Quote:
Originally Posted by dogslayer403
Well lil gun is out on my rifle set up the chrono and loaded up some 20g vmax 5 of each at 9.2,9.3,9.4
First two at 9.2 went 3646 and 3657 i was suprised to be almost at book max velocity on that load then shot 3 went 3580 and sure enough blown primer. Chronoed my factory ammo at 3570. The other day i went to 9.5g before it showed pressure signs when i didnt have my chrono now im having blow outs at 9.2g way to unpredictable for me I think I will grab some cfe blk and try to shoot for 3550-3600 fps if that doesnt work out this gun is getting fed factory 20g heck it might anyway shoots darn good with factory
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You have described much the same results as many have reported. There seems to be more to it than temperature instability and maybe how different primers burn may be the answer? Here is a link to a good article about primers that may not answer the question but is good none the less
http://www.shootingtimes.com/ammo/am...motaip_200909/. This link may partly answer the question
http://www.6mmbr.com/PrimerPix.html. Notice how much more flash a Rem 7 1/2 primer has than a CCI BR4 or Federal 205. Lil Gun is a dual base powder with a high nitroglycerine/nitrocellulose content compared to other dual base powders like RL 10 & 7 , Ramshot Tac & Exterminator and CFE 223 & CFE BLK. In fact I believe it begins to deteriorate fairly fast when exposed to air and/or plastic as I have had it get wet in my RCBS Chargemaster and even etch the plastic. This and the lower load density, coupled with cooler burning primers, may actually lead to detonation which would cause pressures high enough to cause enough primer pocket/web expansion to blow primers followed by a drop in pressure propelling the bullet. I think it best to find some CFE BLK as it looks like it will give a higher load density due to a slower burn rate so this problem may be resolved.