HK SR9TC Accuracy Problems

[samnev]

I have the above rifle with an US Optics ST 10 scope in USO rings on a ARMS Claw mount. Mount is very tight, rings are torqued to the mount @ 40 " pounds and rings to scope at 18" pounds. Absolutely no movement of any of the fore mentioned. Problem is With my 168 grain SMK load the shoots consistent 0.3" groups in my TRG 22 or even less in my AIAW I get groups around 3". Even tried FGMM with the same results. Then tried 147 grain Portuguese late date mil surplus. About the same results. Swapped scopes with one of my AR's. The scope on the AR scope shot 6/10" 5 shot group @ 100 yards. Wit the scope that was on the AR same problem on the SR9TC. Crown and bore are pristine. Has anyone else had similar problems with this rifle or do I have a lemon?

Any opinions welcomed as I am at my wits end.

 

[BigBoss0311]

hkpro forums are your friend.

 

[Razor74]

Never herd of any HK shooting that bad, I had one and it would consistently shoot sub moa. You may have something interfering with the harmonics of your barrel. Are you using a bipod? Check to see if your hand guard is touching the barrel, if none of these are a issue you may need to someone look at the inside of your barrel with a bore scope to see if it is damaged. If you are not the first owner the prior owner may have damaged the bore.

 

[samnev]

I am not shooting with a bipod and the hand guard ( I tried the original and an HK 91 hand guard, no difference) doesn't seem to be interfering with the barrel. I guess the next step is get the barrel looked at with a bore scope. I tried getting ideas on HK Pro and the answers were all over the place ranging from it's only a battle rifle in fancy clothes and I shouldn't expect much better results to owners who say heirs shoot 1 moa.

 

[ORD]

Something is awry with your setup (or the guy pulling the trigger) in one respect or another, but precisely what is unclear. I have an OEM, unmolested SR9TC that will achieve MOA and even some slightly better accuracy with FGMM, not to mention my own reloads ranging from 155gr to 175gr loads (they have 1:11 twist barrels which should perform exceptionally well with all the ammo you mentioned). The 3MOA (give or take) you are experiencing is nowhere near what the rifle is/should be capable of doing.

A couple questions...how are you shooting the rifle for accuracy testing (i.e. - from a bipod, rest, bench, prone, etc.)? Have you let any competent, trusted, proven semi-auto shooters try it out? If so, were the results the same in terms of accuracy? Have you tried shooting it for accuracy with just the irons? If not...remove your scope mount/optic altogether and try the irons. That'll remove any optics-related problems from the equation and the irons are capable of allowing you to achieve excellent accuracy (better than 3MOA anyway) provided your vision is up to the task. Anyway...just some random thoughts/considerations for you. HKPro is another good source of information for you to inquire. I'm a member over there, but just don't get the time to post as much as I used to. There are numerous SR9 and variant owners over there that might be able to help you troubleshoot your issues further.

Good luck!



ETA: Disregard some of the above as you have already looked into HKPro, etc. I didn't see your follow-up post before I replied.

 

[Gildoom]

I'd ask him... http://www.facebook.com/DakotaTactical

Something sounds goofy.

 

[Razor74]

Battle rifle in fancy clothes, that's funny that person does not know what they are talking about. Are you the first owner and how many round has this rifle see? I ask because the bolt carrier rails on HK receivers will over time wear out. You will actually see the roller marks on the outside of the receiver. How the bolt works is crucial to the overall function of your gun. The roller lock system has to been in spec or it will not shoot properly. Does your gun function properly other wise ie cycling, ejection, extraction? I think that I still have my PSG1 service manual I will check and see what it says about your problem and get back to you. They are the exact same rifle except for the barrel.

