9mm load & COAL

[hceuterpe]

Does anyone think 9mm MG 115gr FMJ over 5.0 HP38 seated to 1.125" would be pushing it to exceeding recommended max pressure? I chronoed this same load to 1.150" and it measured about 1130fps out of a 5" barrel. With the .025" shorter COAL, will it push the pressure/velocity pretty significantly?

I know the books and the powder label call for 5.1gr max for 115gr for 1.125", but that's for HP. Not sure how long GDHPs are, but mine are .562" long.

 

[GJSchulze]

Assuming that the FMJ bullets are shorter than the HP bullets, using the same OAL, I.e. 1.125, will likely result in more case volume and therefore less pressure. HP's of the same weight should be longer and therefore have more bearing surface resulting in more friction which translates to more pressure. So this is another reason that the FMJ should have less pressure. But why are you so close to max? If you don't need to be, just reduce your charge by .2 or .3. You really should work up the load anyway.

 

[gamestalker]

In most circumstances, I would consider a .025" reduction of oal for 9mm as extreme, and with the potential to cause a significant increase in pressures. But since Hodgdon shows a tested oal of 1.125" with their data of 4.7 grs. - 5.1 grs. So to safely proceed, I would take the charge down to minimum, make the oal change from 1.150" to the desired 1.125", then work your powder charge back up while watching for pressure signs.

I'm fairly certain you will still experience a significant increase in pressure, but by taking it back down to minimum, you'll be able to safely manage those pressures by working back up in .1 gr. increments. But I sure wouldn't just jump from 1.150" to 1.125" without doing a complete new work up, and especially considering the fact that you are up near maximum already.

Just out of curiosity, why are you wanting to reduce the oal? I'm assuming you decided on the 1.150" oal based on magazine fit, barrel fit (plunk test), and reliable function / feeding. So did the 1.150" oal not function reliably, or did some other fit and feed issue inspire the idea to shorten the oal.. I ask this because I generally use the longest oal that will function best in my firearms, rather than just automatically going with the tested / published oal.

GS

 

[hceuterpe]

I guess I was trying to make a load closer to what Hodgdon listed with their 1.125" COAL, backing down .1gr from their listed max. I already made a batch of 1000 with the shorter COAL. I guess I wanted to bump the velocity about 30-50 fps. I noticed their velocity max of 1167fps is from a 4" barrel, I have a 5" so I'm guessing at least 20-25fps higher in my barrel vs. Hodgdon max if not way more (like 60ish)?

I couldn't take the chrono today to measure, since I had to shoot indoors and my chrono says I need an indoor lighting kit for accurate readings. I shot it out my Beretta 92 pistol today in an amateur league (just slow fire) with the new shorter COAL ammo. I grabbed some box factory load spent brass of Federal and Winchester people didn't want it (mine were all WIN headstamped rounds). So there is some comparison: Granted the 92 has always left a massive crater from day one, boxed factory or reloads, bigger than any other 9mm pistol I've seen making it a bit harder to examine spent primers (light primer strike? I do not know of such things ). I'm not seeing any primer stress indicators, case issues etc. Granted I had way too much caffeine, and shaky hands, the ammo still shot pretty well, and the recoil didn't seen over the top vs. my old load. Wasn't any worse than my prior load which I thought worked well still.

So, am I technically still under max? Am I going to be looking to pull out the bullet puller with all these 1000 rounds, or am I more or less just pushing the max more, but just short of over it?

But yes I understand now. What I should have done is made another 900 of the old 1.150" to have on hand, and worked a batch of 50 or 100 with the new 1.125" in different powder increments instead of just crank out 1000 with the new COAL. I guess I was naive thinking that wasn't that big of a jump, since my velocity readings were lower than I thought.

 

[Blue68f100]

Instead of pulling that many bullets confirm it's over before. Just grab some more brass and work up with the shorter length. Like 10 ea stepping 0.1 gr till you get to your current load. If the workup indicates there is no problem proceed.

With the shorter length I would back off at least 0.3gr. and work up from there.

I never even try to match what is published velocity. It never has worked for me. Ever barrel is different when if comes to performance.

 

[Wreck-n-Crew]

Instead of pulling that many bullets confirm it's over before. Just grab some more brass and work up with the shorter length. Like 10 ea stepping 0.1 gr till you get to your current load. If the workup indicates there is no problem proceed.

