Weight savings of skeletonized lower & upper receivers

[jrdoran]

Thinking about building an ultra lightweight 9mm PCC.     ( I'm aware of the shrouded barrels, placement of weight savings) This is a steel challenge rifle. 

 

I'm intrigued by the leadstar skeletonized uppers / lowers ( they also look super cool ).   I want to convince myself to buy one. 

 

However, I went down and weighted an upper / lower at my local gun dealer ( bare ) .   I was surprised that is was only 16.1oz.     ( 8.8 lower / 7.3 upper ) ( Aeroprecision ) ;   

 

This has me wondering exactly how much lighter can one of the fully modified skeletonized chassis can be ?   If the total weight of a basic receiver is only 1lb, can they save 4oz ?   8oz ?  

 

appreciate some info here.  thx

 

 

 

 

[zzt]

According to the web site, the Leadstar Prime upper/lower set weighs 19.8 oz.  My Prime with Wiland USA LLW 9mm shrouded barrel and Leadstar's new carbon fiber handguard weighs under 5 lbs.  Total weight as I currently shoot it is 5 lbs. 7.5 oz. That is with the LRBHO system intact, the 3 oz. bolt weight installed,  a Tubb long flatwire buffer spring, one quarter, the 3/4" Blitzkrieg solid steel slug for short stroking and a C-More Railway sight.

 

The Short stroke slug weighs 2.5 oz.  The Railway weighs 5 oz.  By removing the 3 oz. bolt weight, using a nylon short stroke kit rather than the steel slug and quarter and a lighter reflex sight you can easily get it down to under 5 lbs. again.

[jrdoran]

34 minutes ago, zzt said:

According to the web site, the Leadstar Prime upper/lower set weighs 19.8 oz. 

 

 

https://www.leadstararms.com/receiver-set-skeletonized-pcc-ar-9-lsa-9-black/

 

I saw the same thing, but I can't square it with my own personal weight check of a basic upper/lower  that weighs 16oz;   

 

All the rest of the stuff we agree, but that is applicable regardless of upper/lower chosen.   @zzt  Should you have yours apart for any reason please verify the 19.8.  I suspect it is actually lower.  I've got some calls into leadstar also.  They really do seem like high quality pieces.

Edited June 1, 2020 by jrdoran

[StealthyBlagga]

In a major match last year, I saw a competitor experience an out-of-battery discharge with his skeletonized blowback PCC. The generous lightening slots cut in his upper allowed flying fragments of brass to exit the left side of the receiver and cut up his forearm so badly he had to go to hospital to have the wounds patched up. While not life-threatening, it looked painful and impacted his match performance (he finished the match on a hurry-up schedule with a heavily bandaged arm).

 

In general, a plain vanilla forged receiver is lighter and stronger than a billet receiver. Although lightening cuts in the upper might look sexy, I don't see the weight saving being significant, especially so close to the center of gravity. Given the safety concerns above, lightening slots in the upper seem like a waste of time and money to me. For a lightweight build, I'd just use a standard forged flattop stripped .223/5.56 upper (long ejection port, no ejection port cover, no forward assist) and spend the money saved on practice ammo (or, if you must, a bitchin' Cerakote job).

Edited June 1, 2020 by StealthyBlagga

[zzt]

I've had two instances with mine where a round hit the feed ramp, pushing the bullet farther into the case, but still chambered.  On both there was case separation and I got splattered in the face with what felt like unburned powder.  On one the case head separated.  On the other is just ruptured and stayed in the chamber.  In neither case was there any brass shrapnel.  Fourtunately.

 

On a Leadstar Arms PCC, the unskeletonized upper and lower weigh 21.3 oz., vs. 19.8 for the skeletonized.  So 1.5 oz. total difference.  If I could have gotten everything that comes with the Prime in the standard set, that's what I would have done.

[Darqusoull13]

57 minutes ago, StealthyBlagga said:

In a major match last year, I saw a competitor experience an out-of-battery discharge with his skeletonized blowback PCC. The generous lightening slots cut in his upper allowed flying fragments of brass to exit the left side of the receiver and cut up his forearm so badly he had to go to hospital to have the wounds patched up. While not life-threatening, it looked painful and impacted his match performance (he finished the match on a hurry-up schedule with a heavily bandaged arm).

 

In general, a plain vanilla forged receiver is lighter and stronger than a billet receiver. Although lightening cuts in the upper might look sexy, I don't see the weight saving being significant, especially so close to the center of gravity. Given the safety concerns above, lightening slots in the upper seem like a waste of time and money to me. For a lightweight build, I'd just use a standard forged flattop stripped .223/5.56 upper (long ejection port, no ejection port cover, no forward assist) and spend the money saved on practice ammo (or, if you must, a bitchin' Cerakote job).

100% agreed with this. You couldn't pay me to shoot a blow back PCC with a cut apart upper. 

You will be far better served with an aluminum shrouded barrel and light hand guard to minimize swing weight for Steel Challenge. 

Most people don't even think to check the weights of the "Gucci" skeletonized uppers as most of them weigh more than a standard forged AR upper. If you must save weight go with a no FA / dust cover upper and save ounces that really don't contribute to a 9mm PCC function. 

