Posted: 7/9/2012 3:53:20 PM EDT
I have been reloading for a couple years now but mainly bulk 55 & 62gr....I bought a few hundred sierra 69gr for longer range...after alot of looking online and in my books i came up with test load of 25gr varget...This is my first time loading varget....i loaded 30 rounds friday before last to test while at creekside that sat and loved it i shot a ten round group at 100yds under 1/2 out of a 14.5 bcm middy my 12yr old built from scratch...so then i put 20 through the 14,5 lmt / 4moa aimpoint i was shooting at tac match this past sat...i shot 20rds 3" with 4moa dot at 100....brass looked good gun felt good. So in the match sat last stage is 200yds and i break out the mag loaded with the sierra first five shots were going ok then the heat came ( any of you there know now i was the guy with the smoking gun ) as the gun started to heat up i lost accuracy and it got so hot the rail burned my fingers...this is a very reliable gun that has been to hell and back and i have gone thru it since and there are no issues with barrel, chamber or gas tube...gun is good ammo is loaded to identical specs as test batch pulled bullet and re weighed powder from saturdays batch..
.any help would be appreciated i want to shoot siera 69 in aug at joes ar sniper match.... And when i say hot i mean it got hottttt |
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Not sure I can help on your load development but I'll offer this.
I was running the match and the CRO, and apologies as I'm not sure which shooter you were, but ALL the guns were hot and many were smoking (literally) at the end of every stage. I personally shot 69 SMK Black Hills at the 200 yd stage w/ no ill effects & I fired 21 rds on that stage ( and now you owe me for publicly announcing that  )
Not sure what that may do to help other than give you a different 69 SMK reference. |
| I was thinking backing off 1/2 gr increments ...i still dont feel like it was weather cause the sat i tested was the day it hit 107 @ creekside and i shot those 20 thru this gun pretty quick that day...but you did help i think im gonna round up some bh sierra due to my minimal time to test loads....thanks and i shot over 21 rds at the steel because i lost all accuracy when she heated up... |
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Quoted:
Have you chrono'ed them my 69gr SMK load is 24.3gr of Varget. OAL matters a great deal depending on the chamber/leade on your barrel as to pressure. as a simple measure, if you haven't noticed any obvious overpressure signs on your extracted cases, I would doubt that the heat you experienced is solely due to the bullet or powder load. if it's 100 degrees in the shade, it doesn't take a lot of rounds to bring the gun up to finger burning temp. and if you fired the gun previously, it probably would take a lot longer to cool down. if you can, take a close-up pic of the case head, and another from the side, of some of your cases and post them here. maybe we can see something you might have missed?.. good luck... |
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25.3 of Varget with the 69 sierra s the go to load for competitors still using it. or 25.0 RE-15. Its not a hot load. I used to load them with 25.0 grains of H4895. 3100fps in a 20 in gun, thats a hot load. Never had the issues your having.