 

[samnev]

Ord,
We have corresponded before on other questions I had and appreciate your advise.I answer to your questions which are all valid points, I have removed the scope and shot the irons only, no significant change. I have been shooting Semi autos for years starting with the M1 Garand in matches, then my Devine, TX National Match that still shoots 0.75" groups @ 100 yards. I also have 4 other scoped 308's an LMT MWS, AR10A4 and a DPMS SASS and a SIG 716 that all shoot 1 MOA or better 5 shot groups @ 100 yards. I have won quite a few match previously with my NM M1A and shot expert with the M1 Garand when in the US Army so I don't think it's the guy behind the rifle. I consistently shoot well under an inch 5 shot groups with my Noveske and Rock River AR 15's.
When accuracy testing the HK I shoot off a bench with a Lyman Front rest with a leather rest (can't remember the name) on top and the same brand leather bag for rear support. The rifle is virtually fixed all I have to to is pull the trigger on the PSG-1 trigger group and follow thru as I do with all my other semis. I have tried 150 flat base Hornady's 165 Sierra HPBT and 168 grain SMK's all with different loads but primarily using H4895 and 3031. But the loads are all on the light side where my M1A, TRG and AIAW shot best. I will next try heavier loads of each powder as well as W 748 and try 175 SMK's. I am not blowing my own horn but in my gun club I don't know anyone that shoots semis any better than I do but my brother comes close. He was also match shooter and shot the HK with similar results. I have NEVER had any rifle that I have owned before excepting some AK 's I previously owned that shot his badly. My old HK 91 with iron sights that I sold a few years ago would shoot 1.5" groups with the same load I am using now for my M1A, SIG 716, DPMS SASS, AR10A4 and LMT MWS. I also regularly shoot my SIG AMT and PE 57 with iron sights and shoot groups well under 2" at 100 yards. So I am totally perplexed at the lousy groups with the SR9TC. Especially since the bore an crown look pristine
In any case thanks agin for your advise it is appreciated. I will post any further results when and if I decide to go any further in testing the SR9TC.

 

[ORD]

Ord,
We have corresponded before on other questions I had and appreciate your advise.I answer to your questions which are all valid points, I have removed the scope and shot the irons only, no significant change. I have been shooting Semi autos for years starting with the M1 Garand in matches, then my Devine, TX National Match that still shoots 0.75" groups @ 100 yards. I also have 4 other 308's an LMT MWS, AR10A4 and a DPMS SASS and a SIG 716 that all shoot 1 MOA or better 5 shot groups @ 100 yards. I have won quite a few match previously with my NM M1A and shot expert with the M1 Garand when in the US Army so I don't think it's the guy behind the rifle. I consistently shoot well under an inch 5 shot groups with my Noveske and Rock River AR 15's.
When accuracy testing the HK I shoot off a bench with a Lyman Front rest with a leather rest (can't remember the name) on top and the same brand leather bag for rear support. The rifle is virtually fixed all I have to to is pull the trigger on the PSG-1 trigger group and follow thru as I do with all my other semis. I have tried 150 flat base Hornady's 165 Sierra HPBT and 168 grain SMK's all with different loads but primarily using H4895 and 3031. But the loads are all on the light side where my M1A, TRG and AIAW shot best. I will next try heavier loads of each powder as well as W 748 and try 175 SMK's. I am not blowing my own horn but in my gun club I don't know anyone that shoots semis any better than I do but my brother comes close. He was also match shooter and shot the HK with similar results. I have NEVER had any rifle that I have owned before excepting some AK 's I previously owned that shot his badly. My old HK 91 with iron sights that I sold a few years ago would shoot 1.5" groups with the same load I am using now for my M1A, SIG 716, DPMS SASS, AR10A4 and LMT MWS. I also regularly shoot my SIG AMT and PE 57 with iron sights and shoot groups well under 2" at 100 yards. So I am totally perplexed at the lousy groups with the SR9TC. Especially since the bore an crown look pristine
In any case thanks agin for your advise it is appreciated. I will post any further results when and if I decide to go any further in testing the SR9TC.

I didn't honestly think it was "you" that was the problem, but I had to throw it out there.

At this point in time, especially considering what you've done thus far in an attempt to get it shooting the way it should, it may be time to get it into the hands of a competent HK smith and have it given the thorough break-down, inspection, T&E by a pro (not, repeat NOT through HK USA). I have seen bad barrels on HK factory rifles in the past...never on an SR9 series rifle...but it is sounding to me like you have something wrong there whether it is the bore or the manner in which the rifle was assembled as a whole. May be time for a nice, new, Lothar Walther LW-50 1:10 twist polygonal match tube for your rifle!

