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Post by flutedbull204 on Sept 16, 2012 18:24:39 GMT -8
I was using this load data for my break in for my new barrel These are shots 26 - 30 26.5 gr of Benchmark with 120 gr Nosler ballistic tip bullet Will be putting this load to the chrony now that I see these groups. Here is the deal, after the fourth shot, I mention to my brother in law how good it looks, of course the fifth opened it up...still, I think this is close to a keeper, the four shot group came in at 0.46" and the 5 shot group come in at 0.72" Attachments:
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Post by flutedbull204 on Sept 16, 2012 18:26:07 GMT -8
Here is the pic with the 5th shot, go figure I pull off on the last shot, but I see some real potential in this load! Attachments:
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Deleted
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Post by Deleted on Sept 16, 2012 18:38:56 GMT -8
Great shooting!!!!!!!! Glad to see your success with your new barrel. Let us know the speeds when you get your chrono results.
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Post by flutedbull204 on Sept 16, 2012 18:58:41 GMT -8
The only problem with this load, is that I am getting flat primers, the min load data is 24.5 gr and the max is 27.3 gr, I am not sure why I am having flat primers (cci 400) If I decrease my load by 5%, I am at 25.2 gr of powder. and that makes no sense to me. Here is a pic of a loaded and fired round for the dif, I am getting no flange at the top of the primer, but I thought that I would have lower pressure out of this barrel. still some tweaking, but i sure like this accuracy, but do not want to damage me or the rifle. Attachments:
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Post by flutedbull204 on Sept 16, 2012 19:17:46 GMT -8
After close examination of the primers after fired and outside of the case, I see there is still an ever so slight curve/ or bevel at the end of the primer, so it is not completely flat and definitely no mushroom shape at all. Also I see no case swelling or any other indications of excessive pressure!
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Post by biggdawg on Sept 17, 2012 4:22:01 GMT -8
After close examination of the primers after fired and outside of the case, I see there is still an ever so slight curve/ or bevel at the end of the primer, so it is not completely flat and definitely no mushroom shape at all. Also I see no case swelling or any other indications of excessive pressure! cci 400 primers have soft cups and will show flat before the 450's, rem 7 1/2's, or any of the br primers. When i had my grendel i used 450's and rem 7 1/2 -- i had lower es and sd with these two primers and i didn't get scared as easy when i looked at the primers. i was using the 400'S in 223 and they would be flat with known mid loads i switch to the 7 1/2's then and no longer use the 400's for that reason. |
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Deleted
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Post by Deleted on Sept 17, 2012 7:21:48 GMT -8
After close examination of the primers after fired and outside of the case, I see there is still an ever so slight curve/ or bevel at the end of the primer, so it is not completely flat and definitely no mushroom shape at all. Also I see no case swelling or any other indications of excessive pressure! cci 400 primers have soft cups and will show flat before the 450's, rem 7 1/2's, or any of the br primers. When i had my grendel i used 450's and rem 7 1/2 -- i had lower es and sd with these two primers and i didn't get scared as easy when i looked at the primers. i was using the 400'S in 223 and they would be flat with known mid loads i switch to the 7 1/2's then and no longer use the 400's for that reason. CCI 400 primers aren't necessarily softer but they do have a thinner cup. This will show pressure that may look to be excessive. On the other hand, using a thick cupped primer can give you case head expansion before the primer starts to flatten out. www.jamescalhoon.com/primers_and_pressure.phpThe primer is NOT the tell all end all sign of pressure. Measuring brass is a better bet. Also look for marks where the case head has started to flow. If you are getting ejector marks or you can see where the bottom of the extractor claw sits in the bolt you need to back off. The Grendel case is a little bit different. It should only operate at 52,000 PSI or less. Because of the size of the case head, the bolt thrust becomes excessive. This does not limit the Grendel in terms of ballistics, but slower burning powders will give better results and still stay within the pressure rating. |
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Post by flutedbull204 on Sept 17, 2012 14:08:29 GMT -8
I have measured fired brass to the virgin brass, and I see no indications of pressure, and def no signs of the case head flowing around the extractor. Even the Max load for benchmark powder is only at 50,200 psi.....by my best guess, with this load I should be around 46k - 47k psi. well within the limits of the platform.
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Post by flutedbull204 on Oct 8, 2012 13:12:25 GMT -8
Here are the chrony results for 26.5 grains of Benchmark it is a consistent 2440 fps with a plus and minus of about 6 fps per shot.
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dr69er
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Post by dr69er on Oct 11, 2012 21:06:04 GMT -8
Here are the chrony results for 26.5 grains of Benchmark it is a consistent 2440 fps with a plus and minus of about 6 fps per shot. What is your barrel length ? |
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Post by flutedbull204 on Oct 12, 2012 2:41:19 GMT -8
24" bull profile with a 3" directional muzzle brake.
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Post by Tooreal on Nov 22, 2012 23:20:20 GMT -8
I have a 18" 264 LBC AR and a 20" and a 24" Grendel that I have loaded for quite a bit and worked up some really good loads and I only used CCI 450 small magnum rifle primers. I started loading for 2 of these rifles when the Load Data was pretty scarce, but that's what was recommended for all of the powders suggested for the Grendel back then and it was really limited. if I'm not mistaken it was to guarantee the ignition of all the powder in the case because it held so much. I was loading with Hodgedon BL(C2) and that may be a slow burning powder? I never had any problems with primers flattening out.
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aftcg
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Post by aftcg on Nov 25, 2012 18:08:03 GMT -8
Magnum primers? Where are you finding data that specs that out?
That is an excellent group for your first time out with a new barrel. I'm looking forward to seeing if it repeats.
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Post by rezwillie on Dec 3, 2012 15:05:03 GMT -8
great info
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dr69er
Senior Member
Protect the US Consitution & the American Way.
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Post by dr69er on Dec 3, 2012 17:41:31 GMT -8
I noticed that the CCI 400 primers showed more deviation
in velocity and premature signs of high pressure (flattened
primers) in some of our 6.5mm PCC rounds from the BHW
barrels...
I had known that certain primer cups had variations
in wall thickness, and thus was giving us signs of pressure.
When we switched to the CCI 450 primers the velocities
became more stable and the primer flattening stopped.
The small rifle magnum primers seem to work well with
the ball powders in the slower burn rate ranges...at least
with the 6.5mm PCC case, based on our testing anyway.
The faster burning extruded powders generally were more
sensitive to the magnum primers and were less stable in
velocity/pressure as you approached maximum loads...
This will likely hold true for the Grendel/LBC case/round.
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