Posts
Load Development for 1k yard supersonic 308 - 168GR TMK - 20 inch barrel
- By Dylan4570
- Reloading Depot
- 24 Replies
Hello,
I thought I would document my journey of developing a supersonic to 1k+ load for my B14 HMR. A key consideration was the limited barrel length of 20". Limiting at least in the context of meeting my goal with some of the lower BC bullets I had on hand. I initially started target shooting about 4 years ago. My first target rifle was a savage 10T-SR with a 24x DBT I barely shot it. I then got a fantastic deal on a B14 HMR in 308. which in the past year I have really enjoyed.
My initial shooting was with a batch of 100x Hornady 178GR BTHP match factory ammo. It was around 1.5 MOA (5 shot groups unless noted otherwise).
I loaded some 168 GR A-max's after that which were accurate at 0.6MOA at 2628 FPS on 43.7GR of Varget. However the commonality between most of the 308 factory ammo and bullets I found was they were not supersonic out to 1k. So I began load development based on the 168gr TMK. I have shot the 77gr TMK before in my 223 bolt gun and was pleasantly surprised. Further to this the BC's were very high.
Rifle: Bergara B14 HMR in 308 20"
Optic: 24x DBT
I was not feeling particularly stable. Below were my initial results.
0.75 MOA is good enough for me. My goal is to hit a 10inch gong at 1k yards. So that gets me in the ballpark. My velocity goal was 2600 and was hoping for near single digit SD's. So both of those goals were met. SD of 7 is great by my standards.
I have started doing larger increments with my initial load development than in the past and it has become a preference. I also do not believe there is much reason to go below 0.2GR increments with the sample size of 5 shot groups. I would expect a 10 shot group minimum to yield repeatable results.
With a ballpark figure of 44.2 GR and COAL of 2.870 feel I have a great starting point. I am beyond fortunate having access to a farm to shoot on 50% of the year when the corn isn't too high, I probably shoot 20 weekends per year, or more. hopefully within a couple weeks I can get out and do this load dev. Below is my next loading table.
I usually am unable to hit the rifling using the standard magazine since I primarily reload 223 and 308 for AR length mags. However in the case of this bullet at 2.887 I am still a long way from the rifling. I like fabricating unnecessary problems for myself, and worrying about things that don't actually matter. so the change in COAL is probably not needed. They will fit in a steel MDT magazine, but not a standard plastic magazine. but that was the primary change this time around. seating the bullets out 0.015 longer.
Within my next update I intend to include; testing results of the second table, a measured distance of jump, And hopefully a final selection on what to load for my 1000 yards goal. Also note I am using nickel plated brass because it makes me feel fancy.
I thought I would document my journey of developing a supersonic to 1k+ load for my B14 HMR. A key consideration was the limited barrel length of 20". Limiting at least in the context of meeting my goal with some of the lower BC bullets I had on hand. I initially started target shooting about 4 years ago. My first target rifle was a savage 10T-SR with a 24x DBT I barely shot it. I then got a fantastic deal on a B14 HMR in 308. which in the past year I have really enjoyed.
My initial shooting was with a batch of 100x Hornady 178GR BTHP match factory ammo. It was around 1.5 MOA (5 shot groups unless noted otherwise).
I loaded some 168 GR A-max's after that which were accurate at 0.6MOA at 2628 FPS on 43.7GR of Varget. However the commonality between most of the 308 factory ammo and bullets I found was they were not supersonic out to 1k. So I began load development based on the 168gr TMK. I have shot the 77gr TMK before in my 223 bolt gun and was pleasantly surprised. Further to this the BC's were very high.
Rifle: Bergara B14 HMR in 308 20"
Optic: 24x DBT
I was not feeling particularly stable. Below were my initial results.
0.75 MOA is good enough for me. My goal is to hit a 10inch gong at 1k yards. So that gets me in the ballpark. My velocity goal was 2600 and was hoping for near single digit SD's. So both of those goals were met. SD of 7 is great by my standards.
I have started doing larger increments with my initial load development than in the past and it has become a preference. I also do not believe there is much reason to go below 0.2GR increments with the sample size of 5 shot groups. I would expect a 10 shot group minimum to yield repeatable results.
