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Discussion Starter #1
I've started comparing 55 gr vs. 77 gr performance in my FS2000.

The 55 gr I am using for comparison is PMC X-TAC. The 77 gr is Black Hills OTM.

The 77 gr groups much better, 1/2 to 3/4 overall group size of the 55 gr at 100 yds, but I have been surprised that the 77 gr shoots about 4 in. lower than the 55 gr at 100 yds. Has anyone else had similar experience with this?

Also I've been worried about loading the 77 gr ammo in aluminum (AL) magazines due to the length of the 77 gr cartridge and the reduced internal space of AL mags so I used SS mags for both (ASC SS mags).

The 55 gr feeds no problem but I get ~ 2 Fail To Feed jams on the 77 gr per mag. It is a simple jam. I rack the charging handle back and lock it, drop the mag and the failed cartridge falls out. It usually has a big dent in the body from where it hung up on the ramp and sometimes the bullet is jammed into the casing. Anyone have increased jams with 77 gr ammo?

I know Brownell mags are put forward as the best of the best mags but they appear to be AL only. Any concerns with reduced internal dimensions of AL mags and 77 gr ammo?

Thanks for any feedback.
 

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#1 thing I would look at is your twist rate, 1 in 7 for the heavier grain bullets. 1 in 9 for the the light ones 55gr and lower. The slower twist rate (1 in 9) might be effecting your accuracy with the black hills ( I love their stuff BTW)

#2 I do find the OAL on the 77's is right at the edge of what feeds effectively in a magazine, I use them in the brownells (brown follower) magazines without much issue.

#3 the increase in jams also might be a FS2000 specific issue, I run 77s and 75s in my 10.5 LMT w/o issue. But I have no idea if the gas regulation (piston) of the FS2000 has different settings, maybe you have it on a lower gas setting, and it needs to be higher so the action can cycle with stronger as the weak cycle may have an effect on the longer OAL

#4 I dont know much about FS2000's but I hope this helps
 

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...1 in 9 for the the light ones 55gr and lower.
1:9 will reliably stabilize .223 bullets from 45 gr up to 69 gr in weight. Anything heavier than that and it's a crapshoot. I've seen 1:9 barrels keyhole 75/77 gr bullets at 50m, then again I've seen them fire 75/77 gr with no issues at all out to 300m+.

As for the OP's issue with 77gr OTM, check your chamber's feed ramp. There could be a nick or burr or something that's hanging the cartridge up due to the shape and open tip of the bullet. But on any rifle with an adjustable gas plug, the first thing I'd do is open the gas regulator to it's max setting and see if that clears it up.
 

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I do have a impact variation with the 77gr match that I shot, can't remember if it was low. I only put a few down range and I had the mag mixed with different rounds. It seems every different round shoots a little different for me. With the FS2K I have been having difficulty getting consistant groups ( at 200 yrds ) and I'm sure that I'm the culprit.The shortness of the weapon & my handling skills come into play at that distance. At 100... I don't see much of an " alarming " difference. I have been shooting with some Adventure Line mags & Brownells. I didn't have any " feed/fire/extract " issues. Everything shot pretty well.

I will do some testing today since that weapon is due for the cleaning cycle and I'm going to the range. I will bring a plethera loads and as far as mags, I will bring some GI, Brownels, and a few others. Truthfully ... I threw some lead down range the other day @100 but they were mostly the Match loads my budds have been getting me ( different loads & powders ) and I just was making sure that everything shot.
I will report back, nothing like going to the range with a purpose.... -vs- a social shoot or me just getting my fix ! Plus I just received my AR500 targets.... this should be fun.... ( cold but fun ) !

Tuna Lover 001.jpg JC AR500 targets.jpg
 

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I have been surprised that the 77 gr shoots about 4 in. lower than the 55 gr at 100 yds. Has anyone else had similar experience with this?
Yes, and it's not unusual for a heavier projectile to impact lower than its lighter counterparts.

As for the feeding problem when handloading, set the COAL to the same specs as the lighter projectiles and that should alleviate any feeding issue. Keep in mind to reduce powder charge according to the load data set forth from the bullet manufacturer during load development.

Check with BH on the recommended use of a BH loaded cartridge.

