RFI: 'Duplicating' Hornady TAP, with H322

[PatEgan]

All,
I'm looking for any verified data to more or less replicate the Hornady TAP 75 grain load. I'm not looking for a perfect analog, but something close in terms of (terminally) effective velocity. Here's what I'm using:

Cases: Once-fired mil spec (LC) 5.56 cases
Powder: H322
Primer: Wolf SRM
Bullets: Hornady BTHP 75 grain w/cannelure

I'm looking for a workable load with H322 for 11.5", 14.5" and 16" barrels. I used the search function here, and looked through other threads on this forum going back about the last two years. This is the closest I could find:
https://www.m4carbine.net/showthread...in-Sierra-TMKs

Any verified data for a load that replicates the velocity of 75 grain TAP?
Thanks,
Pat

[TheFalconeer]

Once that f***ing coronavirus confinement will be over, and my office open once again, I will duplicate your load and make some pressure measurements... I am interested by it.

Envoyé de mon LDN-L21 en utilisant Tapatalk

[TomPenguin5145]

Not Hornady 75 but I load 23.3 gn of H322 under a Hornady 68bthp with S&B primer in 5.56 cases. It gets about 2500fps out of 10.5" PSA and 2650fps out of 14.7" Aero. It's not showing signs of pressure yet but I got above the velocity floor I wanted (2400 at the muzzle) so I stopped there.

It operates the carbine gas system in the 10.5 very well and there is little to no muzzle flash.

[PatEgan]

Thanks, Tom. It looks like T2 muzzle velocity is 2,878 which might be close to (or at) a compressed load.

[opngrnd]

I feel like you should use a slower powder. With XBR 8208 & 77gr TMKs I comfortably get 2660 from an 18" AR. From a 24" bolt action it gave 2800 FPS. You may need to try TAC. Hopefully Markm can chime in.

[joedirt199]

I found hornady tap 55 gr vmax load that someone claimed was from a hornady rep. 24.7 benchmark with 55 vmax is what I use. Good luck on your search.

[markm]

We've been working up a 77 TMK over max published load recently. Haven't matched 5.56 77 velocities yet, but it's shooting well.

With these faster, benchrest rooted powders, I try no to get to exact velocity match because I've had blown primers with powder lot changes. I'm just more comfortable with about a 75 fps +/- cushion.

I could check where we left off on our TMK load for Velocity and charge weight if you want.

[Ironman8]

We've been working up a 77 TMK over max published load recently. Haven't matched 5.56 77 velocities yet, but it's shooting well.

With these faster, benchrest rooted powders, I try no to get to exact velocity match because I've had blown primers with powder lot changes. I'm just more comfortable with about a 75 fps +/- cushion.

I could check where we left off on our TMK load for Velocity and charge weight if you want.

Mark, are you loading any of your 77gr over TAC? What have you found to give decent velocity (somewhere close to 5.56) with a good accuracy node? I’ve had some interesting results (hair pulling) trying to find the sweet spot with different primer/grn weight combos.

ETA: To add to the discussion, OP, I’ve used MarkM’s load of 21.6-21.8 gr H322 with Wolf SRM primers in LC cases with 77gr. Nosler CC’s with VERY good results. Usually around .7-.8” groups when I did my part. I would think starting around there would be a good bet.

I’m only moving to TAC because I wanted a little better velocity.

ETA2: If you’re trying to replicate velocity, shoot some Hornady TAP (assuming you have some on hand) through a chrono for a baseline and work your loads up to that baseline.

[markm]

Mark, are you loading any of your 77gr over TAC?

I haven't. I've used TAC to push 80 gr SMK loads. But those are totally different, loaded way over mag length, etc.

[PatEgan]

All,
Thanks for taking the time to share your knowledge. A chronometer is one thing I've never bothered to buy, mostly because I had data indicating rough parameters with proven loads. I can probably borrow one belonging to a buddy.

ETA: To add to the discussion, OP, I’ve used MarkM’s load of 21.6-21.8 gr H322 with Wolf SRM primers in LC cases with 77gr. Nosler CC’s with VERY good results. Usually around .7-.8” groups when I did my part. I would think starting around there would be a good bet.

Excellent, that sounds like a contender. Thanks!

Pat