Bushmaster Carbon 15 in 9 mm - loading problems

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albog

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I have a Bushmaster Carbon 15 in 9 mm., and i'm using the aftermarket 10 rd. mags (the short double stacked ones). I have the following minor problems with this rifle:

1. with one round chambered in the rifle, the fully loaded mag (with 10 rounds) doesn't go in, only the mag loaded with 9 rounds can go in.

2. when the mag is inserted and you release the bolt on an empty chamber, the first round doesn't properly chamber - it looks like there's not enough bolt spring pressure to strip the first round from the mag and chamber it.

Any suggestions? Where can I get a stronger bolt spring and how to replace it? Will a stronger bolt spring allow a problem free cycling of the bolt under the pressure of 9 mm loads? Also, what can I do to the mags to be able to load 10 rounds and insert them into the rifle with one round chambered and to smooth out their operation overall?
 
mag seating/stripping

I assume you are trying to load 10+1in---there is nothing wrong this mag(RRA lar)/rifle combination.it simply does not work well this way. loaded on an open bolt no problem I bet. most of these mags designed to hold 10rds will not even seat on a full mag/bolt closed. Lots of pistols using factory made 10rd mags are difficult to seat mag on slide forward as well(Sig 226 in .40 is textbook example of this)
Are you having any issue with bolt hold open on last shot? this might be an indication that mag follower is not moving far enough through feed lips or mag engagement slot needs tunning or lips of mag need to be opened up a bit. another option is to pull mag apart (metal with orange follower) and remove a bit of material of bottom (@1/8" to allow follower to go deeper in body) in theory 10 1/2 rounds worth of room. grey follower... your hooped. hope this helps as I had same issues but work fine now.
 
heckler said:
I assume you are trying to load 10+1in---there is nothing wrong this mag(RRA lar)/rifle combination.it simply does not work well this way. loaded on an open bolt no problem I bet. most of these mags designed to hold 10rds will not even seat on a full mag/bolt closed. Lots of pistols using factory made 10rd mags are difficult to seat mag on slide forward as well(Sig 226 in .40 is textbook example of this)
Are you having any issue with bolt hold open on last shot? this might be an indication that mag follower is not moving far enough through feed lips or mag engagement slot needs tunning or lips of mag need to be opened up a bit. another option is to pull mag apart (metal with orange follower) and remove a bit of material of bottom (@1/8" to allow follower to go deeper in body) in theory 10 1/2 rounds worth of room. grey follower... your hooped. hope this helps as I had same issues but work fine now.
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Thanks, Heckler, you're exactly right - no problems sitting a fully loaded 10 rd mag on an open bolt. Will try to do what you've suggested with the removal of 1/8" at the bottom of the mags (I have orange followers). I think (hope) if I can do it, it will take care of all problems as I feel the bolt spring is just right to cycle 9 mm loads. I think the problem is with the mags, they are too tight.
 
Does your mag have a black follower or an orange one?

If black, chances are changing to an orange follower (contact Questar) might fix the issue.

Also, the mag should hold 10.5 rounds. If it foes not, filing the bottom of the follower slightly may fix the issue.
 
Claven2 said:
Does your mag have a black follower or an orange one?

If black, chances are changing to an orange follower (contact Questar) might fix the issue.

Also, the mag should hold 10.5 rounds. If it foes not, filing the bottom of the follower slightly may fix the issue.
Click to expand...

The mags have orange followers, and yes, I can hardly squeeze 10 rounds in, forget about 10.5. So, I should dust off my file....
 
So long as you cannot fit 11 rounds into the mag, I believe you are still within the letter of the law if you relieve the follower slightly.
 
I have done the same ( filed 1/8" ) and now my mags seat no problem but still only hold 10rds.

I also made a handy modification similar to the idea of the LAR .223 mag connectors. I took 2 base plates and riveted them together reattached the mags to the base plates and wrapped around the joining section with good old duck tape to make a reasonably sturdy and aesthetic double ended mag. They work well, make for better handling and quicker reloads during action shooting. Give it a try and see what you think.

Cheers
 
if you have C-Products mags, throw them away and get other ones.

sounds like the rounds are too tight taking away the energy the bolt needs to chamber a round, used in stripping off the round.
 
