Advice: Hammer Seating Depth Test

[aggie_2010]

I've been working up a load for my .270 Win (1:10" twist Weatherby Mk V) using some 124gn Hammer Hunter projectiles. All projectiles so far have been seated 20 thousands off the lands. Below is one of my groups at 200 yards. I'm happy with the velocity (average and ES), but the group spread is around 1.43 MOA. Next, I want to test a few seating depths using this powder and projectile combo to see if I can shrink the group spread to 1 MOA max without greatly affecting the ES. If your in my shoes, what seating depths do you test next? I want to do a thorough test, but I also don't want to burn through any more components than what is necessary.

I have in mind testing these seating depths (each 4-5 shot groups):

• 25 thou off lands
• 30 thou off lands
• 35 thou off lands
• 40 thou off lands
• 45 thou off lands

Note: In the picture below, the far right impact is from a separate load.

 

[rootacres]

From a few different threads I read prior to picking up some hammers I was told to start at .035 off. I made up some loads pushing up to about a .2gr below max (according to Hodgdon). I shot five 5 round groups. My 4th load was .035" off and .2gr off the recommended "max". (57.8gr H4350 143gr HH 7mm SAUM). It shot 1/2 MOA with ~10fps SD. The 5th group was .045" off and also shot 1/2 MOA. It was just a little slower, and a little higher SD.

Kinda comparing apples to oranges but I hope it helps.

 

[MojoTX]

If I had to guess, the seating depth is not the issue. Hammers are not very picky when it comes to seating depth. If you must test, I would go .040 and .080 and call it a day.

 

[PRC_GUY]

Seating depth is not issue with Hammer bullets, I set my 20/1000 of the Land and work on my load data chart and find accurate note. Busing dies help accuracy a lot.

 

[Sykes]

Hammers don't care much about seating depth so I don't think you'll see any difference especially in those small increments. My suggestion, which may not be possible for you because of the powder shortage, is to try a faster burning powder. Hammers tend to shooter better with the faster powders

 

[WeiserBucks]

If I had to guess, the seating depth is not the issue. Hammers are not very picky when it comes to seating depth. If you must test, I would go .040 and .080 and call it a day.

Hammers don't care much about seating depth so I don't think you'll see any difference especially in those small increments. My suggestion, which may not be possible for you because of the powder shortage, is to try a faster burning powder. Hammers tend to shooter better with the faster powders

Both of these guys are correct.

 

[aggie_2010]

If I had to guess, the seating depth is not the issue. Hammers are not very picky when it comes to seating depth. If you must test, I would go .040 and .080 and call it a day.

Any reason in particular you chose .040 and .080 jump? On other projectiles, I see suggestions to test increments of 3-5 thousands at a time.

 

[MojoTX]

Those numbers are loosely based around the approach in the link below. If you don't see a big difference between .020, .040, and .080, you can move on.

Getting the Best Precision and Accuracy from VLD bullets in Your Rifle

VLD bullets are designed with a secant ogive. This ogive shape allows bullets to be more efficient in flight (retain more velocity = less drop and wind deflection). While this result is desirable for many rifle shooters the secant ogive on the VLD bullets produces another result in many rifle.

bergerbullets.com

But again, I would probably be looking at case prep, brass, powder, and primers. The 'hammer time' forum is also a good resource for load development. I have posted load data for this exact bullet and caliber with RL16.

 

[JakeSCH]

Another thing to try is Lee FCD (1/8T) and increasing neck tension to 4 thou. If I can, I always seat the hammers to the middle of the 1st PDR groove and put on a light crimp.

Those things will really tighten up group and shrink ES even more.

 

[aggie_2010]

Those numbers are loosely based around the approach in the link below. If you don't see a big difference between .020, .040, and .080, you can move on.

Getting the Best Precision and Accuracy from VLD bullets in Your Rifle

VLD bullets are designed with a secant ogive. This ogive shape allows bullets to be more efficient in flight (retain more velocity = less drop and wind deflection). While this result is desirable for many rifle shooters the secant ogive on the VLD bullets produces another result in many rifle.

bergerbullets.com

But again, I would probably be looking at case prep, brass, powder, and primers. The 'hammer time' forum is also a good resource for load development. I have posted load data for this exact bullet and caliber with RL16.

Thank you, this is helpful!

 

[aggie_2010]

Another thing to try is Lee FCD (1/8T) and increasing neck tension to 4 thou. If I can, I always seat the hammers to the middle of the 1st PDR groove and put on a light crimp.

Those things will really tighten up group and shrink ES even more.

I was reading the same thing on the Hammer forum yesterday. I have a Lee FCD in route to my home and plan on using it when I load for the jump test.

 

[wapitibob]

Another thing to try is Lee FCD (1/8T) and increasing neck tension to 4 thou. If I can, I always seat the hammers to the middle of the 1st PDR groove and put on a light crimp.

Those things will really tighten up group and shrink ES even more.

I’ve seen that mentioned on hammers site. The case mouth doesn’t touch the bullet when centered over the groove.

 

[JakeSCH]

I’ve seen that mentioned on hammers site. The case mouth doesn’t touch the bullet when centered over the groove.

Correct, it does not touch until you crimp it.

If you don't plan on crimping than I would but it in the middle of the band.

 

[452b264]

IMHO the lee factory crimp die is a must have. Definitely try different seating depths, my 280 AI went from 3/4 moa to see below.

 

[MTAntelope]

In a very similar rifle using the same bullets, I’ve been able to get 0.3MOA consistently using IMR4451 setting .03” off the lands at about 3150FPS. I’ve loaded Hammers for several calibers and they all seem to like powder on the faster end of the scale for that cartridge. I always start at 0.03” from the lands and only increase seating depth if the magazine requires it. Another recommendation I’ve been given for the 270 is to use magnum primers with the hammer bullets.

 

[shmtastic]

How accurate is the rifle? Do you have a pet load for it? You can polish a turd but in the end it's just a shiny turd. A mk v should be capable of moa, are you?

This is by no means an attack on you and your skills. After getting my first 270 last year I had to learn to shoot it, it wasn't like my 7mm RM and it wasn't like any of my 30-06s. Just needed time and practice. This year I'm finally starting real development for it. I took a nice doe with that rifle last year, and I had it just over an inch at a hundred.

 

[tom338]

My rifles that I use Hammer bullets in ARE sensitive to seating depth. Adjusting seating depth made a big difference in group size. Every barrel is different!!

 

[MTAntelope]

My rifles that I use Hammer bullets in ARE sensitive to seating depth. Adjusting seating depth made a big difference in group size. Every barrel is different!!

Absolutely it can make a difference. My rationale for adjusting seating depth last is that copper bullets tend to be less sensitive to it, and cartridges loaded with hammers are pretty expensive as far as hand loads go, so testing another variable ups the load development cost. However, if nothing else works, that may.

Steve at Hammer has been a good resource for my questions and is always quick to respond to emails if you can’t quite find answers elsewhere. They are a great MT company.

 

[SouthPaw]

My .270 likes the 124g HH at .050 off, which on my rifle puts the case mouth on the first valley. I use the Lee FCD 1/8 turn.

Sent from my SM-G950U using Tapatalk

 

[BjornF16]

Don't worry too much about how much jump...find a good seating depth with accuracy.

My 6.5 RPM has .230" of jump (sitting at max internal box length) with good accuracy.