-SS
 

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Here is some pics of our shoot today. We used 4 different mags ( 1 mag per target ) , 4 different types of ammo and 2 different distances.
Our Mags
1) Brownel's
2) Adventure Line
3) Colt
4) Cammenga ( GI style heavy / thick )
We loaded the mags with 4-4-5-5 rds each of
1) 55 gr.Nosler Varmageddon Ballistic Tip
2) 62 gr PMC Xtac
3) 55 gr PMC Bronze
4) 77 gr Privi Part ( Match )

The 77 was slightly lower, Orange targets 100 yds
The 77 didn't show much difference @ 50 RED targets
We pretty much burned thru all the ammo, one after another, no feeding problems what so ever, and at the 50 yds we made it rapid fire since there wasn't much challenge, otherwise.
Take into consideration the EO set up got dropped, that''s why everything is to the right a little.
It was fun.
FS2K ammo mag comp 001.jpg
FS2K ammo mag comp 002.jpg
 

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Discussion Starter #7
#1 thing I would look at is your twist rate, 1 in 7 for the heavier grain bullets. 1 in 9 for the the light ones 55gr and lower. The slower twist rate (1 in 9) might be effecting your accuracy with the black hills ( I love their stuff BTW)

#2 I do find the OAL on the 77's is right at the edge of what feeds effectively in a magazine, I use them in the brownells (brown follower) magazines without much issue.

#3 the increase in jams also might be a FS2000 specific issue, I run 77s and 75s in my 10.5 LMT w/o issue. But I have no idea if the gas regulation (piston) of the FS2000 has different settings, maybe you have it on a lower gas setting, and it needs to be higher so the action can cycle with stronger as the weak cycle may have an effect on the longer OAL

#4 I dont know much about FS2000's but I hope this helps
FS2000 twist is 1/7 so should be no problem there.
I have been running all on "normal" gas setting. I was intending to try "adverse" today but that's another story...
 

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Discussion Starter #8
Yes, and it's not unusual for a heavier projectile to impact lower than its lighter counterparts.

As for the feeding problem when handloading, set the COAL to the same specs as the lighter projectiles and that should alleviate any feeding issue. Keep in mind to reduce powder charge according to the load data set forth from the bullet manufacturer during load development.

Check with BH on the recommended use of a BH loaded cartridge.

-SS
Sarge, thanks. I may not have been clear but the cartridges are all factory. No handloaded ones. And as I don't handload (no time), I did not understand most of your comments (ignorance on my part).
 

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Discussion Starter #9
Here is some pics of our shoot today. We used 4 different mags ( 1 mag per target ) , 4 different types of ammo and 2 different distances.
Our Mags
1) Brownel's
2) Adventure Line
3) Colt
4) Cammenga ( GI style heavy / thick )
We loaded the mags with 4-4-5-5 rds each of
1) 55 gr.Nosler Varmageddon Ballistic Tip
2) 62 gr PMC Xtac
3) 55 gr PMC Bronze
4) 77 gr Privi Part ( Match )

The 77 was slightly lower, Orange targets 100 yds
The 77 didn't show much difference @ 50 RED targets
We pretty much burned thru all the ammo, one after another, no feeding problems what so ever, and at the 50 yds we made it rapid fire since there wasn't much challenge, otherwise.
Take into consideration the EO set up got dropped, that''s why everything is to the right a little.
It was fun.
Thanks! Looks like your results are similar but some better than mine.
I had intended to try something like this today but then reality set in.
 

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Discussion Starter #10
Worst Range Day Ever

Went out today to try to verify / duplicate some of my original observations. (We are visiting relatives in North Carolina where it is warmer). Took along some help to try different hands at it too just to make sure it's not just me.
Right from the start I was getting jams on every type of ammo in every magazine. Simple jams, Failure to Feed, Failure to Chamber, even had one Failure to Eject that was so bad I had to dissemble the gun. The Moving Parts Group was stuck to the Barrel Support Group through a casing that was stuck in the chamber. I had to pull them apart from each other. The casing came out with the Moving Parts Group and was so badly deformed from hitting the ramp that it stuck in the chamber after firing. Never had that happen before! After about the 20th jam in 120 rounds I gave up in disgust. When I got back to the house I disassembled the thing and could find nothing wrong. I closely inspected the feed ramp and throat area. The feed ramp had a lot of copper buildup on it that I don't normally see. It came off with the nylon brush.
My wife reminded me that the last time I had major malfunctions was when my brother-in-law was with us (we are at his house and he was with us at the range today). He retired from the Marines in October after 20 years. He tries to run it like an M4 and gets seriously confused with the thing but he's a dead shot with it once he figures out where the trigger is. I'd like to blame him for bad juju but I don't think so.
I'll try this all again when I get home to Central Ohio. Maybe it was just shy because of all the people jammed onto the range today trying out their Christmas toys.
BTW, I got so disgusted that I ordered a pack of Brownell magazines when we got back to the house. Maybe that's the problem. They should be waiting for me when I get home.
 

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Discussion Starter #14
So what was the variable that may have caused the malfunction?
Same gun. Same magazines. Same ammo. Drove from Ohio to North Carolina but it worked fine on 12/24 at the local range here. 3 days later. Didn't get a chance to clean it in between. Different weather. Recently retired Marine at the controls today. Got me. That's why I will attempt to reproduce this when I get home.

