40 S&W load problem

[jim8115]

I loaded some 155 Grain XTP's with 8.5 Grains Power Pistol ( just under max according to latest hornady manual ) Shooting from my XD40

Every couple of rounds, it locks the slide open, even though it isnt empty. Are they just too hot? I chron'ed them at 1236 FPS

Everything else shoots just fine

JIM

 

[rcmodel]

What is your OAL?

Anyway, take the slide off and insert a loaded magazine.

Look for bullet ogive interference with the slide stop tab the empty mag follower hits..
The rounds slide forward in the mag under recoil and bump it up.

rc

 

[jim8115]

OAL is 1.125. The exact same bullet, same length with a load of 6.0 Grains of W231 works perfectly ( AVG 1090 FPS ) .

JIM

 

[rcmodel]

Are they just too hot?

Maybe??
Lyman #49 shows 7.8 Power Pistol as max with a 155 Silvertip.

Might try backing off a little and see if it works.

rc

 

[jim8115]

That is my plan. Strange, 8.5 isnt even max, according to the Horn manual. it lists 8.9

JIM

 

[beatledog7]

Strange, 8.5 isnt even max, according to the Horn manual. it lists 8.9

But the guys at Hornady didn't work up the test loads in your XD. Every gun is different.

 

[popper]

When it comes to the timing of SA, speed counts.

 

[rsrocket1]

Hmm, no first hand experience here, but a run on QuickLoad says
40 S&W
0.400 155 Hornady HP/XTP 4000 bullet
1.125" COAL
Seat Depth 0.305"
8.5g Power Pistol
Powder fill ratio:121% <- claims you are compressing the powder when the bullet is seated.
Pmax:= 46,748 psi (!!)
MV= 1,326 fps out of a 4" barrel

max safe load is about 7.6g for 1196 fps. I would stay at 7.0g as that is the amount where you have the bullet touching the powder with no compression, 27.7 kpsi, 1094 fps.

Disclaimer: Alliant's load of 9.0g for 155g Speer GDHP calculates to a 39k psi which is 4k above max, but Alliant tends to only show max loads and tends to show loads which are on the hot side.

 

[LiveLife]

40 S&W load problem ... 155 Grain XTP's with 8.5 Grains Power Pistol ... XD40

Every couple of rounds, it locks the slide open, even though it isnt empty. Are they just too hot? I chron'ed them at 1236 FPS

Everything else shoots just fine

So what I am reading is that some of your reloads work but some don't?

Do you have similar issues with other bullets (bullet weight, factory vs reloads)?

 

[jim8115]

So what I am reading is that some of your reloads work but some don't?

Do you have similar issues with other bullets (bullet weight, factory vs reloads)?

That is correct.No probs with any other load For example, 155XTP(same bullet) set at same length, with 6.0 w231 works just fine, as well as my 170 grain lead..........

 

[LiveLife]

If the same bullet/OAL (155 gr XTP) and 170 lead bullet work fine with W231, then I would guess that Power Pistol powder charges may not be consistent.

Could you test a batch of reloads using powder charges weighed/verified on a scale for consistency? If you are using a powder measure, could you check the consistency of your powder drops?

When I conduct a powder workup with a new bullet, I initially look for powder charges that reliably feed from the magazine and cycle the slide - then look for powder charges that produce the most accurate shot groups.

If you have not, conducting a powder workup from start charge with incremental charges towards max charge should provide you with charges that provide reliable feeding/slide cycling and accurate loads.

 

[rg1]

8.0 grains of Power Pistol with Hornady's 155 XTP-HP using Win brass and CCI 500 primers gets 1142 avg. fps in my Glock 23. Shot well and no issues. I used Hornady's recommended overall length of 1.125".