With a ballpark figure of 44.2 GR and COAL of 2.870 feel I have a great starting point. I am beyond fortunate having access to a farm to shoot on 50% of the year when the corn isn't too high, I probably shoot 20 weekends per year, or more. hopefully within a couple weeks I can get out and do this load dev. Below is my next loading table.
I usually am unable to hit the rifling using the standard magazine since I primarily reload 223 and 308 for AR length mags. However in the case of this bullet at 2.887 I am still a long way from the rifling. I like fabricating unnecessary problems for myself, and worrying about things that don't actually matter. so the change in COAL is probably not needed. They will fit in a steel MDT magazine, but not a standard plastic magazine. but that was the primary change this time around. seating the bullets out 0.015 longer.
Within my next update I intend to include; testing results of the second table, a measured distance of jump, And hopefully a final selection on what to load for my 1000 yards goal. Also note I am using nickel plated brass because it makes me feel fancy.
Attachments
In CA? Please sign Gavin's and Bass recall/resign petition.
- The Bear Pit
- 12 Replies
Scrape the newscum out of CA.
While you're at it.... one for the fish stinking C Bass.
While you're at it.... one for the fish stinking C Bass.
SOLD WTS-Spuhr 4602. SOLD!!
- By J_D
- Buy - Sell - Trade
- 11 Replies
$375 Shipped. Price is firm.
No trades. Zelle or Paypal F&F only.
No trades. Zelle or Paypal F&F only.
SOLD SOLD. 6.5 Creedmoor w/ Nightforce 5-25 and KRG whiskey-3 chassis
- By gse1015
- Buy - Sell - Trade
- 11 Replies
Attachments
SOLD Impact 737 short action .308 bf RH
- By mpk1996
- Buy - Sell - Trade
- 2 Replies
Impact 737 RH short action
Very nice condition
308 bf. RH
$1325 shipped
No trades
Very nice condition
308 bf. RH
$1325 shipped
No trades
SOLD ** price reduced** WTS- leupold BX-5 Santiam HD 15x56
- By Trippm
- Buy - Sell - Trade
- 20 Replies
Attachments
Precision Rifle Gear 3D Printing a Better Ammo Box
- By Stangs55
- The Armory
- 21 Replies
Attachments
Gavin Newsom Asks Social Media Users to Help Design New California Coin and it Blows Up in His Face.
- By PatMiles
- The Bear Pit
- 5 Replies
Oops: Gavin Newsom Asks Social Media Users to Help Design New California Coin and it Blows Up in His Face | The Gateway Pundit | by Cullen Linebarger
California Governor Gavin Newsom asked social media users to help design a new $1 coin to honor the state’s innovations on Thursday, and it unsurprisingly blew up in his face.
www.thegatewaypundit.com
California Governor Gavin Newsom asked social media users to help design a new $1 coin to honor the state’s innovations on Thursday, and it unsurprisingly blew up in his face.
As Gateway Pundit readers know, the Golden State is suffering from various maladies under Newsom’s watch. These include a severe homelessness epidemic, skyrocketing crime, unaffordable taxes, and high electricity costs.
This has led to a mass exodus of businesses and residents. But Newsom, for some reason, thought social media users would lavish California with praise instead.
Newsom probably wishes he never clicked “publish” because the replies he received were universally negative. Many of these focused on the filthy streets, Californians leaving for greener pastures, and even Newsom’s tyrannical COVID-19 pandemic policies.
Here are some of the most savage replies:
YOU KNOW THAT THE COIN IS GOING TO DEPICT CALIFORNIA AS THE LAND OF MILK AND HONEY!
SOLD Manners LRH SA w/ mini chassis
- By EmanP
- Buy - Sell - Trade
- 4 Replies
Test fit at home, otherwise new. It has extra color which isn't an option anymore. Placed a piece of neoprene foam on the cheek riser and put it in the safe. All the stock specs are in the last picture and weighs 37.8 oz. It's about a 10 month wait to get one. $1100 shipped **SOLD**
SOLD AR15 PWA Comp
- By EmanP
- Buy - Sell - Trade
- 4 Replies
PWA FSC556/223 Comp/Flash Suppressor brand new $55 $50 **SOLD**