The thing is kinda picky about magazines. Started out with some C-Products (old and new versions) in aluminum but it did have some jams. Tried ACS (new, rebranded, old C-Products) in stainless steel and it was better but there were a couple of ACS mags it did not like at all. I've been toying with the idea of trying other mags, especially the highly recommended Brownells, but preferred the roomier interior dimensions of the stainless steel and the matching black color.
At this point I'll take whatever works and all the problems track back to feed ramp interface problems. Most of the cartridges that jam due to bent cartridges also have bullet noses that are scraped and out of shape so the whole feed process in whacked on these. Either the ramp is a mess or the magazine interface is bad. I can replace the barrel and see if that changes things but I want to change the magazines again and see if that changes things again first.
 

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Here is some pics of our shoot today. We used 4 different mags ( 1 mag per target ) , 4 different types of ammo and 2 different distances.
Our Mags
1) Brownel's
2) Adventure Line
3) Colt
4) Cammenga ( GI style heavy / thick )
We loaded the mags with 4-4-5-5 rds each of
1) 55 gr.Nosler Varmageddon Ballistic Tip
2) 62 gr PMC Xtac
3) 55 gr PMC Bronze
4) 77 gr Privi Part ( Match )

The 77 was slightly lower, Orange targets 100 yds
The 77 didn't show much difference @ 50 RED targets
We pretty much burned thru all the ammo, one after another, no feeding problems what so ever, and at the 50 yds we made it rapid fire since there wasn't much challenge, otherwise.
Take into consideration the EO set up got dropped, that''s why everything is to the right a little.
It was fun.
View attachment 22004
View attachment 22005
You shoot right of the POA, and your partner shoots left of POA. Is he a left handed shooter? Curious...

I'm a bit fuzzy on what mag ran what ammo.

-SS
 

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Same gun. Same magazines. Same ammo. Drove from Ohio to North Carolina but it worked fine on 12/24 at the local range here. 3 days later. Didn't get a chance to clean it in between. Different weather. Recently retired Marine at the controls today. Got me. That's why I will attempt to reproduce this when I get home.

The thing is kinda picky about magazines. Started out with some C-Products (old and new versions) in aluminum but it did have some jams. Tried ACS (new, rebranded, old C-Products) in stainless steel and it was better but there were a couple of ACS mags it did not like at all. I've been toying with the idea of trying other mags, especially the highly recommended Brownells, but preferred the roomier interior dimensions of the stainless steel and the matching black color.
At this point I'll take whatever works and all the problems track back to feed ramp interface problems. Most of the cartridges that jam due to bent cartridges also have bullet noses that are scraped and out of shape so the whole feed process in whacked on these. Either the ramp is a mess or the magazine interface is bad. I can replace the barrel and see if that changes things but I want to change the magazines again and see if that changes things again first.
Brownells. They're on sale (10 pack) along with a 50 cal ammo can - $110.

The 2K likes them very much so.

Stack 'em tall and deep!

-SS
 

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Check the feed lips of your mags. Perhaps they've become mis-shapened or deformed and it's time to replace a couple of them.
 

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You shoot right of the POA, and your partner shoots left of POA. Is he a left handed shooter? Curious...

I'm a bit fuzzy on what mag ran what ammo.

-SS
Paul Harvey's " The Rest of the story ".... LOL

1) Yes he is a lefty , with a cast on and he just had surgery and shouldn't even been at the range.

2) I had to rotate his target 90 degree's ( for viewing ease ) , since he started in the top left with the Ballistic Tip Reloads ( that shot all over the place )
He just started in the wrong quadrant, after he had seen my groups looking better than his he took his time ( cast & all )

3) I had all 4 mags loaded with all 4 types of rounds, ( 20 rds per mag ), that way we were trying to work out any cycling issues for the" OP " when changing ammo loads we went from 1 type of ammo to another to another to another ( 55BT, to 62,to55 bronze, to 77 Match )

I can't help but wonder if some of the " OP's issue ... after reading all the struggles , and then reflecting on my PS90/AE experiences .... IF... some of what he is experiencing now isn't due to powder contaminating the " internals"... ( trigger pack, moving parts area ). It sounds real similiar to what happens to me after a couple of AE bullets misfeed then push back in the case ... which produces powder in the moving parts group area... then the gun runs like shat.

For the gun to run , then 3 days later , FTF, jam, and whatever plethra of problems he is having... just doesn't sound right , unless something was damaged or it is loaded with " powder / dirt from something .

Just a thought.
mjk1
 
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Discussion Starter #19
Have you checked your gas port setting?
Running it in Normal. Port looks OK but I don't have proper tools down here to really check it out.
I was going to try Adverse just to see if that made a difference before things went sour and I gave up in disgust.
 

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Discussion Starter #20
Brownells. They're on sale (10 pack) along with a 50 cal ammo can - $110.

The 2K likes them very much so.

Stack 'em tall and deep!

-SS
Already on the way Sarge. Every time I listen to you I come out ahead. When I don't, I wind up fiddling around until the only option left is your original suggestion.

Any idea how annoying that is?
 
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