Accuracy potential - MG CMJ vs JHP

[racer-x]

I've used MG JHP's for years and they have proven exceptional accuracy. 

Would like to eliminate the task of picking corn cob out of the JHP's, so I'm evaluating the accuracy of Montana Gold 115 & 124 CMJ's in my 9 major open guns.

 

First round testing with MG CMJ's is disappointing. Shooting fully supported on bench, 4 out of 10 in a 10" circle at 25 yards disappointing.

Same load with a MG JHP, (170PF, AA#7, 115, 1.165OAL), all shots in same ragged hole.

Repeated multiple times with same results.

 

Got to thinking about possible differences in freebore between the round node and JHP and setup a plunk test for each profile in my barrel.

 

JHP plunks & spins out to 1.205 OAL (1.205 - 1.165OAL=.04)

CMJ plunks & spins out to 1.270 OAL (1.270 - 1.165OAL=.105)

 

Wondering if this big difference in freebore is responsible for the lack of accuracy?

I would need to load the CMJ's out to 1.230 in this barrel to have the same freebore as the JHP's and that's not gonna work with 9.

 

 

 

[Ssanders224]

Shouldn’t need to pick Cob. 

 

With the right JHPs and the right cob, you shouldn’t have an issue. 

[Hi-Power Jack]

I don't tumble my loaded ammo.    

 

But you might get better accuracy with the CMJ's at different OAL's - worth a try.  

[racer-x]

My last 4 cases of MG JHP's were full of corn cob straight from MG.

Tiny little pieces that hide in the HP and have made it into my gun if I don't pick it out. Worst case was when it got into trigger and blocked trigger from moving enough to break shot. I pick it out now.

 

I'm going to try some of the longer 124 CMJ's out to 1.200 to test the freebore theory, but there isn't room to increase OAL significantly on the 115's and maintain reliability (i.e. bullet staying in case).

 

I like how 115's feel with AA7 best and also like knowing I can hit a 10" plate at 25 yards 10 out of 10 times. Might end up just picking corn cob.

 

 

 

 

[B_RAD]

12 minutes ago, racer-x said:

My last 4 cases of MG JHP's were full of corn cob straight from MG.

Tiny little pieces that hide in the HP and have made it into my gun if I don't pick it out. Worst case was when it got into trigger and blocked trigger from moving enough to break shot. I pick it out now.

 

I'm going to try some of the longer 124 CMJ's out to 1.200 to test the freebore theory, but there isn't room to increase OAL significantly on the 115's and maintain reliability (i.e. bullet staying in case).

 

I like how 115's feel with AA7 best and also like knowing I can hit a 10" plate at 25 yards 10 out of 10 times. Might end up just picking corn cob.

 

 

 

 

So you don't want to try another JHP?  I can bring you some Sunday. 

Edited January 25, 2019 by B_RAD

[Ssanders224]

Like B-Rad said, you might want to give a different  JHP a shot. (And you might save money while you’re at it). 

 

You shouldn’t need to deal with cob in JHPs. 

[Sarge]

1 hour ago, racer-x said:

I've used MG JHP's for years and they have proven exceptional accuracy. 

Would like to eliminate the task of picking corn cob out of the JHP's, so I'm evaluating the accuracy of Montana Gold 115 & 124 CMJ's in my 9 major open guns.

 

First round testing with MG CMJ's is disappointing. Shooting fully supported on bench, 4 out of 10 in a 10" circle at 25 yards disappointing.

Same load with a MG JHP, (170PF, AA#7, 115, 1.165OAL), all shots in same ragged hole.

Repeated multiple times with same results.

 

Got to thinking about possible differences in freebore between the round node and JHP and setup a plunk test for each profile in my barrel.

 

JHP plunks & spins out to 1.205 OAL (1.205 - 1.165OAL=.04)

CMJ plunks & spins out to 1.270 OAL (1.270 - 1.165OAL=.105)

 

Wondering if this big difference in freebore is responsible for the lack of accuracy?

I would need to load the CMJ's out to 1.230 in this barrel to have the same freebore as the JHP's and that's not gonna work with 9.

 

 

 

Do you happen to use a hundo gauge ? If you do you can flip it over before boxing up and use a mini compressor to blow it out. Takes 5 seconds. If you don't use the hundo you can make or buy a flip tray of sorts and flip from box to box. Just offering up possible fixes. I tumble my loaded rounds to clean them up before gauging so I have corn in either MG or PD's. I figured out how to blow it out rather than picking.

