.308, win brass, leaky primers

[Heavies]

Hello all,

I have just started to use Winchester brass, new cases, and I am fire forming the lot to my chamber. I did usual prep, uniformed primer pockets to depth, etc. I had noticed the some of the pieces had very tight primer pockets when trying to seat the primers (PMC LR). I would say excessive force was necessary to seat the primers below flush. It seems that these cases, when fired, caused the pressure to leak out from the primer pocket. I do not believe this load to be a very hot charge, and it is my basic load I have used many times before in Lapua and other brand .308 brass. There has been no signs of excess pressures, ejector flow, tight bolt, primers not too flattened, etc.

Has anyone had similar experiences, and what did you do to remedy the situation?
Do you think that the primer had not been seated completely causing a gas leak?

Thank you for any advice, opinion, or theory.

 

[jonbearman]

I would try a different primer and back that load off alittle as its looking a touch warm. What exact load is it and what bullet and do you seat the bullet touching or are you jumping the bullet.Your primers are really flat.Mic the case ahead of the extraction groove and see if it exceeds the book specs for that measurement.

 

[Keith Glasscock]

While some of the primers show rounded edges, others are mashed flatter than... well, you get the idea.

How much headspace do you have with the new brass? Were the bullets jumped or jammed? Is it a good, warm-to-hot charge or a bit of a low pressure one?

I've seen recent lots of 308 brass that were extremely short for headspace, and the bullets had to be jammed to prevent backing the primers out and stretching the snot out of the case.

I think that might be what is happening here.

Take a really serious look into the cases for a stretch ring - if you have any significant stretch, I'd bet that excessive headspace (in this case the difference between the brass and chamber, not the actual chamber dimension) would be the prime suspect.

 

[Heavies]

Thank you for the input.
The chamber is a Palma 95 match chamber, bullets where jumped 20 thou, load was 44 grains XBR under a 168 Nosler. Load might be slightly warm. I had never had any problems with this load showing pressure previous with heavier wall brass.

Chamber is not suspect. I have about 700 rounds down the tube and no problems with Lapua and old Palma headstamped brass.

I will inspect the new brass dimensions and report back.

How about the primer seating problems I was having? Might I have damaged the cup pressing them in? Perhaps get a crimp remover and ream the diameter to the correct dimension?

 

[CJ6]

You said usual brass prep ,but you still had TIGHT pockets ? Did you uniform the pockets ? check neck thickness ? length ?

 

[243winxb]

Reduce the powder charge. A check of the Hodgdon web site shows your over maximum. I know, different bullets, but check all loads for that powder using different weight/make bullets. Different Component = Different Pressure. When you change a component, work up the load again. If the primers seat easer the next loading, the web has expanded from over pressure.

 

[243winxb]

Hodgdon Data

Cartridge Information
Case: Winchester Barrel Length: 24"
Twist: 1:12" Trim Length: 2.005"
Primer: Federal 210M

308 Winchester
Cartridge Load Data Starting Loads

--------------------------------------------------------------------------------
Maximum Loads

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

Bullet Weight (Gr.) Powder Bullet Diam. C.O.L. Grs. Vel. (ft/s) Pressure Grs. Vel. (ft/s) Pressure
110 GR. BAR TSX FB IMR 8208 XBR .308" 2.690" 45.5 2975 37,700 PSI 50.0C 3266 50,000 PSI
125 GR. SFIRE IMR 8208 XBR .308" 2.700" 42.0 2830 41,200 PSI 46.5C 3110 54,100 PSI
125 GR. SIE SP IMR 8208 XBR .308" 2.700" 46.0 3000 50,200 PSI 49.2C 3174 60,100 PSI
130 GR. SPR HP IMR 8208 XBR .308" 2.615" 43.0 2834 46,900 PSI 48.0C 3110 62,100 PSI
150 GR. NOS BT IMR 8208 XBR .308" 2.800" 40.0 2604 45,500 PSI 44.5C 2870 60,800 PSI
150 GR. NOS E-TIP IMR 8208 XBR .308" 2.800" 40.8 2659 45,900 PSI 44.3 2889 60,000 PSI
155 GR. SIE HPBT IMR 8208 XBR .308" 2.775" 41.0 2619 47,300 PSI 45.3 2854 60,900 PSI
165 GR. HDY SP IMR 8208 XBR .308" 2.750" 38.5 2491 49,100 PSI 42.8 2691 60,200 PSI
168 GR. BAR TTSX BT IMR 8208 XBR .308" 2.800" 39.0 2505 46,500 PSI 43.0C 2724 60,700 PSI
168 GR. SIE HPBT IMR 8208 XBR .308" 2.800" 39.0 2493 49,000 PSI 43.3 2707 61,500 PSI
175 GR. SIE HPBT IMR 8208 XBR .308" 2.800" 39.0 2511 52,200 PSI 42.5 2664 61,800 PSI
180 GR. SPR SP IMR 8208 XBR .308" 2.800" 36.0 2340 51,600 PSI 40.0 2497 60,100 PSI
190 GR. HDY BTSP IMR 8208 XBR .308" 2.740" 36.0 2303 51,700 PSI 40.0 2459 59,800 PSI
200 GR. SFT SP IMR 8208 XBR .308" 2.700" 35.5 2250 51,900 PSI 39.5 2400 59,900 PSI


NEVER EXCEED MAXIMUM LOADS

 

[Heavies]

Thank you all for your input.

After the suggestions and re-evaluation of the my data, i have come to the conclusion that i have made many mistakes and made a few assumptions that has lead to the issues i have been seeing.

1. New Winchester brass out of the bag has LESS volume and a lot more neck tension than that of the fire formed brass that i had been using to work up to the load that i use. Therefore the load IS over the limit for this combo. The new brass is approximately .004" shorter headspace than my chamber dimension.
2. When testing to see if the new brass and bullet could handle the load, my initial work up to the load mentioned was inadequate.
3. i became complacent in the load development because of the great accuracy i had achieved in such few rounds fired.
4. Seating depth i used, when encountering the problem, was less than that of what i had used during pressure test i had conducted a week earlier. i believe my notes where in error and i had the seating die set incorrectly to a deeper seating depth.
5. In my rush to get these brass fireformed, for an upcoming match, shortcuts where taken and errors where made.

Conclusion,
i am at fault for the issues that i am having.
Ignoring the signs of trouble in lieu of finding out exactly what was going on to save time led me to the mistakes made.

i will start over and work up properly this time around.




Notice all my "i"s are in the lowercase. i need to humble myself somewhat, thinking i know what i am doing, i became too confident and made a lot of "newbie" errors.

Your input and suggestions are greatly appreciated; these has helped me to see my errors though new eyes, and correct my mindset.
Thank you.

 

[243winxb]

Heavies, we can only give you suggestions, some may be correct, some not. The problem may have something to do with the primer pocket or primers?? Don't assume its your fault till you do more testing.