Please help with C.O.A.L

[alybra]

I bought a 550 from Brian last July and finally have time to set it up. Loading 9mm I have Montana Gold 124 CMJ RP and Titegroup powder. On Hodgdon's website the data says to load to a C.O.A.L of 1.090. The bullet seems to seat very deeply to accomplish this (I'm at 1.092 w/ a digital caliper). My worry is that there will be excess pressure due to decreased volume behind the bullet. I've always been cautious regarding safety.

I've searched on this forum and seem to find most C.O.A.L. for this bullet to be 1.125-1.135 and see that any factory loads I have are all in this range. Does anyone have data for this exact combination of bullet and powder that they've used sucessfully.

If I've left anything out please let me know. Thank you.

[The_Vigilante]

One thing you left out is which pistol you loading for. OAL is going to vary depending on the pistol you are reloading for. Your barrel is the ultimate case gauge.

Edited March 22, 2010 by The_Vigilante

[blankyrick]

I've seen the 1.090 OAL listed for that bullet but I have never loaded below 1.125 OAL. My standard load for my Glock 34 using that bullet is 3.9 grains of TG at 1.135 OAL. As has already been mentioned, use your barrel as a case gauge.

[CocoBolo]

I've seen the 1.090 OAL listed for that bullet but I have never loaded below 1.125 OAL. My standard load for my Glock 34 using that bullet is 3.9 grains of TG at 1.135 OAL. As has already been mentioned, use your barrel as a case gauge.

1.090 sounds like a good OAL for a FN (Flat Nose) bullet but the CMJ should be around 1.140. I loaded a bunch of ammo for my Son-in-law to shoot area 8 with 124gr MTG's with 4.3gr of TG at 1.140 and the chrono there was 131PF. You could just check the link of std factory rn ammo, and it would fit just about any SAMMI spec gun. Depending on temp you might what to throttle back a tenth or two, the 4.3 was at 90, its going to have more bang at 50.

[Sarge]

MG 124 CMJ 4.2 TG OAL 1.14 made 130+ PF out of my M&P PRO if I recall.

I now run MG 124 FMJ(same profile as CMJ) 4.1 Solo1000 @1.14 and made 130.3 at this weekends BITB match out of a G34.

How much TG did the recipe call for at that short oal you mentioned?

[jimzim]

My load for Glock 17 utilizing same bullet and powder has an OAL of 1.130.

[edison]

I bought a 550 from Brian last July and finally have time to set it up. Loading 9mm I have Montana Gold 124 CMJ RP and Titegroup powder. On Hodgdon's website the data says to load to a C.O.A.L of 1.090. The bullet seems to seat very deeply to accomplish this (I'm at 1.092 w/ a digital caliper). My worry is that there will be excess pressure due to decreased volume behind the bullet. I've always been cautious regarding safety.

I've searched on this forum and seem to find most C.O.A.L. for this bullet to be 1.125-1.135 and see that any factory loads I have are all in this range. Does anyone have data for this exact combination of bullet and powder that they've used sucessfully.

If I've left anything out please let me know. Thank you.

I was wondering the same thing about why most guys load it 1.125 to 1.135. I'm just confused because I also read to load it as long as the round can clear the mag. Or find the max OAL of where the bullet touches the rifling, which is around 1.175. Then minus a hundreth. So 1.165 for my glock19. So is it more reliable or more precise at 1.125-1.135 range? for you guys that load at that range. Thank you.

Edited March 22, 2010 by edison

[Flexmoney]

I was wondering the same thing about why most guys load it 1.125 to 1.135. I'm just confused because I also read to load it as long as the round can clear the mag. Or find the max OAL of where the bullet touches the rifling, which is around 1.175. Then minus a hundreth. So 1.165 for my glock19. So is it more reliable or more precise at 1.125-1.135 range? for you guys that load at that range. Thank you.

If you know no different, stick with what the book says. For sure.

[CocoBolo]

I was wondering the same thing about why most guys load it 1.125 to 1.135. I'm just confused because I also read to load it as long as the round can clear the mag. Or find the max OAL of where the bullet touches the rifling, which is around 1.175. Then minus a hundreth. So 1.165 for my glock19. So is it more reliable or more precise at 1.125-1.135 range? for you guys that load at that range. Thank you.

