Home Forums Reloading Big Game Rifles Hornady 7mm Interlocks - flat based vs boat tail

I have a curiosity question. I know every gun is different, such and such, but do those of you who have loaded the 139 grain flat based and also the boat tails, notice a lot of difference in how they shoot?

As far as charge weight, velocity, accuracy, etc?

Reason being, I've always heard that flat based bullets are "easier" to obtain accuracy up to ~300 yards over their boat tail brothers. I have some boat tail bullets coming(Hornadys get loaded program) and I am not sure if I want to mess with them or leave them unopened and trade for flat based ones.

I'm only looking to use them up too 300 yards so I am not that concerned with the boat tails added efficiency. Just using them for hunting, so if there is minimal difference in how they shoot then I wont be too concerned. I've just not messed with boat tail bullets in any caliber much, much less used them and compared results to flat based ones.

I have used them for many years in a 7 mag. They are incredibly accurate out to my limit of 550 yards. At those ranges, you will notice no difference in performance.

They both shoot equally well in my rifle.

I've only used the BT version and it will shoot 1/2 MOA pretty consistently in my 280. I doubt the flat based would do measurably better from this rifle. I think that FB are more accurate thing came from the BR world where they are measuring groups to the third decimal place and the systems are capable of showing minute differences. No doubt FB are easier to produce than BT so bullet to bullet consistency should be better, and thus overall accuracy. Also, BT bullets drag efficiency really doesn't come into play until you get past 300yds depending on the bullet/speed combo. Crap shoot as to which your barrel will like. I'll say one thing though, the 139 BT kills stuff and expands and stays together very well. I'm sure the FB does as well or better on game.

If you're just interested in getting some ammo loaded up and sighted in for deer killing accuracy I'll bet it don't matter. Got an expanded boat tail around here somewhere that came from Hornady factory 7x57. Son made a quartering to shot on a 120 lbish doe between left shoulder and neck found against the right femur. Hit the bone hard enough to put a flat spot on the bullet. Jacket and lead still intact. Have loaded the BTs for wife's 7mm-08 but never caught one and her Micro Hunter grouped them very well. Don't think I'd go to the trouble of getting rid of the BTs and buying FBs for hunting.

I have several 7mm Mauser chamberings...

the 139 SP/FB has proven a lot more accurate over the 139 grain BT/SP...

could just be my rifles, but I only buy the FB version of the 139 grainer....

same with the 154 SP or RN...

Thanks for the info guys. I know its a really tough question to answer, simply because every gun is different. I just am curious to what extent the difference has been for those who have tried both.

If the average difference is 1/2" or less at a 100 yards then I am not concerned, but if its a lot more than that - and its always the boat tails that shot worse - then I would rather not spend my time finding out if my gun likes them or not. I know it likes the flat based ones that are in the factory rounds.

I don't know a whole lot about the 139 interlocks what I can tell you the 154 Spire point is one awesome shooter in just about every 7mm I've tried it in.
150 Spire Point flat base in a 30 caliber is another Stellar shooter in almost all cases.

It has been said that the boat tail versions jacket will slip away from the core easier but most of those people that found those jacket and lead core pieces found them in dead deer. Accuracy is a minor issue w/both bullets. powdr

I can't push the 154 SST as fast in my 7x57 as I can the flat based bullet.

So I'm sticking with the flat based. It's worked for years.

I imagine the results with the 139 gr would be similar.

Dan

Flat base bullets have always been more accurate for me. Ive had bt bullets shed their jackets on frontal shots on bucks where the shots were pretty close.