Subsonic load testing in a M96 swedish mauser

[Andy]

Hi everyone, I am a reloading novice so please take that into account with what I'm writing here. I have been dying to try out my swedish mauser since I got into reloading/casting about a year ago and finally got around to it yesterday. I have read a ton on this rifle (mostly on this board) and realize it is hard to get high velocity out of it with cast, so I decided to go the other route and see how slow and quiet I could load it down to.

There is a thread here where an experienced shooter discusses his quiet/silent loads for a swedish mauser and reading that got me thinking of trying to make this a dedicated silent-shooter for yard work and or general fun factor. In particular someone mentioned in the thread "too bad you don't have all the length of the original m96 barrel, that would be even quieter" (he was using the shorter m38 if I remember right) That got me thinking: hey, I have the full length one, maybe I should try that.

So, toward that end I started working down with bullseye loads to see how quiet a round I could develop. Since this is a bit of an oddball experiment I thought I would post my results here for anyone else interested in the concept.

Here is my detailed data so you know how I got my results:
Brass: PMC HS brass from factory jacketed loads once fired in my rifle (so formed to my chamber), SS tumbled clean
Primers: CCI large rifle regular primers
Powder: Bullseye from an old cardboard 4lb tube, hercules brand so pretty old and not the same as new I think
Bullet: lyman 266469, COWW+2% tin, air cooled, 50/50 white label lube, all grooves filled, sized .266 (.264 bore slug)
Sizing: Only 1/2 of neck sized with sizing die ("partial sized" with regular full length die)

Rifle: As issued M96 swedish mauser (roughly 29" barrel), all matching with a perfect shiny bore and nothing oddball about it, looks like it sat on a rifle rack for 50 years.

Method: Powder measured by weight for each charge with ohaus scale, bullet just barely seated in case. Only seated up to half of the second driving band on this bullet, in other words over 75% of the bullet was not inside the case (very long throat on this rifle). No crimp, no gas check, loaded one at a time into the rifle. Shot over chrono about 5' away.

Initial test: This was just to see how low I could go before I got close to sticking a bullet in the barrel, just did one round of each charge weight so I would know where to test for my next batch.

***I was VERY careful to absolutely ensure the bore was clear after every single shot, I know there is a huge risk of sticking a bullet in the barrel with this type of testing and destroying the gun with the next shot, so I had a borelight in the chamber after every shot and made sure to observe a 100% clear bore before the next shot.

All loads below in Bullseye (hercules old powder not the newer stuff), had people listen at 10' and 300' during testing to observe the noise level
6.0gr : 1105 fps sounded like a stinger .22 round, possibly sonic?
5.5: 978 sounded about like a remington .22 subsonic at distance, louder up close
5.0: 936
4.5: 870
4.0: 782 not as quiet as I wanted so loaded another 5:

3.5: 705 (sounding quieter than a remington.22 subsonic about now)
3.0: 609
2.5: 544 from this point on the rounds were inaudible to two people deliberately listening for them from 300' away
2.0: 377
1.5: 190 About the sound of a remington .22 cb, not quite as quiet as a colibri .22, I could hear this bullet clipping branches in the woods after the intial report which was kind of interesting.

A stabilization calculator I used indicated that this bullet would not be adequately stabilized in this rifle below 225 fps so I stopped there.

My main intent with this is to have the absolute quietest load I can out of the rifle that will hold a 4" group at 25 yards, I would also like to find the quietest load that will hold 1" group at 25 yards and compare them.

Anyone have any recommendations on where to start further load testing at this point? I only have 20 brass to dedicate to this so will be doing my testing in 5, 10 or 20 round increments. I have already loaded up 10 at 3.0gr and hope to fire them on paper this week (all of the original test was just firing at a large tree without observing impact).

Hope you enjoyed reading this, I intend to pursue this to completion over the coming months and will update this thread as I continue along. Any thoughts/advice that will save me time/bullets are very welcome. It is only a 7 cent round as is so I can afford to play with this one.

[SciFiJim]

An interesting test. I will watch for your updates.

From you test results so far, it looks like 2.0 grains is about as low a load as you would want for anything usable for yard pest control.

An interesting test though would be to see how low you can go before a boolit sticks in the barrel. Wonder if just a primer would get it out of the barrel or would it take a tiny amount of powder. At that low a charge, it might be position sensitive.

[RPRNY]

Very cool. Very heartening to see a new reloader so focused on precision and safety but also experimenting.

My Swedish Mauser is a 94 Sporter. It is disturbingly accurate and easy shooting but I don't shoot cast with it.

[RU shooter]

I did some down loading like your attempting with a 30-06 and a 32 spl about 8 years ago and I'm suprised you got down to 1.5 grs of BE without sticking one in the barrel lowest I went was 1.8 gr with a 185 gr in the 06 and bullet ended up an inch from the muzzle so I stayed at 2.0 gr this was the same with the 32 spl with a 170 gr bullet accuracy was well within your 4 inch at 25 yd limit . And penatration was still surprising how far they went into a pieces of pine 2x10 . One thing I wanted to try but didn't was to use lighter weight bullets . Good luck in your experiment

Tim

[Blammer]

how much does the bullet wt?

if you want a really small bullet check out NOE's 57gr 6.5, miserly on lead.


http://noebulletmolds.com/NV/product...oducts_id=2309

[Andy]

Thanks for the encouragement guys. I am having a lot of fun with this. My responses to your posts are at the bottom of this update.

