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SGC

Ideal PF for Blowback PCC?

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Ever since I built my PCC earlier this year I have not been able to achieve the dot tracking that many here describe.  I originally loaded a 124 grain everglades plated bullet to 130 pf  (3.2 grains PrimaV) and called it good for load development and have run this load for 1500-2000 rounds without issue.  I've seen others here mention that hotter loads worked better so just for kicks I loaded up some test rounds at 3.5 and 3.7 grains and went to the range to shoot pairs.  To my surprise the 3.5 was marginally better than 3.2 and 3.7 was significantly better that either of the other loads.  Typically I get dot movement up and to the right but at 3.7 the dot tracked straight up and down and returned faster.

 

My question is from your testing what has been the ideal PF to shoot for in your builds?  I debating if I should continue tweaking or just leave it at 3.7 grains and call it good, but was curious where I was compared to what others have found as ideal.  I don't care about recoil, but am focused on minimizing dot movement. 

 

Obviously bolt, buffer, recoil springs will play into this but ideal loads will likely be similar.  For reference I have a taccom extreme bolt with the weight installed, taccom 3 stage buffer short stroked, rifle spring that came with the buffer, hiperfire 24C trigger, and MBX barrel with pinned comp. 

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From my testing with my JP setup, before it was short stroked I could tell when I shot 147gr syntech, the action felt "lazy" and while I never had a problem locking up the trigger, it just didn't feel crisp. When I went to the short stroke setup, for me everything cycles fast enough I can do splits much faster than I can accurately do splits for most targets beyond 10yds. I run 124gr acme coated that hits 133pf in my 5" pistols, never checked with it does in the 14.5" since I'm switching my PCC to a JP ULW that only has 5.5" of actual barrel.

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Its really comes down for what works for you and your equipment.

 

Late 2017/early 2018 I played with 147 gr RN plated bullets.  I developed a load that seemed reasonable and made minor. 

 

Then I played with different combinations of buffers, springs and bolts. Once I felt I had the perfect setup, I went back to experimenting with the ammo.  With the 147 gr bullets I ran everything from 115 to 150+ Power Factors.  For most of the 2018 season I ran this bullet with a 144 PF and loved it.  Good accuracy, OK recoil and little dot movement. It was hot enough that the bolt did not feel sluggish.

 

Late Fall of last year friends recommended I give some 98gr .380 bullets a try.  Again after a bunch of experimenting, I settled on this bullet run at 138 PF. Its now my "go to" load.   I did try different weight buffers and bolts as well as different springs but found that (for me) the perfect setup for my 147 gr load was also the perfect setup for the 98 gr bullet.

 

Again, for me its the perfect setup and load.  I've allowed several others to shoot my gun and very few liked it.  Some felt the recoil needed to be reduced.  Others felt that the dot moved too much.  Others thought the gun is too heavy (6# 4 ounces),

 

I've only shot one other PCC that "felt" better to me than my gun.  Like mine, its a Frankengun but something about that gun just felt better. It was a prop gun in a man-on-man shootoff and I got to shoot a little over 100 rds through it.  The owner was gracious enough to answer all my questions but I was not able to "exactly" duplicate that gun and feeling.

 

Can't please everyone so please yourself.

 

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3.8g of N320 with a Precision Delta 124g JHP with an OAL of 1.100, this load makes a 141 PF across our clubs CED chrono. The dot is tracking identical to your 3.7g load and although I have not shot a lot of this load a bunch, its definitely the "sweet spot". when I came up with this load I didn't have a lot to go off of so I winged it and developed several different loads, the 3.8 was the "base line" starting load. I them went with 4.0g & 4.2g w/124g and then tried 4.0g behind a 147g Extreme.

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19 minutes ago, Flatland Shooter said:

Can't please everyone so please yourself.

 

Ricky Nelson??

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6 minutes ago, PewPewJohnson87 said:

and then tried 4.0g behind a 147g Extreme.

 

Have you chrono'd that load?  Shot with a Taccom ULW barrel?

 

At 3.3 gr N-320 and Xtreme 147 gr RN bullets in a 16" barrel I got a 144 PF.

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Posted (edited)

I think it was from a Ricky Nelson song from the 60s. Darned if I can remember the name though.

 

ETA OH, "Garden Party"

Edited by egd5

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Posted (edited)
7 minutes ago, Flatland Shooter said:

 

Have you chrono'd that load?  Shot with a Taccom ULW barrel?

