it is slightly tight in the chamber - this would eliminate any possible problems associated with lack of fireforming, headspace, etc. And your brass lasts longer...
 
OK - Had the brass been fired in the rifle previous to neck sizing? If not, then you could still be vulnerable to the problems described. Did you find a lot of soot around the neck of the case? (Another indicator that the cases arent fireforming fully...)
 
I had Spanish 1916 small ring whose chamber was stretched beyond belief. I loaded low-pressure rounds as you describe, but later found that it was nearly impossible to resize the spent brass due to the chamber being so out of spec. Likely due to a steady diet of commercial ammo before I owned it. I sold it off for parts. Didn't trust the action after that. Have you checked the headspace? You may wish to try to resize the spent brass. If all is OK and the brass not deformed, then it should be no problem shooting low-pressure rounds. You may wish to try a slower powder like 4064. Won't stop the primers from backing out but will reduce the pressure and wear & tear.
 
OK - Had the brass been fired in the rifle previous to neck sizing?
Click to expand...

It was range picked brass that had been FL resized and then fired in the M1916.

Did you find a lot of soot around the neck of the case?
Click to expand...

Some but not much. No more than brass fired in my Savage 10FLP.

Have you checked the headspace?
Click to expand...

No. I have fired a small amount of 7.62 NATO in this rifle and have never had a problem. I have checked for any sign's of lug set back and have found nothing.

You may wish to try to resize the spent brass
Click to expand...

I resized some military brass I fired in this rifle. It ran through the FL resizer die so I assume the chamber is ok.

Craig
 
Your problem isn't powder, excessive pressure etc. but is what's called headspace. The headspace problem on your gun was probably caused by someone firing loads that generated more pressure then the gun could handle and stretched the action a few thousands. This can be rectified by setting the barrel back a few thousands and that will cure the problem. Take it to a reputable gunsmith and he will tell you what I have just said and will fix it in an hour using the lathe and dial indicator.
 
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