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Bullet weights???


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 I was testing a new buffer combo (blitzkrieg-Tubbs flatwire-1/4"spacer-25#wave spring-short stroked) in my PCC yesterday and found something that seems to be contrary to current thought on bullet weight, or at least what I thought was current.

 I was shooting 100gr and 121gr JHP's (130pf both) and was getting the same feeling in recoil - not bad at all by the way, and decided to try some 165gr .356 dia. plated RN loaded to be 130pf factor out of a 5" barrel that I had loaded for a previous project pistol. I'm using the Taccom ULW 5.5" barrel now.                                                                                                         Anyhow, the 165's were very noticeably softer recoiling and when I checked the splits, they were not that much different. I was getting splits in the .15-.17 range for the 100's, .16-.18 for the 121's and .17-.19 for the 165's. These split numbers are close approximations but representative of the different loads. The 165's didn't feel like they cycled any slower that the other bullets and I thought every one felt that heavier bullets were not the way to go? I cant see why I should not use 165's? A hundredth or so on the splits would only be a second or two more on 100 rounds. The accuracy at 13 yards was not any better or worse for either bullet although the 121's did seem a little tighter of a group.

  What are your thoughts?

 

P.S. I have the Omni Robusta magnetic buffer waiting in the wings to test next. Looking forward to that and will report when done,,,

Edited by texasdawg
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I have found that while heavier bullets do feel softer, the dot bounces more. I’ve found that 95/100 gr bullets feel more harsh but the dot is very stable. ”Better” depends on what your goals are.

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 I understand your point about dot bounce. It didn't seem to me that there was that much of a difference to me in dot bounce or accuracy. I am a one dot sight, two trigger pull kind of shooter within reason, so the dot bounce is important,but where the two shoots hit are more important to me. The splits would be bigger if I waited till the dot settled for the second shot. I shoot the PCC much like I shot my open guns letting the weight of the PCC do what the comp did on my open guns.

 Your input is appreciated,,,

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Heavier bullet weight feels sluggish in recoil. Splits don’t really matter but transitions do. The faster you feel shockwave or recoil impulse travel through your body the sensation of being able to rip to the next target can occur. It’s humanly impossible to outrun any bullet weight in a pcc but the sensation of recoil is what causes the delay. 

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Interesting, the 165's did seem a little less "quick", more of a push verses the 100gr's short sharp hit. I wonder if it can be trained around or would it be an obstacle to fast stage times? More testing,,,,

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  • 3 weeks later...

Everglades Plated RN v2 (heavy plated) 115s with ~4.1gr of Clean Shot get me around 1150-1200fps from a 14.5" barrel on a regular blowback PCC. Ran with plated 147s for a while, and the reshoots due to timer issues was enough of an annoyance to try something else. 

 

For how my bolt+recoil system is set up (somewhat similar to yours), the difference in bolt cycling/dot bounce is pretty small but the 115s seem to reset the dot just slightly quicker. If you want to cut down on the recoil harshness, you'll have to reduce the reciprocating mass in the system, obviously if you reduce it too much you're gonna have an entirely new problem to solve...

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Thanks for the input. I may have encountered the entirely new problem you speak of this weekend in a match. I was ripping along doing very well and I had, I believe, the bolt cycle open before the powder was completely combusted and it was quite a surprise. My new Omni MARRS buffer and bolt weighs 18.6 oz,,, it never happen again that match.

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5 minutes ago, texasdawg said:

Thanks for the input. I may have encountered the entirely new problem you speak of this weekend in a match. I was ripping along doing very well and I had, I believe, the bolt cycle open before the powder was completely combusted and it was quite a surprise. My new Omni MARRS buffer and bolt weighs 18.6 oz,,, it never happen again that match.

 

That's wild! So I'm running a carbine tube with Shooting Innovations Bolt (weight insert removed) + Strike Industries 308 Flatwire Spring + Blitzkrieg 5015HD + NFA Short Stroke bumper in the back. My mass weight seems to be very close to yours so I wonder if the spring tension is the difference. Nonetheless I'm glad to hear nothing catastrophic happened. 