[ChuckS]

6 minutes ago, StealthyBlagga said:

In a major match last year, I saw a competitor experience an out-of-battery discharge with his skeletonized blowback PCC. The generous lightening slots cut in his upper allowed flying fragments of brass to exit the left side of the receiver and cut up his forearm so badly he had to go to hospital to have the wounds patched up. While not life-threatening, it looked painful and impacted his match performance (he finished the match on a hurry-up schedule with a heavily bandaged arm).

 

In general, a plain vanilla forged receiver is lighter and stronger than a billet receiver. Although lightening cuts in the upper might look sexy, I don't see the weight saving being significant, especially so close to the center of gravity. Given the safety concerns above, lightening slots in the upper seem like a waste of time and money to me. For a lightweight build, I'd just use a standard forged flattop stripped .223/5.56 upper (long ejection port, no ejection port cover, no forward assist) and spend the money saved on practice ammo (or, if you must, a bitchin' Cerakote job).

Blowback rifles are so frigging dirty (no matter what powder and bullet) the filth factor alone should discourage you if the fragging doesn't do it for you. SB has sage advice here!

[jrdoran]

Candid and useful feedback.  

 

Also the Prime comes with more than just the skeletonized receiver as ZZT pointed out. 

[Jcgatus]

On 5/31/2020 at 10:24 AM, jrdoran said:

Thinking about building an ultra lightweight 9mm PCC.     ( I'm aware of the shrouded barrels, placement of weight savings) This is a steel challenge rifle. 

 

I'm intrigued by the leadstar skeletonized uppers / lowers ( they also look super cool ).   I want to convince myself to buy one. 

 

However, I went down and weighted an upper / lower at my local gun dealer ( bare ) .   I was surprised that is was only 16.1oz.     ( 8.8 lower / 7.3 upper ) ( Aeroprecision ) ;   

 

This has me wondering exactly how much lighter can one of the fully modified skeletonized chassis can be ?   If the total weight of a basic receiver is only 1lb, can they save 4oz ?   8oz ?  

 

appreciate some info here.  thx

 

 

 

 

I have owned 4 pcc's so far. From the most budget, lightest Taccom build, to the most gucci pricey Limcat Tron. In between were the Iron City. and the MBX. I settled with the Berserker Lite 

 

Here's the kicker. I got into PCC after a buddy let me shoot his MPX in a match. I got hooked. After doing some research, I decided to start off with a budget build. I then sold it and upgraded constantly. 

 

From the 2 years of shooting pcc, here is what I learned so far, which I wish I knew before.

1. Reliability is King.

2. Functionality over looks.

3. Balance over weight.

4. Looks are bonus points. Lol

 

Ive witnessed common issues that most blowback pcc's get, even ones that dealt with the glock and colt mags.

 

There are isolated incidents that can occur with any firearm. Ive seen accidental discharges with a stock m&p that was a result of a reverse primer. Its all about qc.

 

A lightweight pcc may be beneficial for steel challenge but not necessarily for uspsa. Shooting with Max, he said there is more pros with having more weight in the back end. When running long distances with one hand, a balanced pcc will feel like running with an open gun as long as the front end was lighter.

 

Investing in the right parts will also save you a ton of money. Buying a 150 dollar comp for a 16" barrel is almost useless. Dont get a trigger just because it is dubbed a pcc trigger. Achieving .10 splits is near impossible if the reset weight is too light. There are bolts known to easily go full auto so thats an easy dq at a stage. Lastly, the buffer and buffer spring really affects dot bounce. 

 

Dont be afraid to fail and learn.

[zzt]

52 minutes ago, Jcgatus said:

A lightweight pcc may be beneficial for steel challenge but not necessarily for uspsa.

 

I don't see a lot of benefit to a light weight PCC for SCSA if it still swings like a log.  The very last thing you want is weight out front.  I took off the 16" pencil barrel my PCC came with and substituted a Wiland USA LLW barrel.  Now there is no weight out front and transitions are greased lightning.  The gun balances at the magwell.

[jrdoran]

So is it safe to conclude that the notion of a skeletonized chassis being lighter than a standard forged AR chassis has been debunked ?   

I have not been able to find any evidence that the leadstar uppers / lowers are in fact lighter.   

 

PS,  I already have a sub 5lbs PCC  ( Net wet is 4# 9oz without iron sights )  but was thinking of building another hence the exploration of skeletonized; 

 

 

 

Edited June 3, 2020 by jrdoran

[Jcgatus]

28 minutes ago, jrdoran said:

So is it safe to conclude that the notion of a skeletonized chassis being lighter than a standard forged AR chassis has been debunked ?   

I have not been able to find any evidence that the leadstar uppers / lowers are in fact lighter.   

 

PS,  I already have a sub 5lbs PCC but was thinking of building another hence the exploration of skeletonized; 

 

 

 

That is impressive. Skeletonized uppers will always be lighter next to a comparable upper of similar design and material. My MBX pcc was close to 6lbs (without magwell). Meanwhile, my iron city pcc was 5.5.  

[Kokeman]

I was going to skeletonize a upper and lower. I was using a 3d cad software and it would give you the weight based on the volume. I took the weight before and after I designed the cut outs in the receivers. The difference according to the cad software was less than 2 ounces. I did not feel that little bit of weight savings was worth the extra machine time. Plus the weakening of them could not not justify the slight weight savings. 

[mahamoti]

120% receivers are dumb.  Almost always heavier than a forged receiver set.  Extra ports for dirt to get in, and blowback gases to get out.  There's just no good reason for it besides "whoa it looks cool."