 

[samnev]

ORD,
No offense taken. If I was answering this thread I would have thrown that out as a possibility as well. I have a good friend that is a master a determining problems with weapons of any type. From simple 22's to almost any machine gun you could name. He owns a specialty ammunition company and probably makes the finest specialty ammunition in the US. He is coming over tomorrow to examine the rifle. He thinks my light loads that I shoot all my 308's in are possibly to slow to stabilize the smk's. If he can't find anything wrong he suggest upping my velocities to see if that has any effect on the groups I am shooting. At this point I will try any thing. I am the second owner of the rifle and I have been trying to get the bore clean having used several very aggressive bore solvents (Sweets, Montana Gold, Blue Wonder) Lead Away Patches as well as Hoppies, Hoppies for Copper removal but the patches are still coming out with heavy deposits that feel like very thick carbon. Yet the bore looks pristine and one would think it is a new barrel. I don't think I have ever seen a bore this dirty. I have cleaned a Japanese Type 96 LMG whose bore looked like a sewer pipe and it cleaned up fairy quickly compared to this barrel, go figure.

 

[Razor74]

I looked in my PSG1 Manual and it says that some times the barrel can develop a bulge, if this happens in the first half of the barrel from the muzzle back you will need to change to barrel. I don't know how much you are willing to invest in the gun to make it work, but if I were you and was going to have it fixed I would upgrade it to PSG1 specs. A new walther 1-10 barrel and add the action stiffener rails. This will give you optimal accuracy. Again not cheap but if you send it to a quality builder you will be happy with the results.

 

[samnev]

Razor74,
Thanks for the reply. I had the barrel checked out with a bore scope and looked at very closely externally for any problems. No apparent problems found.

 

[ORD]

Razor74,
Thanks for the reply. I had the barrel checked out with a bore scope and looked at very closely externally for any problems. No apparent problems found.

At the time the barrel was being scoped, did you by chance have the chamber/headspacing checked to ensure that it had in fact been properly set up to begin with? Just curious because the bore may be beautiful but it may be all out of whack otherwise which could also easily explain your accuracy woes.

 

[Razor74]

samnev,
ORD may be correct the step I was going to suggest would be to check your head space. All you need to do this is a set of feeler gauges in mm. (1)Take you mag out,(2) Close the breech,(3) uncock the hammer,(4) turn the rifle upside down so that you are looking into the mag well. The gap between the bolt head and the bolt head carrier must not be less than 0.1 mm and must not be exceed 0.4 mm. Optimal gap should be around 0.25 mm and is set from the factory between 0.25mm to 0.4 mm. The head space will not increase but only decrease due to wear on functional parts. If your head space is not correct, you will need to replace the locking rollers (always replace in pairs). If this is the case PM me and I will step you through replacing them if you feel good about doing it yourself. Or send to a qualified gunsmith.

 

[samnev]

Thanks guys for the heads up on the head space. No I didn't think to have the head space checked since the cases showed no signs of having head space problems. I did check the fired cases against cases fired in my AiAW ond there was no significant difference in the case dimensions. I will have the head space checked as soon as I get some feeler gauges. But that will have to wait until my brother's operation today to remove his kidney (cancer) and his recovery as I will be helping tend to him during his recovery.

 

[ORD]

Thanks guys for the heads up on the head space. No I didn't think to have the head space checked since the cases showed no signs of having head space problems. I did check the fired cases against cases fired in my AiAW ond there was no significant difference in the case dimensions. I will have the head space checked as soon as I get some feeler gauges. But that will have to wait until my brother's operation today to remove his kidney (cancer) and his recovery as I will be helping tend to him during his recovery.

Prayers out to you and your family during this difficult time! I hope your brother pulls through to a complete and speedy recovery.

 

[lennyo3034]

hkpro forums are your friend.

Waste of time. They will just tell you to get better at shooting and nothing could possibly be wrong with HK. By "tell", I mean "type" of course since they can't speak with an HK logoed set of balls in their mouths. The OP did good asking here.

To the OP: Prayers for your brother and a swift recovery. Much more important than a rifle.

 

[samnev]

Thanks to everyone for the concern and hopes for a complete recovery. We were at the hospital for 6 hours yesterday. He made it through the operation OK but is still in a lot of pain despite the morphine pump. We have to wait until Friday for a complete pathology report. Right now weapons are the furthest thing from my mind.

