.40S&W Missouri bullet loading ?'s

[traveling1253]

Received my Lyman #49 and a batch of MBC 180gr IDP#5's yesterday. Lyman data has cast bullet data but not for 180gr. They have two loadings for 175gr bullets using Lyman #401043 and Lyman #401638. The given starting charge of W231 is 4.3gr is the same as the charge of HP-38 that I had good results with 180gr RS Berrys plated. Grabbed three samples of the IDP #5's and they weigh between 178.8-179.7gr so as far as bullet weight is concerned I figure it should be safe to use the starting load data for the 175gr Lyman bullets. What has me a bit unsure is the length of the bullets. The MBC bullets are .625" long which is significantly longer than the Berry's(.579") that I have been using. If I seat them to achieve the same 1.126" that has proven to feed and cycle properly in my XDm there will be less space inside the casing which if I understand right will increase pressures. The Lyman data for the 175gr #401043 bullets gives a OAL of 1.125" but I have no idea how long the Lyman bullet is compared to the MBC's. The data for the 175gr Lyman #401638 shows a significantly shorter OAL of 1.100". Opinions,advice wanted.

Thanks

 

[Sin City Shootist]

My .40 will not feed these bullets at 1.125 OAL. I have my OAL at 1.175. You may want to start a little longer, say 1.150.

 

[LiveLife]

Lyman data has cast bullet data but not for 180gr. They have two loadings for 175gr bullets using Lyman #401043 and Lyman #401638. The given starting charge of W231 is 4.3gr.

The data for the 175gr Lyman #401638 shows a significantly shorter OAL of 1.100". Opinions,advice wanted.

If you are using starting charge for lead load data for 175 gr bullet, I would think using the same starting charge for 180 gr bullet should be fine, especially if you are using a longer OAL of 1.126" than the published 1.100".

If you want a sanity check, Hodgdon's website lists 4.1 gr as starting jacketed load data for 1.125" OAL. If you have any concerns, you can start out at 4.1 gr with 1.126" OAL and work up from there.

180 GR. HDY XTP W231/HP38 OAL 1.125" Start 4.1 gr (797 fps) 23,800 PSI - Max 5.0 gr (947 fps) 32,900 PSI

I use 4.3 gr of W231/HP38 for MBC 180 gr TCFP IDP #5 at 1.125". It feeds/chambers well in tight Lone Wolf barreled G22/G27 and M&P40.

 

[traveling1253]

Put some test rounds together last night with overall lengths of 1.125, 1.130 and the max spec of 1.135". Made 10 of each at the Lyman starting charge of 4.3gr and 10 of each 4.5gr. This will be my first experiment trying different lengths to see how my XDm functions and how it affects accuracy. If I understand the things I have read correctly, accuracy should improve at longer OAL as the bullet has less distance to travel before mating with the rifling. Of course rounds need to fit in the magazine and feed correctly. Not sure when I'll get around to testing, supposed to be sub-zero and windy tomorrow
Also made a few dummies to try in the barrel and even at the 1.135" max they dropped right in and did not seem to contact the rifling. Spun them in the chamber, no marks on the lead. I tried three dummies in the magazine at increasing lengths from 1.100" up to the 1.135" max, all chambered properly with the slide release and when hand cycling the slide. I know hand cycling isn't the same as firing but all indications are that my XDm isn't all that fussy about OAL.
I found the Loading data from Ramshot, they have data for their pistol powders using 180gr TC Laser Cast bullets which should be a closer match for the MBC IDP #5's than the Lyman bullets, same weight and profile. Goin to the gun show tomorrow, plan to look for some to try.

 

[LiveLife]

If I understand the things I have read correctly, accuracy should improve at longer OAL as the bullet has less distance to travel before mating with the rifling.

Yes, less distance the bullet has to "jump" means less time for the hot gas to escape around the bullet and generate higher chamber pressure for more consistent powder burn. Especially with lead bullets, the shorter jump also decreases the gas cutting/eroding of the bullet which reduces leading at the chamber end.

Most accurate shot groups are produced at high+ range load data as higher chamber pressure provides more efficient powder burn, but I have gotten very accurate shot groups at starting to mid range load data with certain powders like W231/HP38 using jacketed, plated, Moly and lead bullets. So, range test your loads to determine the powder charge/OAL that produces the most accurate shot groups. Over the years, I have found that "general assumptions" don't always apply and actual holes on targets speaks volumes.