^^^^That.

And don't get in a hurry next time

 

[GJSchulze]

I have a 5" so I'm guessing at least 20-25fps higher in my barrel vs. Hodgdon max if not way more

I just entered your data into Quickload. With the 4" barrel that Hodgdon used, it calculated 1189 fps, so pretty close to 1167. When I change the barrel to 5" the velocity increases by 49 fps. However, QL is also saying you are over max pressure. You need to drop the charge by .2 or by .3 to keep it under max and most of us would drop it even more to start.

Now, when I change the OAL to 1.15 from 1.125, the pressure drops below max, but the velocity only drops 20 fps, so I suggest you stick to 1.15.

And from what I've read on this and other forums, flattened primers are not a good sign of pressure.

If you are just target shooting, why do you want to be so close to max? You don't say you've tested your loads for accuracy, so you can't say that faster is more accurate.

 

[gamestalker]

I think Blue68f100 made the best recommendation considering you already loaded all them up.

As for AL rimless cartridges, being fired from an AL pistol, reading primers is not going to be very effective means of gauging pressures. Usually way before you'll see any pressure signs you'll blow a primer / case wall / head. Short of pulling all 1K of them, try Blue68f100's advice.

I do understand your desire for velocity though. I'm of the type reloader / shooter that prefers full tilt loads also, just learn to approach it a bit more safely in the future.

GS

 

[rsrocket1]

I've also run a few "what if" loads in Quickload where you simply adjust the seating depth and look at the resulting muzzle velocity vs. peak pressure and the change in peak pressure is exponentially greater than the change in muzzle velocity. At long COL's, a slightly deeper seating results in a little increase in MV and Pmax, but as you get shorter and shorter, the MV still goes up, but the Pmax goes up much faster. If you are at or over recommended Pmax, you are really flirting with trouble especially if there are any tolerance issues with the dimensions of the bullet, case thickness, etc.

Another big lesson is in the future, don't load up so many bullets without a lot of testing with smaller batches. My "volume" loading charges account for comfortable tolerances in charge, COL, primer type/brand and seating depth, but that was after quite a bit of testing in smaller batches.

Will your gun blow up with the next round? Probably not. Would it blow up your gun after 50 rounds? Not very likely. SAAMI specs allow for a good deal of safety margin over the spec of 35kpsi, but why stress your barrel more than necessary? That's why manufacturers say you can shoot +P rounds in their guns, but don't recommend doing it regularly.

Good luck and be safe.

 

[hceuterpe]

The first rule I told myself to reloading is not to make overpressure loads. So if you guys are saying right now it's overpressure data, I'm not going to refute or ignore. I shot 1800 rounds with the 1.150" OAL, and the velocity was definitely in spec, and it was accurate to my liking. I went through 50 of the new ones and have to admit the old load was better. Also noticed the inside of the cases were more blackened if memory serves me correct.

Time to buy a collet puller and find some time. I have learned the hard way, but I'm not going to make it worse by being careless.

 

[rsrocket1]

Time to buy a collet puller and find some time. I have learned the hard way, but I'm not going to make it worse by being careless.

Good for you. Been there, done that, except it was with a kinetic hammer puller . It was only a hundred .223 bullets, but it effective penance and a good lesson to test before loading up too much.

 

[1SOW]

5.0/1.150 = X/1.125

Proportionally the new max load is approx. 4.8grs.

Start .2grs LOWER than the starting load and work up will be safe to do.

 

[Steve C]

Not sure how long GDHPs are, but mine are .562" long

Assuming that the FMJ bullets are shorter than the HP bullets

You know what happens when you "assume".



Personally after looking at other data sources both current and past I find some 115gr JRN bullets loaded to a OAL of 1.100" OAL (Nosler and Sierra) with a slightly heavier loading of HP38 and W231 so I wouldn't concern myself but others that are more cautious may opt for dropping the load a bit and working back up.

You may be disappointed in the velocity results and probably will not get significant velocity increase due simply to the shorter OAL and supposedly higher pressure. You will get slightly higher velocities if shot on warmer days or at higher elevations. I've also found the WSP primers give higher velocities than CCI 500's.

There's really no good reason to chase the extra 30 fps as such variation is common for different handguns of the same barrel length shooing the same ammo. As long as the gun functions and is accurate what you have should be all that's needed, esp. for shooing at non living targets.