9MM OAL question

[rawhide]

I just started relaoding this summer and have been learning on 38s. Just loaded my first batch of 9mm. Did a test batch of 10 that shot very nicely so I loaded up 325:

Blazer Brass
J/K 147 gr RNFP
Unique 3.2 gr (starting load)
Winchester primers

Since I am not a competiton shooter or plan to ever carry these for personal defense and will only use for practice I did not trim cases. I measured the first few and adjusted seating until got what I thought was a consistent OAL. The Lyman data says 1.058.

After finishing I randomly measured several and most were under the 1.058. So, I became a little concerned that I may have loaded them too short and measued every one of them. Sorted them into groups: 1.058 - .063; 1.056-.057; 1.050-
.055; and a few were 1.040-.049. Most of them would fall into the 1.053/54 range.

My question is - how short of an OAL is too short before excessive pressure could result in a load this mild?

 

[BadgerLB]

IMO, 1.058 is too short period... max is 1.169... pressures spike fast in 9mm especially with a fast powder like unique... I don't have load data in front of me, but it looks to be 1.13 would be right with a quick google.

 

[Twmaster]

According to my Lyman 48th edition book 1.058 is the length for 147 grain hard cast.

Did you measure the first 10 you did? You really need to be measuring.

These are flat nose? The OAL will look a bit short spec-wise if so. If regular round nose they are waaaay too short for sure.

I adjust my seating die way out first. Seat a bullet and measure. Adjust the seating die down a tad and measure again. Repeat until you get to the correct OAL.

My gut feeling is to not shoot the short ones.

 

[BadgerLB]

I hear ya on what the lyman manual says, but speer and alliant both show 1.13 and 1.14 respectively... 1.058 is awful short for 9mm...

 

[Twmaster]

Badger,

Not trying to be augmentative, but....my Lyman book says 1.115 for a jacketed 147 grain, 1.058 for hard cast. Both flat nose.

 

[Shriner]

Hornady #7 max col 1.169
147 hp 1.100
fmj 1.165

Speer # 13 max col 1.168
147 golddot 1.130
tmj 1.130

Sierra V 4th col 1.169
130 fmj 1.135

Lyman #49 col 1.169
147 tmj 1.115
lead 1.058

Four books pubished in last five years ,each with a differing lt for the same wt bullet .

 

[Twmaster]

And -none- of those examples are for the bullet he is using. All of those are jacketed.

Further, the powder charge is about 14% (.5 grains) less with that hard cast bullet. I loaded a bunch of J-K 125 grain 9MM bullets this weekend. The load data for that calls for 1.065 length with 4.1 grains.

While I agree the bullets seated less than 1.058 might be a problem I'm not convinced the listed OAL is wrong for that bullet.

 

[BadgerLB]

And -none- of those examples are for the bullet he is using. All of those are jacketed.

Further, the powder charge is about 14% (.5 grains) less with that hard cast bullet. I loaded a bunch of J-K 125 grain 9MM bullets this weekend. The load data for that calls for 1.065 length with 4.1 grains.

While I agree the bullets seated less than 1.058 might be a problem I'm not convinced the listed OAL is wrong for that bullet.

I'm not trying to be argumentative either, it's just my not so expert opinion that loading a 9mm at 1.058 may cause detonation. I realize that's what lyman says, and it may be fine, but why risk it given that we know the round is a high pressure round and several manuals state that a short OAL exponentially increases pressure especially with fast powders. Again, it's my opinion, I'm not trying to start a pissing contest, I'm just saying *I* personally would not shoot a 9mm loaded to 1.058.

 

[rawhide]

I adjust my seating die way out first. Seat a bullet and measure. Adjust the seating die down a tad and measure again. Repeat until you get to the correct OAL.

.

That is what I did but apparently didn't measure enough of them.

The bullets are RNFP hardcast lead. I'm confident most of them are ok as they are the same as the test loads I did. But I'll pull the very short and start over.

 

[ryanncass]

I was loading 3.2 tightgroup 147 jk bullet at 1.058 and blew my M&P up. I think the lyman book says the powder should be 2.1 at 1.058. From my personal exprence I would not load anything at 1.058 anymore