I was able to get a chance to shoot it on paper today and was very happy with the results.

I had loaded 10 rds of 3.0 gr to all the specs listed in my original post. Shot these on paper today off bench & bags. First group was only at 12 yards as I wanted to see if I was getting any sort of group on paper before going further. No data on these so I didn't know if they would be flying wildly or tumbling right out of the muzzle or not. I picked 3.0gr randomly so wasn't expecting much. I was pleasantly surprised.

First 4 shot group at 12 yards (after one fouling shot fired over clean barrel) yielded a 3/8" group measured center to center. Very hard to focus sights at a tiny point this close so I feel like my personal aiming ability was low with this. The great thing is that it was only 1" low and right on target as far as windage. Rifle sights were previously hitting 8 or 9" high at 100 yd with jacketed factory rounds (as expected with this rifle) so this was a pleasant surprise. Easy to raise the sight ramp higher to go up but didn't know if I would have that option, sights are at the 300m lowest setting right now so if this hit too high it would have been bad news. The fouling shot center was only 3/8" away from the closest edge of that group (I logged and checked the location of each shot one at a time) so it would be a 3/4" group if you included that.

Repeating the above at 25 yards I got a second 3/4" group of 4 so I feel like the load is holding ok for the sort of distances where you need a quiet backyard load. Sights/target were easier to focus on at this distance so I will repeat future loads at this distance or 50 yards.

A friend was there shooting with me and we agreed that the sound level is right about what a remington "cb22" or what people call "cb caps" sounds like out of a single shot rifle. If you ever have shot the aguila "colibris" from a single shot rifle (quieter than a pellet gun) this is not that quiet, but it is way quieter than a remington subsonic.

I now have the full 20 cases empty again so my plan for subsequent tests is to work out 1/2 grain at a time with 10 shots each higher/lower until I see accuracy fall outside of my limits (see original post) on each end. With that bracketed zone established, I'll start doing more detailed tests of each load to confirm and refine findings.

Seeing that this is already working satisfactorily on the first test and thinking about the possibilities more I have refined my goals to the following:
Primary: Quietest possible load of any velocity that holds a 1" group from 5-15 yards (squirrel and rodent round)
Secondary: Quietest subsonic load that holds a 3" group at 75 yards and remains lethal to a coyote at that distance.
Tertiary: Quietest subsonic load of any velocity that holds the best "point blank" impact pattern (with any sight setting on the rifle) from 10-50 yards.

I'll test to achieve my primary objective before moving on the the secondary, for example.

This is very fun and you get to shoot a classic rifle like this for 7 cents a shot with no recoil and (hopefully) almost indefinite brass life.

In response to the posts above:

Blammer: the 266469 is a 140 grain bullet, I actually haven't weighed my personal castings from it though so I can't say more than that (need to do that though).

Scifijim: I also wondered if a primer would be enough to send the bullet out. I probably would have tried it but my 5 round load session happened to end at 190 fps and I still have this slight worry in my head that sticking a bullet in the barrel would cause some unknown minor damage and didn't want to mess with it as a result. The 190 fps load was so quiet I doubt I would ever want to be below that for practical purposes so I'll probably leave that as my bottom baseline load.

Tim: I was surprised by that too, really couldn't believe that little an amount of powder got a 140gr bullet out of the barrel. It is a very smooth/shiny barrel so perhaps that helps. How far did your loads penetrate into the framing lumber?

[leadman]

One thing to watch for using very light loads is the case shoulder being pushed back by the firing pin blow. Does not happen to all cases, must depend on the strength of the brass case.
You got some great results from your trials and also interesting.

[RU shooter]

The 30 cal bullets were a lee rn design and went through one piece and half through another the 32 cal went thought one and just the nose stuck into the next one it was the rcbs 170 fn .

[Andy]

Leadman thanks for the tip, I'm not resizing the shoulders on these at all (just a tiny partial neck sizing), does the primer/shoulder thing still happen with a fireformed case that fits very tight like this?

I did another range test today, all groups were 5 shots, fired at 25 yards, off bags on paper over a chrono, here are the results:

2.0gr Bullseye:1.75" group, 2.75" below point of aim with sights set to 500m, avg velocity 415 fps, 47 ES
2.5gr Bullseye:1.25" group, .25" above point of aim with sights set to 500m, avg 520 fps, 66 ES
3.0gr Bullseye:.8" group, .25" below point of aim with sights set to 400m, avg 638 fps, 16 ES
3.5gr Bullseye:.5" group, hit dead on with sights set to 400m, avg 730 fps, 10 ES

So, it really tightened up in group and consistency from 2.0 to 3.5, at this point I'll make 2.0gr my low baseline and work up from 3.5gr until the groups widen or I get close to sonic.

