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  #46  
Old 07-23-2021, 08:20 AM
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Video I did talking grip on my hm2 setup.
https://m.youtube.com/watch?v=KDrcKQOlp0c
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  #47  
Old 07-23-2021, 05:55 PM
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I have some rim fires that are hold sensitive and some that are not and a few that i corrected with bedding. etc . It is also important how you have (if useng a rest) the rifle located in the rest for me any way . I place my rifles with the rear sight location directly over the front rest and the rear rest located directly under my check ,works for me. When bench shooting i don't hold the fore end at all and only use my trigger finger on the trigger and my thumb directly behind but not touching the bolt and just squeeze the trigger between them works for me maybe not you.

Last edited by 50Shifty; 07-23-2021 at 06:00 PM.
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  #48  
Old 09-14-2021, 08:43 PM
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Quote:
Originally Posted by squirrel1 View Post
Better be careful evaluating groups on clean barrel right out the gate.
I have seen 17 cal rimfires that needed as many as 35 shots after cleaning, after this they shot real good and tight.
No need to clean a good shooting barrel. If if goes whacko-clean it otherwise shoot it.

For winter 'storage', clean it and RIG the outside heavily.
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  #49  
Old 09-20-2021, 09:02 AM
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Squirrel1, if POI matches POA with a split case neck, it's a fluke, not the norm. You cannot have a complete loss of neck tension, and the resulting large drop in chamber pressure, and expect accuracy. Yes, I agree there are other issues that can cause poor accuracy, but few, if any, will throw a shot as low and wide, as a split case.
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  #50  
Old 09-20-2021, 10:42 PM
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Originally Posted by Chickenhater View Post
Squirrel1, if POI matches POA with a split case neck, it's a fluke, not the norm. You cannot have a complete loss of neck tension, and the resulting large drop in chamber pressure, and expect accuracy. Yes, I agree there are other issues that can cause poor accuracy, but few, if any, will throw a shot as low and wide, as a split case.
All I can do is report what I have seen on paper when a case split after firing hm2. This witness when shooting on paper at lasered distances of 72 and 73 yards. (Rifle and scope zeroed for dead center at 72/73 lasered yards).
Some are spot on.
Some are low.
Some are high.
Now I don’t have many cases Bust hence not a large shot count to evaluate for trends.

May not be the norm. But is can happen. I have seen.
Has anyone ever Chronied a shot fired where case split?

Last edited by squirrel1; 09-20-2021 at 10:45 PM.
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  #51  
Old 09-21-2021, 07:51 AM
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I have. When I first bought my 1502, I had accuracy issues. Groups weren't satisfactory so I began looking into the cause, it was only after a chrono test that I thought to inspect the cases. The string had a large SD, around 400fps. I then repeated the string and examined each case after the shot was fired and there was definite correlation, which wasn't a surprise. As I reload thousands of rounds a year I've seen the effects of low neck tension in mild form, overused brass, to its extreme in split necks. Pistol cartridges are a good example, you dont even need to have a split case, a soft crimp will cause a shot to drop a foot, or more at 100yds. I brought this up, because I know many people dont inspect fired rimfire cases. As stated by other posters, the new lots of cci/hornady perform much better. I have found a significant reduction in case failures when testing the new ammo. One failure in a box of cci and two in a box of hornady, so a 2-4% failure rate. The old ammo had a failure rate closer to 50%. They varied from very small cracks at the mouth, to large splits that traveled past the shoulder. Again, other issues can effect accuracy, but none are as dramatic as this particular failure.
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  #52  
Old 09-21-2021, 08:25 AM
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Other than some of the original "Fast N Furious" ammo I've not had a split case that I've seen, no unexplained flyers but would expect some from a split neck. I truly believe the rifles chamber has more than a bit to do with this, JME. Worst shooting M2 was a Savage Heavy barrel I literally gave away and it wasn't all that bad just not good enough to stay around.
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  #53  
Old 09-21-2021, 10:14 AM
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Sure the rifle has a lot to do with this, even regarding the split cases. A tighter chamber will suffer less from low neck tension. Example, two of my CF's, both chambered in 260rem, but the sako has a slightly larger chamber than one in 700rem. Loading 107 grn bullets for both rifles, with the same charge, 38gr RL15, the same brass, and primer. The sako requires more neck tension to get the light bullets to group, so much that increasing seating depth alone didnt solve it, though it helped, a collet crimper is now also used. So in summary the split case discussion wasn't meant to explain away all sources of accuracy problems with the 17m2, it was meant to point out, what I feel, is the most likely reason a rifle would group well at short range, but open up significantly at longer range. As i mentioned the early lots of cci/hornady suffered from this nearly every other shot... at least the lot that I purchased back when i bought my rifle, 10-12 years ago. The current run seems much improved in this regard.
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  #54  
Old 09-22-2021, 06:27 PM
Lerrab
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Chicken hater. You are right on and I have chronoed quite a few.

