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Post by Cwi555 on Jul 28, 2012 21:23:40 GMT -7
Burn rates are affected by temperature. Think of it like this...does hot gasoline vapor produce a higher fire ball than chilled gasoline?...the answer is yes. Hot vapors expand more rapidly due to increased surface area and oxygen concentration...where as chilled vapors are the opposite. I am very fortunate that in my area the ambient temps are very seldom below freezing and when so, for only brief (3-4 days) periods of time....where I do fall victim to temps is high temps...summers get in the triple digits thus increasing the ambient bore temp and ammo temp in my firearms. tell ya what...take an accurate rifle....from a hot truck/car into an indoor climate controlled range....fire the first ten rounds from ammo that was stored in said truck/car and then fire 10 rounds from ammo that was stored in the indoor climate controlled range and see the difference yourself. Preaching to the choir my friend. I disqualified myself as I've never performed a study to qualify actual values in the difference. I've experienced the difference empirically, but most prefer something silly like the 'box of truth' before they will believe it, which I consider the box of something else. |
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Post by swamprat1 on Jul 29, 2012 20:41:24 GMT -7
Ok so here's what the SF sniper manual(2003) says about temps and bullet velocity:
An increase of 20* F will increase the muzzle velocity by approximately 50 fps. The greatest effect of temp. is on the density of the air. As the temp. rises, the air density is lowered. Since there is less resistance, velocity decreases at a slower rate and the impact rises. This increase is in relation to the temperature in which the rifle was zeroed. How high it rises is best determined by past firing recorded in the data book. The general ruleis that a 20* increase will raise the impact by 1 minute from 100 to 500 meters, 15* will affect by 1 MOA from 600-900m, and 10 degrees over 900m will affect the strike by 1 MOA.
FM 3-05.222
p. 3-65
There is also some stuff on barometric pressures and other environmental effects.
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Post by Sctr22 on Jul 29, 2012 21:48:55 GMT -7
OK, I got one. Glock recommends against using lead bullets in their guns due to the polygonal barrel. Is this really a large concern? I mean I tend to clean my guns after every outing. Is shooting lead out of a polygonal barrel that bad or different than a normal barrel? Is hard cast the same?
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Post by Cwi555 on Jul 30, 2012 2:40:01 GMT -7
OK, I got one. Glock recommends against using lead bullets in their guns due to the polygonal barrel. Is this really a large concern? I mean I tend to clean my guns after every outing. Is shooting lead out of a polygonal barrel that bad or different than a normal barrel? Is hard cast the same? It is a large concern. The button cut rifling tends to blow more of the lead out, but the polygonal forged rifling of a Glock does not. This equates to overpressure with build up. In short, it's strength is also it's weakness. That does not mean you can't shoot them with lead, but you do need to clean more often than you would a similar rifling. I don't shoot lead out of my glocks as a rule of thumb. |
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Post by mud on Jul 30, 2012 5:46:20 GMT -7
Assuming by lead you mean un-jacketed?