 

At 3.3 gr N-320 and Xtreme 147 gr RN bullets in a 16" barrel I got a 144 PF.

yes it was HOT!!! 1103FPS 162PF. FYI I did load this bullet a little longer @ 1.120, it was a 16" barrel

Edited by PewPewJohnson87

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At Orr Tactical , we worked up a USPSA load. 100 grn Berry's running 1310 fps out of my MBX 14" pinned/welded comp barrel.It's making 131 PF. Dot had minimal movement , gun runs flat and doesn't feel sluggish at all :) 

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4 hours ago, SGC said:

 Typically I get dot movement up and to the right but at 3.7 the dot tracked straight up and down and returned faster.

 

The thing is... a rifle needs a good shooter just as much as a handgun does.

 

I’m not directing this at you, moreso at any novice to PCC who reads this.

 

Don’t shoot like a Vietnam era solider: The oldschool technique everyone emulates unless trained otherwise:

* Tucks stock into shoulder pocket

* shoulders bladed to target (so weak side is well ahead of strong, torso around 45 degrees)

* stock extended to comfortable length

* head laid on stock with noticeable lean to the side.

 

This is an awkward stance to move in, and recoil is applied to your torso well out on your shoulder and the dot tracks... yep. Up and outboard of centerline as your shoulder rotates behind the recoil. So up and right for a right, up and left for a lefty. 

 

Instead:

* Mount the bottom corner of the stock on your pec directly below the eye.

Head stays nearly vertical, you don’t lay it over onto the stock. (Just dip your chin straight down to brace your cheek on the stock.)

* collapse your stock a few notches and rotate the shoulders and hips square to the target

* grip the handguard out where it fully extends your weak arm, then pull back about an inch so the elbows is just slightly broken. Drive the gun back hard into your shoulder, and lean forward in the torso and drive the shoulder forward into the gun. You should not need your firing hand to support the rifle. 

* get your weight forward and knees bent

 

Much like with a handgun, clamping down on the gun and making your thigh/abdominal/arm muscles burn while your shooting? It leads to a MUCH more controllable recoil experience.

 

Shooting aggressively shouldn’t be comfortable. You’re driving the gun after all - only novices let things happen the other way around. :D 

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11 minutes ago, MemphisMechanic said:

 

Head stays nearly vertical, you don’t lay it over onto the stock. (Just dip your chin straight down to brace your cheek on the stock.)

 

 

To minimize head movement, play with the height of your red dot.   I added a 1/2" riser to the bottom of my Cmore.  (Initially I made some aluminum spacers each 1/8" thick and stacked them at different heights all the way to 1" before deciding 1/2" was my sweet spot.)  In my case it consistently reduced the time it took to go from the belt to first shot.

 

These are an example. (Cmore Railway requires two.)   https://www.brownells.com/optics-mounting/rings-mounts-amp-bases/rifle-bases/1-2-2-piece-picatinny-riser-mount-prod104294.aspx

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9 minutes ago, MemphisMechanic said:

 

The thing is... a rifle needs a good shooter just as much as a handgun does.

 

 

This is probably the biggest driver of what i'm seeing as I still have much to learn about shooting a rifle fast.  I've been actively working on getting away from the more traditional stance and being able to drive the rifle but still have some old habits to break.  Shortening the stock definitely has helped but still have to ingrain driving it into the shoulder and clamping down while on the clock.  At the end of the day I know no amount of load development is going to make all that much difference in my scores, but the engineer in me can't help but want to optimize the mechanical system as much as possible. 

 

1 hour ago, PewPewJohnson87 said:

3.8g of N320 with a Precision Delta 124g JHP with an OAL of 1.100, this load makes a 141 PF across our clubs CED chrono. The dot is tracking identical to your 3.7g load and although I have not shot a lot of this load a bunch, its definitely the "sweet spot". when I came up with this load I didn't have a lot to go off of so I winged it and developed several different loads, the 3.8 was the "base line" starting load. I them went with 4.0g & 4.2g w/124g and then tried 4.0g behind a 147g Extreme.

 

Seems like I'm on the right track, how did the hotter 124 grain loads behave?  Did going above 3.8 start getting a different dot movement, harsher recoil, etc?

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42 minutes ago, assaultthesalt said:

At Orr Tactical , we worked up a USPSA load. 100 grn Berry's running 1310 fps out of my MBX 14" pinned/welded comp barrel.It's making 131 PF. Dot had minimal movement , gun runs flat and doesn't feel sluggish at all :) 

 

Did the lighter bullets work better for you than a heavier 115 or 124 grain?  I tried some blazer brass 115 grain factory ammo to see if that would be better than my 124's but recoil was much harsher and dot movement was slightly worse.