[racer-x]

Thanks Jason - I cant make match on Sunday.

What JHP's are you using now? No corn cob in them from manufacturer?

 

This is a new situation with MG. I've used tons of them over the years, and this last purchase of 16K is the only time I've ever seen this. Hopefully it was a fluke.

 

So on another tangent, since I've been picking out corn cob anyway, I started using a DIY lanolin case lube and then tumbling for 15 minutes. Figured since I was already picking corn cob, why not ? Love how much easier this makes loading so much, I loaded up 5 gallons of 9 major the next day and wasn't sore at all.

 

Funny though... looking to reduce steps and I added one instead

 

 

[racer-x]

11 minutes ago, Sarge said:

Do you happen to use a hundo gauge ? If you do you can flip it over before boxing up and use a mini compressor to blow it out. Takes 5 seconds. If you don't use the hundo you can make or buy a flip tray of sorts and flip from box to box. Just offering up possible fixes. I tumble my loaded rounds to clean them up before gauging so I have corn in either MG or PD's. I figured out how to blow it out rather than picking.

 

Yes sir, I do and that's exactly how I remove the corn cob. Still have to inspect and use a tooth pick once and a while on the few that resist the air.

Think I picked that trick up from you on another post last year - thanks!

[Sarge]

2 minutes ago, racer-x said:

 

Yes sir, I do and that's exactly how I remove the corn cob. Still have to inspect and use a tooth pick once and a while on the few that resist the air.

Think I picked that trick up from you on another post last year - thanks!

I have used the MG 121 IFP before and it is same profile as 115 JHP. Loads same, shoots same and no HP to deal with. I just prefer 115's. I think I'll go back to the MG after I use up the PD's I got to try out. They tend to feed a tad better for me than the PD. And I had to adjust the MBF for the first time ever because the PD were not flipping 100%. Much bigger hole than MG though. Easier to get the corn out of.

[racer-x]

I recently got a thousand of each - 115 and 124 CMJ's, and also 121 IFP's to test out. Haven't done accuracy testing on the 121 IFP's but like you said, they are just filled 115's - I expect they will be just as accurate. Now that my loads are confirmed, I  need to use & evaluate each in practice.

 

Have always come back to 115's though - just like how dot tracks & returns faster with them.

 

Experimenting with different combinations and building my understanding is part of the fun for me.

 

 

[Joe4d]

56 minutes ago, racer-x said:

My last 4 cases of MG JHP's were full of corn cob straight from MG.

Tiny little pieces that hide in the HP and have made it into my gun if I don't pick it out. Worst case was when it got into trigger and blocked trigger from moving enough to break shot. I pick it out now.

 

I'm going to try some of the longer 124 CMJ's out to 1.200 to test the freebore theory, but there isn't room to increase OAL significantly on the 115's and maintain reliability (i.e. bullet staying in case).

 

I like how 115's feel with AA7 best and also like knowing I can hit a 10" plate at 25 yards 10 out of 10 times. Might end up just picking corn cob.

 

 

 

 

Why tolerate bad products ?
MG has a long established track record...  contact them,, bet they will fix it.

But to your question..   Ive shot a metric buttton of bullets. Most accurate bulk bullets I have ever found was Hornady HAP,,, this was back when bullet prices were reasonable and before many went to the roof in price. 

[microham]

Are all the bullets the same diameter? Might check that, will definitely effect accuracy. 

[racer-x]

5 minutes ago, microham said:

Are all the bullets the same diameter? Might check that, will definitely effect accuracy. 

 

Yes, the MG CMJ, IFP and JHP's all measure the same exact diameter.

[B_RAD]

2 hours ago, racer-x said:

Thanks Jason - I cant make match on Sunday.

What JHP's are you using now? No corn cob in them from manufacturer?

 

This is a new situation with MG. I've used tons of them over the years, and this last purchase of 16K is the only time I've ever seen this. Hopefully it was a fluke.

 

So on another tangent, since I've been picking out corn cob anyway, I started using a DIY lanolin case lube and then tumbling for 15 minutes. Figured since I was already picking corn cob, why not ? Love how much easier this makes loading so much, I loaded up 5 gallons of 9 major the next day and wasn't sore at all.

 

Funny though... looking to reduce steps and I added one instead

 

 

PD.

 

I've never seen big pieces like you. I'm sure there may be small specs from time to time. 

[Hi-Power Jack]

8 hours ago, Sarge said:

 MG feed better than PD.  I had to adjust the MBF because the PD were not flipping 100%. 