I had this problem with my 9mm ARs too. I stuck with just loading 9 rounds per mag. Filing back the bottom of the follower is a great idea. I use a 10%+ strength carbine spring to ensure enough energy is there to strip off a cartridge. With a 10 to 16 1/2"barrel you should have enough back pressure to cycle the bolt. If not go to a heavier bullet. Once the spring takes some set and the parts wear in nicely (may take up to 1,000 rounds) your AR will feed anything. 9mm AR carbines demand a lot of back pressure until they wear in. My cousin lives in WA state and we shoot the same stuff. Because their government trusts their citizens to some degree He lets me shoot his 9mm AR with hicaps. He experienced the same problems, solved them the same way and that is with 32 and 100 rounders!
 
P0WERWAGON said:
if you have C-Products mags, throw them away and get other ones.

sounds like the rounds are too tight taking away the energy the bolt needs to chamber a round, used in stripping off the round.
Click to expand...

Exactly WHICH other 10 round mags? The Promag ones that are made of unobtainium?
 
Yes, I do have the mags with black followers - the bad ones. Are those the C-Products? Can they be somehow filed / modified to function properly? If not, where do I get the good 10 rounders?

If somebody can provide the links to the websites where I can get good mags and stronger carbine springs for 9 mm AR, that would be greatly appreciated.
 
Just found the only 10 rd. mags on the Promag site - COL 23 - Colt SMG/CARBINE 9mm (10) Round Magazine (black phosphate steel). Will those work? On the outside they look a lot like what I have now. Will Promag ship to Canada?
 
SFRC (site sponsor) has a good deal on the orange follower C-prod mags.

As for the Promag stuff, no, I was referring to their thermold-type mags. And I don't think they ship to Canada. Also, those steel mags are not certified pistol mags that I know of.
 
Questar has 10 packs of metel 9mm pistol mags, There ir nothing wrong with pro-mag mags I have a dozen of them and only one was NFG from factory. I have had more problems with metal ones such as your experiencing. there is no need to play with spring these Carbon 15's function better than any colt or RRA I've ever owned.
Ammo: if useing factory stuff in a16+ inch barrel 124-147gr. recommended.
If your reloading send me a PM and I will give you a load that works flawlessly for both 115 and 124gr bullets. I have used the same load in 16",14",10.5" and now a 7"barrell.
These sub guns can be tricky to get flawless performance out of,but it is totally possible to achive. Better be reloading cause they eat ammo like crazy...crazy amount of fun included
 
heckler said:
Questar has 10 packs of metel 9mm pistol mags, There ir nothing wrong with pro-mag mags I have a dozen of them and only one was NFG from factory. I have had more problems with metal ones such as your experiencing. there is no need to play with spring these Carbon 15's function better than any colt or RRA I've ever owned.
Ammo: if useing factory stuff in a16+ inch barrel 124-147gr. recommended.
If your reloading send me a PM and I will give you a load that works flawlessly for both 115 and 124gr bullets. I have used the same load in 16",14",10.5" and now a 7"barrell.
These sub guns can be tricky to get flawless performance out of,but it is totally possible to achive. Better be reloading cause they eat ammo like crazy...crazy amount of fun included
Click to expand...

Thanks, Heckler, appreciate this. I'm using American Eagle 124 gr. ammo and, as I am not shooting 9 mm competitvely (I'm in Standard division in IPSC), I don't reload it. The factory ammo is fine for occassional IDPA match or a club level 3-gun match where I use the 9 mm Bushy.

I had a gunsmith disassemble one black follower C-Product mag and file off the protruding ends of the follower. He also adjusted something in the lips as well. I'm going to try it out during the weekend and see if this works. If yes, I'll have all remaining 9 mags modified in the same way. BTW, what gave birth to a statement that black follower C-Products mags cannot be worked on and should be just discarded? There must be something behind it. Maybe I shouldn't bother playing around with them and get the ones with orange followers or whatever Questar is selling? Let me know what you think.
 
If I recall, the black follower mags had issues aligning with the feedlips of SOME rifles. I have a few mixed in with my orange ones and they work fine in my rifle, but the same mags fail in other rifles I have tried them in.
 
Actually, if I am able to sit the mag and strip the first round, there are no more problems in feeding from those black follower mags, they feed all rounds and lock the bolt open on the last one - all 10 mags.
 
black/grey followers

Claven2 said:
If I recall, the black follower mags had issues aligning with the feedlips of SOME rifles. I have a few mixed in with my orange ones and they work fine in my rifle, but the same mags fail in other rifles I have tried them in.
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Spot on Claven,they have a slight diference in their shape and do not always feed through the lips exactly right,if they do the lips need a tune up to work in all platforms. The bushmaster being a dedicated/purpose built lower the adapter block is bushmasters own and though similar is slightly different than Colt or RRA style. there is nothing wrong with any of these,just each has its own little nuances.
 
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