Originally Posted By Sailormilan2:
On my 22Mag , I found that the buffer was way too light at 1.7oz. I first used a heavier standard length AR15 buffer(5.6oz) and a Bore Buddy spacer to make up the length. It worked fine.
I then added weights to the supplied BCA buffer to bring the weight up to 6oz. It worked okay. Fully ejecting with 3 of 4 brands of 22Mag ammo. With every single Fiocchi I tried, it short stroked, and would not eject.
I have just switched over to an A2 stock, and I’m using a standard weight rifle buffer. But, I have not yet tried this combination.
So, I’m pretty sure the supplied buffer is too light.

Originally Posted By EDL: His 17 HMR upper was gas operated and roller delayed.

Originally Posted By Russ4777:

I am going to discuss all of these issues with BCA tomorrow.  I am going to request a new barrel with proper feed ramp cut.

Updates later.

Originally Posted By EDL:
Interesting.  I looked up the RRA upper and found a few articles on it.  Seems Garrow sold the patent and rights to his upper to Inland.  Inland planned to sell the uppers and RRA was to sell the complete rifles.  Obviously other things transpired between then and now as Inland does even list the upper or the rifle, but RRA is now selling it.  Another article I read says RRA spent two years developing this upper.  Weird.

Either way, RRA wants $1020 for that upper, nearly double the price Garrow was charging.  No thanks. I like the idea, but I don't $1020 like it.

Originally Posted By Russ4777:
Got an email from BCA this morning.  They have received the upper I sent back.  They quote 1 to 14 days for a determination.  One day would be nice to get a replacement on its way to me.  Fingers crossed that it will be as accurate as the "bad" one but with all the cuts made properly.  I am going to try the recommendations posted above.  Got a Tubb's spring yesterday and will upweight the buffer with steel weights and rubber washers.  Hope that keeps things in battery a little longer but still cycles OK.

More later.

Originally Posted By Russ4777:
Received the replacement upper assembly yesterday.  Looks good.  Both the feed ramp and extractor cuts do not reach the chamber wall.  The chamber should fully contain the case during firing.  Per the suggestions above, I have upweighted the buffer with steel weights from a rifle buffer and installed a lightweight flat wire spring.  Had surgery on my hand today so won't be able to test fire it for a few days.  BCA's customer service is pretty good.  Will report on performance in about a week.

Originally Posted By Russ4777:
Well, I finally got to the range on Friday with the replacement upper.  As mentioned above, I upweighted the buffer to 4.2 oz and installed a Tubb's flat wire universal spring.

Generally, cycling was excellent with revised buffer and spring.  10 round groups were all under 1.00 In at 50 yards.

Downside was that the chamber was still not cut correctly leading to some more problems during firing.  Visually it looked pretty good before firing.  The feed ramp was not cut up into the chamber nor was the extractor groove cut too deep.  However, after about 25 rounds or so the cases were still showed some extrusion down into the feed ramp area.  I was almost as though the lower portion of the chamber had been deformed during firing.  Without warning, a case head completely separated blowing out the bottom of the magazine.  Fucked up the glued-together Black Dog mag but no other damage.  The round cleared the barrel OK.  Fired another 100 rounds or so and then another blown case at the bottom of the chamber in the feed ramp area.  Another damaged magazine.  At this point I gave up and came home.  Upon closer inspection at home, it was also noted that there was also a noticeable annular groove/step in the chamber about 0.100 in ahead of breach face.  Looks like their chamber reamer had a chip in it.

Called BCA this morning and their CS people were very nice and apologetic.  They quickly issued an RMA and sent me a prepaid FedEx label for the return of the upper.  I am going to give them one more try before I request a refund and give up on the .1 7 HMR.  Too bad because it is a very flat shooting round.

More info forthcoming on the third upper assembly.

Originally Posted By hdcharlie:


You might want to try an even heavier buffer, 6 oz. or so. I'll never figure out why BCA continues to ship these uppers with that light buffer and too light spring.

