[Goose]

Focusing on the big howitzers from the US and others being provided to Ukraine, how long before this equipment begins to make a significant impact on the battlefield?  Will they help a little or be decisive?

Obviously no way to be certain, but Russia has at least 1k weapons directly comparable  to the ones the US sent. They are not all in Ukraine, but it is probable Russia has several times the number of howitzers the US just sent to Ukraine. Russia is using these guns to shell Ukrainian troops and infrastructure (like cities).

The Ukrainians should use their howitzers in a counter-battery role wherever possible. Shelling the Russian troops would pit them in the same game as the Russians, who have more weapons. Counter-battery requires fewer tubes. Unfortunately, it usually requires better crews and leaders than just banging away at cities does. You have to get your target coordinates, translate them to firing parameters, get the guns set up, shoot several rounds quick before your enemy moves. Then, you must move. At least, that is what should happen. Russia has probably got in the habit of not moving after firing because they don't fear counter-battery. Towed howitzers take minutes to limber up to move and require significant manual setup for each distinct fire mission.  New crews can be slow at this and also make mistakes. The "modern" 155 mm self-propelled howitzers have this all computerized. They can stop, fire, and move on very quickly. Both sides in this battle will be using a significant number of towed weapons and older self-propelled weapons, so who knows what will actually happen.

These new weapons can be very useful if they can wreck significant numbers of Russian guns/gunners without getting destroyed themselves. At the very least, making the Russians move periodically will cut down their firing rate, increase the opportunity for errors, and require better logistics (more POL, food, ammunition and spare parts to different places that can change at a moments notice). Of course, Ukraine will have these issues too. So decisive? IMHO, No. But it will give the Ukraine the ability to neutralize/degrade Russian artillery, which is a big deal.

How long before Ukraine can/will use this capability, I have no idea. I do not think it will be real soon unfortunately. Creating an effective artillery battery takes quite a bit of training. Even a maximally compressed course takes a couple of weeks. Then you have to get the entire unit together and practice. The more of this you can do, the better. Under the circumstances, it probably won't be much. That isn't good. If I were a Ukrainian I wouldn't be calling in any fire missions danger close until I knew they could do it. You also don't want to lose a large fraction of your new artillery to accidents or counter-battery (because they are slow).

[Goose]

Focusing on the big howitzers from the US and others being provided to Ukraine, how long before this equipment begins to make a significant impact on the battlefield?  Will they help a little or be decisive?

Obviously no way to be certain, but Russia has at least 1k weapons directly comparable  to the ones the US sent. They are not all in Ukraine, but it is probable Russia has several times the number of howitzers the US just sent to Ukraine. Russia is using these guns to shell Ukrainian troops and infrastructure (like cities).

The Ukrainians should use their howitzers in a counter-battery role wherever possible. Shelling the Russian troops would pit them in the same game as the Russians, who have more weapons. Counter-battery requires fewer tubes. Unfortunately, it usually requires better crews and leaders than just banging away at cities does. You have to get your target coordinates, translate them to firing parameters, get the guns set up, shoot several rounds quick before your enemy moves. Then, you must move. At least, that is what should happen. Russia has probably got in the habit of not moving after firing because they don't fear counter-battery. Towed howitzers take minutes to limber up to move and require significant manual setup for each distinct fire mission.  New crews can be slow at this and also make mistakes. The "modern" 155 mm self-propelled howitzers have this all computerized. They can stop, fire, and move on very quickly. Both sides in this battle will be using a significant number of towed weapons and older self-propelled weapons, so who knows what will actually happen.

These new weapons can be very useful if they can wreck significant numbers of Russian guns/gunners without getting destroyed themselves. At the very least, making the Russians move periodically will cut down their firing rate, increase the opportunity for errors, and require better logistics (more POL, food, ammunition and spare parts to different places that can change at a moments notice). Of course, Ukraine will have these issues too. So decisive? IMHO, No. But it will give the Ukraine the ability to neutralize/degrade Russian artillery, which is a big deal.

How long before Ukraine can/will use this capability, I have no idea. I do not think it will be real soon unfortunately. Creating an effective artillery battery takes quite a bit of training. Even a maximally compressed course takes a couple of weeks. Then you have to get the entire unit together and practice. The more of this you can do, the better. Under the circumstances, it probably won't be much. That isn't good. If I were a Ukrainian I wouldn't be calling in any fire missions danger close until I knew they could do it. You also don't want to lose a large fraction of your new artillery to accidents or counter-battery (because they are slow).