Over Gassed and Accuracy

[minnesotamulisha]

I ran my can on my AR for the first time this past weekend. I have an adjustable gas block, and started with the port wide open. I slowly closed it down so the rifle would still accurately cycle, but ran out of ammo before I had it dialed in.

I had switched to a different lot of Varget so I was trying different charges to match the accuracy I had as I have experienced great differences when switching from one lot to the next. Accuracy was no where near what I have seen in the past.

Can being over gassed cause accuracy issues?

 

[joshb]

In my humble opinion, yes. More gas causes a more "violent" bolt cycle. I have an M1A that shoots best when I turn off the gas and shoot it .

 

[minnesotamulisha]

Thanks Josh. I loaded up more rounds last night and will hopefully get to the range this week and try it out again. Although, this time I think I will start with the gas port closed and work my way open.

 

[Twitchy]

In my humble opinion, yes. More gas causes a more "violent" bolt cycle. I have an M1A that shoots best when I turn off the gas and shoot it .

I have to agree with this. I have a few ARs with adjustable gas blocks and usually get the most consistent results with the gas block closed/turned off. Depending on the load, somewhere in the range will be very good groups/SD/ES. As I cycle through the range of gas permitted past the block, my results vary a lot.

 

[jonbearman]

One note to think about but Varget is not the end all powder for everything. There are other powders that work quite well and you will get as good or better results.

 

[mac86951]

One note to think about but Varget is not the end all powder for everything. There are other powders that work quite well and you will get as good or better results.

Varget has classically large lot to lot variation. I switched to N140, bug velocity is down a little.

 

[joshb]

Thanks Josh. I loaded up more rounds last night and will hopefully get to the range this week and try it out again. Although, this time I think I will start with the gas port closed and work my way open.

I think if you do it, it will give you a benchmark of accuracy for your gun. I've been cycling my thoughts on this and checked my records. Call it second guessing. I have a Stag 6 Heavy barrel, no adjustments for the gas block. My records say that it shoots best with near max or max loads. Not the case with my M1A. ???? The comments on Varget from Jon and Mac are spot on. I had better luck and better metering with H335 and BL-C2. I guess what it comes down too is try everything you can. Good luck. Josh

 

[243winxb]

http://m.hornady.com/ammunition/superformance-in-gas-operated-firearms This has a tendency to flood the system with a larger volume of gas, at a higher velocity, that tries to open the bolt of the gun too fast. It’s a timing issue. The cartridge case is still swollen from the application of pressure during firing while the gun is simultaneously trying to extract the cartridge case before it has had an opportunity to settle back to its original size, or more simply: the gun is still in the process or firing while it’s trying to extract the cartridge case.

 

[minnesotamulisha]

One note to think about but Varget is not the end all powder for everything. There are other powders that work quite well and you will get as good or better results.

I realize this, but I've had excellent results with Varget and 69 SMKs so I'm just sticking with what has already proven itself.

I have shot the 50 Gr VMAX with IMR 4895 with also exceptional results. I do have access to 500 yards which is why I am staying with the 69 SMK. After my two pounds of Varget is gone, I'm going to look in to another powder, or possibly just purchasing a much larger quantity.

Thanks for all the input everyone.

 

[joshb]

I think I know how you are thinking. I don't like to move off a good load to chase another. I tried BL-C2 and whatever else I could find during the shortage. A lot of guys had posted H335 as their pet load along with Varget. My stash of Varget is now dedicated to my 6brs, and I finally found some 335. The metering is what beats Varget. Same or better accuracy and I can dial in my powder thrower to throw without weighing. There is no jambIng on a stick of powder. I still check every 20th charge but most times it's spot on or just a tenth of a grain off. I can load hundreds in the time it takes me to do 50 with Varget.

 

[minnesotamulisha]

I weigh my charges with an RCBS Chargemaster, so metering isn't very high on the priority list when selecting a powder. I do have a thrower, a trickler and a beam, but for the accuracy I was getting using the Chargemaster, it just wasn't worth it.