I mentioned the chamber dimensions from several rifles and reported on their dimensions and what I thought the correct diameter should be. I am glad to see that some are using my chamber idea! It will lead to less splits in my estimation. I think the chamber diameter should be specified at .227

I have new lots of Hornady that split like crazy. This is out of a .230 chamber .

Last edited by Lerrab; 09-22-2021 at 06:30 PM.
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  #55  
Old 09-22-2021, 07:36 PM
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I checked several cartridges of both cci and hornady (unshot). Shoulder reads .2230-.2235” using my caliber. This is less it seems than what spec some have given the cartridge. Seems .226” is listed as shoulder or base diameter for cartridge on different sites on internet.
For gee whiz I went outside on back of my truck and got several shot hm2 cartridges out of 2 lilja barrels used on CZ 455 and measured them. They tend to read .227”. Few read .228”. So my chamber dimensions diameter for cartridge has to be around .228” one would think.
Manson reamer used on Lilja barrels it seems.
I don’t know exact specs of all 3 of my barrels.
Two of them have been shot.
Estimated I have had 6 split cases using both hornady and cci (more cci though) in around 5000-6000 rounds fired.
Thus far since 28 Aug this year, with 99 shots fired at squirrels using same lot of cci, no split cases at all.

Btw, if I am not mistaken.
There was actually some false advertisement/claims with 17 hm2 when it was debuted.
What exactly?
Has anyone ever seen (I haven’t) a totally brass case on a 22 lr stinger round?
Why did cci use the nickel plated (I think it’s nickel) on the stinger rounds ?
Reckon it was because the cases split?

Last edited by squirrel1; 09-22-2021 at 07:58 PM.
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  #56  
Old 09-22-2021, 08:15 PM
Lerrab
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squirrel, If you get any at all that read .228 then your chamber has to be at least .229. I know I mentioned this before, it is a caliper not a caliber but it is an easy mistake to make.
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  #57  
Old 09-22-2021, 08:49 PM
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Spent case from my 1502 measures 0.223" at the neck and 0.2245" just above the rim. New lot cci and hornady measure 0.221" top to bottom. Measured with both mitutoyo caliper and starrett micrometer. Disagreement between instruments was about -0.0005"... with the micrometer providing the slightly smaller reading.
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  #58  
Old 09-22-2021, 08:56 PM
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Quote:
Originally Posted by Lerrab View Post
squirrel, If you get any at all that read .228 then your chamber has to be at least .229. I know I mentioned this before, it is a caliper not a caliber but it is an easy mistake to make.
So a round’s case would never expand to exact chamber dimensions? Some might get within .0005” I think surely.
I said close to .228”.
I also stated I hadn’t measured chamber.

I also stated hm2 case diameter spec is listed as .226”
My ammo sure ain’t !!

So it would seem hm2 made by cci/hornady can expand .002/.003 total and split cases not much of an issue. Based on my results gotten with my barrels. Like to see some of the older cz452 hm2 fired cartridges measured before and after shot to see how they compare.

Cci really should have stuck with nickel plated cases. Like what’s used in newer round they released. Cost was a factor I suppose.
All those 22 lr guns, if brass was used on stingers cases would have been split by the loads. They witnessed this I think.
There were other hyper velocity 22 lr rounds that did use brass. I used them. Remington I think was one. No problems either. But I think stinger had highest velocity best I remember. As least what was printed on the boxes.

Last edited by squirrel1; 09-22-2021 at 09:02 PM.
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  #59  
Old 09-22-2021, 09:00 PM
Lerrab
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This is what I think I know about the .17 mach 2. When Dan Lilja started chambering for it his barrels were running .229-.230 and cases were splitting. I had an original Remington that split cases only seldom. The original specs if I recall and I may be a little off were for a cartridge diameter at the shoulder of .226 with a tolerance of -.003 or something close. The Chamber had a spec of .227 with a tolerance of plus two or three thousands.
It appears in my conversation that some companies knew the ammo was going to be on the small side so ordered reamers spec'd to the minimum. .227. most reamer companies allowed for the large side to allow for what they thought may be feeding issues in semi's and went with a sloppy .229 which was often .230-.231. Early Lilja reamers were in this ballpark and I don't know about later ones! But I did talk to Dan about oversize chambers. Poor annealing is exacerbated by overly large chambers- and there is your split!
It doesn't matter who makes a reamer it is what size that is asked for by the end user!

Last edited by Lerrab; 09-22-2021 at 09:20 PM.
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  #60  
Old 09-22-2021, 09:07 PM
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A case will expand to full chamber dimensions to seal off the escaping gas that may otherwise escape around the case, collapsing it and blowing back into the action. A case must shrink back from the chamber walls after firing to be released so that it can extract. This shrinkage is generally in the .001 range. If your case measures .228 after extraction it is safe to assume you have a .229 chamber diameter!

Last edited by Lerrab; 09-22-2021 at 09:19 PM.
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