Chronographing - Powder Orientation

[Hi-Speed]

In an attempt to obtain better consistency in my chronographing, I’ve been loading my chambers, then tilting barrel to approx 10:00 (safely to a mark down range against a steep mountainside) to get the powder oriented back towards the primer, level gun and shoot over chronograph for readings.

I’ve seen the following on another forum which shows how SAAMI and manufacturers test regarding powder orientation in the cartridge case…I’m going to try this method as opposed to mine above:

Western Powders says: “SAAMI guidelines for testing require that the loaded cartridge be twirled slowly end over end to loosen the powder within the case. It is then carefully oriented with the primer end down to settle the powder rearward within the case. The technician then inserts it into the test barrel, being careful not to move the powder forward and away from the primer. This powder-rear orientation produces the highest pressure and velocity for that load combination and provides the baseline for published data.”

Appreciate your inputs regarding powder orientation while chronographing your loads. I hope Larry Gibson and Outpost75 can chime in with their experience.

Thank you all,

Eric

[Larry Gibson]

That SAAMI method is used by many and is referred to many times as the "SAAMI twist". I use a very similar method of the SAAMI twist in that I hold the cartridge with my index finger on the bullet nose and lightly tap the base a couple times on the bench. Then I twist the cartridge back and forth a couple times. Then, assuming the rifle is horizontal on the bench on rests, I insert the cartridge base first onto the magazine follower with holding the nose up at an angle to keep the powder positioned at the base of the case. The base (head) of the cartridge is placed against the bolt and lay the cartridge down gently on the follower. It the rifle is a CRF I the gently push the round into the magazine. The bolt is the slowly and smoothly closed with the rifle then being ready to aim and fire. Sounds complicated to do but with a bit of practice it becomes second nature and is easily done.

That was with a bolt action rifle. Other types of actions require a bit different procedure but usually the "twist" is still used albeit, in a bit different fashion.

[gumbo333]

Mr Gibson, not to hijack this tread , but with your pressure equipment have you tried firing rounds with your “twist” loading method and just putting a cartridge in your rifle any willy - nilly way then firing, to see if there is a significant difference? I’ve shot tons of 45/70 mouse fart loads in lever Marlins and a Henry using unique, red dot, blue dot, 700x and a few more. Most have given accuracy better than I can shot. I use a magnum primer, have given no thought about cartridge position. Mostly with PC’d cast 405 gr boolits. Thank you for your years of outstanding info.

[Hi-Speed]

That SAAMI method is used by many and is referred to many times as the "SAAMI twist". I use a very similar method of the SAAMI twist in that I hold the cartridge with my index finger on the bullet nose and lightly tap the base a couple times on the bench. Then I twist the cartridge back and forth a couple times. Then, assuming the rifle is horizontal on the bench on rests, I insert the cartridge base first onto the magazine follower with holding the nose up at an angle to keep the powder positioned at the base of the case. The base (head) of the cartridge is placed against the bolt and lay the cartridge down gently on the follower. It the rifle is a CRF I the gently push the round into the magazine. The bolt is the slowly and smoothly closed with the rifle then being ready to aim and fire. Sounds complicated to do but with a bit of practice it becomes second nature and is easily done.

That was with a bolt action rifle. Other types of actions require a bit different procedure but usually the "twist" is still used albeit, in a bit different fashion.

Thank you Larry, I may start loading one chamber at a time in my revolver and then shoot over the chronograph, record, empty case, repeat, with the powder position technique you and SAAMI delineated.

I’ll try out this technique this week…but as the N340 load I discussed, which was shot and recorded with my current technique noted, how can changing my method improve its resulting stats of ES 10 and SD 3…

[ascast]

not to hijack thread, but I have done similar to gunbo333. 45/70 with Unique or 4759 loads that shoot groups 2-3" wide by 6 " high at 20yds. Same load at 600 yd will do about 8-9" wide by 5 ft high. Tried settling the powder and saw no effect. Charges were thrown. Always suspected powder stuck to bottom of bullet or in case mouth.

