ok, so I know the factory specs for this load are 2790fps roughly, but Im not sure what barrel length or twist. Probably 20" 1/9 is what my guess as thats what Hornady’s 7th Edition Reloading manual says they tested the load in the book with.
Heres my dilemma, I dont have any extra 75gr Match ammo here to test it with. I need a rough guess on velocity from a 11.5in 1/7 twist barrel. Im guessing right around 2450-2500fps?
Reason I ask is there’s a “Tactical 3-gun” here this weekend, and Im wanting to shoot my 11.5in SBR. Ive shot the 75gr match ammo thru it already, but never over a chrono and at 200yds it keeps a very acceptable group for this kinda competition.
Just lookin for a 2nd, 3rd, 4th or how ever many opinion.
If i’s similar to their .223 TAP round it’s around 2,538 fps in a 16" chrome lined & NATO chambered barrel. I would guestimate 20-25 fps per inch loss per inch of barrel below that.
thanks for the reply. I think Gander Mountain, as much as I dislike that store because of their prices, has some of the 75gr match. I may go up after work today and get a box… to bad its a 45min drive, lol
Also incorrect. The velocity of the Match load and the .223 TAP load are basically the same, excluding lot to lot variations. The .223 TAP load only does 2450 fps from a 14.5" barrel, so an 11.5" barrel isn’t going to come anywhere near that.
I got all my info from the Hornady 7th Edition Reloading Handbook, which is sitting in front of me. Their test gun was a Colt 20" 1/9 twist. Id take a picture but dont have a way of uploading it at the moment.
Also says in that book that for the 75gr to travel 2600+ fps its 21.8gr of AA2495 and thats the highest it goes to, which is interesting as the box the match ammo comes in says on the side 2790fps factory.
it was a little curious to have 2 different numbers. Book says dont go past 2600 some odd fps and the box says 2790. Guess Ill just make the drive up and see if I can find some of the ammo and run a test tonight. I was supposed to have some in tomorrow but ammo2go.com didnt ship my order till yesterday, when it was placed last friday. Guess I shoulda ordered from Natchez, I have 2 days after I order.
I can’t tell if you’re serious or being a smart ass.
If it’s the latter, Molon is well versed on the subject and there’s really no need.
I’d hate to run off a valuable resource, especially when he provides free information.
Moving along… I was under the impression that the OP was referring to the factory 75gr BTHP Match ammunition from Hornady?
If so, I wouldn’t automatically assume that the same barrel from their reloading manual was used on their factory ammunition.
That’s the barrel they used for testing the reloading of their components, not the actual factory ammunition……?
I brought up the factory load and the one from the reloading manual as they have 2 different numbers, didnt know if they tested it with the same barrel or not.
When I tested the factory load with a 20in AR-15 1/9 barrel, I got close to what the “factory box data” was showing, but the reloading manual says 2600fps is the max.
Its all good, I found some of the factory ammo locally, retested it and got the same numbers as before, using my 20in 1/9 National Match AR15 and developed a load to match that(actually I stayed 100fps slower than the factory as at 100yds my slower 75gr load is slightly more accurate/consitant as the factory), plus I shot it thru my 16in BCM 3gun build, and all I can say is it REALLY liked the load I developed.
I just posted the pics from the book and my tests to show Im not making anything up, just in case Molon and shootist thought I might be.
Seriously, a 1/9 twist barrel with a 75gr bullet. That is not adding up to me. 1/9 twist tops out stability around 68/69gr bullets. You want a 1/8 or 1/7 twist to properly stabalize the round.
My thoughts exactly as well. Curious they would use a 1/9. But obviously they did, manual says it, and the pic is there to prove. All my barrels are 1/7, except my national match A2, and I got that before 1/7 was rly on the market big time(2003).
Though the 1/8 and 1/7 twists are the better choice, my Colt 20 inch with 1/9 twist doesn’t seem to mind 75 grain Hornadys. It is the length of the bullet that matters rather than the actual weight. I agree that the cutoff should be 68-69 grain, but it depends on the barrel.
That is just a general rule regard 68/69 grain loads through a 1/9. There are exceptions to every rule but I would not buy any 1/9 barrel expecting to shoot 75 grain loads through it.
FWIW @ 300 yards through my Mk12 build SSA/Mk262/T2 is down 11-12 clicks for me, Hornady Match 75 is down 14, and Hornday Training 75 is down 18. This with .10 MRAD clicks.
Velocity is key for the 1/9’s a 20" barrel will stabilize the 77’s if pushed hard and I had a 16" 1/9 that stabilized them too but only tried em in the summer. I was told they likely wouldn’t in colder climates.