 

[samnev]

Well my brother is now home from the hospital and the biopsies on the kidney, ureter all came back negative he is in some pain but otherwise OK and in good spirits. The poor guy wasn't allowed to eat anything but ice chips for 3 1/2 days. I will get feeler gauges asap and check the head space as was suggested. In the mean time I have loaded up ammo with 168 and 175 smk's using Varget, 4895, and W748 to about 2550 fps to see if the suggestion my original loads were to light to stabilize the projos. Again thanks to all of you for thinking about my brother.

 

[ORD]

Well my brother is now home from the hospital and the biopsies on the kidney, ureter all came back negative he is in some pain but otherwise OK and in good spirits. The poor guy wasn't allowed to eat anything but ice chips for 3 1/2 days. I will get feeler gauges asap and check the head space as was suggested. In the mean time I have loaded up ammo with 168 and 175 smk's using Varget, 4895, and W748 to about 2550 fps to see if the suggestion my original loads were to light to stabilize the projos. Again thanks to all of you for thinking about my brother.

That's an excellent report on your brother thus far. Hopefully, now that he's home and able to rest in peace without somebody bugging the crap out of him on the hour, he'll rest, eat and drink better and get off on a good start toward a full and speedy recovery. My family and I will continue to keep you and yours in our thoughts/prayers.

Good luck with checking your bolt gap when time permits. If you have any questions or run into any issues with the process, feel free to drop me a PM or e-mail if I can help walk you through it.

 

[gyz77]

My 91 and SR9 T shot bad with a certain scope mount. I tightened it too tights. It was squeezing the recieved. I have gorilla hands!! Probably not the problem but could be!!

 

[samnev]

That's an excellent report on your brother thus far. Hopefully, now that he's home and able to rest in peace without somebody bugging the crap out of him on the hour, he'll rest, eat and drink better and get off on a good start toward a full and speedy recovery. My family and I will continue to keep you and yours in our thoughts/prayers.

Good luck with checking your bolt gap when time permits. If you have any questions or run into any issues with the process, feel free to drop me a PM or e-mail if I can help walk you through it.

Ord, thanks for your very kind reply. I visit my brother every day to help keep his spirits up and remind him with the scans he has had if there was anything else the least bit questionable it would have been seen. He has been healthy all his life so this hit him very hard.
Thanks for the offer of help. If I run into a problem i'll pm you. I will pick up the feeler gauge Saturday and post the results. I do have one question on the head space check. When it is done is the chamber closed on and empty case or is the chamber empty. I've done head space checks on other rifles and machine guns with head space gauges but the roller lock system is new to me as far as checking head space. I have never had to do it in either my SIG PE 57 or SIG AMT.

 

[samnev]

My 91 and SR9 T shot bad with a certain scope mount. I tightened it too tights. It was squeezing the recieved. I have gorilla hands!! Probably not the problem but could be!!

Thanks for the reply. I am using an ARMS claw mount. As far as I can determine the tension is preset. If someone else can chime in on the ARMS mount a possible cause of my problems it would be appreciated. What kind of mount were you using that caused the problem? I also have the MFI low profile mount that I can use but I have heard some problems have been caused by that mount so I am hesitant to try it out.

 

[gyz77]

I can't remember what brand it was but it could be adjusted. I just squeezed it too much. The carrier was catching just a little to throw off the accuracy. Not enough to tell if you ran the action by hand but enough to where I could only get a 2" group max. GYZ

 

[Razor74]

Ord, thanks for your very kind reply. I visit my brother every day to help keep his spirits up and remind him with the scans he has had if there was anything else the least bit questionable it would have been seen. He has been healthy all his life so this hit him very hard.
Thanks for the offer of help. If I run into a problem i'll pm you. I will pick up the feeler gauge Saturday and post the results. I do have one question on the head space check. When it is done is the chamber closed on and empty case or is the chamber empty. I've done head space checks on other rifles and machine guns with head space gauges but the roller lock system is new to me as far as checking head space. I have never had to do it in either my SIG PE 57 or SIG AMT.

samnev. I'm glad your brother is ok. The chamber is closed and empty when checking the head space, remember to drop the hammer also.

