Mag Length AR - 68 vs. 75 BTHP

[MMH]

I want to buy a bunch of Hornady BTHP bullets as cheaper alternatives to the ELD-M bullets. Will I be better off w/ the 68 gr. if I want to stay within mag. length or will the 75 gr. seated a little deeper perform OK?

 

[Fast14riot]

I shoot the 75 at mag length just fine. I like that I can shoot one bullet for all stages.

 

[mic2377]

I shoot the 75 BTHP and the only reason I would go to the 68/69 gr class of bullets would be if the twist rate of your barrel isn't fast enough. All of mine are also loaded mag length.

The performance of the 75 great loads is very good.

 

[chkunz]

What is the application?

 

[MMH]

What is the application?

600 yard F-Class & PDog. I understand that F-Class is single load only, but want to develop ONE load for my precision AR and I want to be able to fire that load from a magazine fed gun!

 

[retired]

seems silly to give up precision when shooting in competition...

600 yard F-Class & PDog. I understand that F-Class is single load only, but want to develop ONE load for my precision AR and I want to be able to fire that load from a magazine fed gun!

 

[chkunz]

600 yard F-Class & PDog. I understand that F-Class is single load only, but want to develop ONE load for my precision AR and I want to be able to fire that load from a magazine fed gun!

Either the 75 HTHP or the 77 SMK loaded to magazine length of 2.25 in would fit your requirements of magazine length ammo only if you have a 1 in 8 barrel. It sounds like you already know that you are giving up some performance at 600 yards by restricting yourself to magazine length but you must have your reasons so it is your call. Best wishes, Clyde.

 

[Fast14riot]

Often times, in SR, we use the same powder charge for magazine length 75 as we do for long loaded (2.4ish) 80gr bullets. So, you could have both with one load, just different bullets.

 

[MMH]

Either the 75 HTHP or the 77 SMK loaded to magazine length of 2.25 in would fit your requirements of magazine length ammo only if you have a 1 in 8 barrel. It sounds like you already know that you are giving up some performance at 600 yards by restricting yourself to magazine length but you must have your reasons so it is your call. Best wishes, Clyde.

My barrel is a 1-7 twist, 22", 4 groove Bartlein. Yes I figured that some performance would be lost restricting to mag length for the 75 gr. bullet - some accuracy because of the bullet jump & some velocity due to bullet set back. I guess that the only way I will know is to develop some magazine length loads & compare them to the loads w/ the bullet seated out.

I am less concerned about 'competition' than I am about practical rifle accuracy in field conditions. Plan on long range PDog shooting in Wyoming to better gauge what my long range field accuracy is for mule deer & antelope, and have no intention to single feed. I guess I'll have to give up all of that money that I would have otherwise won winning in 'competition'.

 

[USMCDOC]

seems silly to give up precision when shooting in competition...

Not everything is "F-Class" shooting..

 

[Dusty Stevens]

I have a compass lake chamber in my comp AR. A 75bthp at mag length is perfect. You need to find out what chamber and freebore you have before anybody can tell you anything. A 5.56 nato chamber is a lot different than a precision chamber

 

[Rodney]

Go with the 75 grain. I’ve got Hornady 68 and 75 BTHP and they are the same length. Might as well go with the higher B.C.

 

[MMH]

I have a compass lake chamber in my comp AR. A 75bthp at mag length is perfect. You need to find out what chamber and freebore you have before anybody can tell you anything. A 5.56 nato chamber is a lot different than a precision chamber

Me Too!

 

[MMH]

Go with the 75 grain. I’ve got Hornady 68 and 75 BTHP and they are the same length. Might as well go with the higher B.C.

Thanks - that's kind of what I was hoping to hear.

 

[Dusty Stevens]

The 75bthp seem like they were made for your chamber then- youre in luck!