Rate of fire and ambient temp/humidity will get your gun hot. If you get it hot enough to smoke, you really didn't get it as hot as you think you did. Is your rifle free floated? if not, than you will loose accuracy with heat no matter what. ETA a few more things, the lighter profiles will get hot much faster than a heavy profile (M4A1) and the smoke is just oil burning off, and depending on the oil can be 400-600 degrees to get smoke. It's really not an issue. I ran a M249 once with two continuous boxes of 200 rds, sparks flew off the barrel as the rounds went down, the barrel turned white after it cooled and you could see the glowing barrel with the naked eye in the dark. Didn't hurt it. If you get your AR barrel too hot, the gas tube will usually fail first. The accuracy issue with the heat is from the thin profile. The M4 profile or govt heavy barrel profile ( not the new M4A1) are only heavy from the gasblock fwd. still really thin underneath the hand guard. The rails have NO heat shield and will get real hot real fast. Most of the rails the military use, while not free floating do have heat shields. For a reason. We also wear gloves for a reason too. So add more covers, real ones not ladders where you grip it, and wear gloves. Once all te oil burns off it will quit smoking. My match AR's have a 1.0 in diameter under the float tube, which is steel, and they have been run hard enough to make the handguards too hot to touch barehanded. Still shoot 1/2 MOA out to 600. Also a heavy build up on your bore will create more heat from friction. Most of your barrel heat comes from that. It can be enough to melt the lead in te bullet as it travels down the bore. Just some thoughts. Might want to try some 75-77 grain bullets as well. 24.0 of just about anything and they will shoot good. Much better bullet for longer ranges as well. And one last ETA, not trying to poke holes in your skill or anything, but are you sure it was heat from the gun causing misses? Have you ever shot that rifle at that distance not on a bench? Shooting an AR unsupported can be HARD. They are very unforgiving of sighting errors, positional errors, etc... Very unforgiving. I see alot of 1/2 minute rifles have a hard time staying in 19 in black circle at 300 yds prone with a sling.... Just a thought what it can do from a bench vs what you can do with it in your hands are more often than not 2 separate things. Not bustin your balls man just my experiences Seeing alot of people Shoot AR's... Read my signature.... It's absolute truth. |
| I would venture to say that the rate at which your gun heats has virtually nothing to do with how "hot" your ammo is loaded. The two things are mutually exclusive. The sun, and 105 degree temps coupled with multiple rounds had much more to do with it. I will tell you that high temps can increase the pressure of a given load. Different powders are more or less susceptible to this depending on the brand and type. Varget is one of the lease volatile as I understand it. My pet load is a bit less than your charge, but with 75 grainers. |
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24gr of RL-15 or 24.5 of Varget.
2.255" COAL 2775 fps. Both are very accurate out to 400 yards (longest I have tested) and pressures are mild. Shot in .223 Wylde and Noveske chambers. Work up for your rifle as always! Also, 77gr SMK's on top of 24.0gr of TAC works very nice too. |
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Quoted:
...so then i put 20 through the 14,5 lmt / 4moa aimpoint i was shooting at tac match this past sat...i shot 20rds 3" with 4moa dot at 100........... So in the match sat last stage is 200yds and i break out the mag loaded with the sierra first five shots were going ok ...... This was at the tactical rifle match, correct? What position were you shooting in when you tested vs at the match? In theory if you were keeping a 3" group at 100, that would open up to 6" at 200 given the same conditions. How big of a target were you shooting at the match? Quoted:
.................... And one last ETA, not trying to poke holes in your skill or anything, but are you sure it was heat from the gun causing misses? Have you ever shot that rifle at that distance not on a bench? Shooting an AR unsupported can be HARD. They are very unforgiving of sighting errors, positional errors, etc... Very unforgiving. I see alot of 1/2 minute rifles have a hard time staying in 19 in black circle at 300 yds prone with a sling.... Just a thought what it can do from a bench vs what you can do with it in your hands are more often than not 2 separate things. Not bustin your balls man just my experiences Seeing alot of people Shoot AR's... Read my signature.... It's absolute truth. This is my train of thought as well. Again, not discounting the OP's ability, just the simple fact that at a match things can go downhill really quick. The adrenaline pumping under the stress of a timer, last stage on a hot day, less than ideal rest on a barricade, barrel possibly touching the barricade..... lots of variables to consider in additon to the possible hot barrel. |
| I have no doubt that some of the accuracy issue wasthe match factors time stress and so on and have been alot of good points made here. I did test from bench but not off of a rest supported on elbows ( because i knew i wasnt gonna get a bench at match) and i do alot of 100-300 with this gun and others when shooting at home and it just so happens that my range i shoot doubles for barrel racing for my nieces so i actually have a ton of rounds supported from a barrel identical to the match. It may have just been the hot day that heated gun like it did but i have just never seen that kinda heat from a gun other than shooting auto and even then it would have been a little much...i am sure the fact that my finger tips were melting didnt help my accuracy either |