I purchased a M&P .45 recently and started reloading for it. My problem is that about half of the first reloads would not chamber in the gun as I was shooting.
Then I bought a Dillon reloader and Dillon dies and they got better, but out of the last group of 50 there were about 5 that would not chamber. What am I doing wrong. I have been told go to .451 bullet. I am currently loading 230 grain LRN bullets and taper crimping them.

....are you removing all the bell when you crimp? I'd put a tad more crimp on the rounds that would not chamber and then try them.

There are a lot of variables when it comes to reloading even though it's fairly straight forward. When you say "won't chamber" what do you mean? Is the round too long? (excessive OAL) Is the round too wide? (like said above, bell not flattened)

I don't think you should spend any more money of new equipment until you find the problem. Please give us more information...

BTW, you can check all your ammo using your barrel as a gauge. Remove the barrel and put each round in the barrel chamber before you place it in the ammo box. You will find the problem rounds before you go to the range and you will be able to examine those rounds and hopefully find the problem.

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SWCA #3437

Yes, .451 is the correct diameter for a .45ACP LRN bullet, or any other cast bullet. .452 is for jacketed bullets (FMJ, JHP). In addition to (or instead of) using the barrel to check whether rounds will chamber, you can get a max cartridge gage from Midway. Use a very light taper crimp.
L.E. Wilson Max Cartridge Gage 45 ACP - MidwayUSA

I always use a cartrige gauge to check my loads before putting them into the magazine. You should visually inspect the loads for absence of bulges etc. M&P45's will digest any properly crafted ammo

Be very careful, this information is incorrect! It is in fact reversed, "normal" for 45 ACP is .451 jacketed projectiles. Most handloaders will use +.001 over for lead, or .452. SAAMI spec is actually .452, and max OAL is 1.275
And while there is nothing wrong with buying a case guage, it sounds like you are already spending a lot of money chasing something that you don't know what. As mentioned you already have the perfect case guage, the barrel of your gun.

My M&P45 has a very tightly cut chamber and I suspect yours does too. Very little room in front of the chamber before the rifling begins.

First, buy a maximum ammunition gage like the Wilson product. Your gun will probably protest any cartridge that does not drop into the Wilson gage.

Next, if your bullet has a full-diameter profile that extends more than about 0.030" from your case when seated, you are going to have trouble. Seat it deeper, or change to a design of bullet that is not full-diameter in front of the case mouth when seated.

My guess is that your gun will run 100% with something like Federal American Eagle 230 gr FMJ round nose... ? Mine also works fine with, for example, Winchester Ranger hollow-points (that have a profile very similar to the FMJ back in the area of the case mouth). It will also shoot Nr. 68s, but I have to seat them 0.020-0.030" deeper than the normal 1.250" COL recommended for this design. Since my loads with the 68 are never full-charge, the slightly deeper seating is no sweat.

I ran thousands and thousands of 230GR lead conical flat nose thru all 3 of my Kimbers, 25 & 625s. I loaded them long (less Pressure)

I used 231 until I switched to Tightgroup, I never had problems until I got the M&P.

The M&P needs them seated deeper in the case. The slide would not always go all the way forward into battery. Now that I figured out that they need to be deeper the M&P runs like a champ!





This M&P is the first bottom feeder I would grab if it was needed.

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Shoot fast & live long
Warren

My most relaible 45's are the old S&W 645, the current M&P45, and a Glock-36 carry piece. My M&P45 will feed any bullet shape from 185 gr. LSWCHP to 230 gr. FMJ RN without a single issue.

Yes, try dropping the bullets into the removed barrel. Taper crimp only enough to remove the bell flair. More than likely your not seating the bullets quite enough for your chamber. Try seating them more and I think you will solve your problem.

You do realize this thread is over 2 years old, right? If he didn't find the problem by now he probably gave up...

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Freedom is never free!!
SWCA #3437

So did he? Inquiring minds want to know...