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Posted (edited)
8 hours ago, SGC said:

This is probably the biggest driver of what i'm seeing as I still have much to learn about shooting a rifle fast. 

 

That’s true of all of us when learning to run a new weapon.

 

Quote

I've been actively working on getting away from the more traditional stance and being able to drive the rifle but still have some old habits to break.  Shortening the stock definitely has helped but still have to ingrain driving it into the shoulder and clamping down while on the clock.

 

If the stock is further from centerline than your nipple, you’re doing it wrong.

 

I find this helps: Mount the gun exactly as you want it - stock inboard and head not excessively tilted. Don’t move your head. Activate the safety and move the gun to the required start position, such as stock on belt. Then consciously (1) snap the stock back up against your cheek and (2) drive it hard into your shoulder with the offhand. Begin shooting as usual.

 

After a few weeks that’ll be your new normal and you won’t want to shoot any other way.

 

 

Edited by MemphisMechanic

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The issue I see here, is that there's lots of anecdotes about how things 'feel' and how much dot movement you see....

 

What I don't see is times/HF.

 

IMO shoot a few drills that require different skills (entry/exit, shoot on the move, etc.) and see what works better. If you're running to a spot, standing place, and shooting a pair, fine.... but then you're not competitive anyways, so who cares about 135 vs. 145 PF

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Posted (edited)

Great points here regarding proper stance / grip. I took John Mcphee's 100yard carbine class over the winter and my big takeaway from the slow-motion video analysis was that at the beginning of the class, none of the shooters had their body weight leaned forward enough nor were any of us holding the gun tightly enough or pulling the buttstock back vigorously enough into our bodies. The difference that correcting these two factors made in our group sizes (standing, kneeling and prone) by the end of the class was astonishing. The same applies to recoil control / double-tap speed when shooting quickly. To Acer2428's point, there is definitely a measurable, quantifiable difference between holding the rifle loosely and with bodyweight back on the heels versus pulling buttstock in aggressively and maintaining an athletic stance with the weight forward. Even with my height and (over)weight, the recoil will still bounce me around, making double taps open up (A/C or A/D versus double alpha), if I don't mount the gun properly and get the right cheek weld, buttstock positon and lean into the gun with knees broken, weight on the balls of the feet, and shoulders forward of hips.

 

Getting the buttstock positioned further into the centerline of the body as MemphisMechanic suggests is also helpful, but I still try to roll my strong-side shoulder forward and up toward my ear and drop my chin slightly to form a pocket for the butt of the gun between the pec / shoulder / cheek, then I really pull the gun into that pocket hard with both hands. I also have more of a break in my support-side elbow and that hand a little closer to me, not elbow all the way locked out and hand close to the end of the handguard. You want to maximize your contact with the rifle, kind of wrap yourself around it and get your weight into it. This all gets exponentially harder when you are also trying to move around, I struggle to maintain that upper body tension while shooting on the move. That's something I just need to practice more.

 

I am still new to PCC, but in 5.56 carbine / shotgun I find that adjusting length of pull for your height/reach is really helpful. I'm large and most carbine stocks are marginal LOP for me at full extension.Those wacky stocks with adjustments for comb height, toe drop, cant, LOP etc are popular in 3-gun for good reason. It is far easier to get a consistent mount, proper cheek weld and eye position and thus superior recoil control if the gun is properly fit for your anatomy. Take a few minutes to make sure you have the right setup then practice mounting the gun as MemphisMechanic suggested. I try to get the LOP adjusted so that if I hold the rifle in my firing hand with elbow bent around 90 degrees, the buttstock touches my bicep. Some prefer a shorter LOP but in my experience you are then forced to compensate by pulling the gun in even harder. Over even a short time period, recoil and muscle fatigue will gradually open up a gap and the gun will start to bounce forward and backward as you shoot when seen in slow motion video. I'm pretty sure Max Leograndis had a video about his preferred LOP somewhere, and if I recall correctly he also goes for a longer LOP.

 

edit: found the Max Leograndis thing on LOP buried in 2 year old youtube comments: "BTW I run my stock full out on the A5 tube. There is a noticable different in recoil control between the 6th and 7th positions. Having a longer LOP on a rifle is super super stable"

Edited by JGT

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3 hours ago, JGT said:

 I'm pretty sure Max Leograndis had a video about his preferred LOP somewhere, and if I recall correctly he also goes for a longer LOP.

