I leave a Taurus 85 Titanium loaded in my glove box. The temp inside gets VERY hot in these Texas summers. Will the factory ammo be affected???

No, there are tons of ammo being stored in very hot places around the world.

Just to be safe I would shoot the stuff every six months, then reload with fresh.

High storage temperatures do bad things to ammunition. In particular, heat is likely to melt lead bullet lubes and cause powder or primer contamination, resulting in squibs or duds.

The constant heating/daytime and cooling/nighttime temperature cycling draws moisture into the cartridge case past primer and bullet weather seals. These are long-term effects, of course, and is well understood and documented by generations of military ammunition storage experience. For the short term, there may not be any noticeable effects, but in the longer term, muzzle velocity and reliability is affected.

It would be an excellent idea to track the "freshness" of your ready-to-use ammunition and replace it regularly.

This business of proper ammunition storage is well understood by the military. It's in ammo storage regulations to take all precautions to avoid prolonged direct sunlight/heat exposure to small arms ammunition, and to avoid using it when so exposed. Lot numbers marked on ammo cans, crates, and such are there for a reason: in case of malfunction, lot numbers provide traceability to previous storage, distribution, and manufacturer.

I was involved in TOW missle and artillery test firing in a previous life, and recall the routine of removing from storage at periodic intervals random samples of ammunition to test and fire. The results were documented and applied to ready-use war munitions.

There was an interesting experience with the Kuwait Army in 1995. They had literally bulldozed trenches out in the desert and buried enormous amounts of munitions before the 1990 Iraq invasion. Two or three years later, the stuff was dug up and issued for training use. As I recall, the several monthly range firing sessions we had each consumed 20,000 rounds of 7.62 x 51mm Pakistani manufactured ammunition fired in M240 machine guns, and there was not a single malfuntion attributed to the ammo. It was stored in horrible conditions (buried), the ammo crates were rotted, the metal cans rusted shut, and the rubber weather seals badly deteriorated. Even though cosmetically bad looking, it was determined that the stuff was safe to fire since the M240 is a gas-operated design, unlike the Pakistani-manufactured copy of the G3 rifles and machine guns which were roller-locked blowback actions.

The ten-year old TOW missiles fared less well. Almost certainly because of the lousy storage conditions, plus they were higher tech than small arms ammo, the fired missles suffered from inaccuracy and malfunctions.

What to be gained from this is that small arms ammunition can be incredibly durable even under poor storage conditions, but the wise user keeps track of how long and under what conditions it was stored.

I had a partial box of Remington .22s, Thunderbolts, spill in the glove box of my old van.

It stayed there for at least four years through summmers and winters with extremes of 100 degrees (a few days) and 20 below (a few more days).

When I dug it out it all fired and was as accurate as Thunderbolts I'd kept in better conditions in the house.

Thanks guys, I should rotate the ammo.

I did have one thing happen to some .17HMR rounds which I kept in a dry box with a cleaning kit and solvent. The solvent leaked and I guess the amonia caused the rims to split on most of the rounds. These were new un-opened plastic boxes of ammo.

Lesson learned there.