Originally Posted By shultz:
No joke! Not a direct comparison, I have the 22WMR upper. I assume the 17HMR could easily handle the same and maybe more buffer weight...

At first I put all steel weights in the included empty extened buffer for 4.10oz. I used the stock spring. I also added 2 quartes to the RE so the bolt handle didn't over travel and slam in to the rear of its upper slot. It functioned but threw CCI MAXI mag HP empties 12+ft. I should also mention all shooting is suppressed with an AAC element 3.


Then I went to an H3 buffer and tried stock and carbine springs also shimmed to limit bolt travel. Same ammo, Better but still tossing brass 8-10ft.

So, I had a 9mm 7.5oz extended buffer in the parts bin. Using it, carbine spring and a DIY shim made from a cheap aluminum carbine buffer to limit bolt travel, I finally settled on this combo. Brass still ejects about 8ft but it shoots so much smoother and functions 100% with CCI Maxi mag HP that's proven to be my goto cheap ammo. Maxi mag HP groups less than 2" at 100yds for 10rds on average. I've shot 1", 5 shot groups but average is 2" especially for 10rd groups. This is plenty accurate for my needs ending pests on my property.
Largest pest so far was a 200'ish lb hog that came out as I was waiting for a skunk that had been hanging around. Head shot at about 100yds dropped that porker where it stood, it twitched for a few seconds before expiring.

Bottom line. BCA didn't buffer these uppers well at all The included POS buffer and spring might get you function but you're beating the heck out of the gun. Adding insult to this issue, at least in my case. The included extended buffer was not even long enough to keep the charging handle from impacting the rear of the slot in the upper without adding shims...

Originally Posted By hdcharlie:


Did it stop screwing up cases?

Originally Posted By Russ4777:
Well....new update on my .17 HMR journey.  The #2 replacement upper arrived about a week ago and I have inspected everything closely before assembly.

1.   The extractor slot is cut properly and does not protrude into the chamber wall.
2.  The feed ramp does not extend up into the chamber.  It terminates before the chamber wall.
3.  There are no tool marks in the chamber wall.
4.  BCA still grinds a very shallow relief in the chamber wall just above the feed ramp.  The only reason they must do this is to aid feeding above the feed ramp into the chamber.  Personally, I don't think they need to do this.  The previous two barrels I got had this same little cut and I was getting case failures in this area due to the cases bulging and cracking in this area.  I'll see how this one works when I go to the range later this week.
5.  As reported previously, I have upweighted the BSA buffer to 4.2 oz.  and installed a Tubbs flat wire spring.  I have some tungsten weights on order.  Based on your recommendations I will run the buffer weight up to about 7 oz and see how that works later.
6.  The bolt face on the new upper assembly is cut correctly to match the case rim outer diameter.
7.  Installed a light trigger spring and the trigger pull is now 4 lb 4 oz up from 5 lb with the stock spring.
8.  Removed the BCA flash suppresser and installed a simple thread protector.  The barrel has a good clean crown.
9.  Installed a KAW Valley carbon handguard tube in place of the unit delivered by BCA.  Looks better to me than the swiss cheese thing that comes with the upper.

Range results:  150 rounds fired, three flavors.

1.  No blown cases.  Very slight case bulges down into the relief cut described above on about 25% of the fired cases back by the case rim.
2.  A few split case necks.  Not sure why.  All three barrels have done this in about 5-10% of the cases.
3.  One failure to fire.  A bad round.  Rechambered it 4 times and it never fired.
4.  Two failures to fully eject the spent case.  The hammer cocked and to next round started into the chamber, but the bolt caught the spent case between the breech and the bolt face.
5.  Accuracy was pretty good at 50 yards using CCI A17, Federal V-Max, and CCI V-Max ammo.  10 round groups averaged between .500" and .825".   A couple of groups opened up to 1.000".  Did not go out to 100 yards on this trip.  Next time.  I am using a 1.5-5X Leupold scope on this rifle.

Overall, I think this final setup is working pretty well.  I'll see what happens with the 7 oz buffer next time.

