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Discussion Starter · #1 ·
Just got a 17 HM2 barrel for my TC. It's a 23" plain jane TC barrel for going carbine. I just started breaking it in so don't know much about this cartridge or ammo, accuracy or anything... Don't even have scope on it yet since I am cleaning the barrel a lot.

Anyway, I am shooting Hornady V-Max ammo and the case necks are splitting.

Has anyone else had this problem and/or know what to do about it?
 

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17 Mach 2

I have been shooting a single shot rifle (BSA Martini small action with Douglas match barrel) in 17 Mach 2 for a few months - I tried Hornady, CCI, Remington, and Eley ammo. All were very accurate. The worst group was just about even with the best 22 LR group fired from another rifle with match ammo (Eley Tenex). Accuracy in my BSA was marginally best with the CCI ammo, but I bought 5000 rounds of Eley - at $371 including shipping, that's a deal I could not pass!

The 17 Mach 2 ammo was so accurate that I had to fire 10 shot groups at 60 yards to ascertain the difference in group sizes between brands. I did not have a single split neck, or any other problem with the ammo, in shooting over 2000 rounds.

JLC
PS: I was told CCI makes the 17 Mach 2 ammo for Hornady, but I don't know if this information is correct.
 

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Yep, seems like the Hornady, with Winchester in a close second, is more prone to splits. I have found that CCI has fewer splits and the Federal has not had a single one in my Marlin 717m2. It is suprising to find out that the Federal with no splits is the most accurate for my rifle compared to the otehrs. On our old board, and on others around the net, this neck splitting delima has been tossed about alot. Some think it is the size of the chamber, some the ammo brass others think it is the pressure the different ammo is loaded for. So far I have not heard of any negative (injuries or damage to firearms) affects from these splits. Have you tried other ammo?
 

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Discussion Starter · #4 ·
Check it out.

Gary, This was the only box in the store, so I am just getting going with this one. I have a 17HMR in a Marlin that my 16 yr old has glommed onto for PD shooting. I am lucky to be able to pry it out of his hands for a shot. He is a true Constitutionalist. (kidding...mostly).

JLC - I don't know if my Contender will be that accurate, but that is good info. Thanks.

Anyway, I figured out how to upload the comparison photos, if you are interested.



You can see how much the shoulder has to stretch here. Could be the fitup of the barrel to my contender and excessive headspace, I suppose.
 

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Federal and Winchester

I did try 17 HM2 Federal ammo, I did not try Winchester. Seems I did not shoot enough ammo when trying out different 17 HM2 ammo manufacturers to get splits from Hornady or CCI cases, and I am surprised to hear this may be a common occurence. I definitely have had no splits with Eley, and I shot plenty enough of that to find split cases if it were a problem.

JLC
 

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StevenD, I got splits like you show on the Hornady, had them on about 6 out of 10 rounds fired. The Winchester were not as many but the splits were just as long. Only had a couple of small splits on the CCI and as previously stated not a single one with the Federal.

More of the debate has centered around chamber size, pressure, and rifle action used. Some originally thought that semi-autos were the worse but now they are seeing it happen equally with bolt actions. I will be interesting to see how the T/C barrel behaves.
 

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17 HM2 splits depend on action?

Wow... when I tried various 17 HM2 ammo, I had a minimum of 100 rounds of each - Federal, CCI, Hornady, Remington, Eley. Not a single split case. I shot a lot of Eley since. Still no split case. Not one.

I am worried now, as I wonder how long the 17 HM2 will be around, if shooters experience this kind of problem on a regular basis. I also wonder why I have had no problems with my custom Martini, while Gary had up to six cases split out of every ten!

JLC
 

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Well, to clarify..... some people think that the type of action may have an influence on splits, others think it is how the chamber is cut and others think it is just in the ammo. I do not know for sure what the cause is, I just know that Federal gives me no splits and is the most accurate in my gun. I think the real reason may eventually be found but no matter what the cause I do believe this round will stay with us for many years to come.
 

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17 Hm2

Gary,

Thanks for the posting. I do hope you are right, and that the HM2 thrives for a long time to come, as I love that round! It is no more expensive to buy than good 22 LR target ammo (cheaper than Tenex for sure!), more accurate than 22 LR ammo, and great fun to shoot. I have not tried the 17 HM2 on varmints yet, but I believe it would be a very effective round on small varmints up to 100 yards, or maybe even 150 yards. It is flat shooting, and I find no need to change my scope settings from 50 yards up to 100 yards.

The first I heard of the split cases was here today, and I hope someone finds out the cause of this problem!

