My first pierced primers?? 6.5x47 and the 136 Scenar

[ttfreestyle]

Testing the 136 scenar with varget went great the first 100 NEW lapua brass loads, then full length sized them and hmmm got some pressure signs and a pierced primer with the exact same powder charges, bullet, seating depth and primer. The only difference was a different lot of primers (still cci 450 though) and using a 287 neck bushing to resize them(loaded round measures 289 to 290) . The headspace checks out with go and no go , the overall chamber length for the brass checks out , It is a Criterion barrel with a no turn neck n a Savage action. Redding type S bushing dies were used. Charge weight was varget 36.8 and 37.0, I checked the weight on two different scales and even pulled the bullet on a loaded round to make sure the weight was correct. What am I missing other than its just to hot?? Why did the new brass do fine?? thanks for any replys

 

[stacy]

YOUR BRASS IS NOW FITTED TO YOUR CHAMBER SPEC.BEFORE YOUR BLOWING YOUR BRASS OUT TO FIT CHAMBER THERE NO ROOM TO EXPANNED NOW SO BACK YOUR CHARGE OFF .5 GRAIN AND YOU WANT POP PRIMERS ALREADY BEEN THERE DONE THAT..................

 

[6BRinNZ]

Are the bullets seated into the neck shoulder area?

 

[ttfreestyle]

No, I am 12 thou off the lands and not into the shoulder area . I will back it off to 36.0 and see what happens this weekend. I just didn't understand why it wasn't to hot with new brass and now it is, hadn't thought of it not having room to expand now that it is once fired.

 

[queen_stick]

YOUR BRASS IS NOW FITTED TO YOUR CHAMBER SPEC.BEFORE YOUR BLOWING YOUR BRASS OUT TO FIT CHAMBER THERE NO ROOM TO EXPANNED NOW SO BACK YOUR CHARGE OFF .5 GRAIN AND YOU WANT POP PRIMERS ALREADY BEEN THERE DONE THAT..................

first I've heard that... interesting.

the chamber dimensions are the same with the new, and the one fired cases, so how does that make sense? If it's too hot of a load, the new brass should have showed signs of it as well, right?

 

[navyrad8r]

TT,
when I first started working up my .260 I has primer problems at very mild-mid conservative charges at mag length. sent the bolt to gre-tan and got firing pin bushed. problems gone... I don't think its the primers but maybe wolf or other military type might be a little harder cup? those 450s are great primers though!
cheers,
Doc

 

[jonbearman]

Seeing as I own a bunch of savage's I am gonna back up Doc. Some bolt heads are not bad and others have way to much slop to be used with warm loads.I would think about a new PTG bolthead,they are right on and you wont have near the problems after you change it out.I would also start over when you get the new bolthaed,reset the headspace,start lower and work up.

 

[6BRinNZ]

I am curious about this one.

CCI 450 - IME they can take a lot of pressure before piercing.

I would have expected that the first fire would have at least showed a lot of primer flow...so what other pressure symptoms did you see? I agree with the small firing pin approach but not if there are other relevant symptoms.

I take it temperatures weren't materially different?

Do you have chrony numbers to support the "hot load" theory?

I'm not convinced of the new case theory and wonder if the new batch of primers (one of the few variables changed) are running hotter for the load.

 

[FilippoMo]

There was an article published on precision shooting concerning primers.There were up to 5000 psi difference in pressure while velocity was only 40 fps lower.So the cronograph is not a useful instrument in this matter.
Filippo

 

[stubbicatt]

I suspect that bushing the firing pin will be the correction for the problem you describe, but backing off on powder charge may also address this issue for the short run.

 

[ttfreestyle]

The 36.8 charge had a five shot average of 2870 fps with the 136 Scenar which was higher than I expected(28 inch barrel), it pierced the fifth primer so I stopped. It did show some cratering at that load but bolt lift is not hard. It seems I am just to hot with this load. I can run 38.0 grains of varget with the 130 berger 10 thou in the lands so I thought I was at a low enough place to start with the 136 scenar. I was just confused as to why it ran the first 100 NEW brass without problems and I even went up as far as 37.5 (only 5 rounds ) the first testing. The weather was within 10 degrees each day as well.

 

[dooley]

Had this problem with my 260, I had the firing pin hole bushed smaller also the firing pin made smaller, and problem disapeared, it is now time to have the same treatment done to my 6.5x47 rifle after cratering and piercing a few primers recently running 2.000 PSI under max,according to according to Quickload. dooley UK

 

[ttfreestyle]

Looks like I need to send my bolt off , and back powder charge down. Thanks for all the replys

 

[navyrad8r]

TT,
you wont regret doing it. If you have other bolts or some buddies thinking about it, do them all together. when I did mine we saved a few bucks each. the turn around time is pretty fast form Gre-tan. please post your outcome after getting it back and the decreased powder charge.
cheers,
Doc

 

[DJ111]

Did you full length size them the first time you fired them or did you just load and shoot them out of the box?

When you full length sized them you probably pushed the shoulder back too far, and also back farther than they originally came from Lapua.

This will in turn create too much head space and cause primers to pierce.

It only takes .005-.006 head space to start running into issues.

I shoot for bumping the shoulder back .002-.003, some like tighter fitting cases and only bump .0005-.0015. I like my bolt to open easy so I bump a little extra.

Hope this helps.

 

[deadwooddick]

It only takes .005-.006 head space to start running into issues.

I shoot for bumping the shoulder back .002-.003, some like tighter fitting cases and only bump .0005-.0015. I like my bolt to open easy so I bump a little extra.

Hope this helps.

When bumping… I get a majority at 0.002" but also get some that are bumped 0.005".

Loads are in the 2890 to 2945 fps (105 VDL in 6BR and 6x47 SwM) yet I haven'tseen issues w/primer cup flow or piercing… no matter that some are "right on" and some "overbumped."

I guess I'm just lucky.

 

[DJ111]

(When bumping… I get a majority at 0.002" but also get some that are bumped 0.005".

Loads are in the 2890 to 2945 fps (105 VDL in 6BR and 6x47 SwM) yet I haven'tseen issues w/primer cup flow or piercing… no matter that some are "right on" and some "overbumped."

I guess I'm just lucky.)

I said it could start to cause issues....if you take a 6 BRX case and have .006-.007 shoulder bump or head space and do not have the bullet jammed with a full load it will sometimes pierce a primer where if you would not have had the extra head space it would not even show any pressure. This is in a custom action with tight firing pin fit also.

Just my experience, take it or leave it just giving ideas before he bushes the bolt face and could have the same issue when he gets it back.

 

[queen_stick]

(When bumping… I get a majority at 0.002" but also get some that are bumped 0.005".

Loads are in the 2890 to 2945 fps (105 VDL in 6BR and 6x47 SwM) yet I haven'tseen issues w/primer cup flow or piercing… no matter that some are "right on" and some "overbumped."

I guess I'm just lucky.)

I said it could start to cause issues....if you take a 6 BRX case and have .006-.007 shoulder bump or head space and do not have the bullet jammed with a full load it will sometimes pierce a primer where if you would not have had the extra head space it would not even show any pressure. This is in a custom action with tight firing pin fit also.

Just my experience, take it or leave it just giving ideas before he bushes the bolt face and could have the same issue when he gets it back.

Does a plunger style ejector contribute to this?

 

[TonyR]

The shoulder bump could be inconsistent because the brass is not the same hardness and should be annealed. I have to set my dies different when I resize brass that hasn't been annealed vs brass that has.

 

[ttfreestyle]

I loaded straight out of the box the first time, full length sized after initial firing. I try to bump my 6br no more than .002. I will look into this, thanks