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Short OAL HP for high velocity (powder options)


JOHNNYGLOCK
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So here’s my dilemma and forgive me if it has already been discussed. I want to load the RMR 124gr HP I have on hand  for 1,150-1,200 FPS. These have a very long OGIVE for HP’s and my PCC’s have very short chambers. I need to seat them at 1.070” to fit the chamber for my 9mm carbines which is the main platform they are to be used. In a pinch, I also don’t want to blow up my pistols if I have to use them. 

Current Powder’s on hand AA#7/blue dot/power pistol/WSF/tite group

i want to do this safely without crazy pressures and was wondering if anyone could help on the matter. 
I started last night and figured AA#7 would be the safest place to start given its burn rate. So I loaded 50 each 

124gr RMR HP OAL 1.070”

Once fired cases/WSP/heavy taper crimp

AA#7 at 7.0gr

AA#7 at 7.5gr 

AA#7 at 8.0gr (this is starting compressed) 

looking for a cheap HP load for my AK-V but also safe to shoot in my CZ’s/glocks/beretta’s.... 

what are your thoughts? Can this be done safely? 
Also, bullet specs if you’ve never used the RMR HP’s before 

weight avg 123.7gr 

avg length .556”

avg OGIVE LENGTH .350”

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AA#7 is a good one for for you wanting ,the eight grain load is a +p load at the oal your loading at. The 7.5 grain load should be giving you the velocity you wanting pending the barrel length. The pcc’s will be giving you 1300-1400 with your 7.5 gr load. Power pistol is also a good powder for high vel.

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PCC chambers do not fully support the case.  Loading that short at the velocity you want produces a max pressure load.  Having suffered two case head separations, I would not do it.  Your PCC chambers are not short, the leade is short.  Have the barrel throated to take a longer JHP OAL.  Every time I've had a barrel throated it cost me a whopping $10.  Why take a chance?

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23 hours ago, Dwbsig said:

AA#7 is a good one for for you wanting ,the eight grain load is a +p load at the oal your loading at. The 7.5 grain load should be giving you the velocity you wanting pending the barrel length. The pcc’s will be giving you 1300-1400 with your 7.5 gr load. Power pistol is also a good powder for high vel.

Thanks for the data! Was this knowledge obtained with a loading program such as “quick load” or something you have experienced personally? 

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23 hours ago, zzt said:

PCC chambers do not fully support the case.  Loading that short at the velocity you want produces a max pressure load.  Having suffered two case head separations, I would not do it.  Your PCC chambers are not short, the leade is short.  Have the barrel throated to take a longer JHP OAL.  Every time I've had a barrel throated it cost me a whopping $10.  Why take a chance?

Thanks for replying and I will take it Under consideration. My V isn’t easily throated, and yes you are correct I meant to say leade/freebore not short chamber. 
 my hornady manual lists the 124 XTP at 1.060” and a max charge of AA#7 at 7.9gr which should be standard pressure specs. If I remember correctly, when I measured both bullets the XTP was .030” longer then the RMR but the OGIVE length was shorter. The V is rated for +P+ so this should be safe. 

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23 hours ago, Dwbsig said:

Power pistol is also a good powder for high vel.


He’s obviously loading ammo for non competition purposes, where the thunderous fireball produced by power pistol is a good reason not to use it.

 

Blue dot and AA7 are some of the most popular low flash powders that can get a 124 comfortably to 1,200 FPS without +P pressures.

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10 minutes ago, JOHNNYGLOCK said:

The V is rated for +P+ so this should be safe. 


The barrel is more than strong enough for it. 
 

However, having seen several PCCs go down for the day with blown-out cases and hearing about many many more in BEs PCC forum? I’d listen to the warning.

 

Hot ammo + used brass + poor chamber support from a PCC? Bad combination. You don’t want half a case stuck in the gun, so keep the pressures down. Even the minimum load will easily hit 1,200 FPS out of a 14”+ barrel anyway.

 

If you need convincing? Drop a round into the chamber and look at how much of the lower walls are exposed all the way around. Compare that to your handguns. 😉

 

Edited by MemphisMechanic
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1 hour ago, MemphisMechanic said:


He’s obviously loading ammo for non competition purposes, where the thunderous fireball produced by power pistol is a good reason not to use it.

 

Blue dot and AA7 are some of the most popular low flash powders that can get a 124 comfortably to 1,200 FPS without +P pressures 

👍🏻

Thanks Memphis! I haven’t yet played with blue dot that much but have with all the others. First time using the RMR HP’s, I’ve mainly loaded the Speer GD and XTP in 9 for my pistols I bring in the deer woods with me. 
well aware of the PP bright flash. I use that in my .357SIG flame thrower 😎

I will come off a grain or two with the AA#7 and chrono every round I fire. Soon as I get the velocity I’m looking for I will stop!! I know these blow back blasters aren’t designed for a healthy supply of HOT ammo but I also know 1,200FPS should be easy with a 10.5” barrel. Just was looking for insight from someone who has done this. 
since were on the topic, do you think a roller delayed would be better suited for the high pressure stuff? Thinking about a roller delayed stribog. 

