Straight- I have a 243 Ultra and have been down the same path as you. I say that a 243 is very good on deer with a bullet from 85 to 100 gr. If you follow the minimum 2000 fps/1000 ft-lb rule of thumb, some of these 243 loads maintain these figures out to 350 or 400 yards. However, here is the problem. In the H&R 243 Ultra (heavy barrel), many owners have not been able to stabilize the standard 100 gr deer loads, as infact you have read. A few have, but many cannot. I have a hunch, as do many others here and on the old NEF site, that the Ultra heavy barrel was meant for varmit shooters and thus lighter bullets and thus possibly a twist closer to 1:12 than the advertised 1:10 twist on NEF 243 barrels. Why can't the company verify this or prove wrong? I don't know. I have tried to measure my twist rate on the Ultra with no such luck. I just can't get an accurate enough turn. Well, on to the solution for you. If you want to use your 243 for mostly deer, possibly the standard handi with standard size barrel would be best for you as most owners of this model have reported good luck with 100 gr. cartridges. Yes, I know this is not the Ultra and does not have the Ultra stock, but you can buy an Ultra stock from NEF and they are all interchangable. This setup may also prove to shoot varmit size bullets well also. Second option is to purchase the 243 Ultra and see whether that particular gun will shoot the 95/100 gr. deer loads. If not, try the 85 gr. Sierra BTHP as these are a classic 243 deer getter with some folks. This bullet does come loaded as a Federal Cartridge option. This is where I am at currently, as my upper limit seems to be at 80 or 85 gr. without keyholing. I am very happy with this as I can shoot my 55/58/70 gr. varmit loads as well as the 85 gr. BTHP for deer. Some will not agree with the notion of a 243 for deer, but it just plain works. It has very low recoil, very good trajectory and sufficient energy. It just has a smaller frontal area, so choose a soft point bullet for expansion. DO NOT use a 243 ballistic tip on deer. My own opinion, but the ballistic tips on the 243 are too thin and the velocity is too high. Good Luck and please let us know how it shoots. BuzzKill