 

[ORD]

samnev. I'm glad your brother is ok. The chamber is closed and empty when checking the head space, remember to drop the hammer also.

+1 on the above info. Sorry I missed your questions about how to properly check the bolt gap the other day, but as usual, Razor is right on.

 

[samnev]

Thanks guys. I am picking the feeler gauges up today and will report back. I may try a different mount. I am currently using the ARMS claw mount but I also have a MFI low profile mount for the HK. I know the scope is OK having put it on one of my rock river's and shot five 5 shot 100 yard groups averaging 0.6" with my custom hand loads.

 

[samnev]

Well I measured the headspace 0.229mm was a little lose the next size up 0,254 was to tight so the headspace is somewhere between the 2 readings. So I guess it's close to the optimal reading. I went to the range with the 4 recommended loads 1 load using 43.7 grains of H4895 produced with 175 SMK's 1 decent 5 shot 100 yard group. Fist 3 shots into 5/8" the next 2 shots opened the group up to 1.4". I only load 10 rounds of it. The 2nd groups was not anywhere as good I didn't even measure it. 44.2 grains of W748 produced a decent first 3 shots, 0.75" the last 2 were opened the group up to 2.8". The other loads were worse. I also took my DPMS SASS to the range to see if the lousy shooting was my fault but with my 168 grain SMK's 3 5 shot groups averaged 0.73". I decided to use the MFI low profile mount on the rifle just in case is the ARMS Claw that's causing the problem. I doubt it but it's the last thing I am going to try before it becomes a safe queen.
Thanks again to everyone who has tried to solve the accuracy problem and kept my brother in thier prayers.

 

[Razor74]

samnev, I went back thru my notes from my SR9T as far as load data I used 44gr of Varget with sierra 168 BTHP. In my rifle I averaged 0.75 or less. Just to humor me the next time you go out to test, try shooting a group loading 1 round at a time, putting the round in the chamber by hand 3-5 shots. then try the same 3-5 shots from you magazine and see if there is a difference between the two. I did have a mag that came with the gun was not right, it would dip causing some of the bullet heads to be damaged and would open up my groups.

 

[ORD]

From your measurements, you are more or less smack dab in the middle of the "acceptable" range 0.10mm-0.50mm (ABSOLUTE MAX is 0.5...0.4mm is often in the printed materials) so it doesn't sound like that's your issue.

As Razor mentioned, you CAN sometimes get rounds getting badly beaten up loading from the mag. If you are getting the kind of "damage" that Razor mentioned, then you can easily swap mags and see if that happens to resolve the issue.

Sometimes it is an issue of insufficient "crimp" or hold of the bullet by the case neck allowing it to get jammed back into the case somewhat upon chambering. If that IS the case, then you can usually find it out by simply manually cycling through a sample mag of say 10 rounds. Measure (or know) your COAL before and then measure after chambering to see if you are getting any set back. If so...it may be time for a Lee (or similar) crimp die. As with all things of this nature, I recommend doing that kind of a test on the range with the line hot just in case you would happen to have any "goofs" (not likely to be caused by you...but hey, @#$% happens).

 

[samnev]

Razor 74 & Ord,
I will try to see if I am getting any set back and wii use a lee factory crimp die. My oal is 2.80 on all my loads. I wii also follow the suggestion of loading single rounds follow buy rounds from a new magazine. I have been using the same magazine thru all the testing so maybe that is the problem. I never thought of either the set back or a bad magazine. Perhaps the reason the rifle shot reasonable groups with the Portuguese ammo is because it is crimped and I do not usually crimp my 308 loads never had any accuracy problems with my 308 loads in any other semi 308 and in have 6 of them including a SIG AMT with the roller lock action and use to have an Hk 91 that I never had problems with. I will also make up dummy rounds, so there will be no chance of an accidental discharge, with out crimping as my 308 dies are RCBS and I will have to order the Lee factory crimp die. I forgot that I am using 308 RCBS dies. But at this point I am wiling to try anything at this point as I don not have any more ideas to try.
Regards
Sam

 

[samnev]

