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Posted: 2/28/2016 8:44:09 AM EDT
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I have been trying to work up a load with these bullets in my AR 15 for about a month without success . The specifics are as follows: 1) GS Custom Bullets 50 grain .224 HPBT HV bore rider 2) Lake City Brass 3) CCI 41 primers 4) powders tried RL 7 and VN 120. The last powder I tried was the VN 120 in the range of 22.5 grains to 23.5 grains! My Quick Load program shows all the loads as being high pressure with the last load, 23.5 gr as being extremely hot! The rifle will not extract the rounds! Every time I have to cycle the action by hand! My AR15 is effectively a single shot using this bullet. I will say that the GS bullet is the absolutely the most accurate bullet I have ever fired in my AR and this is the reason for all the effort! The brass shows no signs of pressure problems in the least! I believe that the bullet has such a small bearing surface that I am effectively firing a blank. Velocity using the 23.5 grains of VN 120 is in the 3350 FPS range. Any thoughts or suggestions would be appreciated. |
Welcome to Arfcom and the Reloading Forum. First I would be using Rem 7 1/2 primers in a precision load. I never use CCI 41's in any load, but that's me. Never used VN 120, but Re 7 is a faster burning powder than I would use. Did you do work up loads? That should have told you when the pressures started to get too high. If you just picked a load to try, then working up is the answer. Your rifle is telling you that it won't tolerate your present load, so start over. Maybe you entered something wrong in Quick Load, I don't know. I prefer to use published loads from a reloading manual or powder makers web site. If it were me, I would have tried BLC2, Tac, H-335, or CFE 223. (all ball powders) |
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Hello Dryflash,
Thank you for the input ! The problem as I see it is that the bearing surface of these bullets is so small that it take a really fast powder to generate enough pressure to propel the bullets in a reasonable fashion. According to the manufacturer it only takes 900 psi to fully engrave the rifling onto the bearing surface. I would bet that on .224 bullet there is about .100 inches contact between the Bullet and the rifling. The bullet sort of resembles a Barnes TSX with much smaller bearing rings. If you have the time, check out the GS Custom Bullet web sight and look at the HV bullet to see an example of what I am talking about. Thank you for the time and effort spent in consideration of my question! |
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I answered your question over in trouble shooting, hence your using powder that has too fast a burn rate, and although the rounds might have a working pressure of 55K over all, its the lower residual pressure in the bore once the bullet passes the gas port, the problem instead.
So either use a slower burning powder that will push the spike burn dwell closer to the gas port to increase the residual declining bore pressure at the gas port to get more pressure to the gas system to cycle it correctly, or tune the rifle for the reduced gas pressure to the gas port isntead. |
| Just thought I would jump in if you are still checking this post and say that I am experiencing the same problem working up a load in my 25DTI which I bought some GS custom bullets for. Great speed, but gun wasn't cycling. I too got similar advice on going to a slower burning powder and trying over. |
| Don't let quickload fool you, as GS bullets can be pushed fairly hard because they utilize a drive band system and have reduced surface contact with the rifling. Because of that, GS recommends a faster burning powder than usual. I'm using the 40gr HV with the coating and H4198 and I'm getting an average of 3,900 fps out of my 14.5" barrel. Do a proper work up but use the powders that GS lists on their website. |
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If pressure is high, then the likely culprit is inadequate gas volume.
Need both for function. However, I would think that charge would be sufficient. Try a slower gunpowder and a larger charge weight, if you have Reloder 15 on hand, I would fill the case with 27.0 grains and give it a try. |
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