Had a great time shooting it, nice sunny and warm day, fun to get to work the bolt a lot. I feel like I could load up the 3.5gr load and have a functional squirrel load right now so I feel as thought I have been quickly rewarded with something useful for my efforts thus far.

At some point if I have some soft lead (not coww+2% tin which is my usual) I'll make up a batch of really soft bullets as I imagine that would help accuracy on the lower end of things.

[jonp]

andy, this is some kind of interesting stuff. Thanks for posting.

[Blammer]

what are you sizing them to?

[leadman]

Andy, yes, it can happen to fireformed brass. The extractor will keep it back to the bolt face so it will fire even if it is short. A short case fired with a full load can split and dump gas in the action. Considered excessive headspace. Some folks drill out the primer flash hole to help prevent the shortening of the case but I just keep the low pressure cases separated from full pressure cases.

If you start seeing a line around the case just up from the base this is a sign that the case is being shortened and stretched. Should be able to feel a groove inside the case with a straightened and sharpened paper clip.
Just something to watch for so you can enjoy your shooting safely.

[Andy]

leadman, I appreciate you taking the time to explain that to me, I never thought about the extractor possibly holding the cartridge back from shoulder/chamber full contact, that makes good sense. I have segregated these by headstamp (that's why I'm only doing 20 at a time) and your info reinforces maintaining that policy (or being very careful if I deviate from it).

Blammer I'm sizing to .266, bore slugged at .264


Had a slight delay in the process as I ran out of cast bullets, but fixed that today by casting about 200 more of these (single cavity and might soften the alloy later or I would have done more). Had a great day and got the hot plate temp right on and only had 3 rejects and about 6 "plinker" grade bullets out 200 mold openings. Will lube tomorrow and continue testing.

My reading says that air cooled coww+2% tin is close to max hardness after 48 hours of age hardening, anyone have conflicting info?

[Blammer]

you really need to try some fly wt bullets in this testing of yours.

[RU shooter]

you really need to try some fly wt bullets in this testing of yours.

I'd like to see this too . Vel would go up some but wondering if the sound levels would stay the same if same powder charge was used ?

[Andy]

I am a new guy and don't know what "fly wt bullet" means, please elaborate, do you just mean lighter bullets?

If anyone wants to send me some lighter weight bullets I would be happy to test them out. Someone mentioned a 60 gr 6.5 bullet and I would actually try a primer-only load if I had something like that on hand. PM if you want to send me some of any weight/style and I'll give my address, happy to test out anything you guys are interested in. If you keep parcel under 1lb you can ship 1st class for $2-4 so not too expensive for this weight class.

[Blammer]

if you buy GC's from me I'll toss in a hand full of the "fly wt" bullets I have. yes 56gr bullet fully dressed.

here is a picture of them before I put GC's on them.

[Andy]

Blammer I would love to get some 6.5 gcs but need to replenish my reloading fund first, it will probably be a few months but I may take you up on that offer come summertime.

Did another range session today, here are the results, all are 5 shot groups at 25 yards, it was very cold and windy so my shooting probably wasn't up to par with the previous session. Center mass of all the groups was roughly .5" low with sights at 300m.

4.0 Bullseye, .9" group, avg 787 fps
4.5: .8" group, avg 875 fps
5.0: 1.1" group, avg 930 fps (started feeling like it was too loud for what I want here)
5.5: 1.75" group, avg 1030 fps

This completes my intial 5 shot test of all powder weights from 2.0-5.5 in 1/2 grain increments. Best accuracy was in the 3.0-4.5 gr range so that is the bracket that I will do 20 round tests for.

For the next test I have already loaded up 20 rounds of 3.0, one of the lee dippers hit this charge right on the nose every time so I just charged with that without weighing (after testing 5 in a row that weighed perfect) so we'll see how that does.

Had to seat the bullets a little deeper as I had one stay in the chamber when I ejected a loaded round today. I had previously tested my seating depth to make sure this wouldn't happen but it must have been right on the edge, so I seated to cover one more lube groove. Am now getting a tiny shaving of lead when I seat bullets so probably need to order the M die for this caliber, but will continue testing without as funds are short and it doesn't seem too bad.

Wanted to mention those things since starting with the next test some variables have changed. While that isn't ideal, this is at least the right time to change them as the test is entering a new complete phase.

[leadman]

A punch or even a wooden dowel that is shaped can expand the neck enough to prevent lead shaving. Needle nose pliers have been used also.

[Wolfer]

Paco Kelly says if you want quiet it takes a heavy boolit and a long barrel.
Ive only played with this a little. 8mm and the Lee 170 gr. I went as low as 2 gr of clays and never stuck a boolit. I could hear the firing pin fall over the sound of the shot. The boolit whapping the target was about as loud as the shot.
While this is super fun I live out in the country with no neighbors and can shoot in the yard. Other than just to play with I don't have a purpose for these rds. I tend to go toward the 5 gr load.

Your experiment and your writing about it is very well done. Keep up the good work.