If you know no different, stick with what the book says. For sure.

This only works when the book entry is the bullet you are loading. I load 9 major long mainly because you can't loadit short as the powder won't compress that far so stick to your 1.125-1.140 or so for CMJ 124's. If it works in my CZ's it will run in just about any thing. At 130pf your not going to blow yourself up now at 175pf wear good safety glasses.

I have 3 or 4 books and those guys that write the books are not buying the same bullets I use. Sierra is a good bullet, but if you got that much money why would you reload, just hire a reloader to go with the maid and the butler.

[alybra]

Thank you for all the input. As for the questions, these are for a Sig P-226 and the Hodgdon load data showing a COAL of 1.09 is showing a range of 4.1-4.4 gr of Titegroup.

From your responses it seems best to adjust the COAL out to around 1.125 for a starting point (less pressure) and invest in a chrono.

Thanks again

[GForceLizard]

For sure.

Flex have you been watching F1? All the F1 guys say, For Sure.

[The_Vigilante]

Before you load a bunch of them at 1.125 load about 15-20 and make sure they work in your gun. Also use your barrel for a case gauge to make sure they fit properly.

[fltbed]

The first thing I do when developing a new load is determine what the OAL should be for my gun.

I found this procedure in an old book by a guy named Pope. Used it for years and it works for me.

Finding your OAL

Things youll need:

1. Dowel rod that fits down your bore. (cleaning rod will work in a pinch)

2. Exacto knife, razor blade or scribe.

3. Dial calipers

With the action closed, insert the dowel rod through the muzzle till its resting against the breach face and scribe a line on the rod at the muzzle.

Now insert the bullet you plan on loading into the chamber and hold it against the rifling with something. (another piece of dowel rod, cleaning rod, etc.)

Reinsert the dowel rod till its resting against the nose of the bullet and scribe another line on it at the muzzle.

Measure the distance between the two lines and you now have the maximum OAL for that bullet in your chamber. I normally back off my OAL another .010 or, if it's real long, to the max OAL that will function through the magazine.

(I know there are other ways of determining OAL that are more precise and more expensive, but Ive always found this method more than adequate for my needs.)

After I know what OAL to load to, Ill work up my powder charge.

Hope this helps.

Jeff

Edited March 24, 2010 by fltbed

[Sarge]

Can't you just load a dummy round long, drop it in the barrel, keep running it through the press while shortening it up until it does not touch the rifling anymore?

[alybra]

My question regarding the COAL is not so much as to fitting in the chamber. Going shorter than maximum length should present no problems. My question is that by seating the bullet deeper into the case would it create more pressure which may potentially be dangerous as would be an excessive powder charge. The dummies that were made up setting the COAL have been run flawlessly from magazine through ejection when I manually cycle them.

With more research, I have found data supporting an OAL of 1.09 so I'll load that with min powder charge. I can now see that having a chrono is a necessity (more to research).

Thanks again for the input.

[njl]

My question regarding the COAL is not so much as to fitting in the chamber. Going shorter than maximum length should present no problems. My question is that by seating the bullet deeper into the case would it create more pressure which may potentially be dangerous as would be an excessive powder charge. The dummies that were made up setting the COAL have been run flawlessly from magazine through ejection when I manually cycle them.

With more research, I have found data supporting an OAL of 1.09 so I'll load that with min powder charge. I can now see that having a chrono is a necessity (more to research).

Thanks again for the input.

Going shorter in COAL will decrease the case volume which will increase the pressure. That's why you shouldn't load any shorter than the min COAL a given load lists...but even then, the case volume for their 124gr bullet at 1.09" may not be the same as the case volume for your 1.09" since the bullets themselves could be of different lengths.

1.09" is awfully short for 9mm with 124gr FMJ/CMJ. I've been loading the MG 124gr CMJ to anywhere from 1.140"-1.155" and don't see any reason to go shorter. If you have any, measure some factory rounds to see what COAL they use. For 9mm FMJ, I suspect you'll find generally around 1.150" give or take 0.01". 1.169" is the max. Your barrel or mags may require shorter (or may not if they're loose and forgiving like Glock).

I'd say pick a COAL, load 20 or so, and go chrono them...but it sounds like you don't have one yet.