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Post by Sctr22 on Jul 30, 2012 7:54:23 GMT -7
Assuming by lead you mean un-jacketed? Yep unjacket, LRN... |
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Post by Sctr22 on Jul 30, 2012 7:59:46 GMT -7
OK, I got one. Glock recommends against using lead bullets in their guns due to the polygonal barrel. Is this really a large concern? I mean I tend to clean my guns after every outing. Is shooting lead out of a polygonal barrel that bad or different than a normal barrel? Is hard cast the same? It is a large concern. The button cut rifling tends to blow more of the lead out, but the polygonal forged rifling of a Glock does not. This equates to overpressure with build up. In short, it's strength is also it's weakness. That does not mean you can't shoot them with lead, but you do need to clean more often than you would a similar rifling. I don't shoot lead out of my glocks as a rule of thumb. Honestly I think the only handguns I've shot LRNs out of are revolvers. But I was thinking about a scenario where you might have to cast your own to reload. Guess nothing is perfect is it? Perhaps buying another barrel such as a Lone Wolf to throw in a kit to use with lead would be a better solution. Just to clarify, I would assume this is inherent to all polygonal rifling, correct? Not just Glocks. Take...Black Hole Weaponry AR Barrels...same deal right? |
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Post by Cwi555 on Jul 30, 2012 8:49:42 GMT -7
It is a large concern. The button cut rifling tends to blow more of the lead out, but the polygonal forged rifling of a Glock does not. This equates to overpressure with build up. In short, it's strength is also it's weakness. That does not mean you can't shoot them with lead, but you do need to clean more often than you would a similar rifling. I don't shoot lead out of my glocks as a rule of thumb. Honestly I think the only handguns I've shot LRNs out of are revolvers. But I was thinking about a scenario where you might have to cast your own to reload. Guess nothing is perfect is it? Perhaps buying another barrel such as a Lone Wolf to throw in a kit to use with lead would be a better solution. Just to clarify, I would assume this is inherent to all polygonal rifling, correct? Not just Glocks. Take...Black Hole Weaponry AR Barrels...same deal right? Yes it is inherent to polygonal rifling. That rifling is very accurate and with jacketed bullets, less prone to overpressuring concerns. I keep spare barrels with standard rifling for the glocks. Little to no fitting is required usually, and they interchange readily. Regarding a BHW barrel, I've own several of them and consider them to be an excellent deal for the money (though more people are catching on which is beginning to show in their pricing and availability). I would not shoot lead 22 caliber bullets out of any AR. That lead can foul up your action in a hurry. |
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Post by Sctr22 on Jul 30, 2012 9:59:00 GMT -7
I would not shoot lead 22 caliber bullets out of any AR. That lead can foul up your action in a hurry. That's good to know, I have thought about getting a conversion to 22lr for my AR. Perhaps I'll just build a new dedicated 22 upper. |
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Post by alex on Jul 30, 2012 16:46:12 GMT -7
I would not shoot lead 22 caliber bullets out of any AR. That lead can foul up your action in a hurry. That's good to know, I have thought about getting a conversion to 22lr for my AR. Perhaps I'll just build a new dedicated 22 upper. I have a CMMG 22 LR conversion for my AR but I only shoot plated bullets through it...Same goes for the Glock. I reload the .223 and the .40 and in the .40 I only use a jacketed bullet or a plated bullet. |
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Post by Cwi555 on Jul 30, 2012 18:26:11 GMT -7
That's good to know, I have thought about getting a conversion to 22lr for my AR. Perhaps I'll just build a new dedicated 22 upper. I have a CMMG 22 LR conversion for my AR but I only shoot plated bullets through it...Same goes for the Glock. I reload the .223 and the .40 and in the .40 I only use a jacketed bullet or a plated bullet. Either plated or jacketed should prevent any real concerns. |
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Post by alex on Jul 31, 2012 16:32:37 GMT -7
I have two buddies who reload with me and we've now put about 1500 copper plated 165grain X-treme bullets through 3 different Glock 22's (one Gen 3 and two Gen 4's) with no problems and of the ones collected after range time all still had their plating intact.
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Post by mud on Aug 3, 2012 7:28:55 GMT -7
CWI how about the myth that commander frames are week and fail after about ten thousand rounds?
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Post by Cwi555 on Aug 3, 2012 7:56:18 GMT -7
There is some truth to that. Not specifically related to the number of rounds fired, but depending on the specific model of commander, there were some weak models produced. Post WWII the military put out a req for a lighter service model. Colts entry was in 9mm with a lightweight aluminum alloy frame. That was the lightweight commander. In 1970 colt brought out the Combat commander in a steel frame which did not have the same weaknesses the LW commander has. The other model that had the same issues with frame weakness was the CCO (concealed carry officers) for the same reason as the original LW commander. Neither model should ever shoot +P. Fatigue cracking of the frame is a concern with both, but using standard ball, there shouldn't be much of a problem. If I had one, I wouldn't shoot it anymore but not for any concern of weakness, but for the value of collectors item. CWI how about the myth that commander frames are week and fail after about ten thousand rounds? |
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Post by mud on Aug 3, 2012 8:07:18 GMT -7
My Recon is commander frame with officer acp upper. I believe it is circa 1991. Exact numbers are hard to find but most sources say under 500 produced.
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