Here a pic of the breach end of the barrel described above,

https://www.ar15.com/media/mediaFiles/306/IMG_7088_JPG-3658031.JPG

Originally Posted By Russ4777:
I'm OK on bolt travel.  The charging handle stops short of the back of the upper slot by about .125".

Originally Posted By backbencher:
Split necks in .17 HMR is probably due to the case extracting quickly w/ too much pressure still present in the barrel.  .22 WMR less likely to split due to the shallower taper of the case & lower pressure.

Originally Posted By Russ4777:
Perhaps once I can get the buffer up around 7 oz it will slow the bolt travel speed down to help the split case necks.  The .17 HMR is a pretty energetic round.  It's hard to believe this little round will cycle all of this weight. It nearly has as much felt recoil as a .223.  

I posted some pic above of the case problems I was having.  Much better now with the mods you folks suggested.  Thanks.

Originally Posted By Russ4777:  Here's the final configuration....

https://www.ar15.com/media/mediaFiles/306/IMG_7443_JPG-3661875.JPG

Final mod will be upweighting the buffer to 6.9 oz with 3 tungsten and 1 steel weights.  More info later.

Originally Posted By Russ4777:
Here's the final configuration....

https://www.ar15.com/media/mediaFiles/306/IMG_7443_JPG-3661875.JPG

Final mod will be upweighting the buffer to 6.9 oz with 3 tungsten and 1 steel weights.  More info later.

Originally Posted By Russ4777:
Curious how the .17HMR performs against hog-sized game.  Get a sheep dog to herd them onto your property.

Originally Posted By Russ4777:
Well, this may be my final report on the long saga of building an AR with a BCA .17HMR upper.  

Went to the range a couple of days ago with all the final mods in place.  Final thing I did was install an upweighted BCA buffer that contained 3 tungsten and 1 steel weight.  Still has the Tubb's flat-wire universal buffer spring installed.  Total buffer weight is 6.9 oz.  The BCA bolt assembly weighs 11.4 oz.  Total reciprocating weight is 18.3 oz.  I thought that would be too much for a .17 HMR to cycle properly but I was wrong.  The gun ran perfectly and ejected cleanly with every shot.  Ran 80 rounds through it with no bulged case heads, no split necks, no ruptured cases, and no failures to feed.  All rounds fired just fine with a light trigger spring installed.  The ejected cases were all very clean with almost no carbon blown back along the case walls and just a small amount of residue at the mouths.  I believe that the increased mass was the real trick to getting this thing to run right.  Thanks to all you folks for these suggestions above.

With two different kinds of ammo, I was getting 5-round groups that ranged from .375" to .675" with most at .500" at 50 yards.  Have not fired it at 100 yards yet but expect something around 1 MOA or a bit more.

I'm satisfied with this rifle now.

Originally Posted By Russ4777:
Well, this may be my final report on the long saga of building an AR with a BCA .17HMR upper.  

Went to the range a couple of days ago with all the final mods in place.  Final thing I did was install an upweighted BCA buffer that contained 3 tungsten and 1 steel weight.  Still has the Tubb's flat-wire universal buffer spring installed.  Total buffer weight is 6.9 oz.  The BCA bolt assembly weighs 11.4 oz.  Total reciprocating weight is 18.3 oz.  I thought that would be too much for a .17 HMR to cycle properly but I was wrong.  The gun ran perfectly and ejected cleanly with every shot.  Ran 80 rounds through it with no bulged case heads, no split necks, no ruptured cases, and no failures to feed.  All rounds fired just fine with a light trigger spring installed.  The ejected cases were all very clean with almost no carbon blown back along the case walls and just a small amount of residue at the mouths.  I believe that the increased mass was the real trick to getting this thing to run right.  Thanks to all you folks for these suggestions above.

With two different kinds of ammo, I was getting 5-round groups that ranged from .375" to .675" with most at .500" at 50 yards.  Have not fired it at 100 yards yet but expect something around 1 MOA or a bit more.

I'm satisfied with this rifle now.