[BLAHUT]

I DON'T USE BLACK. I USE BLACKHORN 209, WITH A PAPER MILK CARTON CARD OVER POWDER WITH A PLASTIC CARD WAD, COFFIE CAN COVER, OVER THAT UNDER BULLET WITH A SLIGHT COMPRESSION> WITH BLACKHORN, I GET ABOUT 2X TIMES MORE OF LOADS, THAN I WOULD GET FROM BLACK, PER POUND< I THINK IT SHOOTS CLEANER, GIVES BETTER ACCURCY, I USE MAG PRIMERS. I USE THIS IN MY 45/70s AND 45/60 AND 50 CAL IN LINE>> VERY ACCURATE IN ALL OF THEM< VERY CONSINSTSNT. I STAY ABOUT 1200fpsOR A TAD LESS, WITH PURE LEAD. VERY ACCURATE OUT TO 1000yds/1000meters. IF I DO MY PART... THE 50 IN LINE, WILL DO ABOUT 5 IN ONE HOLE AT 100 yds> YOUR GUN WILL LEAD YOU TO THE BEST LOAD>>

[dverna]

My question is...."Why?"

Don't you want the load to be representative of how it performs normally? If you have a position sensitive powder, "masking" or compensating for that by single loading a round that has been twirled and tapped "just so" does not make sense. Especially if the round will be carried in a revolver or magazine before being fired in the real world. Might be OK for single shots.

I can see the rationale when pressure testing to get the highest pressure possible, but not for evaluating the SD or ES of loads.

[Hick]

My question is...."Why?"

Don't you want the load to be representative of how it performs normally? If you have a position sensitive powder, "masking" or compensating for that by single loading a round that has been twirled and tapped "just so" does not make sense. Especially if the round will be carried in a revolver or magazine before being fired in the real world. Might be OK for single shots.

I can see the rationale when pressure testing to get the highest pressure possible, but not for evaluating the SD or ES of loads.

Yep-- when I have a light load, such as lower velocity cast loads, I intentionally chrono 5 or 6 the way I would normally load them in the firearm, then a couple tipping the barrel up, then a couple tipping the barrel down. I want to know just how position sensitive my load might be. I wouldn't normally tip the barrel down before shooting-- but I want to know if it will matter much.

[Hi-Speed]

My question is...."Why?"

Don't you want the load to be representative of how it performs normally? If you have a position sensitive powder, "masking" or compensating for that by single loading a round that has been twirled and tapped "just so" does not make sense. Especially if the round will be carried in a revolver or magazine before being fired in the real world. Might be OK for single shots.

I can see the rationale when pressure testing to get the highest pressure possible, but not for evaluating the SD or ES of loads.

Thank you Don, great points, you’re right for what I’m doing this for.

[Hi-Speed]

Yep-- when I have a light load, such as lower velocity cast loads, I intentionally chrono 5 or 6 the way I would normally load them in the firearm, then a couple tipping the barrel up, then a couple tipping the barrel down. I want to know just how position sensitive my load might be. I wouldn't normally tip the barrel down before shooting-- but I want to know if it will matter much.

Thank you Hick from Winnemucca! Greetings from Douglas County (still America as your county Humbolt)!

[georgerkahn]

Just an added bit of germane trivia, the British Army regulations for many, many years included that the muzzle of the rifle be pointed straight up, and then lowered to target orientation -- this to uniformly "settle" the powder at cartridge case bottom -- before trigger pull...
geo

[charlie b]

FWIW, I have only noticed a difference when there is a certain amount of air space left in the case (30-70%?). My .308 can show over 100fps difference if tipped up or down with reduced loads. Very light loads (8-10gn) I do not see a difference.

If you have a loading that shows sensitivity, then you can use the careful method, or, use some filler.

[Larry Gibson]

charlie b pretty much nailed it.

[charlie b]

Yes, the filler does affect the load. The idea is if you use a filler for the duty/hunting load, then use it when doing load development and zero.

If you do decide on using a filler read through the sticky on fillers. Larry did a great job explaining when and how to use them.