40 S&W issues.

[Tackleberry41]

Was loading some 200gr from my NOE mold. Sized .402, powder coated. All one brand brass, same primers. Issue is velocities are nowhere near what the Lyman book says.

Figured I would try the True Blue I had bought. Lyman doesn't list for the 200gr NOE, just the the RCBS 10mm-200gr-SWC. Barrel length is the same, 4" in the manual, Im running a FNS40 w 4in barrel. So w a min load of 5.8gr of True Blue says 947FPS. I went w 6.1gr and best I can get is 934fps. Listed OAL is 1.135, shortened them a little to pass the plunk test, 1.127OAL. Tried some 800x, same thing a good 60fps drop from min data with a medium charge.

So is the RCBS bullet that much longer where the base is deeper in the case? Or whats going on? I know books are rarely right on, sometimes your a little low, sometimes a little hotter. But one would think a mid range load should at least come close to the min data, when everything is the same as the book.

[Yodogsandman]

Maybe it's your chronograph. Have you checked it lately with ammo that's known for consistent velocity? I check mine sometimes with Federal Match .22's with very consistent velocities.

[Tackleberry41]

I was using it for other stuff. It reads fine, tho does not seem to like white powder coat. The 40 loads were consistently low. be nice to know the length of a RCBS bullet to compare, but cant find any specs.

[popper]

Trying to use 10mm data for 40SW and expect fps the same - cases are different size. Try a know 40 min load and work up from there. Slow powder may be burning after exit.

[Tackleberry41]

Im not using 10mm data and expecting it to be the same. The BULLET is labelled as 10mm-200gr-SWC. Not the load data.

[kayala]

Interesting. My Lyman manual shows around 1000 fps with 200 gr out of 4" receiver with 6.5 gr of TrueBlue.

[Tackleberry41]

I know, be one thing if it was a shorter barrel, but not sure how they measure, total length including chamber, or just the actual rifled part. I didn't expect exactly the same, but close. Thats only thing I can think of, is the RCBS bullet is longer, I just dont have a spec to compare to. The NOE is .627 long. I tried 800x just in case it was the powder, but got the same low results.

[popper]

Ok, understand you post now. I used HF white years ago, no different than red ESPC. I don't crony pistol but did some 30/30 today, red vs BLL. Very close. Other lubes may make a difference. Length shouldn't make any difference unless the drive band length is greatly different.

[leeggen]

Questions here, 1. Could the pc be allowing the boolit to travel easier down the barrel?
2. Could the longer boolit being deeper in the case causing higher presure thus faster boolit?
3. Are you crimping the longer boolit more than the shorter one?
4. Have you tried crimping the case alittle more to increase presure?
I have not used those powders but the 40 can be a little presure sensitive at times causing changes in speed.
CD

[leeggen]

Tackleberry try to contact GearGNasher on this forum he has alot of experience with the 40S&W. There are otthers here also that I hope will get involved.
CD

[Tackleberry41]

Im thinking its the depth of the bullet. That RCBS is maybe longer, so the base is deeper. I will mess with it, when I can. My chrony did not like the white bullets tho, guess just doesnt see them good. Had same bullet in a different color. Need to find the HP versions I made.

Not seen where PC is a huge factor in velocity if at all. I was messing with lubed vs PC in my 30-30, same load, no real difference in velocity, I just didnt have to lube them. Only place I have seen PC as 'faster' is you can drive them harder.

[Jupiter7]

Also, a major factor in velocity readings with semi-autos is the lock time of the action. For example, Glocks can show changes in velocity by simply changing the recoil spring assembly. Also, the difference in brass, powder and primer variation from lot to lot can change these numbers.

[popper]

800x with 200 XTP shows 6.1 @ 950, don't expect to get any 'book' value exactly with your stuff. Published value for 170gr. RNFP 30/30 1:12 is 1350, I get 1450 with 1:10, 10 gr. Unique load. You get what you get. Talked with a guy who worked for Co. making sensors for the Magnetospeed. said it would 'see' Pb but sensitivity setting had to be higher. I saw a LabRadar unit in use a while back. Optical units don't care if the coating is white/black or jacketed. I did notice that my Chrony didn't show any results till the lube smoke (or shock wave?) disappeared, unit 15' from the muzzle.

[runfiverun]

if your powder coating you have to increase the powder amount to compensate for the slippery coating.
it's just like looking at much of the data for cast/jacketed.
all else equal, you need more powder to equal velocity's because lead is slipperier than copper.
about 3-4% should get you there.

good luck getting Gear to see this thread..

[dverna]

I suspect barrel to barrel and gun to gun differences can affect results. I certainly would not worry about it. Find a safe load - and shoot it. The target, either paper or other, will not notice the difference.

[Tackleberry41]

Guess I will need to a) lathe the pins that come with the mold, or b) shim what holds them in place. The flat nose pins wont give a flat nose bullet, always a little ring where it protrudes just a little. Might be in spec when its cold.