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3 hours ago, JOHNNYGLOCK said:

I know these blow back blasters aren’t designed for a healthy supply of HOT ammo but I also know 1,200FPS should be easy with a 10.5” barrel.

 

Some shooters are approaching major PF in 16" guns.  124gr NATO ammo is 1200fps in a 4-5" barrel, so you will have no problems in a 10.5".  One of the things you can consider is leaving the weight in the bolt and going to a Tubb flat wire recoil spring.  That evens out the pressure, applies more pressure against the bolt to keep it closed slightly longer, and avoids spring stacking.  You can go to a 308 spring if you need more pressure on the bolt.

 

The thing you really have to watch is set back.  My PCC has a small feed ramp built into the lower specifically to allow good feeding of JHPs.  The promlem is with mags.  Both the SGM and Glock brand mags are held lower my the mag catch.  So shooting truncated cone JHPs is a problem.  Sometime the round is stripped and hits the bottom of the feed ramp and gets set back.  This jams the gun, but at least you can get the round out.  The real problem is when the round hits really low on the feed ramp, sets back, but still chambers.  That is a dangerous situation with max loads.  ETS mags sit higher in the gun than the other two and the feed lips are such that the top round is pointing directly into the chamber.  Since I have lots of Glock, SGM and Magpul mags, I'm going to all round nose bullets for the PCC.  My receiver is skeletonized, so every time I have a case failure, I get debris blown in my face.

 

If you have problems with your RMR JHPs, you can try Everglades Gen2 JHPs.  They have a more rounded profile and feed a lot better, in more circumstances.

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Zzt, I appreciate the advice on the PCC! Keep in mind that this is a AK design. I do have an AR9 that I use in for PCC class and I will put your advise into motion with it. The RMR HP’s are very rounded and that is the reason why I’m having to seat them so deep. As long as my chrono corporates I will find something that works.  My CED m2 has always given me fits recording. 
My go to round for all is a 124 FMJ with tite group. I have a lot of these HP and I want to use them in the PCC’s 

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9 hours ago, JOHNNYGLOCK said:

Thanks for the data! Was this knowledge obtained with a loading program such as “quick load” or something you have experienced personally? 

I’ve been playing with AA 7 in my open gun a couple months backs. I just ran some loads over my chronograph last week, some of the loads I ran over the chrono was with power pistol Thur my Ruger Pcc with a 16” barrel. These was some old stuff that I had was just curious what they would do Thur the rifle. The rifle seems to be running 150-200 FPS faster then my pistol.

124 gr jhp P.D. 1.135 oal 5.4 grs power Pistol  1256 FPS.

124 gr r/n  1.15   oal.        6.0 grs power Pistol  1379 FPS.

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1 hour ago, Dwbsig said:

I’ve been playing with AA 7 in my open gun a couple months backs. I just ran some loads over my chronograph last week, some of the loads I ran over the chrono was with power pistol Thur my Ruger Pcc with a 16” barrel. These was some old stuff that I had was just curious what they would do Thur the rifle. The rifle seems to be running 150-200 FPS faster then my pistol.

124 gr jhp P.D. 1.135 oal 5.4 grs power Pistol  1256 FPS.

124 gr r/n  1.15   oal.        6.0 grs power Pistol  1379 FPS.That’s what I’m looking for, thanks! I have a bunch of PP at the moment. I will try that next. Thanks, wow 1250 with 5.4 😀

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5 hours ago, Dwbsig said:

124 gr jhp P.D. 1.135 oal 5.4 grs power Pistol  1256 FPS.

124 gr r/n  1.15   oal. 6.0 grs power Pistol  1379 FPS.


~155 and ~170 power factor. Booking. 😎

 

Slow burn powders really take advantage of the additional barrel length to push that bullet up to speed.

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3 hours ago, igolfat8 said:

The same load crono’d through a 5” pistol and a 16” rifle will NOT be the same velocity. A longer barrel will yield a higher velocity, period.


Not always. A long time back I had a minor 124gr load with a sprinkling of Clays in the case. Barely hit 128pf with a G34.

 

It was *slightly* slower through a 16” AR9. I assume the extra 10.5 inches of friction caused more drag than the tiny amount of gas could compensate for.

 

Everything else has definitely been faster. Even powders as quick as Titegroup and N320. And the slower the powder burns, the more of a boost you’ll probably see.

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