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 I do not believe it was a case separation. There were no brass particles flying that I saw or felt. It was a "soft" blast, but very eye opening (or rather eye closing!). I have witnessed two or three case separations in other peoples gun's and this was not violent like those. I am figuring a way to get another ounce or two into my set up. I was running 121gr bullets with 4.7gns of W231 and SRP. I was running pretty fast and double tapping a three target, two steel array. Going to try to science it out to find out what causes one out of two-hundred rounds to open too soon,,,

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Talked with some people and thought about the"blast". I now believe it may have been a primer that came out after igniting the powder. From others accounts that's what it was. Much relief on my part. I use range brass till it cracks. 

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On 9/5/2020 at 7:52 AM, texasdawg said:

 I am a one dot sight, two trigger pull kind of shooter within reason, so the dot bounce is important,but where the two shoots hit are more important to me.


Where the holes land IS what we mean by dot bounce. Don’t stop at two: my load development involved assuring I was crushing the gun between shoulder and offhand grip as hard as I could, leaning into it aggressively, and ripping off 4 to 6 shots on multiple targets at 10 to 25 yards in search of the smallest group size.

 

I wound up happiest with a 125gr around 140 powerfactor in my personal PCC build.

 

Heavier bullets and/or lighter powder charges softened the recoil, but the gun didn’t cycle as crisply or stay as flat.

 

Soft doesn’t matter in Open guns or PCCs. Only flatness. Like you said. ;) 

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I run a stock Leadstar Prime PCC, except that I added the Blitzkrieg short stroke plug and a JP polished carbine spring.  If I were shooting USPSA I would use a 147gr JHP @ 980 fps.  If the dot moves, I'm not aware of it.  I can put rounds right on top of each other at 50 yards as fast as I can pull the trigger.

 

If I were shooting SCSA I want a lighter load, because the recoil with the 147 load above is significant in a 5 lb. PCC.  I liked 115s @ 1000 fps.  I'm out of plated and the 115 JHP are dedicated to major.  I've tried 105s, 124/5s and 147s plated and coated, but haven't found the perfect load yet.  Loaded light I feel like I'm waiting on the gun more.  Also the dot moves more than with the USPSA load.

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We run Taccom bolts and 3-stage buffers in both of our PCC's with weights out. I have tried all different weight bullets from 100's to 147's. Really liked the 95/100 the best, but always had a few issues loading them. 

 

Have settled on 115's RN both plated & coated over 3.8grs of Titegroup. We both like the faster bolt cycle and less dot bounce. Doubles regular are almost 1 hole. Zero at 25 yards and shoot a quarter sized hole. 

 

gerritm

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  • 2 weeks later...
On 9/28/2020 at 11:29 AM, gerritm said:

We run Taccom bolts and 3-stage buffers in both of our PCC's with weights out. I have tried all different weight bullets from 100's to 147's. Really liked the 95/100 the best, but always had a few issues loading them. 

 

Have settled on 115's RN both plated & coated over 3.8grs of Titegroup. We both like the faster bolt cycle and less dot bounce. Doubles regular are almost 1 hole. Zero at 25 yards and shoot a quarter sized hole. 

 

gerritm

 

I also run the same bullet same powder 3.8gr and I too think they cycle faster, my Bill Drill splits come in around .12~.13 (4" groups). 

Just curious about the bolt weigh, why take it out?

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Funny thing is in my Granddaughter's PCC she likes the weight in, says the recoil, dot movement, & cycling is better for her. She has tried it both ways. By the way she is one of the top PCC shooter in the Houston area, and beats my sorry old butt all the time. Might be the difference in weight of the barrel. She has a lighter Taccom 13/16 barrel. We run the dame 3-stage Taccom buffer and carbon fiber hand guards. Hers is about 1 pound lighter. 

 

I like it out in my JP 14.5/16 barrel. I like the dot movement & fast cycling. Doesn't seem like the bolt hits the buffer as hard. My doubles many time touch each other. So I would say it is just personal preference and experiment to decide. 

 

gerritm

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Agreed,

I have the Brekke/Max 10.5" barrel comp system, and in corresponding with Max about optimizing the setup, he prefers the weight in the bolt and the added weight from Blitz. I'm running the Blitz buffer, and altogether my "tail heavy" setup is much softer and has less dot movement than most of the other blowback PCC I've tried.   

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