ORD and Razor,
I made up 10 dummy round using 168 grain smk's. Loaded the in the same magazine I was using and ejected them Surprisingly there was no set back. Just the opposite occurred. The inertia of the bullet was enough to case the OAL to elongate from 2.80 2.81. I then reseated the bullets and used the Lee factory crimp die that I had forgotten I had bought sometime in the past. There was no elongation of any of the rounds.
I did notice using the original magazine I had been using some very slight damage (burred) on the tip of the smk's. Using a new magazine there was no further damage. I don't know if the elongation or the very slight damage to the tip could cause the erratic groups but any boat in a storm at this point. I won't be able to shoot this week until friday as it will be very windy here in Prescott until then.
On thing that is till bothering me I have tried Sweets, Montana Gold and Blue Wonder to clean the bore and even though it looks clean (very shinny) the patches still come out as if they had been in a coal mine. You can actually feel the course black residue on the patches. I estimate I have run over 100 patches after waiting as instructed using both nylon and regular brushes thru the bore and the patches still come out filthy.
Regards,
Sam

 

[ORD]

I doubt that a 0.01" difference in COAL would cause the level of accuracy issues you were experiencing (3MOA), but that combined with damaged bullets certainly MIGHT explain it at least some of it.

Furthermore, I'm not sure on your barrel fouling issues. Are you SURE that the fouling is coming from the bore itself and not from the chamber/flutes and/or the face? HKs (ALL OF THEM) are just dirty buggers in most respects, but depending on the tools and your method of cleaning, you can get the bore cleaned well and still get a metric TON of fouling from the chamber (especially in the flutes) and on the chamber face. If you don't have them yet, you owe it to yourself to pick up the chamber flute brush and chamber face cleaning tools which will help tremendously with the work involved in getting those hard to reach/hard to clean areas nice and tidy:

HK 91 & HK G3 Tools and Brushes

Also, you didn't indicate how you were cleaning the bore (using a guide, cleaning from the chamber or muzzle, etc., etc.), but I break my rifles down completely so that I can use a bore guide and clean from the chamber end of things. There are some ultra-special bore guides out there for the HK91 and similar rifles including some nice ones made by an HKPro member (Covert53 if I recall correctly), but I just use the run-o-the-mill Possum Hollow guide which is made specific to the HK91 and runs around $15 or so. I know it is a pain to have to break down the rifle every time you need to clean it, but it'll save your crown from all sorts of nastiness and will actually allow you to get the rifle a whole lot cleaner.

 

[Razor74]

Samnev, it does not take very much damage on the tip of a bullet to upset the aerodynamics of it. Also you may see more elongation when the bolt is in operation under fire rather than dropping it by hand. The pressure from the fired bullet will generate more force and should cycle harder. Ord is correct it is hard to clean the chamber area of these guns.

 

[samnev]

Ord and Razor,
I clean the rifle just as ORD does. I break the rifle down and clean it from the chamber only as I do with all my semi's AR's that can be cleaned from the chamber end. I have a bore guide that I use on semi AR's as well as the HK. As I said before I never had the cleaning problems with the HK 91 or 93 I use to own. I also have the SIG AMT, PE 57 and several SVT 40's that also have fluted chambers I use a 45 caliber brush to keep the flutes clean that has worked for me for many years. I leaned about cleaning the flutes many years ago when I bought my first SVT 40 and shot that horribly corrosive com block ammo. I haven't used that on the HK so I will give that a try as it makes sense that the carbon would be coming from the chamber rather than the bore. I don't know why I neglected cleaning the flutes on the HK. I should have known better. Thanks for the link on the chamber face brush and flute brush. I will order both as it really bothers me to have any of my weapons have that much crud anywhere on them let alone in the chamber.
I can't thank you guys enough for taking up so much of your valuable time trying to get me squared away.

 

[Razor74]

samnev
No problem buddy if my limited knowledge has been any help to you or others I'm glad I could help. One more thought, look at your feed ramp to see if it has any abnormalities burrs or groves. If your bullets are moving outward, then it is likely that some may be getting pushed deeper into the case. This can lead to poor accuracy and worse yet over pressure.

 

[samnev]

samnev
No problem buddy if my limited knowledge has been any help to you or others I'm glad I could help. One more thought, look at your feed ramp to see if it has any abnormalities burrs or groves. If your bullets are moving outward, then it is likely that some may be getting pushed deeper into the case. This can lead to poor accuracy and worse yet over pressure.

Will do, thanks.