 

That's the first time I've heard that - sounds like my plans to buy copious quantities

of PD may have just ground to a grinding halt.     

[Sarge]

38 minutes ago, Hi-Power Jack said:

 

That's the first time I've heard that - sounds like my plans to buy copious quantities

of PD may have just ground to a grinding halt.     

They just have such a wide nose that they were about 5 per hundred falling into the MBF upside down. I was able to adjust the cardboard thingies to cure it though.

  As for feeding in my guns, the wider nose strikes again. You really have to stay on top of mag maintenance. At the first hint of weak springs the  rounds catch on the ramp. Again, it can be cured by keeping the gun and mags cleaner and changing mag springs more often.

 

[B_RAD]

57 minutes ago, Hi-Power Jack said:

 

That's the first time I've heard that - sounds like my plans to buy copious quantities

of PD may have just ground to a grinding halt.     

 

12 minutes ago, Sarge said:

They just have such a wide nose that they were about 5 per hundred falling into the MBF upside down. I was able to adjust the cardboard thingies to cure it though.

  As for feeding in my guns, the wider nose strikes again. You really have to stay on top of mag maintenance. At the first hint of weak springs the  rounds catch on the ramp. Again, it can be cured by keeping the gun and mags cleaner and changing mag springs more often.

 

When I switched my MBF to 9mm JHP, I simply read the instructions and in less than 5 min I had it adjusted.  My MBF has never dropped a single bullet upside down. 

 

I shoot only MBX mags but I've never had a single feeding issue with PD JHP. I've never tweaked any MBX mag. 

 

 

 

 

[Sarge]

34 minutes ago, B_RAD said:

 

When I switched my MBF to 9mm JHP, I simply read the instructions and in less than 5 min I had it adjusted.  My MBF has never dropped a single bullet upside down. 

 

 

 

 

 

My MBF Was adjusted to drop MG JHP and was pretty much flawless. Dropped some PD’s in there and not all were flipping. Had to readjust the wafers to get it 100%

[Shadyscott999]

I buy PD's by the pallet.  Everyone I know around me uses PD's.  

If you are having feeding issues, it's your gun not the bullets.  You might want to sort that out.  

Not only are they as or more accurate than MG, they are faster with the same load and significantly cheaper.  

[Ssanders224]

2 hours ago, Hi-Power Jack said:

 

That's the first time I've heard that - sounds like my plans to buy copious quantities

of PD may have just ground to a grinding halt.     

 

MBFs feed PD’s like butter. 

Absolutely zero compatibility issues whateosever.  

 

[MVPFc]

4 minutes ago, Ssanders224 said:

 

MBFs feed PD’s like butter. 

Absolutely zero compatibility issues whateosever.  

 

Unless you call someone out on being wrong. Then they all of a sudden have nothing but bad things to say about your product.

[Sarge]

30 minutes ago, Shadyscott999 said:

If you are having feeding issues, it's your gun not the bullets.  You might want to sort that out.  

LIKE I SAID, THEY FEED FINE. I JUST HAVE TO STAY MORE ON TOP OF MAG MAINTENANCE.

Not only are they as or more accurate than MG, they are faster with the same load and significantly cheaper.

  THEY ARE SOMEWHAT CHEAPER BUT ACCURACY IS ABOUT THE SAME FOR ME. AND FOR SOME REASON THEY RUN A TAD SLOWER IN BOTH MY GUNS.  

  Too be fair, I never said PD weren’t good bullets. 

[OHIOAFC]

I used MG n Berry's before i switch to PD 124 JHP ..i start reloading ammo 3yrs ago , 4 presses .. Lock-n-load , 1050 with forcht drive, 1050 with Mark 7 pro and the new Mark 7 Revolution .. There is no issues running PD JHP on 3 of my MBF after fine-tune ..  Guns i used  AKAI V8 38SC, AKAI tungsten V8 38SC, AKAI LTD 9, LIMCAT 9, LIMCAT 38SC,  SVI IMM 38SC, PT 9MM, PT 38SC, STI STEEL MASTER 9, STI GRANDMASTER 38SC, STI TACTICAL 9, STI DVC OPEN 9, STI TROJAN 1911 9, STI SPARTAN 1911 9, SIG MPX , SIG X5, SIG P320,  PPQ Q5 MATCH, CZ SHADOW 1 & 2, XDM 5.25, HK VP9, GLOCK 19,34,43 ... all feed with PD 124 JHP 

 

[Hi-Power Jack]

Sounds like I'm back in PD's stable, after all.