Keyholes left in targets. Bullets Tumbling.

[Lobonca]

I shoot an M&P Pro 9mm. Load 147 gr. Montana Gold bullets with 3.2 gr Titegroup. Today at a match it was brought to my attention that about 4 our of evey 15 shots are leaving a "Keyhole" shaped hole (not round) in the targets which indicates that my bullets are tumbling.

Any ideas on what may be is causing this?

The M&P Pro is new and only has about 3,000 rounds through it.

[lugnut]

You can try changing your load, powder, etc. Some barrels just don't seem to like heavier bullets. People will argue regardless.

Edited February 10, 2013 by lugnut

[rangerguy]

Try putting more crimp on it. Friend had that problem put a tighter crimp and it solved the problem.

[ltdmstr]

Try putting more crimp on it. Friend had that problem put a tighter crimp and it solved the problem.

Actually, it's probably just the opposite. Semi-auto should have taper crimp not roll crimp. Latter is for revolvers only. SAAMI crimp spec for 9mm is .380".

[JeremyM]

I had the same issues. Changing to a 124 grain fixed it. Some say the rifling in the old M&P barrels aren't sufficient to stabilize a heavier projectile. I haven't tried the new barrels in the CORE YET.

[mlmiller1]

With one of my glocks, I just couldn't get the tumbling to stop as long as I was using titegroup powder so I changed powder. I tried more crimp, less crimp, no crimp, longer, shorter, lighter, heavier & finally gave up. Went to a different powder, no more problems. Shame, too as the tg powder is pretty cheap!

MLM

[superdude]

Try putting more crimp on it. Friend had that problem put a tighter crimp and it solved the problem.

Actually, it's probably just the opposite. Semi-auto should have taper crimp not roll crimp. Latter is for revolvers only. SAAMI crimp spec for 9mm is .380".

I don't believe SAAMI gives crimp dimensions. The illusion of a crimp dimensions is typical of tapered cartridges. I think what the drawings show are just case dimensions at specified points. The .380" is just the case mouth dimension for the 9mm Luger. Note how the case dimension points correspond to the chamber dimensions.

Look at the 357 mag and 38 special dimensions. Both have a roll crimp, yet their SAAMI specs indicate no crimp, just a single cylindrical diameter. Same for 38 Super and a couple of other straight-walled cartridges.

[ltdmstr]

Yes, SAAMI spec is max, but for semi-auto, crimp should not be more than a couple of thousandths under. Some revolver cartridges use roll crimps to keep the bullet in place under recoil (this is particularly true for .44 magnum, and other high caliber rounds). Semi-autos rely on an interference fit to hold the bullet in place and the crimp is intended merely to facilitate feeding. In any event, it's probably the bullet/barrel combination that's causing the problem here.

[sroe3]

I've heard M&P's don't care for the heavier bullets. Also sometimes pushing up velocity a little can help (that's ultimately what you accomplish switching to lighter bullets).

[L3324temp]

I had the same issue with another 147g bullet/TG in the M&P Pro. Upping the charge and reducing the crimp helped but it still wasn't ideal. I switched to 135g bullet and don't have any issues.

Many people suggested I switch to a different powder, so you may want to give that a try.

Edited February 10, 2013 by L3324temp

[justmike]

My older M&P Pro with 147 bayou's and WST keyhole. I tried different charges and messed around with the crimp but couldn't stop it. My new M&P Pro with a build date of Dec. 2012 does not keyhole. I'm not positive but I think the barrel twist is faster so that may have something to do with it.

[Lobonca]

Thank you for all of your replies.

Justmike: This M&P Pro was purchased Nov 2012 from a dealer with a high turnover of stock so it would be close to the one you are talking about.

I just micked my cartriges (147 gr. Montana Gold CMJ with 3.3gr Titegroup) and they are:

1.1050" long

0.3765" wide at crimp

If any other M&P Pro users out there who use Montana Gold 147 gr. with titegroup would care to measure their cartridges, it would be appreciated.

A friend uses and M&P Pro, same ammo recipe with same size cartriges with no problems.

I have access to an older M&P Pro that I can send some bullets through to see what happens as well.

Edited February 10, 2013 by Lobonca

[justmike]

Go figure, my FS and compact shoot them just fine. I settled on 124's so I gave up on the 147's.