JLC
 

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Discussion Starter · #12 ·
Update on 17 HM2 - New TC Barrel

Folks,

Thanks for all the help. Just ot update you on where I stand with this issue...

I had cleaned the barrel before the first 3 shots in the first firing sequence, which all split about as bad as the first photo. After shooting, I cleaned the barrel again and shot 5 more rounds through it in a second sequence. (Again this was not for accuracy since I still haven't put a scope on the barrel). As you can see from the 2nd photo below, it is not as bad as what I had experienced with the first 3 shots in the first sequence. But, I did still have one case out of the 5 split slightly.

First Firing from first post:


Second Firing after re-cleaning the bore:


I am not quite as panicky as I first was, but am still looking at it pretty close.

To answer questions about the neck and shoulder, the dimensions to the extent that I could measure them are on the attached table.

I have no way of saying this is within acceptable limits or is not. But it looks like the mouth is being pinched a little as it is smaller than the bullet diameter. Granted there can be some elastic rebound since it appears that the neck is crimped around the ogive of the bullet and is smaller than the bullet diameter at the outset.

Description-----------Before firing----------After firing

Overall case length-------.709----------------.708
ID Diameter @ mouth-----No data-------------.171
OD Diameter @ mouth-----.181----------------.183
OD Base of neck----------.186-----------------.194
Ht from head to shoulder--.565-----------------.573
Ht from head to neck------.620----------------.623

Near the rim of the case, there is a bulge. This is on all of the spent cases and is where the case is pressure formed into the extractor groove.

Thanks.
 

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17 HM2 case bulge

StevenD,

All cases fired in my Martini 17 HM2 show the same bulge - every single one, and that since the first HM2 round I put though it. Interesting. Anybody else with a bulge near the rim of the case after firing?

From what a few forum members have written, some rifles (like mine) do not experience the split cases, so at least we can say if there is a problem, it is not the ammo alone, and there must be some other contributing factors.

I'll measure the cases before/after firing next time I go to the range, and compare with your findings.

JLC
 

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I have worked with the 17M2 in building up a 10/22 action. After Ruger nixed their 10/22 for this round, several aftermarket barrel companies stopped offering barrels. But this was because of the recoil/pressure spike issues and bulged or even ruptured case heads. I fixed mine and it works flawlessly.

I have NEVER had a split case neck. I don't personally see how it could even happen if the chamber is cut right. Your picture shows that the neck stretched out so either the chamber is not cut right, or it is not seating far enough into the chamber. Both of those conditions should be pretty easy to check.

Here is a typical 50 yard group from my 10/17Hm2 build:


FWIW mine shoot Remy and Eley ammo best.


ETA: Sorry I didn't see the latest pics before posting. I am not familiar with the T/C rimfire extractor, but it looks like it is not actually seating on the rim, but inconsistently. The rim on the right looks as if it has been pinched and appears to have some slight separation on the left side. The rim on the right appears that the extractor did not seat against the rim, which could be holding the case slightly out of the chamber, thus the splitting. That rim looks a little thicker too... ?
 

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Discussion Starter · #16 ·
Chamber cut right??

I have NEVER had a split case neck. I don't personally see how it could even happen if the chamber is cut right. Your picture shows that the neck stretched out so either the chamber is not cut right, or it is not seating far enough into the chamber. Both of those conditions should be pretty easy to check.

FWIW mine shoot Remy and Eley ammo best.
That is a nice group.

You may have something with the issue of the chamber. It is a Thompson Center Arms Contender barrel. It could be the fitup to the breech too. Either way, I guess I get what I paid for. I have never been much of a Thompson fan. This doesn't help much. The crown of the muzzle is awful as well. I could trim a finger nail on the edge of it.

Time to go custom. I will probably make this barrel into something else. I guess I have some choices. Maybe a 17-AH, or a 17 Rem, or a 17-204, or 17-PPC. Or maybe all of the above.
 

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.17HMR?

BTW, you had asked about performance. The Hm2 is definitely a 'tweener. it has the same explosive performance of the HMR, but at much more limited range. While I can still make very small groups @ 100 yards, it is starting to run out of steam.

I think of absolute max shooting distances:
22LR - 75 yds
17HM2 - 125 yds
22Mag - 150 yds
17HMR - 200 yds
 

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For what it is worth I have also had multiple split cases when shooting Hornady 17H2. Mine has been fired from a Savage MK-II heavy barrel. I have noticed that the all the split cases were from a bulk purchase of ammo made when it first came to the market. When firing my lastest batch of Hornady from the same MK-II I have not experienced any case spliting.
Gary
 
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