 

edit: found the Max Leograndis thing on LOP buried in 2 year old youtube comments: "BTW I run my stock full out on the A5 tube. There is a noticable different in recoil control between the 6th and 7th positions. Having a longer LOP on a rifle is super super stable"

 

I think Max has changed his LOP over the last few years...

 

This is a more current picture with his LimCat...

 

 

Max Leograndis PCC Hand Grip.jpeg

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Posted (edited)

I agree with you that in the picture it appears as though the stock is not fully extended on the buffer tube, HOWEVER, look at the distance between his chin and firing-hand thumb. It matches up with the Patrick Kelley video on length of pull or is even longer (3 fingers width distance). Link: 

 

In the picture, if Max were to reposition the gun such that the buttstock were parallel with his forearm while keeping the arm bent 90 degrees it appears as if it would approximately reach the crook of his arm / bicep.

 

Further, if you look at his support hand, it is quite close to the receiver with elbow slightly bent, another piece of the evidence that the LOP on the buttstock is sufficiently long for his frame. When guys run the stock too short for their height/reach, they end up with their support hand much further out on the gun, even without doing the extreme Costa grip with the elbow locked and thumb on top of the handguard.

 

Mr. Leograndis messes with his setup a lot and I have no doubt that it evolves over time, but this photo still appears (in my mind) to show a relatively longish LOP despite the apparent positioning of the buttstock on the buffer tube. Remember this is all relative to one's personal anatomy.

 

edit: here's a link to a video where he has his new Limcat held with arm at 90 degrees and the buttstock is actually well past the crook of the arm / bicep. I could be wrong but I think he is not very tall.

 

 

 

Edited by JGT

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5 hours ago, JGT said:

then I really pull the gun into that pocket hard with both hands.

 

I heartily agree with you excellent post with one minor exception.  Be it right or wrong, I do not exert much force on the pistol grip.  I find a looser grip helps my trigger control.  Pull too hard with the strong hand and my trigger finger loses that delicate touch needed for long shots and the speed needed for fast splits.

 

Like I said, be it right or wrong.   But I would like to hear from others how they do it.

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I agree more with you JGT. The lop really depends more on body size than just running it short. I'm 6'5" and to me all the way out is not all that long. As both you and Memphis said, I believe the biggest thing to help is keeping the gun pressed into wherever you shoulder it on your body. Holding it loosely and letting it bounce is the biggest thing that will increase dot bounce. Of course knees bent and weight forward is a big part of it too.

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Posted (edited)

I'm also 6'5" so it makes sense that you'd be in the same boat as me. For 80% of shooters they probably don't have to worry about LOP as much, just pull the stock out a notch and go.

 

I should make it clear that I'm a total FNG in competition shooting and you could fill a tanker with what I don't know. I might learn in 6 months that I have this all wrong. That being said, I try to pay attention and watch what the  more experienced people say and do, and I can chime in with my direct experiences from classes or matches with some of the top folks.

 

Flatland shooter, I agree with your point on firing hand grip pressure and the potential effect on trigger finger motor control. I grip the PCC pistol grip pretty much the same way / same pressure I hold a handgun: tight but not so hard it compromises my ability to manipulate the trigger.

Edited by JGT

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Agree on the grip. I also put the ERGO Deluxe Tactical grip on mine. It is fat and rubbery feeling and fills my hand better so the my finger hits the trigger in a better spot. It just feels more natural.

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I’ve tried all the way in and on the peck and, stock all they way out  my peck hand closer to middle of the hand guard. When I say I’ve tried I’m talking multiple matches and minimum 1000 rounds. What gives me the best hits is stock all the way out. I’m not going to talk in absolutes because we are all built different and stronger and weaker in different areas. Try everything find what works for you. My go to is mbx buffer, blue internal, shortest setting, longest spacer, yellow sprinco and 137-140pf. I stick to medium burn rate powder (wsf) and 115gr jhp. 

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23 hours ago, SGC said:

 

Did the lighter bullets work better for you than a heavier 115 or 124 grain?  I tried some blazer brass 115 grain factory ammo to see if that would be better than my 124's but recoil was much harsher and dot movement was slightly worse.

Yes....WAY less dot movement with the 100's.On my MBX , I'm running the Blue recoil spring and yellow buffer tube spring.FWIW

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