[Hammbone]

For what its worth... I wasn't having tumbling problems, but I was having horrible groups with 147gr Berry's and TG in my Beretta M9. I played with OAL and found that groups really tightened up at 1.160" OAL. (I started at 1.145"). That's with 3.3gr TG. It runs 127-129PF on a 32ºF day.

[jcc7x7]

Neat part about reloading is that we can try all sorts of combo's and see what works best.

I shoot 147 lead with WSF,AA5 and Universal all of them work at the right velocity 850 or more seems to be the spot. It also happens to be whare 125 PF is appox.

Keep experimenting (safely of Course) and find what works in your gun the best. Then you can know cause you know that its tuned just for you

good fortune

[tambarika]

Try putting more crimp on it. Friend had that problem put a tighter crimp and it solved the problem.

understand what a tighter crimp is doing: it is increasing the pressure of the round. i don't see this as the solution. you want the *proper* crimp here, not a tighter one (unless the original crimp was not sufficient)

crimp = diameter of bullet plus + (thickness of brass X 2) - 0.002

you increase pressure by either increasing powder of decreasing OAL (every 0.010 is about 10 fps).

Edited February 11, 2013 by tambarika

[LikesToShoot]

Thank you for all of your replies.

Justmike: This M&P Pro was purchased Nov 2012 from a dealer with a high turnover of stock so it would be close to the one you are talking about.

I just micked my cartriges (147 gr. Montana Gold CMJ with 3.3gr Titegroup) and they are:

1.1050" long

0.3765" wide at crimp

If any other M&P Pro users out there who use Montana Gold 147 gr. with titegroup would care to measure their cartridges, it would be appreciated.

A friend uses and M&P Pro, same ammo recipe with same size cartriges with no problems.

I have access to an older M&P Pro that I can send some bullets through to see what happens as well.

You might have your buddy with the Pro shoot your ammo and see what his results are. Then swap barrels with him and retest.

If the problem stays with your ammo then measure the bullets, maybe they're undersized? You recipe looks to be on the low side of PF, 125 per Hodgdon, if you up the charge the bullet may stabilize better for you.

[Classic_jon]

I think there is some truth to what others are saying about the powder being part of the equation. I shoot 147 gr Bayou with 3.6gr of N320 and a 1.148 OAL and have very good accuracy out of them in my M&P pro 5". That same setup with 231 or titegroup is nowhere near as accurate.

I have generally found that if you load ammo to the 135 to 140 PF range you can eliminate many of the basic issues many people have . 3.2gr of titegroup with a 147gr bullet is the minimum load on Hodgdon's site. I would say to push it up to 3.4 and check the crimp as others have said and see if that spins the bullet up enough to be stable. Too many people chase the "minimum PF" and forget that minimum PF does not always mean best or most accurate It may do nothing, but it may "fix" your problem.

Remember, each gun is different and what works in mine may not work as well in yours so experiment a bit and see what happens.

As always, reload safely!

[bugsy]

I don't have an M&P Pro 9, but I have seen this same problem when I was developing my load for my CZ 85C. I did not change powder, bullet weight. The culprit: OAL. With your barrel on hand, try fitting your seated load, un-crimped. The bullet should barely touch your rifling, and at the same time, your bullet should seat flushed in the chamber. Then, do a light crimp, enough to remove the bell when the bullet is seated. Try several loads of varying OAL's. and choose the OAL that suits your barrel length. I might be wrong or missing few parameters. But this worked for me.

Safe shooting!

[Bob DuBois]

OAL can come into play. I like to load as long as possible usually 1.145 to 1.150 for my Trojan. Rounds loaded as short as yours would stovepipe in my pistol. Always check the first ten or so loaded in a magazine before starting a run.

Mike the bullet in the case should be .380 subtract .002, crimp should be set at .278.

To much crimp and accuracy will suffer usually.

Might bump your load up just a little. I this doesn't work try another powder. Test with a chronograph.

9mm can be one of the harder calibers to load for because of the tapered case. Loading on a Dillon 650 I prefer Lee's first stage sizer, sizes closer to the extractor groove and a little tighter overall. The first stage sizer holds the bullet in the case. Crimp allows the bullet to chamber easier.

Lee's seating die has a small knob on top that allows small adjustments without breaking the lock nut. Having OAL problems for a few bucks you can send a bullet to Lee and they will cut a insert to fit that bullet shape. Lee's locking nuts are weak might order a set from Dillon. Sizer may need to be locked from the bottom depending on your press.