Having trouble obtaining desired velocity

[KevinA.]

[scamp62]

My data shows 4.4gr (with a 4.5" barrel) at 1.145" AOL to just hit 1000fps.....could be your a .5" of barrel short?? if you still not sure, measure out the powder on a scale, one at a time, just make up 10 round each (so you know that the charge is right) head bake to the range...........good luck!

[scotty99]

[KevinA.]

[scotty99]

[Sandspider500]

I'm going to say the opposite, load out longer and work your load up again. Take a look a few over in your Lyman manual at 9x21 load data.

Let's use WSF and the Speer 147gr TMJ as an example for the effect of OAL.

9mm
OAL 1.115
WSF start 3.5gr 790fps 21,500cup
WSF Max 4.4 983fps 30,800cup

Same exact bullet now loaded out longer
9x21mm
OAL 1.169
WSF start 5.1gr 856fps 24,700cup
WSF Max 6.2gr 1144fps 33,000cup

The Speer 147 TMJ is .65 long so at 1.115 .286 is inside the case in the Lyman data as they trim cases to .751. As you can see from the load data of 9mm and 9x21 .054 difference in seating depth has a substantial effect on pressure, use some calipers and set them to .054 to see just how small this is. I don't know how long your rmr bullet is but I wouldn't load them shorter, load them out as long as you can and work your load back up making sure to figure out how much of your bullet is inside the case compared to the Speer bullet.

Also for reference Speer #14 list the 147gr TMJ 9mm at max 4.3gr of unique at 954fps from a 4" barrel.

[scotty99]

I'm going to say the opposite, load out longer and work your load up again. Take a look a few over in your Lyman manual at 9x21 load data.

Let's use WSF and the Speer 147gr TMJ as an example for the effect of OAL.

9mm
OAL 1.115
WSF start 3.5gr 790fps 21,500cup
WSF Max 4.4 983fps 30,800cup

Same exact bullet now loaded out longer
9x21mm
OAL 1.169
WSF start 5.1gr 856fps 24,700cup
WSF Max 6.2gr 1144fps 33,000cup

The Speer 147 TMJ is .65 long so at 1.115 .286 is inside the case in the Lyman data as they trim cases to .751. As you can see from the load data of 9mm and 9x21 .054 difference in seating depth has a substantial effect on pressure, use some calipers and set them to .054 to see just how small this is. I don't know how long your rmr bullet is but I wouldn't load them shorter, load them out as long as you can and work your load back up making sure to figure out how much of your bullet is inside the case compared to the Speer bullet.

Also for reference Speer #14 list the 147gr TMJ 9mm at max 4.3gr of unique at 954fps from a 4" barrel.

[Sandspider500]

Your misunderstanding what I suggested, re read it.

9mm and 9x21 cases are the same diameter, only difference is the 9x21 is 2mm longer. If you take a 9mm case and load a bullet in it to 1.10 then take the 9x21 case and load the same bullet in it to 1.10 they have the same case capacity. Basically 9mm and 9x21 load data is interchangeable as long as the same OAL is used. 9x21 was designed as a work around for countries that civilians aren't allowed to use military cartridges.

[BajaJames83]

As others suggested try a different powder.
My suggestion is CFE pistol it likes being loaded hot and will hit 1000 pretty easily while keeping pressures safe.
Check out this website he has some good data

http://www.natoreloading.com/

[divingin]

If you suspect inconsistent drops, measure each charge. That will eliminate that problem.

Load 10 or 20 rounds, measuring the charge and adjusting if it's not your target weight (I use a small scientific spatula - you could do the same thing with any flattish piece of metal or clean dry plastic.) Chrono and check results.

[divingin]

9mm and 9x21 cases are the same diameter, only difference is the 9x21 is 2mm longer. If you take a 9mm case and load a bullet in it to 1.10 then take the 9x21 case and load the same bullet in it to 1.10 they have the same case capacity.

Have you verified that the interior case dimensions are the same? i.e. head thickness, wall thickness, etc?

Sounds like you're making an assumption based solely on external measurements, which could lead to trouble. Or not, depending on what, if any, differences there are.

[Sandspider500]

Have you verified that the interior case dimensions are the same? i.e. head thickness, wall thickness, etc?

Sounds like you're making an assumption based solely on external measurements, which could lead to trouble. Or not, depending on what, if any, differences there are.

No, I don't have a 9x21 case available to measure if the capacity would be exactly the same, I only know that 9mm luger is it's parent case and it was lengthened from 19mm to 21, so you got me there. There are manuals that state that the load data is interchangeable.

We can also use Richard Lee's formula of seating depth.
By seating a bullet farther out of a case using the same powder charge. For every +10% of case volume gained will get a drop of -3% in velocity and -13% in pressure.

DONT USE THIS ACTUAL DATA ITS JUST AN EXAMPLE
So let's say at a Winchester 9mm case holds 13.2gr of h20 and if a Speer 147gr TMJ bullet is seated inside the case .286 at this depth the case holds 5.5gr of h20. 5.5x10%=.55 right. So in goes .55gr h20 now seating depth is .255 or .031 less. So if we had seated at lymans 1.115 with 4.5gr unique they say they got 29,100Cup, now we're at 1.146 and have lost 3% velocity which according to them was 1039 so 31fps. So its at 1008 fps now and also a 13% reduction in chamber pressure 29,100-13%= 25,317cup. Do you think there's more room now to work the load back up

He also states that by increasing the powder charge weight by 10% we will get a 8% increase in velocity but a 20% increase in pressure! But he also says compressing powder can change its burn rate Making it faster